Clinicians › Spine

Lumbar fusion

156 citationsUpdated Oct 2026

For patients: a plain-language version of this topic is available. See the patient guide.

Overview

Lumbar fusion is indicated for patients with persistent, disabling pain that remains unrelieved by non-surgical treatment [14]. Patient selection is critical, as evidence supporting spinal fusion or disc replacement for non-specific low back pain is poor; consequently, fusion should only be performed within randomised controlled trials, and lumbar disc replacement is not recommended [7]. For degenerative lumbar spondylolisthesis, individual patient factors must guide the specific surgical strategy [30]. Preoperative hemoglobin levels can assist surgeons in counseling patients regarding their specific postoperative risk profile for major complications and surgical site infections after single-level lumbar fusion [4].

Posterior decompression with instrumented fusion is the most common surgical treatment for degenerative lumbar spondylolisthesis [30]. Minimally invasive posterior lumbar fusion has demonstrated satisfactory one-year postoperative radiological results and functional outcomes [3]. Lateral lumbar interbody fusion at the L4-L5 level carries a low rate of persistent neurological, psoas-related, and abdominal complications in appropriately selected patients using standardized techniques [69]. Posterior lateral lumbar fusion that preserves partial facet joint unilaterally during neural decompression offers greater benefits to patients with degenerative lumbar spinal stenosis presenting bilateral lower limb symptoms, provided strict adherence to surgical indications [70]. Oblique lumbar interbody fusion and transforaminal lumbar interbody fusion exhibit comparable fusion rates, complication rates, and lumbar pain improvements [8]. Noninstrumented posterolateral lumbar fusions and instrumented posterolateral approaches show no differences in 90-day aggregated postoperative adverse events and 5-year lumbar revision surgery rates for lumbar degenerative spondylolisthesis [6]. Isobar hybrid dynamic stabilization with posterolateral fusion presents general clinical efficacy equivalent to titanium rod fusion surgery for individuals with mild and moderate lumbar degenerative disease [61]. Lumbar spine fusion and pedicle fixation with C-D screws for lumbar iatrogenic instability showed early results of symptom relief, solid fusion, and maintenance of the lumbar curve with no major complications [10]. Clinical outcomes and pain reduction after lumbar spinal fusion with a PEEK-based dynamic instrumentation device demonstrated significant improvements with topping off at 2 years after surgery [23]. New hybrid "topping off" systems might improve the outcome of lumbar spine fusion, but there is no convincing published data on their effectiveness or safety to date [73].

One- and two-level lumbar fusion procedures demonstrated high durability with an overall revision surgery rate of 15% [5]. Instrumented fusion demonstrated superior long-term durability compared to non-instrumented procedures for recurrent lumbar disc herniation, as shown by significantly lower reoperation rates over extended follow-up [27]. In a study of workers' compensation subjects, the reoperation rate was 27% for surgical patients, and 36% of lumbar fusion subjects had complications [20]. Laminoplasty shows lower complication rates than fusion, and arthroplasty shows reduced revision rates for adjacent segment disease [45]. Approximately one-third of adverse events after posterior lumbar fusion were diagnosed 31 to 90 days after surgery, highlighting the importance of looking past the 30-day mark for adverse event characterization [1]. Patients with lumbar fusion are at increased risk for post-operative dislocations requiring revision after total hip arthroplasty [13]. A meta-analysis summarized evidence regarding demographic, surgical, and radiographic risk factors for symptomatic adjacent segment disease following lumbar fusion [11].

Anatomy & Pathophysiology

Lumbar Spine Anatomy

The lumbar vertebral bodies are large, with a transverse diameter exceeding the anterior-posterior diameter [100]. Pedicles arise from the superior aspect of the vertebral bodies and project more horizontally than thoracic pedicles [100]. While L1 pedicles are minimally medially angled, orientation becomes increasingly medial down the lumbar spine, particularly at L5 [100]. Transverse processes project more perpendicular to the vertebral body; in the upper lumbar spine, they are large and flat, whereas L4 and L5 transverse processes are often smaller [100]. Spinous processes are thick and project straight dorsally [100].

The superior articular facet arises at the junction of the pedicle and lamina, with the articular surface facing dorsomedially [100]. The inferior facet extends down from the lamina and nestles snugly on the medial side of the superior facet [100]. This sagittal orientation allows flexion and extension while providing resistance to axial rotation and translation [100]. In the thoracic and lumbar spine, the named nerve root exits below the named pedicle [97]. Intervertebral discs are formally named for the vertebral bodies between which they lie [97]. Lateral recess pathology, such as lateral recess stenosis or posterolateral disc herniation, typically involves the next nerve root exiting caudal to that disc [97]. Consequently, an L4-5 posterolateral disc herniation is expected to cause L5 nerve root symptoms [97].

The dorsal root ganglion lies within the outer confines of the intervertebral foramen [97]. The sinuvertebral nerve, a small filamentous branch of the ventral ramus, progresses medially over the posterior aspect of the disc and vertebral bodies, innervating these structures and the posterior longitudinal ligament [97]. The dorsal ramus courses dorsally, piercing the intertransverse ligament near the pars interarticularis [97]. The medial branch of the dorsal ramus separates into three branches to innervate the facet joint at that level and the adjacent levels above and below [97]. Disc innervation occurs through afferent axons with cell bodies within the dorsal root ganglion [97].

Animal studies reveal two paths between the annulus and the dorsal root ganglion: one from the sinuvertebral nerve and another along the paravertebral sympathetic trunk [97]. In animal models, the lateral annulus was innervated by fibers coursing from the index level and two additional superior levels through the sinuvertebral nerves [97]. The lateral annulus also received innervation through the sympathetic trunk by the dorsal root ganglion from three levels even more superior than the sinuvertebral innervations [97]. Contralateral dorsal root ganglion involvement occurs through both the sinuvertebral and sympathetic pathways [97]. Similar nonsegmental, multilevel innervation patterns have been reported for the ventral disc surface [97]. Innervations of the disc from the vertebral endplate have been shown [97]. Endplate innervation is through the sinuvertebral nerve and the basivertebral nerve [97]. The basivertebral nerve enters the foramen, and its nerve fibers enter the vertebral margin with the vessels [97]. The density of endplate innervation is similar to that seen in the outer annulus [97].

The organization of neural elements is strictly maintained throughout the entire neural system, including within the conus medullaris and cauda equina [97]. The most cephalad nerve roots lie lateral and the most caudad lie medial within the dural sac and at the conus medullaris [97]. Motor roots are ventral to the sensory roots at all levels [97]. The arachnoid mater holds the nerve roots in their specific positions [97].

A study of 2905 pedicle measurements from T1 to L5 found that pedicles were widest at L5 and narrowest at T5 in the horizontal plane [99]. The widest pedicles in the sagittal plane were at T11, and the narrowest were at T1 [99]. The largest pedicle angle in the horizontal plane was at L5 [99]. In the sagittal plane, lumbar pedicles angle caudal at L5 and cephalad at L3-T1 [99]. The depth to the anterior cortex was significantly longer along the pedicle axis than along a line parallel to the midline of the vertebral body at all levels except T12 and L1 [99]. The thoracic pedicle is a convoluted, three-dimensional structure filled mostly with cancellous bone (62% to 79%) [99]. The cortical shell of the thoracic pedicle is of variable density, with the lateral wall significantly thinner than the medial wall [99].

Intervertebral Disc Structure

The human spine possesses 23 intervertebral disks that separate the vertebrae and provide flexibility [103]. Intervertebral disks account for about 20% to 30% of the length of the spine [103]. Disks increase in size from the cervical to the lumbar regions [103]. The disk contains a central gelatinous nucleus pulposus surrounded by a fibrous ring, the annulus fibrosus [103]. Each vertebral body has cartilage end plates, which are a thin layer of hyaline cartilage tissue separating adjacent vertebrae [103].

The nucleus pulposus consists mainly of a high concentration of proteoglycans and water surrounded by a loose type II collagen network [103]. In the nucleus pulposus, collagen fibrils assume a random orientation and are interspersed in a matrix rich in proteoglycans and water [103]. The annulus fibrosus has a low proteoglycan and water content and a high concentration of type I collagens as well as a small concentration of type II collagens [103]. The annulus fibrosus is described as possessing 20 to 25 lamellae rich in collagen fibrils arranged in a parallel fashion [103]. In each adjacent lamella of the annulus fibrosus, collagen fibrils along the axis are fashioned in the opposite direction to create an alternating pattern between the lamellae [103]. The content of water and proteoglycan concentration within the disk increases when progressing from the annulus fibrosus to the nucleus pulposus [103]. The content of collagen within the disk decreases from the outer annulus to the nucleus [103].

With increasing age, the proteoglycan and water content of the nucleus decrease [103]. The collagen content of the nucleus is highest in cervical disks and lowest in lumbar disks [103]. The proteoglycan content of the disk shows an opposite trend to collagen content when evaluating spinal levels [103]. The endplates are 1-mm thick concave-shaped structures with two distinct layers: the cartilage endplate consisting of hyaline cartilage and the bony endplate consisting of semi-porous cancellous bone [242]. Until skeletal maturity, endplates have penetrating microscopic blood vessels from the vertebrae adjacent to the bony endplate that provide vascular supply to the disc during spinal growth [242]. The endplate functions as a physical barrier protecting the vertebrae from disc herniation cranially and caudally [242].

Spinal Stenosis Anatomy

The central spinal canal is defined as the space posterior to the posterior longitudinal ligament, anterior to the ligamentum flavum and laminae, and bordered laterally by the medial border of the superior articular process [49]. The lateral recess is defined by the superior articular facet posteriorly, the thecal sac medially, the pedicle laterally, and the posterolateral vertebral body anteriorly [49]. The intervertebral foramen is bordered superiorly and inferiorly by the adjacent level pedicles, posteriorly by the facet joint and lateral extensions of the ligamentum flavum, and anteriorly by the adjacent vertebral bodies and disk [49]. Normal foraminal height is 20 to 30 mm [49]. Normal superior foraminal width is 8 to 10 mm [49].

Central spinal stenosis denotes involvement of the area between the facet joints, which is occupied by the dura and its contents [96]. Stenosis in the central region is usually caused by protrusion of a disc, bulging anulus, osteophyte formation, or buckled or thickened ligamentum flavum [96]. Symptomatic central spinal stenosis results in neurogenic claudication with generalized leg pain [96]. The lateral canal contains the nerve roots, and compression in this region results in radiculopathy [96]. The lateral recess, also known as "Lee's entrance zone," begins at the medial border of the superior articular process and extends to the medial border of the pedicle [96]. The borders of the lateral recess are the pedicle laterally, the superior articular facet dorsally, the posterior ligamentous complex to disc and floor of the canal, and the central canal medially [96]. Facet arthritis most frequently causes stenosis in the lateral recess zone, along with vertebral body spurring and disc or anulus pathology [96].

"Lee's midzone" describes the foraminal region, which lies ventral to the pars [96]. The borders of the foraminal region are the lateral recess medially, the posterior vertebral body and disc ventrally, the pars and intertransverse ligament dorsally, and the lateral border of the pedicle laterally [96]. The foramen is essentially the area between the cephalad and caudal pedicles [96]. The dorsal root ganglion and ventral motor root occupy 30% of the foraminal space [96]. The foramen is the point where the dura becomes confluent with the nerve root as epineurium [96]. Causes of stenosis in the foraminal area include pars fracture with proliferative fibrocartilage or a lateral disc herniation [96]. Thickening of the ligamentum flavum sometimes extends into the foramen and can be associated with a spur from the undersurface of the pars, especially if foraminal height is less than 15 mm and posterior intervertebral disc height is less than 4 mm [96].

The exit zone is identified as the area lateral to the facet joint [96]. The nerve root in the exit zone can be compressed by a "far lateral" disc, spondylolisthesis and associated subluxation, or facet arthritis [96]. Degeneration of the disc occurs with disc narrowing and subsequent ligamentous redundancy, which compromises the spinal canal area [96]. Instability may ensue from disc degeneration and ligamentous redundancy [96]. Relative hypermobility precipitates the formation of facet overgrowth and ligamentous hypertrophy [96]. The ligamentum flavum may be markedly thickened into the lateral recess where it attaches to the facet capsule, causing nerve root compression [96]. The most common type of spinal stenosis is caused by degenerative arthritis of the spine, including Forestier disease, characterized by hyperostosis and spinal rigidity in elderly patients [96]. Acquired forms of spinal stenosis are usually degenerative and most commonly localized to the facet joints and ligamentum flavum [96]. The L4-5 level is the most commonly involved in degenerative spinal stenosis, followed by L5-S1 and L3-4 [96]. Congenital spinal stenosis usually is central and evident on imaging studies [96]. Idiopathic congenital narrowing usually involves the anteroposterior dimension of the canal due to short pedicles, with the posterior otherwise normal [96]. In achondroplasia, the canal is narrowed in the anteroposterior plane owing to shortened pedicles and in lateral diameter because of diminished interpedicular distance [96].

Pathophysiology of Degeneration and Stenosis

Lumbar spinal stenosis is the final stage of a cascade of events [49]. The event that begins the process that eventually results in lumbar spinal stenosis is thought to be disk degeneration [49]. As disk height decreases, the loading characteristics of the facets are altered [49]. Facet joint capsules become incompetent, leading to capsular, ligamentum flavum, and facet hypertrophy [49]. The ligamentum flavum also becomes less pliable with age [49]. The final stage of the degenerative continuum is a decrease in the diameter of the spinal canal [49]. When the spine is in extension, the spinal canal diameter diminishes resulting in buckling of the shortened, hypertrophied ligamentum flavum [49]. In flexion, a relative increase in the spinal canal diameter is present [49]. Most authors support a multifactorial etiology of low back pain and leg pain associated with lumbar spinal stenosis [49]. Mechanical compression, nutritive insufficiency, heredity, structural decompression, individual pain perception, and chemical insult all likely play a role in lumbar spinal stenosis symptoms [49].

Lumbar spondylosis is due to a degenerative cascade that has an association with intervertebral disk degeneration [98]. Mechanical progression and associated disk space narrowing leads to adjacent level pedicle approximation with narrowing of the superior-inferior dimensions of the intervertebral foraminal canal [98]. Laxity of associated ligaments and vertebral column translates into altered loading mechanics and an altered pressure relationship on the vertebral bone and joint surfaces [98]. Altered loading mechanics and pressure relationships are believed to influence both osteophyte formation and facet joint hypertrophy [98]. Intervertebral disk degeneration is a complicated multifactorial process characterized by altered biomechanics of loading, an imbalance of extracellular matrix synthesis and degradation, increased secretion of proinflammatory cytokines, and increased apoptosis and senescence in the nucleus pulposus cells [98]. Altered biomechanics lead to further degenerative changes and osteophyte formation [98]. Degenerative changes have the potential to cause lumbar central and foraminal stenosis leading to symptomatic nerve compression and radiculopathy [98].

The degenerative process has been divided into three separate stages with relatively distinct findings [158]. The first stage of spinal degeneration is dysfunction, seen in individuals 15 to 45 years old, characterized by circumferential and radial tears in the disc annulus and localized synovitis of the facet joints [158]. The second stage of spinal degeneration is instability, found in 35- to 70-year-old individuals, characterized by internal disruption of the disc, progressive disc resorption, and degeneration of the facet joints with capsular laxity, subluxation, and joint erosion [158]. The final stage of spinal degeneration is stabilization, present in individuals older than 60 years, characterized by progressive development of hypertrophic bone around the disc and facet joints leading to segmental stiffening or frank ankylosis [158]. Each spinal segment degenerates at a different rate [158]. Disc herniation is considered a complication of disc degeneration in the dysfunction and instability stages [158]. Spinal stenosis from degenerative arthritis is a complication of bony overgrowth compromising neural tissue in the late instability and early stabilization stages [158]. The natural history of degenerative disc disease is one of recurrent episodes of pain followed by periods of significant or complete relief [158].

Endplate changes such as fissuring and tears cause depletion of proteoglycan molecules in the cartilage endplate and microfractures and sclerosis in the bony endplate [242]. Degenerative bony endplate changes have been associated with reduced nutrient supply to the disc, a decline in proteoglycans and water content within the annulus fibrosus and nucleus pulposus, structural changes in the disc, and subsequent disc degeneration [242]. Endplate microfracture is considered an important biomechanical factor for the occurrence of Modic changes [18]. Inflammatory factors and metabolites after disc damage may directly permeate into the endplates and vertebral body through microfracture gaps in the endplates [18].

Pathophysiology of Spondylolisthesis

The presence of an isthmic spondylolisthesis is not sufficient to identify the cause of the patient’s symptoms because 7% of the population has spondylolysis, with or without spondylolisthesis, and most are asymptomatic [157]. About 80% of acquired lytic defects occur between the ages of 5 and 10 years, with the remaining 20% of fractures occurring before the age of 20 years [157]. Mechanical back pain in isthmic spondylolisthesis can originate from the pars defect but also from the disc [157]. The disc in isthmic spondylolisthesis is often more degenerative than expected for the patient’s age because of abnormal stresses applied due to lack of stability [157]. As the disc degenerates and loses height in isthmic spondylolisthesis, the

Classification

Spinal Deformity Study Group: This classification of lumbosacral spondylolisthesis lacks robust clinical outcome studies to support its recommendations [207]. Observers demonstrated disagreement, particularly when classifying low-grade spondylolisthesis using this system [207].

Meyerding: The Meyerding classification divides spondylolisthesis slip into five grades based on percentage of slip: Grade I (0 to 25%), Grade II (25 to 50%), Grade III (50 to 75%), Grade IV (75 to 100%), and Grade V (greater than 100%) [245].

French: The French classification of lumbar degenerative spondylolisthesis demonstrated intraobserver reliability K values ranging from 0.721 to 0.835 across four graders [229].

CARDS: The CARDS classification of lumbar degenerative spondylolisthesis demonstrated intraobserver reliability K values ranging from 0.762 to 0.835 across four graders [229]. Patients of different CARDS types had comparable demographics regarding gender, age, and BMI [229]. Preoperative VAS (back) scores for CARDS Type D were higher than for other types [229].

Kulowski: Kulowski’s classification evaluates the degree of end-plate destruction in infectious spondylitis. Grade I is defined as only disk space narrowing, Grade II as bony destruction limited only in the end-plate, Grade III as vertebral body destruction of less than 50% of vertebral height, and Grade IV as vertebral body destruction over 50% of vertebral height [80].

Modified Clavien–Dindo: The modified Clavien–Dindo classification scheme contains five types of complications: Type I (normal recovery without any treatment), Type II (pharmacologic treatment needed), Type III (invasive intervention under general anesthesia needed), Type IV (intensive care unit admission needed), and Type V (death) [212].

Bridwell: The Bridwell grading criteria for radiographic fusion assessment considers grades I and II as signs of successful fusion, while grades III and IV indicate the opposite [212].

Lenke et al.: The Lenke et al. grading scale for posterolateral fusion assessment defines Grade A as "definitely solid [with] big trabeculated bilateral fusion masses," Grade B as "possibly solid [with] unilateral large fusion mass [and] a contralateral small fusion mass," Grade C as "probably not solid [with] small, thin fusion masses bilaterally [and probable unilateral pseudarthrosis]," and Grade D as "definitely not solid [with] graft resorption bilaterally or fusion mass with obvious bilateral pseudarthrosis" [241]. In this scale, Grades A and B are considered fused, while Grades C and D are considered not fused [241].

AO Spine: The AO Spine classification for thoracolumbar fractures includes subtypes B1, B2, and B3 [234].

Other Considerations: A new classification system that incorporates spinopelvic balance in the radiographic assessment may aid orthopaedic surgeons in identifying patients who would benefit from partial reduction and fusion [166]. A separate study proposes a practical classification system with preliminary feasibility in surgical approach selection for cage retropulsion [232].

Clinical Presentation

General Principles and Indications

Surgical intervention for discogenic back pain remains controversial and should be avoided whenever possible, with conservative measures exhausted before any consideration of surgery [40]. Currently, no good surgical option reliably reduces symptoms of discogenic back pain [40]. Operative treatment provides benefit only when it corrects a deformity, corrects instability, relieves neural compression, or treats a combination of these problems [165]. The natural history of degenerative disc disease involves recurrent episodes of pain followed by periods of symptomatic or complete relief [165]. More than half of patients seeking treatment for low back pain recover in 1 week, and 90% recover within 1 to 3 months [40]. Greater use of fusion-based procedures for lumbar spinal disorders is found in the private sector, irrespective of the clinical condition [19].

History and Physical Examination

The approach to the active patient with low back pain begins with a thorough history and physical examination to establish a timeline and identify the nature, duration, onset, and characterization of symptoms [178]. Red flag signs indicating potential underlying pathology warranting a timely workup include fevers, chills, weight loss, history of cancer, immunosuppression, and intravenous drug abuse [178]. Reports of clumsiness, gait instability, bowel, bladder, or sexual dysfunction should prompt assessment for causes of spinal cord dysfunction such as cervical or thoracic myelopathy [178].

Pain characterization helps distinguish etiologies. Diskogenic pain related to disk degeneration or herniation may be worse in flexion, while sitting, or with prolonged axial loading and is often described in a diffuse, bandlike distribution [178]. Facet-mediated pain related to facet arthrosis or spondylolysis may be worse in extension and is often activity related and well localized [178]. Physical findings for discogenic back pain include a paucity of physical findings, back pain greater than leg pain, and no radiculopathy or absence of tension signs [40].

Inspection and palpation should begin by observing the patient walk to assess coordination, strength, and symmetry of motion [178]. Palpation of the back should assess for points of maximal tenderness such as the facets, paraspinal musculature, or sacroiliac joints [178]. Assessing the range of motion of the hips can help to rule out referred pain due to hip arthrosis [178].

Provocative tests for lumbar disk herniation include nerve root tension signs such as a straight leg raise, contralateral straight leg raise, or femoral nerve stretch test [178]. For detecting lumbar disk herniation, the straight leg raise is more sensitive but less specific than the contralateral straight leg raise in patients with single leg radicular pain [178].

Nonorganic signs are categorized into five groups: tenderness, simulation, distraction, regional disturbances, and overreaction [178]. The presence of three or more Waddell signs should prompt evaluation for other etiologies such as depression, hypochondriasis, or secondary gain issues [178]. Presence of three or more Waddell signs is associated with higher pain scores and poorer treatment outcomes overall [178].

Other pathologies that can mimic or overlap the signs and symptoms of degenerative spondylolisthesis include vascular claudication, degenerative hip arthritis, and peripheral neuropathy [177]. If history and physical examination findings are inconsistent with degenerative spondylolisthesis, evaluation for vascular claudication, degenerative hip arthritis, and peripheral neuropathy should be considered [177]. At a minimum, hip range of motion and irritability should be evaluated as well as peripheral pulses in the feet and proprioception when evaluating for mimicking pathologies [177].

Diagnostic Imaging

Radiographs are negative for instability but may show disc space narrowing or other stigmata of spondylosis in discogenic back pain [40]. Standing lateral and posteroanterior scoliosis radiographs should be obtained to adequately assess the patient's global balance and pelvic parameters [34]. These images should include the skull and both proximal femoral heads so the hip axis can be determined [34]. Standing lateral, seated or standing flexion/extension laterals, and anteroposterior radiographs are imperative because 15% of deformities spontaneously reduce on supine imaging such as an MRI [177]. Instability is considered to be present when 4 mm of translation or 10 degrees of sagittal rotation greater than the adjacent level is identified [177]. Upright flexion-extension lateral views may reveal translational motion, indicating a more unstable motion segment [177]. The Ferguson anteroposterior view shows any significant degenerative changes in the lumbosacral joint and allows a better view of the transverse processes of L5 [177]. Hypoplastic transverse processes should prompt consideration for interbody fusion because of the paucity of bony substrate for fusion, especially for lumbosacral fusions [177].

MRI typically reveals decreased signal intensity in the disc space on T2-weighted imaging (dark disc), with or without annular tear or HIZ, in discogenic back pain [40]. If the patient has significant radicular symptoms, an MRI is usually obtained to determine the specific location and etiology of the nerve root symptoms [34]. The health of the adjacent disc levels can be assessed on MRI, which will influence how many levels may need to be fused and the method of fusion [34]. MRI is generally satisfactory for advanced neuroimaging, but a significant subset of patients cannot have an MRI because of the presence of a pacemaker or cardiac stents [177]. In patients who cannot have an MRI, lumbar myelography and post-myelogram high-resolution CT scans are quite satisfactory and often demonstrate the bony pathology better than MRI [177]. Post-myelogram CT scans do not show pathology as well in the mid and lateral foramen because the subarachnoid space is not present out to the dorsal root ganglion [177]. Intraforaminal stenosis is relatively common, affecting the L4 nerve root, which is compressed against the inferior aspect of the L4 pedicle by annulus from a pseudohermiation due to the spondylolisthesis [177]. The most severe stenosis usually is located at the level of the spondylolisthesis, but the entire course of each symptomatic nerve root must be thoroughly assessed [177]. Usually the L5 root is compressed in the L4-L5 lateral recess, but there may be other pathology, such as a synovial cyst or disc herniation, affecting the same root or a different root level [177]. The presence of a facet joint effusion more than 2 mm in width is highly suggestive of instability at that level and should prompt close inspection of the upright dynamic radiographs [177]. Snoddy et al. found a 42% probability of dynamic instability for each 1 mm of facet joint effusion [177].

CT and Discography provide additional anatomic and functional data. A high-resolution CT scan is obtained to evaluate pedicle morphology, adequacy of the L5 transverse process, sacral morphology, facet arthritis at adjacent levels, and bony foraminal dimensions when more thorough anatomic evaluation is needed [34]. Discography is a controversial study designed as a preoperative study to correlate MRI findings with a clinically significant pain generator [40]. For a discography result to be considered reliably positive, the procedure should elicit pain after injection similar to that usually described by the patient (concordant pain) [40]. The discography study should involve at least one minimally painful, nonconcordant level [40]. The discography study should be performed at multiple levels to include all abnormal levels and one or more normal levels as identified on MRI [40]. Evidence suggests that annular tears created by the needle during discography may accelerate the rate of symptomatic disc degeneration, resulting in discography falling out of favor [40]. Bone SPECT/CT was useful to identify the specific cause of pain in elderly patients with lumbar degenerative disease and to provide appropriate treatment, avoiding the unnecessary use of invasive spinal fusion surgery [64]. Abnormal magnetic-resonance scans of the lumbar spine are found in asymptomatic subjects [52]. The diagnostic accuracy of magnetic resonance imaging, work perception, and psychosocial factors in identifying symptomatic disc herniations has been evaluated [52]. Provocation discography has been used as a guide to planning operations on the spine [52]. The value of the joint block in patient selection for lumbar fusion has been evaluated [52]. Nonorganic physical signs in low-back pain have been described [52].

Specific Conditions and Natural History

The natural history of developmental spondylolisthesis is different from that of acquired spondylolisthesis because of a lytic defect in an otherwise normal pars, and degenerative spondylolisthesis is different from both [67]. The association of spondylolysis and spondylolisthesis with clinically relevant low back pain is not clear [67]. A recent systematic review by Andrade et al. failed to establish a link between spondylolysis/spondylolisthesis and clinically relevant low back pain and suggested careful evaluation of the cause of low back pain in patients with isthmic spondylolisthesis [67]. With spondylolytic spondylolisthesis there appears to be a familial association, with approximately 26% of those with isthmic spondylolisthesis having a first-degree relative who also had an isthmic spondylolisthesis [67]. A long-term follow-up study (45 years) by Beutler et al. found the risk of progression to be very small, and no children with a unilateral lytic defect had a slip that progressed [67]. Clinically there was no difference between the general population and those with a grade I or II slip regarding the development of back pain [67]. Most children (approximately 90%) with a lytic defect have been found to have spina bifida occulta, suggesting a dysplastic etiology [67]. The incidence of lytic defects increases with age, from 4.4% at age 6 to 6.0% in adults [67]. Risk factors for progression of spondylolytic spondylolisthesis remain unclear [67]. Some authors have found that females, those with higher grade slips (>50%) at the time of diagnosis, and those diagnosed before adolescent growth have a greater probability of progression [67]. In a risk study by Eroglu et al., facet tropism was identified as a risk factor for isthmic spondylolisthesis in males [67]. Developmental spondylolisthesis with dysplasia is more likely to progress than the spondylolytic type [67]. Dysplasia of the anterior sacrum correlates best with progression in the dysplastic group [67].

Long-term follow-up of Meyerding types III and IV spondylolisthesis treated both operatively and nonoperatively found that most patients had done relatively well [67]. None of the patients with Meyerding types III and IV spondylolisthesis had severe neurologic sequelae, and only 45% had even mild neurologic symptoms [67]. At 18-year follow-up, 36% of patients with Meyerding types III and IV spondylolisthesis treated nonoperatively were asymptomatic [67]. Yue et al. studied 27 patients with spondyloptosis and found pars defects in 89% and also spina bifida occulta in 89% [67]. All of the patients with spondyloptosis had an abnormality of the proximal sacrum with rounding, suggesting that a physeal injury may have contributed to the deformity of the sacral endplate [67]. In patients with doming or rounding of the S1 endplate, the measurement of pelvic incidence is unreliable [67]. Sebaaly et al. showed that a similar measurement using the L5 superior endplate rather than the S1 endplate, which is termed L5 incidence, was more reliable [67]. Sebaaly et al. found that a value of 60 degrees was a threshold to define spinopelvic balance versus unbalance in high-grade developmental spondylolisthesis [67].

Measurement parameters include the slip angle and lumbosacral angle. The slip angle is a measure of the local kyphosis at the L5-S1 level [67]. The slip angle is defined as the angle formed between a line perpendicular to the posterior aspect of the upper sacrum and a line parallel to the L5 inferior endplate [67]. The slip angle has been found to have some predictive value for slip progression when it is larger than 30 degrees [67]. The lumbosacral angle is defined as the angle formed by the intersection of a line perpendicular to the upper sacrum and a line parallel to the upper endplate of the L5 vertebra [67]. The lumbosacral angle has been found to have some predictive value for progression when it is larger than 10 degrees [67].

Degenerative spondylolisthesis usually occurs at the L4-L5 level, primarily affects females over the age of 50, and is more frequent in people of African descent [67]. Slip progression has been found to occur in about 30% of patients with degenerative spondylolisthesis, but there usually is only mild progression [67]. If neurologic symptoms are present, operative treatment is superior to nonoperative treatment for degenerative spondylolisthesis [67]. Matsunaga et al. found that 76% of patients without neurologic symptoms remained stable over long-term follow-up (10 to 18 years) [67].

The degenerative process has been divided into three separate stages with relatively distinct findings: dysfunction, instability, and stabilization [165]. The first stage of spinal degeneration is dysfunction, seen in individuals 15 to 45 years old, characterized by circumferential and radial tears in the disc anulus and localized synovitis of the facet joints [165]. The next stage of spinal degeneration is instability, found in 35- to 70-year-old patients, characterized by internal disruption of the disc, progressive disc resorption, degeneration of the facet joints with capsular laxity, subluxation, and joint erosion [165]. The final stage of spinal degeneration is stabilization, present in patients older than 60 years, characterized by the progressive development of hypertrophic bone around the disc and facet joints leading to segmental stiffening or frank ankylosis [165]. Spinal stenosis from degenerative arthritis is considered a complication of bony overgrowth compromising neural tissue in the late instability and early stabilization stages [165].

The literature supports an active care approach, minimizing centrally acting medications [165]. The judicious use of epidural steroids is supported for short-term relief but does not have effect on long-term outcomes [165]. Nonprogressive neurologic deficits can be treated nonoperatively with expected improvement clinically [165]. If surgery is necessary, it usually can be delayed 6 to 12 weeks to allow adequate opportunity for improvement [165]. The important exceptions to delaying surgery are patients with cervical myelopathy or progressive neurologic deficits, who are best treated surgically [165]. It is doubtful if there is any other area of orthopaedics in which accurate diagnosis is as difficult or the proper treatment as challenging as in patients with persistent neck and arm or low back and leg pain [165]. More patients with pain have absent neurologic findings other than sensory changes and have normal imaging studies or studies that do not support the clinical complaints and findings [165]. Inability to easily determine an appropriate diagnosis in a patient does not relieve the physician of the obligation to recommend treatment or to direct the patient to a setting where such treatment is available [165]. Careful assessment of these patients to determine if they have problems that can be successfully treated (operatively or nonoperatively) is imperative to avoid overtreatment and undertreatment [165]. Matching the diagnosis and treatment to the results of diagnostic studies is risky because numerous studies have documented abnormal imaging in asymptomatic populations [165].

Low back pain is a common report of the young, active patient and most often will be a self-limiting episode without underlying etiology [188]. Careful attention to the history and a diligent physical examination can help diagnose those cases of underlying spinal pathology [188]. Nonsurgical treatment is often successful in cases of thoracic and lumbar disk herniation, spondylolysis, and spondylolisthesis [188]. Low back pain and thoracolumbar spine-related issues continue to increase in adolescent and young adults [188]. Careful attention should be paid to any inciting trauma, history, and related symptoms in adolescent

Investigations

Plain radiography: Standing lateral and posteroanterior scoliosis radiographs are obtained to assess global balance and pelvic parameters, including the skull and proximal femoral heads [34]. Flexed-seated radiographs obtained preoperatively in patients with prior total hip arthroplasty scheduled for lumbar fusion may help communicate potential risks of postoperative dislocation [266]. In patients with lumbar spinal stenosis who do not respond to nonsurgical treatment or deteriorate neurologically, plain radiographs are indicated to delineate the pattern and degree of stenosis [49].

MRI: MRI is the standard for advanced imaging of the spine and is superior to CT in most circumstances, particularly for identifying infections, tumors, and degenerative changes within discs [107]. It is superior for directly imaging neural structures and the nerve root in the foramen, which is difficult even with postmyelography CT [107]. MRI is usually obtained to determine the specific location and etiology of nerve root symptoms in patients with significant radicular symptoms [34]. MRI evidence of lumbar disc degeneration was found in 35% of patients aged 20 to 39 years and in 100% of patients older than 50 years [107]. Consequently, MRI findings must be carefully correlated with the clinical impression, as demonstrated abnormalities may be asymptomatic [107]. The most effective approach to obtaining meaningful clinical information from MRI is to pose a specific question derived from history and physical examination, focusing on neural compression, instability, or deformity [107]. Additional evaluation with MRI is typically not necessary for thoracic and lumbar spine injuries, although there are circumstances where it is appropriate [119]. In patients with lumbar spinal stenosis who do not respond to nonsurgical treatment or deteriorate neurologically, MRI is indicated to delineate the pattern and degree of stenosis [49]. The volume of multifidus muscles was markedly decreased after posterior lumbar fusion, as apparent in MRI [243].

CT: CT is the diagnostic imaging modality of choice for injuries involving the thoracic, lumbar, or sacral regions of the spine [119]. High-resolution CT scans are obtained to evaluate pedicle morphology, adequacy of the L5 transverse process, sacral morphology, facet arthritis at adjacent levels, and bony foraminal dimensions when more thorough anatomic evaluation is needed [34]. CT may help diagnose endplate sclerosis in patients with type 2 Modic change and inform the choice of the best site for spinal fusion [265]. In patients with lumbar spinal stenosis who do not respond to nonsurgical treatment or deteriorate neurologically, myelogram with CT is indicated to delineate the pattern and degree of stenosis [49].

Bone scan: Bone SPECT/CT is useful for identifying the specific cause of pain in elderly patients with lumbar degenerative disease, potentially avoiding unnecessary invasive spinal fusion surgery [64]. 18F-fluoride PET/CT bone metabolism of the operated intervertebral disc space at six weeks had the highest diagnostic accuracy for predicting fusion status at one year after posterior lumbar interbody fusion [254].

Laboratory: Preoperative hemoglobin levels are associated with the risk of major complications and surgical site infections after single-level lumbar fusion [4].

Other Considerations: EMG may be helpful to distinguish peripheral neuropathy from lumbar spinal stenosis [49]. Provocative discography has not been found to be reliable for evaluating adjacent levels in the context of isthmic spondylolisthesis [34]. Pars injection with a small volume of long-acting local anesthetic is a helpful diagnostic tool when evaluating patients with extensive degenerative changes at multiple levels in addition to isthmic spondylolisthesis [34]. Preoperative spinopelvic assessment is recommended for all patients undergoing total hip arthroplasty, as only a minority of those with limited lumbar flexion have an instrumented fusion [76].

Modic changes, particularly Type 2, are common radiological findings in lumbar spine imaging, most frequently occurring at L4/L5 and L5/S1 levels [256]. Approximately one-third of adverse events after posterior lumbar fusion were diagnosed 31 to 90 days after surgery [1]. Twenty-nine percent of patients developed radiologic adjacent segment degeneration two years after lumbar fusion for degenerative spondylolisthesis [261]. Higher magnitudes of cage subsidence following oblique lumbar interbody fusion were associated with worse clinical improvements and lower intervertebral fusion [78]. Pre-existing L5-S1 degeneration does not affect clinical and radiographical outcomes after isolated L4-5 fusion [36]. Prognostic factors influencing outcomes after lumbar fusion surgery include higher BMI, larger facet joint angle, and wider sagittal and coronal diameters [37]. Radiographic fusion status is associated with clinical outcomes in single-level instrumented lumbar arthrodesis [65]. Poor bone quality is associated with pseudarthrosis and poor clinical outcomes in single-level instrumented lumbar arthrodesis using local autologous bone graft [65]. Clinical relief does not necessarily depend on roentgenographic evidence of fusion [262]. No completely reliable method of spine fusion has been developed, with success rates varying widely and often overestimated by roentgenographic methods [12]. The evidence for spinal fusion in non-specific low back pain is poor, and spinal fusion should only be performed as part of a randomised controlled trial [7]. Greater use of fusion-based procedures for lumbar spinal disorders was found in the private sector, irrespective of the clinical condition [19].

Treatment

Non-Operative

Nonsurgical management remains the standard of care for lumbar degenerative disk disease and spondylolysis, with successful outcomes typically achieved without intervention [88]. For discogenic back pain, conservative measures must be exhausted before surgical intervention is considered [40]. Decompressive treatment is appropriate for patients with neurogenic claudication and/or pain that significantly affects quality of life [56].

Operative

Indications: Arthrodesis is the best surgical treatment for the persistently painful degenerative back, though it carries risks of non-union and increased morbidity [72]. Decompressive surgery is clearly indicated for lumbar spinal stenosis presenting with progressive neurologic deficit, cauda equina syndrome, or disabling lower-extremity weakness [56]. In patients with spinal stenosis and degenerative spondylolisthesis, decompression alone is noninferior to decompression with instrumented fusion for reducing impairment at 2 years [57], demonstrating non-inferiority for low back pain with additional benefits in operation time and blood loss [185]. Lumbar decompression remains the benchmark for lumbar spinal stenosis, with no benefit to routine fusion [42]. Operative treatment offers significant benefit over nonoperative treatment for lumbar stenosis and degenerative spondylolisthesis in patients at least eighty years of age [224]. For adult spinal deformity, patients must be counseled on high complication rates and the potential need for revision surgery [42].

Surgical Approach / Technique: Posterior decompression with instrumented fusion is the most common treatment for degenerative lumbar spondylolisthesis, though individual factors guide strategy selection [30]. Among adult patients with isthmic spondylolisthesis undergoing single-level fusion, 81.5% underwent posterior surgery and 7.9% combined anterior-posterior surgery [31]. The optimal technique remains controversial and should be based on the pathologic entity, biomechanics, healing potential, and surgeon experience [126]. Minimally invasive posterior transforaminal lumbar interbody fusion (TLIF) yields satisfactory one-year radiological and functional results [3]. Oblique lumbar interbody fusion (OLIF) and TLIF have comparable fusion rates, complication rates, and pain improvements [8]. Lateral lumbar interbody fusion at L4-L5 has a low rate of persistent neurological, psoas-related, and abdominal complications when standardized techniques are used [69]. Posterior lateral lumbar fusion preserving partial facet joint unilaterally offers greater benefits for degenerative stenosis with bilateral lower limb symptoms under strict indications [70]. Unilateral biportal endoscopic TLIF is an effective minimally invasive technique [104], and using a large cage in this approach is a straightforward, safe method for treating lumbar instability [111]. Anterior approaches are increasingly used due to proven efficacy and low morbidity, provided vascular risks are mastered [48]. Anterior lumbar interbody fusion (ALIF) is effective for revision surgery [21]. For high-grade spondylolisthesis with lumbosacral kyphosis in children and adolescents, non-instrumented circumferential arthrodesis after gradual correction remains relevant [86]. Circumferential fusion is recommended to regain stability in lumbosacral dislocation [77]. Transsacral fixation/fusion may allow safe lumbosacral fusion without iliac fixation in long-segment constructs for carefully selected patients [170]. Instrumented posterolateral approaches show no differences in 90-day adverse events or 5-year revision rates compared to noninstrumented approaches [6]. A combined approach using an interbody PEEK cage and posterior pedicle-screw fixation should be considered before lumbar fusion [2].

For in situ posterolateral instrumented fusion using the Wiltse and Spencer approach, the procedure involves a midline skin incision, fascial incisions 3 cm off midline, exposure of the L5 transverse process and sacral ala, facetectomy, pedicle screw preparation at L5 and S1, and bone graft placement [161]. S1 screw holes are prepared for a bicortical technique by penetrating the sacral cortex medially at the promontory just caudal to the endplate [161]. Removal of hypertrophic bone from the lateral aspect of the L5 superior articular mass may be needed to allow L5 screw placement and enlarge the area for bone graft incorporation [161]. Polyaxial pedicle screws are placed bilaterally at L5 and S1 after thorough decortication and bone graft placement under direct vision [161]. A separate autologous iliac graft is harvested or local autograft is combined with allograft cancellous bone soaked in antibiotic solution for at least 30 minutes [161]. Off-label use of BMP or demineralized bone matrix to augment local autograft is recommended by some; if BMP is used, irrigation should not be performed after placement [161]. Patients are mobilized without a brace the morning after surgery and can be discharged on the second or third postoperative day [161].

For minimally invasive direct lateral anterior lumbar fusion and extreme lateral interbody fusion, complications related to nerve root injury or irritation have been reported in 22% of patients [143]. Knowledge of “safe zones” and familiarity with dilating retractor systems are essential to avoid complications [143]. The overlap between adjacent neurovascular structures and the vertebral body endplate increases from L1-2 to L4-5, resulting in a very narrow safe zone at L4-5 [147]. The lumbar plexus is at the greatest risk of injury at the L4-5 level during this approach [147]. Direct lateral or far lateral approaches are useful for degenerative scoliosis, allowing complete disc resection, coronal deformity correction, and indirect decompression of foraminal stenosis [152]. Reported complications of combined transpsoas extreme lateral interbody fusion and posterior pedicle screw instrumentation include intraoperative bowel injury, motor radiculopathy, and postoperative thigh paresthesias or dysesthesias [152]. The rate of major complications after a far lateral approach was 12% in one study [152]. Mini-open OLIF is safe for accessing L2 down to L5, but another approach is advised for L5-S1 due to the danger of injuring iliac vessels [196]. The minimally invasive lateral trans-psoas approach offers advantages including less blood loss, decreased operative times, shorter hospital stays, and less postoperative pain [196]. Access to L5-S1 via this approach is extremely difficult due to the iliac crest and iliolumbar vein [196].

Posterior fixation can improve segmental alignment of lumbar degenerative spondylolisthesis with OLIF [214]. Self-anchored lateral lumbar interbody fusion provides immediate stability and good results for lumbar degenerative diseases without posterior internal fixation [218]. The surgical sequence for minimally invasive hybrid lumbar interbody fusion is ALIF followed by OLIF followed by percutaneous pedicle screw fixation [225]. In this hybrid approach, ALIF is performed first to open the L5-S1 gap, especially in patients with high iliac, to facilitate L4–5 segment surgery [225]. For single-segment lumbar degenerative diseases, modified TLIF involves preserving the isthmus, removing a portion of the degenerative side’s lamina, and resecting specific portions of the articular processes to expose the lateral spinal canal [217]. In unilateral biportal endoscopic TLIF, en bloc resection of the ligamentum flavum allows for bilateral decompression [220]. For thoracic and lumbar tuberculosis without severe kyphosis, minimally invasive far lateral debridement combined with posterior instrumentation involves inserting pedicle screws only in adjacent normal vertebrae to eliminate interference with the TB focus [215]. In lumbar tuberculosis treatment, unilateral pedicle screw fixation should be accomplished first, and the rod should not be installed until TB lesions are removed through the debridement incision [215]. For lumbar degenerative disease with osteoporosis, S1 pedicle screws with PMMA augmentation provide better stability and less screw loosening compared to other sacral screw techniques [205]. Severe abdominal aortic calcification is associated with poor two-year outcomes after posterior lumbar interbody fusion in osteoporotic patients [219]. The decision to perform cement augmentation in posterior lumbar interbody fusion for osteoporotic patients is based on intraoperative assessment of bone quality and screw purchase, without predefined objective criteria [219]. For lumbar iatrogenic instability, fusion and pedicle fixation with C-D screws showed early results of symptom relief, solid fusion, and maintenance of the lumbar curve with no major complications [10]. For L5S1 spondylolisthesis in children and adolescents, only long-term follow-up of functional results on quality-of-life scales combined with radiological results for surgery aiming at lumbosacral angle correction will demonstrate superiority over in situ fusion surgery [9]. Successful treatment of complete spondylolisthesis in an infant consisted of spine fusion from the third lumbar vertebra to the sacrum [15]. For anterior lumbar fusion in Pott's disease, 36 out of 38 patients had complete relief from pain and discomfort along with radiographic fusion [44]. For single-stage posterior debridement and TLIF in lumbar tuberculosis, successful fusion is defined by the absence of local pain, tenderness, abnormal motion, correction loss, and instrumentation failure, and the presence of trabecular bone bridging [35]. For indolent infection after lumbar interbody fusion, all patients demonstrated resolution of symptoms after placement of an anterior lumbar interbody cage without intraoperative complications, followed by an antibiotic regimen [33].

Implant Selection: Both PEEK rods and titanium rods are effective fixation materials in lumbar fusion surgery [155]. The biomechanical benefit of a stand-alone two-part fusion cage can be justified [58]. A new assembled lumbar interbody fusion cage provides more advantageous endplate stress distribution, peak von Mises stress, and cage stress compared to the assembled state [75]. Spinal fusion is more reliably achieved and more rigid if accompanied by spinal instrumentation [195]. Biodegradable rods may present more favourable clinical outcomes by providing sufficient initial stability while gradually transferring loading to adjacent segments as rigidity decreases [194]. The polymer enhanced AS-ELARIS® pedicle screw system using ultrasonically liquefied polylactide has biocompatibility, biodegradability, safe removal, and ease of handling [223]. A fusion rate similar to that of metallic implant systems was demonstrated with a carbon-fiber PEEK pedicle screw and a TLIF cage system [186]. Significant improvements in clinical outcomes and pain reduction after lumbar spinal fusion with a PEEK-based dynamic instrumentation device top off at 2 years after surgery [23]. Both the Topping-off technique and lumbar fusion surgery achieved satisfactory clinical outcomes in treating lumbar degenerative diseases [109]. Non-operative treatment for stable thoracolumbar burst fractures and uninstrumented fusion for low-grade lytic spondylolisthesis demonstrate established clinical proficiency with excellent long-term outcomes and lower complication rates compared to instrumented approaches [221]. Pedicle screw instrumentation has been used in all levels in the treatment of spinal deformities, with excellent and radiographic results [152]. For lumbar curves, pedicle screw instrumentation is applied to the convexity and compressed to create lordosis; for typical thoracic curves, pedicle screws are applied to the concavity of the deformity and distracted to restore kyphosis [152]. For lumbar arthrodesis in patients sixty-five years of age or older, transverse process exposure and lateral gutter preparation is critical to obtaining a solid fusion [227]. Osteotomy of the facet joints improves exposure and greatly facilitates lateral gutter preparation, particularly if the facets are osteophytic so as to avoid an errant lateral starting point for screw insertion [227]. Pedicle screw placement is guided by a preoperative anteroposterior radiograph that indicates the medial-lateral position of the pedicle with respect to the pars interarticularis [227].

Adjuncts: Computer-navigation and robotic devices can be helpful in the placement of pedicle screws, but are typically reserved for placement across a fusion mass that has lost all anatomic landmarks or in severe deformities where anatomy is difficult to identify [152]. Image guidance and robotics can facilitate instrumentation placement and correction while reducing radiation exposure to the surgeon and patient in less-invasive decompression and fusion procedures [152].

Other Considerations: Elderly patients undergoing minimally invasive transforaminal lumbar interbody fusion had comparable rates of perioperative complications and similar improvements in pain, function, and quality of life as younger counterparts when clinical and surgical heterogeneity were minimized [251]. Patients with cystic fibrosis undergoing posterior lumbar fusion are at increased odds of perioperative complications [74]. Preoperative hemoglobin levels can assist surgeons in counseling patients on their specific postoperative risk profile for major complications and surgical site infections after single-level lumbar fusion [4]. For lumbar spinal stenosis, surgical treatment is successful in 80% to 85% of cases, defined as significant pain relief with a return to activities of daily living [56]. In a retrospective review 4 years after lumbar decompression, “successful outcomes” were found in only 57% of cases, with factors associated with unsuccessful outcomes including multiple comorbidities, single-level decompressions, and a 5% annual incidence of degeneration at levels adjacent to the decompression [56]. Predominating low back pain is a factor associated with poor outcomes after surgical treatment of lumbar stenosis [56]. Additional studies are required to elucidate which patients with degenerative spondylolisthesis can undergo decompression only, which require fusion, and which can benefit from interbody fusion [42]. The role of novel minimally invasive strategies for decompression, fusion, and deformity correction remains to be fully elucidated, and better high-level studies are required [42]. For removal of infected lumbar interbody cages, the most common infected cage level was L4–L5 (52%), followed by L5–S1 (19%) and L3–L4 (15%) [80]. Cage migration occurred in 48% of cases and cage subsidence in 44% of cases among patients with infected lumbar interbody cages [80]. The mean elapsed time to the diagnosis of cage infection from the previous primary surgery was 72.1 days (range, 27–170 days) [80].

Complications

Neurologic Injury: Perioperative neurologic injury rates range from 0% to 7% during instrumented PLIF and TLIF [38]. At one institution, the complication rate was higher with PLIF (7.8%) than with TLIF (2%) [38]. Lower rates of neurologic injury have been reported with open TLIF than with minimally invasive procedures [38]. Iatrogenic injury can lead to temporary or permanent impairment, including radicular pain, paresthesias, numbness, and weakness [38]. Radicular pain is the most commonly reported postoperative symptom following TLIF or PLIF [38]. Traction on nerve roots during these procedures can reduce nerve root blood flow, causing ischemic nerve root injury [38]. No effective surgical options exist for managing postoperative radicular pain, paresthesia, numbness, or weakness resulting from neurologic injury [38]. In a prospective trial of cellular bone allograft for lumbar fusion, a single serious adverse event of postoperative radiculopathy was reported as definitely related to the graft due to extrusion of material from the interbody [138].

Pseudarthrosis and Fusion Failure: One- and two-level lumbar fusion procedures demonstrated an overall revision surgery rate of 15% [5]. The reoperation rate was 27% for surgical patients in a study of workers' compensation subjects undergoing lumbar fusion [20]. The incidence of reoperation was higher in patients who underwent lumbar fusion surgery than those who underwent cervical fusion surgery for degenerative spinal diseases [130]. A systematic review and meta-analysis identified 17 risk factors for pseudarthrosis after lumbar fusion, emphasizing age, smoking status, and the number of fusion levels as significant predictors [286]. The rate of fusion was 90% in patients with painful degenerative disease, 93% in those with spondylolisthesis, and 65% in those with preoperative pseudarthrosis treated with pedicle screw-plate fixation [291]. At a mean of 47 months postoperatively, 90.5% of lumbar fusion patients using supercritical CO2-processed bone allografts had radiographic evidence of bone fusion [22]. In a study of allogeneic bone matrix for one- and two-level posterolateral lumbar arthrodesis, a fusion rate of 90.7% of subjects and 89.4% of surgical levels was observed at 12 months [110]. The overall fusion rate was 94.6% in a comparative study of ALIF, OLIF, and TLIF, with rates of 92.9%, 95.1%, and 94.9% respectively [134]. Indolent infection is an under-recognized cause of pseudarthrosis after lumbar interbody fusion [33]. Patients with multiple-level infected disks had a low bone union rate after minimally invasive posterior fixation without bone grafting [290]. Instrumented fusion demonstrated superior long-term durability compared to non-instrumented procedures for recurrent lumbar disc herniation, shown by significantly lower reoperation rates [27]. The addition of interbody fusion to posterolateral fusion was associated with a higher risk for additional surgery and showed no advantages in patient-reported outcome [279].

Infection: 36% of lumbar fusion subjects in a workers' compensation cohort had complications, with surgical site infection being the most common reason for early reoperation [20, 278]. The most common reason for early reoperation following lumbar fusion surgery is surgical site infection [278]. Delayed infections after posterior instrumentation and fusion for adolescent idiopathic scoliosis have an incidence of 1% to 10% [171]. In a study of 467 patients with posterior spinal fusion for adolescent idiopathic scoliosis, the delayed infection rate was 2.4% [171]. Risk factors for delayed infection after posterior spinal fusion include a significant past medical history, receiving a blood transfusion, and not having a deep drain placed [171]. Patients on chronic preoperative steroid therapy are at increased risk of surgical site complications following elective posterior lumbar fusion [268]. For single-level posterior lumbar fusion, cefazolin alone versus cefazolin with gentamicin or tobramycin did not differ in rates of 90-day adverse outcomes or 2-year revisions [294]. Pedicle screw insertion into infected vertebrae during minimally invasive posterior fixation does not increase the occurrence of unplanned reoperations due to surgical site infection [85].

Adjacent Segment Disease: The most common reason for late reoperation following lumbar fusion surgery is adjacent segment disease [278]. A meta-analysis summarized evidence regarding risk factors for symptomatic adjacent segment disease following lumbar fusion [11]. Adjacent degeneration of the L4/5 level occurred in one case after percutaneous endoscopic transforaminal lumbar interbody fusion, requiring a repeat conventional fusion extension [248].

Hardware and Implant Complications: The overall incidence of reoperation after posterior instrumentation and fusion for adolescent idiopathic scoliosis is below 10% in more recent series [171]. The incidence of pseudarthrosis associated with modern double-rod systems, segmental instrumentation, and allograft bone for adolescent idiopathic scoliosis is reported as 1.4% [171]. Low bone mineral density and large correction of both main curve and fractional curve are predictive factors for distal pedicle screw loosening after posterior corrective surgery for degenerative lumbar scoliosis [281]. Posterolateral fusion is a protective factor against distal pedicle screw loosening after posterior corrective surgery for degenerative lumbar scoliosis [281]. The overall subsidence rate was 12.6% in a comparative study of ALIF, OLIF, and TLIF, with the TLIF group having a significantly higher subsidence rate (16.1%) than ALIF (7.1%) and OLIF (9.8%) [134]. Symptomatic migration of cages requiring secondary reoperation occurred in 13 cases after percutaneous endoscopic transforaminal lumbar interbody fusion, with a mean delay of eight months [248]. Asymptomatic migration of cages occurred in two cases after percutaneous endoscopic transforaminal lumbar interbody fusion and required no further operation [248]. Screw migration of the posterior construct occurred in one case of L1/2 fusion after percutaneous endoscopic transforaminal lumbar interbody fusion [248]. Major surgical complications occurred in 11.6% of patients receiving high-dose rhBMP-2 for adults [285]. 11.6% of patients receiving high-dose rhBMP-2 for adults experienced major medical complications [285].

Perioperative and Medical Complications: The complication rate for patients undergoing adult spinal deformity surgery is high, requiring counseling on short- and long-term complications and potential revision surgery [42]. Patients with osteoporosis undergoing 2- to 3-level lumbar fusion for degenerative disc disease experienced a higher rate of medical and surgical complications, as well as revision surgeries, at the 2-year follow-up [270]. Patients with cystic fibrosis undergoing posterior lumbar fusion are at increased odds of perioperative complications [74]. Patients on chronic preoperative steroid therapy are at increased risk of venous thromboembolic events following elective posterior lumbar fusion [268]. The combined use of intravenous and topical tranexamic acid reduced total blood loss and blood transfusion rate in patients aged over 60 scheduled for a 2-level lumbar fusion without increasing the incidence of DVT and PE formation [257]. There is often a substantial unmeasured blood loss in lumbar fusion surgeries [287]. Despite an increasing comorbidity burden of patients undergoing posterior lumbar fusion from 2010 to 2022, the incidence of adverse events overall did not increase [274]. Patients with underlying liver disease have specific 30-day outcomes after posterior lumbar fusion, where identification of modifiable risk factors can decrease complication incidence and severity [272]. Knowledge of risk factors for new-onset cardiac arrhythmias may improve the selection of outpatient versus inpatient settings for lumbar fusions [60]. Self-harm is a rare but potentially devastating complication after lumbar fusion, with specific demographic and comorbidity risk factors identified [133].

Impact on Other Procedures: Lumbar fusion surgery was associated with a higher rate of hip prosthesis dislocation and higher risk of revision surgery [68]. Lumbar fusion before total hip arthroplasty is an independent risk factor for dislocation leading to increased risk of revision total hip arthroplasty [259]. Patients undergoing lumbar fusion and subsequent total hip arthroplasty have significantly higher risks of dislocation and revision of their hip arthroplasty than a matched cohort with similar pathology but only undergoing total hip arthroplasty [267]. Lumbosacral spinal fusions prior to total hip arthroplasty increase the risk of dislocation within the first six months, with fusions involving the sacrum and multiple lumbar levels notably increasing the risk [275]. Patients with a history of lumbar fusion have significantly greater rates of revision hip arthroscopy and conversion to total hip arthroplasty compared with patients without previous fusion [87]. Patients with prior total hip arthroplasty undergoing long fusion to the pelvis experienced longer length of stay and more surgical complications compared to those fused to the sacrum [282]. Patients with prior total hip arthroplasty undergoing multilevel thoracolumbar fusions experienced more dislocations, higher spinal revision rates, less frequent discharge home, longer hospital length of stay, and higher 90-day readmission rates [284].

Learning Curve and Technique-Specific Risks: The overall complication rate for minimally invasive TLIF procedures was 20% in a systematic review of learning curve studies [211]. The cumulative complication rate for the initial 10 cases of minimally invasive TLIF was 33% [211]. Complications in minimally invasive TLIF learning curve studies included instrumentation malposition/migration, perioperative infection, nonunions, durotomy, and postoperative contralateral stenosis [211]. The MIS TLIF learning curve in terms of operative time is approximately 20 cases [211]. Anterior approaches to the lumbar spine are associated with low morbidity provided the technique and vascular risks are well mastered [48]. The rate of lumbar fusion in patients with cauda equina syndrome treated with decompression was 3.6% after 1 year, 6.7% after 3 years, and 7.8% after 5 years [81].

Other Considerations: The reoperation rate was 27% for surgical patients, and 36% of lumbar fusion subjects had complications [20]. Patients with lumbar fusion are at increased risk for post-operative dislocations requiring revision [13]. The one-year postoperative radiological results and functional outcome of minimally invasive posterior lumbar fusion are satisfactory [3]. No differences were found in 90-day aggregated postoperative adverse events and 5-year lumbar revision surgery rates between noninstrumented and instrumented posterolateral approaches for lumbar degenerative spondylolisthesis [6]. Instrumented fusion demonstrated superior long-term durability compared to non-fusion procedures for recurrent lumbar disc herniation, as shown by significantly lower reoperation rates over extended follow-up [27]. AQS, ODI, and SF12 scores were improved significantly at follow-up with no differences in clinical improvements across surgical procedure types for degenerative lumbar spondylolisthesis [82]. At mid-term follow-up, PLIF and OLIF provided sustained improvement in pain and function for lumbar spinal stenosis [271]. Following PDS, patients recovered faster and had a better lumbar function, making it a potentially better choice for multi-level lumbar degenerative diseases [230]. Results demonstrate significant improvements in clinical outcomes and pain reduction after lumbar spinal fusion with topping off at 2 years after surgery [23]. At a mean of 47 months postoperatively, 90.5% of lumbar fusion patients had radiographic evidence of bone fusion [22]. The early results of lumbar spine fusion and pedicle fixation with C-D screws for lumbar iatrogenic instability showed relief of symptoms, solid fusion of the spine, and maintenance of the lumbar curve with no major complications [10]. A solid fusion was obtained in all patients, and all had major or complete neurological recovery following single-stage decompression with in situ posterolateral and anterior fusion for spondylolisthesis [269]. Early initiation of a postoperative rehabilitation program based on principles of strength training is safe 3 weeks after lumbar spine fusion and enables earlier functional recovery than standard rehabilitation protocol [120]. Objective activity trackers demonstrated that lumbar surgery results in the amount of activity decreasing 1 month just after surgery followed by gradual postoperative recovery within 3 months [199]. Prompt postoperative mobilization does not prevent fusion when a posterolateral technique is used [216]. Rehabilitation has benefits on the recovery of patients after spine surgery, but further investigation is needed to achieve a standardized rehabilitation approach [213]. The longitudinal trajectory of functional outcomes in patients with metabolic syndrome undergoing lumbar fusion surgery emphasizes the importance of appropriate management and rehabilitation to achieve optimal outcomes [164]. The evidence for spinal fusion in non-specific low back pain is poor; spinal fusion should only be performed as part of a randomised controlled trial [7]. Nonsurgical management is the standard of care for lumbar degenerative disk disease [88]. Opioid utilization findings serve as a baseline in identifying patients at risk for chronic use and alert surgeons to work toward discontinuation of opioids before lumbar spinal surgery [167].

Key Evidence

• [L3] Approximately one-third of adverse events after posterior lumbar fusion were diagnosed 31 to 90 days after surgery, highlighting the importance of looking past the 30-day mark for adverse event characterization. [1] (10.5435/jaaos-d-21-01121)
• [L3] It should be considered by surgeons before realizing a lumbar fusion. [2] (10.1016/j.otsr.2013.09.003)
• [L4] The one-year postoperative radiological results and functional outcome of minimally invasive posterior lumbar fusion are satisfactory. [3] (10.1016/j.otsr.2015.07.001)
• [L3] These thresholds are a unique addition to the single-level lumbar fusion literature and can assist surgeons in counseling patients on their specific postoperative risk profile. [4] (10.5435/jaaosglobal-d-24-00074)
• [L3] One- and two-level lumbar fusion procedures demonstrated high durability with an overall revision surgery rate of 15%. [5] (10.5435/jaaosglobal-d-25-00424)
• [L4] No differences were found in 90-day aggregated postoperative adverse events and 5-year lumbar revision surgery rates, suggesting that instrumentation can be safely performed and that both approaches had similarly durable results. [6] (10.5435/jaaosglobal-d-25-00192)
• [L5] The evidence for spinal fusion or disc replacement in non-specific low back pain is poor; spinal fusion should only be performed as part of a randomised controlled trial, and lumbar disc replacement should not be performed. [7] (10.1302/0301-620x.99b8.bjj-2017-0199.r1)
• [L1] Both methods have comparable fusion rates, complication rates, and lumbar pain improvements. [8] (10.3389/fsurg.2024.1374134)
• [L5] Only long-term follow-up of functional results on quality-of-life scales, combined with radiological results for surgery aiming at lumbosacral angle correction, will be able to demonstrate superiority over in situ fusion surgery. [9] (10.1016/j.otsr.2015.03.021)
• [L4] The early results are most encouraging, showing relief of symptoms, solid fusion of the spine, and maintenance of the lumbar curve with no major complications. [10] (10.1007/bf00393719)
• [L1] This meta-analysis addressed the limitations of prior reviews and summarized evidence with regard to risk factors for ASD following lumbar fusion. [11] (10.2106/jbjs.20.00408)
• [L4] No completely reliable method of spine fusion has been developed, with success rates varying widely and often overestimated by roentgenographic methods. [12] (10.2106/00004623-196850010-00017)
• [L4] Patients with lumbar fusion are at increased risk for post-operative dislocations requiring revision. [13] (10.1007/s00264-018-3955-2)
• [L3] [18] (10.1186/s13018-022-02971-3)
• [L2] We found greater use of fusion-based procedures for lumbar spinal disorders, irrespective of the clinical condition, in the private sector. [19] (10.1097/corr.0000000000003487)
• [L3] The reoperation rate was 27% for surgical patients, and 36% of lumbar fusion subjects had complications. [20] (10.1097/brs.0b013e3181ccc220)
• [L4] ALIF has proven effective for revision lumbar fusion surgery, yielding positive clinical and radiographic results. [21] (10.1186/s13018-023-03972-6)
• [L4] At a mean of 43 and 47 months postoperatively, 95.3% and 90.5% of cervical and lumbar fusion patients had radiographic evidence of bone fusion, respectively. [22] (10.3389/fsurg.2023.984028)
• [L4] Results demonstrate significant improvements in clinical outcomes and pain reduction after lumbar spinal fusion with topping off at 2 years after surgery. [23] (10.1186/s13018-018-0905-z)
• [L3] Although both procedures achieved clinical improvement, instrumented fusion (IF) demonstrated superior long-term durability as shown by significantly lower reoperation rates over extended follow-up. [27] (10.2106/jbjs.25.01113)
• [L4] Posterior decompression with instrumented fusion is the most common surgical treatment, though individual patient factors must guide the selection of the specific strategy. [30] (10.1302/2058-5241.3.170050)
• [L3] Among adult patients with IS undergoing single-level lumbar fusion, 81.5% had posterior surgery while 7.9% had combined AP surgery. [31] (10.5435/jaaos-d-25-00610)
• [L4] All patients demonstrated a resolution of symptoms after placement of an anterior lumbar interbody cage, without intraoperative complications, and a subsequent antibiotic regimen. [33] (10.5435/jaaosglobal-d-21-00259)
• [Paper] [35] (10.1007/s00402-010-1138-8)
• [L3] Pre-existing L5-S1 degeneration does not affect clinical and radiographical outcomes after isolated L4-5 fusion. [36] (10.1186/s13018-015-0186-8)
• [L3] It also identifies several prognostic factors that influence outcomes after lumbar fusion surgery, including higher BMI, larger FJA, and wider sagittal and coronal diameters. [37] (10.1186/s13018-025-05835-8)
• [L5] [38] (10.5435/jaaos-20-05-283)
• [L4] Thirty-six out of 38 patients had complete relief from pain and discomfort along with radiographic fusion. [44] (10.1097/blo.0b013e318067bcd9)
• [L4] Each method offers distinctive advantages and limitations, with laminoplasty showing lower complication rates than fusion and arthroplasty showing reduced revision rates for adjacent segment disease. [45] (10.5435/jaaos-d-22-00956)
• [Paper] Anterior approaches to the lumbar spine are increasingly used due to proven efficacy and low morbidity, provided the technique and vascular risks are well mastered. [48] (10.1016/j.otsr.2019.05.024)
• [L5] [56] (10.5435/00124635-199907000-00004)
• [L1] [57] (10.2106/jbjs.22.00307)
• [L5] The biomechanical benefit of a stand-alone two-part fusion cage can be justified. [58] (10.1186/1471-2474-9-88)
• [L3] Knowledge of these risk factors may improve appropriate selection of an outpatient surgical center or orthopaedic specialty hospital versus an inpatient hospital for lumbar fusions. [60] (10.5435/jaaos-d-22-00884)
• [L3] The general clinical efficacy is equivalent to titanium rod fusion surgery, presenting an alternative treatment for individuals with mild and moderate lumbar degenerative disease. [61] (10.1186/s12891-023-06329-6)
• [L4] Bone SPECT/CT was useful to identify the specific cause of pain in elderly patients with lumbar degenerative disease and to provide appropriate treatment, avoiding the unnecessary use of invasive spinal fusion surgery. [64] (10.1186/s13018-019-1236-4)
• [L3] However, there was an association between radiographic fusion status and clinical outcomes. [65] (10.5435/jaaos-d-23-01124)
• [L3] Lumbar fusion surgery was associated with higher rate of hip prosthesis dislocation and higher risk of revision surgery. [68] (10.1302/0301-620x.102b8.bjj-2019-1037.r1)
• [L3] LLIF involving the L4-5 disc level has a low rate of persistent neurological, psoas-related, and abdominal complications in patients with the appropriate indications and using a standardized surgical technique. [69] (10.1302/0301-620x.106b1.bjj-2023-0693.r2)
• [L3] Under strict adherence to surgical indications, posterior lateral lumbar fusion surgery which preserves partial facet joint unilaterally during neural decompression can offer greater benefits to patients. [70] (10.1186/s13018-024-05020-3)
• [L5] Arthrodesis is at present the best surgical treatment for the persistently painful degenerative back, though it increases morbidity and mortality rates and carries a risk of non-union. [72] (10.2106/00004623-196345070-00016)
• [L2] New hybrid systems might improve the outcome of lumbar spine fusion, but to date there is no convincing published data on effectiveness or safety of these topping off systems. [73] (10.1186/1471-2474-12-239)
• [L3] These findings are pertinent in the perioperative risk assessment, patient/family recommendations, and surgical preparations for patients with cystic fibrosis being considered for posterior lumbar fusion. [74] (10.5435/jaaosglobal-d-24-00304)
• [L5] The new cage provides more advantageous endplate stress distribution, peak von Mises stress, and cage stress compared to the assembled state. [75] (10.1007/s00402-010-1055-x)
• [L3] We recommend preoperative spinopelvic assessment of all patients undergoing THA, as only a minority of those with limited lumbar flexion have an instrumented fusion and may otherwise be overlooked. [76] (10.1016/j.arth.2020.01.031)
• [L4] Circumferential fusion is recommended by several authors to regain stability at the lumbosacral junction. [77] (10.1016/j.injury.2009.06.008)
• [L3] Higher magnitudes of CS were associated with worse clinical improvements and lower intervertebral fusion. [78] (10.1186/s12891-022-05165-4)
• [L3] [80] (10.1186/s13018-021-02535-x)
• [L3] The rate of lumbar fusion in the CES cohort was 3.6% after 1 year, 6.7% after 3 years, and 7.8% after 5 years, significantly higher than the LSS control group at all time points. [81] (10.5435/jaaosglobal-d-22-00153)
• [L3] The AQS, ODI and SF12 scores were improved significantly at follow-up with no differences in clinical improvements across surgical procedure types. [82] (10.1016/j.otsr.2014.07.006)
• [L3] PS insertion into infected vertebrae during minimally invasive posterior fixation reduces the operative time and range of fixation without increasing the occurrence of unplanned reoperations due to SSI or implant failure. [85] (10.1186/s12891-024-07565-0)
• [L4] Non-instrumented circumferential arthrodesis after gradual correction is still relevant in the management of high-grade spondylolisthesis associated with lumbosacral kyphosis in children and adolescents. [86] (10.1016/j.otsr.2021.103093)
• [L3] Patients with a history of lumbar fusion had significantly greater rates of revision hip arthroscopy and conversion to THA compared with patients without previous fusion. [87] (10.1016/j.arthro.2024.08.026)
• [L5] Nonsurgical management is the standard of care for lumbar degenerative disk disease, while spondylolysis is typically managed nonsurgically with successful outcomes, though surgery may be required for return to sports. [88] (10.5435/jaaos-d-16-00135)
• [L3] ULIF is an effective minimally invasive lumbar fusion surgical technique. [104] (10.1186/s13018-024-04674-3)
• [L3] Both the Topping-off technique and lumbar fusion surgery achieved satisfactory clinical outcomes in treating lumbar degenerative diseases. [109] (10.1186/s12891-025-09316-1)
• [L4] [110] (10.1186/s13018-016-0392-z)
• [L4] The technique is a straightforward, safe, and minimally invasive method for inserting large cages in the treatment of lumbar instability. [111] (10.1186/s13018-024-05018-x)
• [L1] The study showed that early initiation of a postoperative rehabilitation program based on principles of strength training is safe, 3 weeks after lumbar spine fusion, and enable earlier functional recovery than standard rehabilitation protocol. [120] (10.1186/s13018-018-0853-7)
• [L2] The incidence of reoperation was higher in the patients who underwent lumbar fusion surgery than those who underwent cervical fusion surgery for degenerative spinal diseases. [130] (10.1186/s12891-021-04491-3)
• [L3] [133] (10.5435/jaaosglobal-d-25-00199)
• [L3] [134] (10.1186/s13018-023-03652-5)
• [L2] [138] (10.1186/s12891-023-06996-5)
• [L1] Both PEEK rods and titanium rods are effective fixation materials in lumbar fusion surgery. [155] (10.1186/s13018-023-03817-2)
• [L3] This study evaluated the longitudinal trajectory of functional outcomes in patients with MetS undergoing lumbar fusion surgery, providing precise information on recovery patterns and emphasizing the importance of appropriate management and rehabilitation for both patients and physicians to achieve optimal outcomes. [164] (10.1186/s13018-025-06003-8)
• [L5] A new classification system that incorporates spinopelvic balance in the radiographic assessment may aid orthopaedic surgeons in identifying patients who would benefit from partial reduction and fusion. [166] (10.5435/jaaos-20-04-194)
• [L3] Our findings serve as a baseline in identifying patients at risk for chronic use and alter surgeons to work toward discontinuation of opioids before lumbar spinal surgery. [167] (10.1097/brs.0000000000002734)
• [L4] Transsacral fixation/fusion may allow for safe lumbosacral fusion without iliac fixation in the setting of long-segment constructs in carefully selected patients. [170] (10.1007/s11999-013-3335-6)
• [L1] Decompression alone demonstrates non-inferiority in terms of efficacy for treating low back pain due to DS compared to fusion, with additional benefits in operation time and blood loss. [185] (10.1186/s13018-025-06550-0)
• [L4] The results demonstrate a fusion rate similar to that of metallic implant systems with the use of a CF-PEEK pedicle screw and a TLIF cage system. [186] (10.1186/s12891-025-08457-7)
• [L5] Biodegradable rods may present more favourable clinical outcomes for lumbar fusion by providing sufficient initial stability while gradually transferring loading to adjacent segments as rigidity decreases over time. [194] (10.1371/journal.pone.0188034)
• [L5] The results show that a spinal fusion can be more reliably achieved and will be more rigid if it is accompanied by spinal instrumentation. [195] (10.1002/jor.1100070610)
• [L4] [196] (10.1016/j.otsr.2016.11.016)
• [L2] The objective activity tracker demonstrated that lumbar surgery results in the amount of activity decreasing 1 month just after surgery followed by gradual postoperative recovery within 3 months. [199] (10.1186/s12891-020-3102-2)
• [L3] When patients with L4–1 LDD with osteoporosis undergo lumbosacral fusion and fixation, the use of S1 pedicle screws with PMMA augmentation has better stability and less screw loosening. [205] (10.1186/s13018-024-05281-y)
• [L5] Although the Spinal Deformity Study Group Classification seems promising, there is a lack of robust clinical outcome studies to support its recommendations, and observers showed disagreement especially in classifying low-grade spondylolisthesis. [207] (10.1097/corr.0000000000001005)
• [L1] [211] (10.1007/s11999-014-3495-z)
• [L3] [212] (10.1186/s13018-023-04507-9)
• [L4] Rehabilitation has benefits on the recovery of patients after spine surgery, but further investigation is needed to achieve a standardized rehabilitation approach. [213] (10.1530/eor-23-0015)
• [L4] [214] (10.1186/s12891-021-04086-y)
• [L4] [215] (10.1186/s13018-020-01703-9)
• [L3] [217] (10.1186/s13018-024-04531-3)
• [L4] SA-LLIF can provide immediate stability and good results for lumbar degenerative diseases with a standalone anchored cage without posterior internal fixation. [218] (10.1186/s12891-023-06974-x)
• [L3] [219] (10.1186/s12891-026-10345-7)
• [L3] [220] (10.1186/s13018-024-05317-3)
• [L5] Non-operative treatment for stable thoracolumbar burst fractures and uninstrumented fusion for low-grade lytic spondylolisthesis demonstrate established clinical proficiency with excellent long-term outcomes and lower complication rates compared to instrumented approaches. [221] (10.1302/0301-620x.98b1.37508)
• [L5] Its biocompatibility, biodegradability, safe removal, and ease of handling make it a valuable addition to spinal fixation strategies. [223] (10.1186/s13018-026-06773-9)
• [L2] Operative treatment of lumbar stenosis and degenerative spondylolisthesis offered a significant benefit over nonoperative treatment in patients at least eighty years of age. [224] (10.2106/jbjs.n.00313)
• [L4] [225] (10.1186/s12891-022-06079-x)
• [L2] [227] (10.2106/jbjs.i.01300)
• [L4] [229] (10.1186/s12891-019-2753-3)
• [L3] Following PDS, patients recovered faster and had a better lumbar function, making it a potentially better choice for multi-level lumbar degenerative diseases. [230] (10.1186/s13018-017-0597-9)
• [L4] The study proposes a practical classification system with preliminary feasibility in surgical approach selection for cage retropulsion, suggesting that early revision may yield better outcomes. [232] (10.1186/s12891-026-09616-0)
• [L4] [234] (10.1016/j.injury.2026.113503)
• [L4] [241] (10.1186/s12891-021-04584-z)
• [L5] [242] (10.1002/jor.25240)
• [L3] After posterior lumbar fusion, the volume of the multifidus muscles was markedly decreased, and the degree of decrease was apparent in the MRI. [243] (10.1186/s12891-020-3104-0)
• [L4] [245] (10.1186/s12891-021-04811-7)
• [Paper] [248] (10.1007/s00264-013-1905-6)
• [L2] When clinical and surgical heterogeneity were minimized, elderly patients undergoing minimally invasive transforaminal lumbar interbody fusion not only had comparable rates of perioperative complications but also experienced similar improvements in pain, function, and quality of life. [251] (10.1097/corr.0000000000001054)
• [L2] Overall bone metabolism of the operated intervertebral disc space at six weeks had the highest diagnostic accuracy for predicting the fusion status at one year. [254] (10.1186/s13018-025-05814-z)
• [L4] Modic changes, particularly Type 2, are common radiological findings in lumbar spine imaging, most frequently occurring at L4/L5 and L5/S1 levels. [256] (10.1186/s12891-025-09182-x)
• [L1] The combined use of TXA effectively reduced the total blood loss and blood transfusion rate in patients aged over 60 scheduled for a 2-level lumbar fusion, without increasing the incidence of DVT and PE formation. [257] (10.1186/s13018-020-01758-8)
• [L3] Results of this study demonstrate that lumbar fusion before THA is an independent risk factor for dislocation leading to increased risk of revision THA. [259] (10.1016/j.arth.2017.10.041)
• [L4] Twenty-nine percent of patients developed radiologic adjacent segment degeneration, with a surgical revision rate of 10%. [261] (10.1016/j.otsr.2016.03.012)
• [L4] Clinical relief does not necessarily depend on roentgenographic evidence of fusion. [262] (10.2106/00004623-196244080-00007)
• [L3] CT may help diagnose endplate sclerosis in patients with type 2 change and inform the choice of the best site for spinal fusion. [265] (10.1186/s12891-021-04461-9)
• [L2] Obtaining flexed-seated radiographs preoperatively in patients with prior THA scheduled for lumbar fusion may be helpful to communicate potential risks of postoperative dislocation and support shared decision-making. [266] (10.1097/corr.0000000000003883)
• [L3] Patients undergoing lumbar fusion and subsequent THA have significantly higher risks of dislocation and revision of their hip arthroplasty than a matched cohort of patients with similar hip and spine pathology but only undergoing THA. [267] (10.1016/j.arth.2016.11.029)
• [L3] Patients on chronic preoperative steroid therapy are at increased risk of multiple perioperative complications following elective PLF, particularly surgical site complications and venous thromboembolic events. [268] (10.1177/2192568218775960)
• [L4] A solid fusion was obtained in all patients, and all had major or complete neurological recovery. [269] (10.2106/00004623-199072030-00015)
• [L3] Patients with osteoporosis undergoing 2- to 3-level lumbar fusion for DDD experienced a higher rate of medical and surgical complications, as well as revision surgeries, at the 2-year follow-up. [270] (10.5435/jaaos-d-21-01258)
• [L3] At mid-term follow-up, PLIF and OLIF provided sustained improvement in pain and function. [271] (10.1186/s13018-026-06818-z)
• [L3] The identification of modifiable risk factors would allow them to be addressed and optimized preoperatively to decrease the incidence and severity of complications and improve patient outcomes after PLF. [272] (10.1016/j.wneu.2019.01.160)
• [L4] Despite an increasing comorbidity burden of patients undergoing posterior lumbar fusion from 2010 to 2022, the incidence of adverse events overall did not increase. [274] (10.5435/jaaosglobal-d-25-00379)
• [L3] Lumbosacral spinal fusions prior to THA increase the risk of dislocation within the first six months, with fusions involving the sacrum and multiple lumbar levels notably increasing the risk compared to controls. [275] (10.1302/0301-620x.101b2.bjj-2018-0754.r1)
• [L3] The most common reasons for early reoperation and late operation were surgical site infection and adjacent segment diseases, respectively. [278] (10.1186/s13018-022-03273-4)
• [L3] The addition of interbody fusion to posterolateral fusion was associated with a higher risk for additional surgery and showed no advantages in patient-reported outcome. [279] (10.1302/0301-620x.101b12.bjj-2019-0427.r1)
• [L3] Low bone mineral density, large correction of both main curve and fractional curve are predictive factors for loosening, while posterolateral fusion is a protective factor. [281] (10.1186/s12891-025-08519-w)
• [L3] Patients with prior THA undergoing long fusion to the pelvis experienced longer length of stay, more surgical complications, and a lower rate of spinal revisions compared to those fused to the sacrum. [282] (10.5435/jaaos-d-22-00897)
• [L3] Patients with prior THA undergoing multilevel fusions experienced more dislocations, higher spinal revision rates, less frequent discharge home, longer hospital length of stay, and higher 90-day readmission rates. [284] (10.5435/jaaos-d-24-00606)
• [L4] Major surgical complications occurred in 11.6% of patients, and 11.6% experienced major medical complications. [285] (10.2106/jbjs.l.01730)
• [L1] The study identified 17 risk factors for pseudarthrosis after lumbar fusion surgery, emphasizing age, smoking status, and the number of fusion levels as significant predictors. [286] (10.1186/s12891-024-07531-w)
• [L3] There is often a substantial unmeasured blood loss in lumbar fusion surgeries. [287] (10.1016/j.otsr.2017.01.011)
• [L3] Patients with multiple-level infected disks had a low bone union rate, suggesting treatment strategies should be cautiously considered. [290] (10.1186/s12891-024-07993-y)
• [L4] The rate of fusion was 90 per cent in patients with painful degenerative disease, 93 per cent in those with spondylolisthesis, and 65 per cent in those with preoperative pseudarthrosis. [291] (10.2106/00004623-199173080-00006)
• [L3] For single-level posterior lumbar fusion, cefazolin alone versus cefazolin and gentamicin/tobramycin did not differ in rates of 90-day adverse outcomes or 2-year revisions. [294] (10.5435/jaaosglobal-d-24-00082)

See Also

• Low back pain
• Lumbar spinal stenosis
• Degenerative spondylolisthesis
• Lumbar disc herniation
• Cervical myelopathy
• Cauda equina syndrome
• Lumbar decompression
• Adult spinal deformity
• Adolescent idiopathic scoliosis

References

[1] Adverse Events After Posterior Lumbar Fusion Are Not Sufficiently Characterized With 30-day Follow-up: A Database Study. Journal of the American Academy of Orthopaedic Surgeons. 2022. DOI: 10.5435/jaaos-d-21-01121

[2] Lumbar-sacral fusion by a combined approach using interbody PEEK cage and posterior pedicle-screw fixation: Clinical and radiological results from a prospective study. Orthopaedics & Traumatology: Surgery & Research. 2013. DOI: 10.1016/j.otsr.2013.09.003

[3] Minimally invasive posterior transforaminal lumbar interbody fusion: One-year postoperative morbidity, clinical and radiological results of a prospective multicenter study of 182 cases. Orthopaedics & Traumatology: Surgery & Research. 2015. DOI: 10.1016/j.otsr.2015.07.001

[4] The Effect of Varying Preoperative Hemoglobin Levels on the Risk of Major Complications and Surgical Site Infections After Single Level Lumbar Fusion. JAAOS: Global Research and Reviews. 2024. DOI: 10.5435/jaaosglobal-d-24-00074

[5] Durability of One- and Two-Level Lumbar Fusion Surgeries: A Survivorship Analysis Based on Revision Surgery Rates. JAAOS: Global Research and Reviews. 2026. DOI: 10.5435/jaaosglobal-d-25-00424

[6] Noninstrumented Posterolateral Lumbar Fusions Continue to Fade Relative to Instrumented Posterolateral Approaches for Lumbar Degenerative Spondylolisthesis Over the Past Decade. JAAOS: Global Research and Reviews. 2025. DOI: 10.5435/jaaosglobal-d-25-00192

[7] The surgical treatment of non-specific low back pain. The Bone & Joint Journal. 2017. DOI: 10.1302/0301-620x.99b8.bjj-2017-0199.r1

[8] Fusion rate and complications of oblique lumbar interbody fusion and transforaminal lumbar interbody fusion in the treatment of lumbar degenerative diseases: a meta-analysis. Frontiers in Surgery. 2024. DOI: 10.3389/fsurg.2024.1374134

[9] L5S1 spondylolisthesis in children and adolescents. Orthopaedics & Traumatology: Surgery & Research. 2016. DOI: 10.1016/j.otsr.2015.03.021

[10] Lumbar spine fusion and pedicle fixation with C-D screws for lumbar iatrogenic instability. Archives of Orthopaedic and Trauma Surgery. 1997. DOI: 10.1007/bf00393719

[11] Demographic, Surgical, and Radiographic Risk Factors for Symptomatic Adjacent Segment Disease After Lumbar Fusion. Journal of Bone and Joint Surgery. 2021. DOI: 10.2106/jbjs.20.00408

[12] Methods of Lumbar Fusion. The Journal of Bone & Joint Surgery. 1968. DOI: 10.2106/00004623-196850010-00017

[13] The relationship of pelvic incidence to post-operative total hip arthroplasty dislocation in patients with lumbar fusion. International Orthopaedics. 2018. DOI: 10.1007/s00264-018-3955-2

[14] Low Backache and Sciatica: Results of Surgical Treatment: PART I. SPINE FUSION ONLY.. The Journal of Bone and Joint Surgery. American Volume. 1964.

[15] Complete Spondylolisthesis in an Infant. 1975.

[18] The effects of lumbar fusion and non-fusion surgery on the development of Modic changes. Journal of Orthopaedic Surgery and Research. 2022. DOI: 10.1186/s13018-022-02971-3

[19] Is Civilian Hospital Treatment of Lumbar Spinal Disorders Associated With Greater Odds of Fusion Procedures?. Clinical Orthopaedics & Related Research. 2025. DOI: 10.1097/corr.0000000000003487

[20] Long-term Outcomes of Lumbar Fusion Among Workers’ Compensation Subjects. Spine. 2011. DOI: 10.1097/brs.0b013e3181ccc220

[21] Surgical outcomes of anterior lumbar interbody fusion in revision lumbar interbody fusion surgery. Journal of Orthopaedic Surgery and Research. 2023. DOI: 10.1186/s13018-023-03972-6

[22] The safe and effective use of supercritical CO2-processed bone allografts for cervical and lumbar interbody fusion: A retrospective study. Frontiers in Surgery. 2023. DOI: 10.3389/fsurg.2023.984028

[23] Clinical experiences with a PEEK-based dynamic instrumentation device in lumbar spinal surgery: 2 years and no more. Journal of Orthopaedic Surgery and Research. 2018. DOI: 10.1186/s13018-018-0905-z

[27] Surgical Treatment of Recurrent Lumbar Disc Herniation: To Fuse or Not To Fuse. Journal of Bone and Joint Surgery. 2026. DOI: 10.2106/jbjs.25.01113

[30] Current trends in the management of degenerative lumbar spondylolisthesis. EFORT Open Reviews. 2018. DOI: 10.1302/2058-5241.3.170050

[31] Anterior Versus Posterior Lumbar Fusion for Adult Isthmic Spondylolisthesis. Journal of the American Academy of Orthopaedic Surgeons. 2025. DOI: 10.5435/jaaos-d-25-00610

[33] Indolent Infection After Lumbar Interbody Fusion: An Under-recognized Cause of Pseudarthrosis, Which Can Be Successfully Treated With Anterior Revision Fusion. JAAOS: Global Research and Reviews. 2022. DOI: 10.5435/jaaosglobal-d-21-00259

[34] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > OPERATIVE TREATMENT > EVALUATION FOR OPERATIVE TREATMENT.

[35] Single-stage posterior debridement and transforaminal lumbar interbody fusion with autogenous bone grafting and posterior instrumentation in the surgical management of lumbar tuberculosis. Archives of Orthopaedic and Trauma Surgery. 2010. DOI: 10.1007/s00402-010-1138-8

[36] Does pre-existing L5-S1 degeneration affect outcomes after isolated L4-5 fusion for spondylolisthesis?. Journal of Orthopaedic Surgery and Research. 2015. DOI: 10.1186/s13018-015-0186-8

[37] Analyses of proximal adjacent segment degeneration and prognostic factors after lumbar fusion surgery: study based on proximal facet joint angle. Journal of Orthopaedic Surgery and Research. 2025. DOI: 10.1186/s13018-025-05835-8

[38] Complications Associated With Posterior and Transforaminal Lumbar Interbody Fusion. Journal of the American Academy of Orthopaedic Surgeons. 2012. DOI: 10.5435/jaaos-20-05-283

[40] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > LUMBAR SPINE > 2. Discogenic back pain.

[42] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Thoracolumbar Conditions > Summary.

[44] Anterior Lumbar Fusion in Pott's Disease. Clinical Orthopaedics & Related Research. 2007. DOI: 10.1097/blo.0b013e318067bcd9

[45] Preservation of Motion in Spine Surgery. Journal of the American Academy of Orthopaedic Surgeons. 2023. DOI: 10.5435/jaaos-d-22-00956

[48] Anterior lumbar fusion techniques: ALIF, OLIF, DLIF, LLIF, IXLIF. Orthopaedics & Traumatology: Surgery & Research. 2020. DOI: 10.1016/j.otsr.2019.05.024

[49] Aaos Comprehensive Orthopaedic Review 3. Lumbar Degenerative Disease and Low Back Pain > VI. Lumbar Stenosis.

[52] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > DIAGNOSTIC STUDIES.

[56] Degenerative Lumbar Stenosis: Diagnosis and Management. Journal of the American Academy of Orthopaedic Surgeons. 1999. DOI: 10.5435/00124635-199907000-00004

[57] In Spinal Stenosis with Degenerative Spondylolisthesis, Decompression Surgery Alone Was Noninferior to Decompression Surgery with Instrumented Fusion for Reducing Impairment at 2 Years. Journal of Bone and Joint Surgery. 2022. DOI: 10.2106/jbjs.22.00307

[58] Biomechanical comparison of a new stand-alone anterior lumbar interbody fusion cage with established fixation techniques – a three-dimensional finite element analysis. BMC Musculoskeletal Disorders. 2008. DOI: 10.1186/1471-2474-9-88

[60] Creation of a Risk Calculator for Predicting New-Onset Cardiac Arrhythmias in Patients Undergoing Lumbar Fusion. Journal of the American Academy of Orthopaedic Surgeons. 2023. DOI: 10.5435/jaaos-d-22-00884

[61] Isobar hybrid dynamic stabilization with posterolateral fusion in mild and moderate lumbar degenerative disease. BMC Musculoskeletal Disorders. 2023. DOI: 10.1186/s12891-023-06329-6

[64] Utility of bone SPECT/CT to identify the primary cause of pain in elderly patients with degenerative lumbar spine disease. Journal of Orthopaedic Surgery and Research. 2019. DOI: 10.1186/s13018-019-1236-4

[65] Association of Poor Bone Quality with Pseudarthrosis and Poor Clinical Outcomes in Single-Level Instrumented Lumbar Arthrodesis Using Local Autologous Bone Graft. Journal of the American Academy of Orthopaedic Surgeons. 2024. DOI: 10.5435/jaaos-d-23-01124

[67] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > NATURAL HISTORY.

[68] Following total hip arthroplasty: femoral head component diameter of 32 mm or larger is associated with lower risk of dislocation in patients with a prior lumbar fusion. The Bone & Joint Journal. 2020. DOI: 10.1302/0301-620x.102b8.bjj-2019-1037.r1

[69] Lateral lumbar interbody fusion at L4-L5 has a low rate of complications in appropriately selected patients when using a standardized surgical technique. The Bone & Joint Journal. 2024. DOI: 10.1302/0301-620x.106b1.bjj-2023-0693.r2

[70] Role of unilateral partial facet joint preservation in postero-lateral approach lumbar interbody fusion for patients with degenerative lumbar spinal stenosis presenting bilateral lower limb symptoms: a retrospective study. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-024-05020-3

[72] Surgical Treatment of Degenerative Disease of the Back. The Journal of Bone & Joint Surgery. 1963. DOI: 10.2106/00004623-196345070-00016

[73] Comparison of standard fusion with a "topping off" system in lumbar spine surgery: a protocol for a randomized controlled trial. BMC Musculoskeletal Disorders. 2011. DOI: 10.1186/1471-2474-12-239

[74] Patients With Cystic Fibrosis Undergoing Posterior Lumbar Fusion Are at an Increased Odds of Perioperative Complications. JAAOS: Global Research and Reviews. 2025. DOI: 10.5435/jaaosglobal-d-24-00304

[75] Design and finite-element evaluation of a versatile assembled lumbar interbody fusion cage. Archives of Orthopaedic and Trauma Surgery. 2010. DOI: 10.1007/s00402-010-1055-x

[76] The Majority of Total Hip Arthroplasty Patients With a Stiff Spine Do Not Have an Instrumented Fusion. The Journal of Arthroplasty. 2020. DOI: 10.1016/j.arth.2020.01.031

[77] Lumbosacral dislocation: A review of the literature and current aspects of management. Injury. 2010. DOI: 10.1016/j.injury.2009.06.008

[78] Clinical and radiological evaluation of cage subsidence following oblique lumbar interbody fusion combined with anterolateral fixation. BMC Musculoskeletal Disorders. 2022. DOI: 10.1186/s12891-022-05165-4

[80] The comparison between anterior and posterior approaches for removal of infected lumbar interbody cages and a proposal regarding the use of endoscope-assisted technique. Journal of Orthopaedic Surgery and Research. 2021. DOI: 10.1186/s13018-021-02535-x

[81] Rates of Future Lumbar Fusion in Patients with Cauda Equina Syndrome Treated With Decompression. JAAOS: Global Research and Reviews. 2022. DOI: 10.5435/jaaosglobal-d-22-00153

[82] Degenerative lumbar spondylolisthesis. Cohort of 670 patients, and proposal of a new classification. Orthopaedics & Traumatology: Surgery & Research. 2014. DOI: 10.1016/j.otsr.2014.07.006

[85] Pedicle screw insertion into infected vertebrae reduces operative time and range of fixation in minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis: a multicenter retrospective cohort study. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-024-07565-0

[86] High-grade L5-S1 spondylolisthesis with lumbosacral kyphosis: Long-term results of non-instrumented circumferential arthrodesis in children, adolescents. Orthopaedics & Traumatology: Surgery & Research. 2022. DOI: 10.1016/j.otsr.2021.103093

[87] Patients With a History of Lumbar Fusion Have a Greater Risk of Revision Arthroscopy and Conversion to Total Hip Arthroplasty After Primary Hip Arthroscopy. Arthroscopy. 2024. DOI: 10.1016/j.arthro.2024.08.026

[88] Management of Lumbar Conditions in the Elite Athlete. Journal of the American Academy of Orthopaedic Surgeons. 2017. DOI: 10.5435/jaaos-d-16-00135

[96] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > STENOSIS OF THE THORACIC AND LUMBAR SPINE > ANATOMY.

[97] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > DISC AND SPINE ANATOMY > NEURAL ELEMENTS.

[98] Orthopaedic Basic Science Fifth Edition Print Ebook. Lumbar Spondylosis, Degenerative Disk Disease, and Radiculopathy > Introduction.

[99] Campbell S Operative Orthopaedics 4 Volume Set. RECONSTRUCTION OF THE PATELLOFEMORAL AND PATELLOTIBIAL LIGAMENTS WITH A SEMITENDINOSUS TENDON GRAFT > ANATOMY OF CERVICAL, THORACIC, AND LUMBAR PEDICLES.

[100] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Spinal Anatomy > Osseous Anatomy > Lumbar Vertebrae.

[103] Orthopaedic Basic Science Fifth Edition Print Ebook. Lumbar Spondylosis, Degenerative Disk Disease, and Radiculopathy > Lumbar Degenerative Disk.

[104] Evaluation of the learning curve and complications in unilateral biportal endoscopic transforaminal lumbar interbody fusion: cumulative sum analysis and risk-adjusted cumulative sum analysis. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-024-04674-3

[107] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > MAGNETIC RESONANCE IMAGING.

[109] Can Wallis topping-off surgery reduce radiographic adjacent segment degeneration? a single-center study with at least 8 years of long-term follow-up. BMC Musculoskeletal Disorders. 2025. DOI: 10.1186/s12891-025-09316-1

[110] Clinical evaluation of an allogeneic bone matrix containing viable osteogenic cells in patients undergoing one- and two-level posterolateral lumbar arthrodesis with decompressive laminectomy. Journal of Orthopaedic Surgery and Research. 2016. DOI: 10.1186/s13018-016-0392-z

[111] Biportal endoscopic transforaminal lumbar interbody fusion with large cage: a technique without additional spacer portal. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-024-05018-x

[119] Campbell S Operative Orthopaedics 4 Volume Set. LUMBAR DECOMPRESSION AND POSTEROLATERAL FUSION WITH OR WITHOUT INSTRUMENTATION > DIAGNOSTIC IMAGING.

[120] Early initiation of a strength training based rehabilitation after lumbar spine fusion improves core muscle strength: a randomized controlled trial. Journal of Orthopaedic Surgery and Research. 2018. DOI: 10.1186/s13018-018-0853-7

[126] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > THORACIC AND LUMBAR SPINE ARTHRODESIS.

[130] Reoperations after fusion surgeries for degenerative spinal diseases depending on cervical and lumbar regions: a national database study. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-021-04491-3

[133] Self-harm After Lumbar Fusion: Incidence of and Risk Factors for a Rare But Potentially Devastating Complication. JAAOS: Global Research and Reviews. 2025. DOI: 10.5435/jaaosglobal-d-25-00199

[134] Comparison of radiographic and clinical outcomes between ALIF, OLIF, and TLIF over 2-year follow-up: a comparative study. Journal of Orthopaedic Surgery and Research. 2023. DOI: 10.1186/s13018-023-03652-5

[138] Twenty-four-month interim results from a prospective, single-arm clinical trial evaluating the performance and safety of cellular bone allograft in patients undergoing lumbar spinal fusion. BMC Musculoskeletal Disorders. 2023. DOI: 10.1186/s12891-023-06996-5

[143] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > MINIMALLY INVASIVE ANTERIOR FUSION OF THE LUMBAR SPINE.

[147] Campbell S Operative Orthopaedics 4 Volume Set. RECONSTRUCTION OF THE PATELLOFEMORAL AND PATELLOTIBIAL LIGAMENTS WITH A SEMITENDINOSUS TENDON GRAFT > PERCUTANEOUS LATERAL APPROACH TO LUMBAR SPINE, L1 TO L4-5 (DLIF OR XLIF).

[152] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > OTHER TECHNIQUES.

[155] Polyetheretherketone (PEEK) rods versus titanium rods for posterior lumbar fusion surgery: a systematic review and meta-analysis. Journal of Orthopaedic Surgery and Research. 2023. DOI: 10.1186/s13018-023-03817-2

[157] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > ADULT ISTHMIC SPONDYLOLISTHESIS.

[158] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > NATURAL HISTORY OF DISC DISEASE.

[161] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > IN SITU POSTEROLATERAL INSTRUMENTED FUSION: WILTSE AND SPENCER APPROACH.

[164] Effect of metabolic syndrome on patient-reported outcome measures following lumbar fusion surgery: a longitudinal study with 24-month follow-up. Journal of Orthopaedic Surgery and Research. 2025. DOI: 10.1186/s13018-025-06003-8

[165] Campbell S Operative Orthopaedics 4 Volume Set. POSTERIOR APPROACH TO THE LUMBAR SPINE, L1 TO L5 > NATURAL HISTORY OF DISC DISEASE.

[166] Radiographic Analysis of Spondylolisthesis and Sagittal Spinopelvic Deformity. Journal of the American Academy of Orthopaedic Surgeons. 2012. DOI: 10.5435/jaaos-20-04-194

[167] Opioid Utilization Following Lumbar Arthrodesis. Spine. 2018. DOI: 10.1097/brs.0000000000002734

[170] Does Minimally Invasive Transsacral Fixation Provide Anterior Column Support in Adult Scoliosis?. Clinical Orthopaedics & Related Research. 2014. DOI: 10.1007/s11999-013-3335-6

[171] Tachdjian S Pediatric Orthopaedics From The Texas Scottish Rite Hospital For Children E Book. Lumbar spine modifier A, B, C rules > Complications of Posterior Instrumentation and Fusion for Adolescent Idiopathic Scoliosis.

[177] Campbell S Operative Orthopaedics 4 Volume Set. OVERVIEW OF LUMBAR AND THORACIC DISC DEGENERATION AND HERNIATION > OPERATIVE PLANNING.

[178] Orthopaedic Knowledge Update Sports Medicine 6. Thoracolumbar Spine > History and Physical Examination.

[185] Decompression, decompression plus fusion and decompression plus dynamic stabilization for degenerative lumbar spondylolisthesis: a network meta-analysis. Journal of Orthopaedic Surgery and Research. 2025. DOI: 10.1186/s13018-025-06550-0

[186] Lumbar fusion using a carbon-fiber PEEK pedicle screw system combined with a carbon-fiber PEEK TLIF cage: a prospective, multicenter study. BMC Musculoskeletal Disorders. 2025. DOI: 10.1186/s12891-025-08457-7

[188] Orthopaedic Knowledge Update Sports Medicine 6. Thoracolumbar Spine > Summary.

[194] Assessment of the suitability of biodegradable rods for use in posterior lumbar fusion: An in-vitro biomechanical evaluation and finite element analysis. PLOS ONE. 2017. DOI: 10.1371/journal.pone.0188034

[195] Roentgenographic and biomechanical analysis of lumbar fusions: A canine model. Journal of Orthopaedic Research. 1989. DOI: 10.1002/jor.1100070610

[196] Mini-open oblique lumbar interbody fusion (OLIF) approach for multi-level discectomy and fusion involving L5–S1: Preliminary experience. Orthopaedics & Traumatology: Surgery & Research. 2017. DOI: 10.1016/j.otsr.2016.11.016

[199] Objective evaluation of postoperative changes in real-life activity levels in the postoperative course of lumbar spinal surgery using wearable trackers. BMC Musculoskeletal Disorders. 2020. DOI: 10.1186/s12891-020-3102-2

[205] Comparison of three sacral screw internal fixation techniques in the treatment of L4–S1 lumbar degenerative disease with osteoporosis: a retrospective observational study. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-024-05281-y

[207] Classifications in Brief: The Spinal Deformity Study Group Classification of Lumbosacral Spondylolisthesis. Clinical Orthopaedics & Related Research. 2019. DOI: 10.1097/corr.0000000000001005

[211] Complications Associated With the Initial Learning Curve of Minimally Invasive Spine Surgery: A Systematic Review. Clinical Orthopaedics & Related Research. 2014. DOI: 10.1007/s11999-014-3495-z

[212] Fusion with and without lever reduction in degenerative lumbar spondylolisthesis: a retrospective study. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-023-04507-9

[213] Rehabilitation after cervical and lumbar spine surgery. EFORT Open Reviews. 2023. DOI: 10.1530/eor-23-0015

[214] Posterior fixation can further improve the segmental alignment of lumbar degenerative spondylolisthesis with oblique lumbar interbody fusion. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-021-04086-y

[215] Minimally invasive far lateral debridement combined with posterior instrumentation for thoracic and lumbar tuberculosis without severe kyphosis. Journal of Orthopaedic Surgery and Research. 2020. DOI: 10.1186/s13018-020-01703-9

[216] AN END-RESULT STUDY OF SEVENTY-THREE PATIENTS *. 1966.

[217] Comparison of safety and efficacy of posterior lumbar interbody fusion (PLIF) and modified transforaminal lumbar interbody fusion (M-TLIF) in the treatment of single-segment lumbar degenerative diseases. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-024-04531-3

[218] Application of self-anchored lateral lumbar interbody fusion in lumbar degenerative diseases. BMC Musculoskeletal Disorders. 2023. DOI: 10.1186/s12891-023-06974-x

[219] Severe abdominal aortic calcification is associated with poor two‑year outcomes after posterior lumbar interbody fusion in osteoporotic patients: a retrospective cohort study. BMC Musculoskeletal Disorders. 2026. DOI: 10.1186/s12891-026-10345-7

[220] En bloc resection of the ligamentum flavum for bilateral decompression in unilateral biportal endoscopic transforaminal lumbar interbody fusion: a 2-year follow-up study. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-024-05317-3

[221] Thoracolumbar spinal treatment without screws. The Bone & Joint Journal. 2016. DOI: 10.1302/0301-620x.98b1.37508

[223] Safety and efficacy of the polymer enhanced AS-ELARIS® pedicle screw system using ultrasonically liquefied polylactide: a short-, mid-, and long-term posterolateral fusion study in sheep. Journal of Orthopaedic Surgery and Research. 2026. DOI: 10.1186/s13018-026-06773-9

[224] Effectiveness of Surgery for Lumbar Stenosis and Degenerative Spondylolisthesis in the Octogenarian Population. The Journal of Bone and Joint Surgery-American Volume. 2015. DOI: 10.2106/jbjs.n.00313

[225] Hidden blood loss of minimally invasive hybrid lumbar interbody fusion: an analysis of influencing factors. BMC Musculoskeletal Disorders. 2022. DOI: 10.1186/s12891-022-06079-x

[227] Outcome of Lumbar Arthrodesis in Patients Sixty-five Years of Age or Older. Journal of Bone and Joint Surgery. 2010. DOI: 10.2106/jbjs.i.01300

[229] Comparison of the French and CARDS classifications for lumbar degenerative spondylolisthesis: reliability and validity. BMC Musculoskeletal Disorders. 2019. DOI: 10.1186/s12891-019-2753-3

[230] The influence of L4–S1 Dynesys® dynamic stabilization versus fusion on lumbar motion and its relationship with lumbar degeneration: a retrospective study. Journal of Orthopaedic Surgery and Research. 2017. DOI: 10.1186/s13018-017-0597-9

[232] Revision surgical treatments and classification system for cage retropulsion in degenerative lumbar disease. BMC Musculoskeletal Disorders. 2026. DOI: 10.1186/s12891-026-09616-0

[234] Percutaneous fixation as definitive care for AO spine type B thoracolumbar fractures in polytrauma patients. Injury. 2026. DOI: 10.1016/j.injury.2026.113503

[241] Lumbar spine fusion outcomes using a cellular bone allograft with lineage-committed bone-forming cells in 96 patients. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-021-04584-z

[242] A definition and clinical grading of Modic changes. Journal of Orthopaedic Research. 2021. DOI: 10.1002/jor.25240

[243] Paraspinal muscle changes after single-level posterior lumbar fusion: volumetric analyses and literature review. BMC Musculoskeletal Disorders. 2020. DOI: 10.1186/s12891-020-3104-0

[245] The study of distance changes between lumbar bi-cortical pedicle screws and anterior large vessels in patients with lumbar spondylolisthesis. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-021-04811-7

[248] Percutaneous endoscopic transforaminal lumbar interbody fusion: is it worth it?. International Orthopaedics. 2013. DOI: 10.1007/s00264-013-1905-6

[251] Elderly Patients Undergoing Minimally Invasive Transforaminal Lumbar Interbody Fusion May Have Similar Clinical Outcomes, Perioperative Complications, and Fusion Rates As Their Younger Counterparts. Clinical Orthopaedics & Related Research. 2019. DOI: 10.1097/corr.0000000000001054

[254] 18F-fluoride PET/CT as an early predictor of bony fusion after posterior lumbar interbody fusion– a prospective study. Journal of Orthopaedic Surgery and Research. 2025. DOI: 10.1186/s13018-025-05814-z

[256] Prevalence of modic changes in patients with low back pain and association with degenerative spinal findings: a retrospective MRI study. BMC Musculoskeletal Disorders. 2025. DOI: 10.1186/s12891-025-09182-x

[257] Combined use of intravenous and topical tranexamic acid efficiently reduces blood loss in patients aged over 60 operated with a 2-level lumbar fusion. Journal of Orthopaedic Surgery and Research. 2020. DOI: 10.1186/s13018-020-01758-8

[259] Total Hip Arthroplasty in Patients With Previous Lumbar Fusion Surgery: Are There More Dislocations and Revisions?. The Journal of Arthroplasty. 2018. DOI: 10.1016/j.arth.2017.10.041

[261] Radiologic adjacent segment degeneration 2 years after lumbar fusion for degenerative spondylolisthesis. Orthopaedics & Traumatology: Surgery & Research. 2016. DOI: 10.1016/j.otsr.2016.03.012

[262] The Results of Anterior Interbody Fusion of the Cervical Spine. The Journal of Bone & Joint Surgery. 1962. DOI: 10.2106/00004623-196244080-00007

[265] Type 2 sclerotic Modic change affect fusion result in patients undergoing PLIF with pedicle screw instrumentation: a retrospective study. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-021-04461-9

[266] How Is Lumbar Fusion Associated With Compensatory Hip Motion After THA?. Clinical Orthopaedics & Related Research. 2026. DOI: 10.1097/corr.0000000000003883

[267] Prosthetic Dislocation and Revision After Primary Total Hip Arthroplasty in Lumbar Fusion Patients: A Propensity Score Matched-Pair Analysis. The Journal of Arthroplasty. 2017. DOI: 10.1016/j.arth.2016.11.029

[268] The Effects of Chronic Preoperative Steroid Therapy on Perioperative Complications Following Elective Posterior Lumbar Fusion. Global Spine Journal. 2018. DOI: 10.1177/2192568218775960

[269] Spondylolisthesis treated by a single-stage operation combining decompression with in situ posterolateral and anterior fusion. An analysis of eleven patients who had long-term follow-up.. The Journal of Bone & Joint Surgery. 1990. DOI: 10.2106/00004623-199072030-00015

[270] The Impact of Osteoporosis on Adverse Outcomes After Short Fusion for Degenerative Lumbar Disease. Journal of the American Academy of Orthopaedic Surgeons. 2022. DOI: 10.5435/jaaos-d-21-01258

[271] Mid-term effects of posterior versus oblique lumbar interbody fusion on spinopelvic alignment and clinical outcomes in lumbar spinal stenosis: a retrospective comparative cohort study. Journal of Orthopaedic Surgery and Research. 2026. DOI: 10.1186/s13018-026-06818-z

[272] Effects of Underlying Liver Disease on 30-Day Outcomes After Posterior Lumbar Fusion. World Neurosurgery. 2019. DOI: 10.1016/j.wneu.2019.01.160

[274] Posterior Lumbar Fusion Is Being Performed for Patients of Increasing Comorbidity Burden Over the Years, but Adverse Events Are Not Going Up. JAAOS: Global Research and Reviews. 2026. DOI: 10.5435/jaaosglobal-d-25-00379

[275] Lumbar fusion involving the sacrum increases dislocation risk in primary total hip arthroplasty. The Bone & Joint Journal. 2019. DOI: 10.1302/0301-620x.101b2.bjj-2018-0754.r1

[278] Incidence and risk factors for early and late reoperation following lumbar fusion surgery. Journal of Orthopaedic Surgery and Research. 2022. DOI: 10.1186/s13018-022-03273-4

[279] Long-term outcome of fusion for degenerative disc disease in the lumbar spine. The Bone & Joint Journal. 2019. DOI: 10.1302/0301-620x.101b12.bjj-2019-0427.r1

[281] Predictive factors of distal pedicle screw loosening followed posterior corrective surgery for degenerative lumbar scoliosis. BMC Musculoskeletal Disorders. 2025. DOI: 10.1186/s12891-025-08519-w

[282] Evaluating Outcomes of Spinopelvic Fixation for Patients Undergoing Long Segment Thoracolumbar Fusion with a Prior Total Hip Arthroplasty. Journal of the American Academy of Orthopaedic Surgeons. 2023. DOI: 10.5435/jaaos-d-22-00897

[284] Patients Undergoing Multilevel Thoracolumbar Fusions With Prior Total Hip Arthroplasty Are at Higher Risk for Prosthetic Dislocations. Journal of the American Academy of Orthopaedic Surgeons. 2025. DOI: 10.5435/jaaos-d-24-00606

[285] High-Dose rhBMP-2 for Adults: Major and Minor Complications. Journal of Bone and Joint Surgery. 2013. DOI: 10.2106/jbjs.l.01730

[286] Pseudarthrosis risk factors in lumbar fusion: a systematic review and meta-analysis. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-024-07531-w

[287] The further exploration of hidden blood loss in posterior lumbar fusion surgery. Orthopaedics & Traumatology: Surgery & Research. 2017. DOI: 10.1016/j.otsr.2017.01.011

[290] Unique characteristics of bone union at the infected vertebrae after minimally invasive posterior fixation without bone grafting in thoracolumbar pyogenic spondylitis: a retrospective multicenter cohort study. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-024-07993-y

[291] Results of spinal arthrodesis with pedicle screw-plate fixation.. The Journal of Bone & Joint Surgery. 1991. DOI: 10.2106/00004623-199173080-00006

[294] Cefazolin Alone Versus Cefazolin with Tobramycin or Gentamicin as Intraoperative Antibiotic Prophylaxis for Single-Level Posterior Lumbar Fusion. JAAOS: Global Research and Reviews. 2024. DOI: 10.5435/jaaosglobal-d-24-00082