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Periacetabular osteotomy

103 citationsUpdated Sep 2026

Overview

Periacetabular osteotomy (PAO) is an effective technique for treating symptomatic developmental dysplasia of the hip and acetabular retroversion in selected patients, particularly those with closed triradiate cartilage [3, 16, 20]. The procedure provides pain relief and improved hip function in most patients over short- to midterm followup [1]. Refinements in the PAO technique and perioperative management have markedly improved clinical outcomes and recovery [2]. While the Bernese PAO yields favourable mid-to long-term outcomes, this is conditional on stringent patient selection criteria [10]. For patients older than 40 years, PAO provides excellent quality of life outcomes in a high percentage of cases, though it should only be performed in highly selected individuals [5]. In patients with mild arthritis who do not qualify for PAO, total hip arthroplasty is a reasonable surgical intervention [24].

The procedure is associated with a 5.9% risk of grade-III or IV complications beyond the learning curve for experienced surgeons [11]. However, complications may be expected in as many as 15% of cases [17]. The preoperative presence of acetabular cysts does not influence results [15]. When performed by an experienced surgeon, the addition of arthroscopy before PAO can be done safely and does not increase the complication rate [13]. Combined PAO and femoral head-neck junction osteochondroplasty provides effective correction of associated femoral head-neck deformities and produces similar early functional outcomes compared with isolated PAO [8]. Single-stage combined hip arthroscopy with PAO results in improvement in patient-reported outcomes and arthroplasty-free survivorship of 92% at median 2.5 year follow-up [26].

Optimal combined anteversion should be considered during the procedure [4]. The HOOS appears to be the most appropriate measure of patient-reported outcome in patients undergoing PAO [7]. PAO used as a salvage procedure for patients with hip instability recalcitrant to prior arthroscopy demonstrated substantial improvement in patient-reported outcome measures and radiographic correction of acetabular coverage [6]. Sufficient acetabular reorientation with concomitant arthroscopic debridement showed successful long-term outcomes for acetabular dysplasia in adults [18]. The combination of hip arthroscopy and PAO is safe and effective, but clearer definitions for labral pathology and indications for repair or debridement are required [29]. Authors argue for moving beyond generalized results to identify specific patient subgroups who do not do well with hip arthroscopy alone and should be considered for initial treatment with PAO [27]. Patients with a history of PAO were more likely to deliver future children by cesarean section, which could be attributable to obstetrician preference [12]. Elevation of hip joint centers as much as 10 mm is one therapeutic option in the case of severe acetabular defects following total hip arthroplasty after PAO [9].

Anatomy & Pathophysiology

Bony Anatomy and Morphology

Acetabular retroversion is managed with acetabular rim trimming or periacetabular osteotomy [3]. Hips exhibiting lower anteversion or a larger discrepancy between anatomic and functional anteversion are more likely to present with symptoms [75]. Increased cam morphology significantly reduces internal rotation without affecting hip flexion [73]. Patient age and hip shape are critical determinants of resulting hip mechanics [61]. Lumbopelvic hyperlordosis correlates with higher femoral head coverage, lower femoral anteversion, and younger age at the time of periacetabular osteotomy [102]. Concomitant lumbopelvic deformity affecting hip joint morphology can aggravate clinical symptoms, leading to earlier presentation in patients undergoing periacetabular osteotomy [102]. Acetabular retroversion and decreased posterior coverage are associated with sports-related posterior hip dislocation in adolescents [51].

The three primary factors involved in hip joint preservation are femoroacetabular impingement, hip dysplasia, and femoral torsion abnormalities [104, 148]. An imbalance among femoroacetabular impingement, hip dysplasia/instability, or femoral torsion abnormalities may result in damage to the acetabular labrum and femoroacetabular cartilage [148]. In acetabular dysplasia, instability and anterolateral migration of the femoral head lead to chronic shear stress at the acetabular margin [149]. This chronic shear stress can lead to labro-chondral dissociation and extensive full-thickness chondral defects [149]. In femoroacetabular impingement, repeated compression forces during hip flexion and internal rotation lead to cartilage injuries in the anterosuperior region of the acetabulum and the anterolateral region of the femoral head [149]. Cartilage damage frequently occurs in the pericotyloid fossa area of the acetabulum and the apex of the femoral head in patients with borderline dysplasia [149]. Overall, hip morphology influences the pattern of hip articular cartilage injury [149].

Soft Tissue and Biomechanics

Hip dysplasia is a pathoanatomic osseous morphology associated with hip instability that may, in part, be due to hip capsular thickness [77]. Individual and postural variations in physiologic pelvic tilt affect joint contact pressure in the hip [72]. Muscle-induced biomechanics may have wide-reaching effects on loads within the hip and on patients' perceptions of their health and function [57]. Muscle-induced biomechanical variables in patients with developmental dysplasia of the hip are associated with worse function and pain outcomes [94]. Weightbearing postural radiographs are crucial for understanding hip biomechanics in hip dysplasia [74].

Periacetabular osteotomy causes reductions in hip abduction and internal rotation but greater increases in hip adduction and external rotation [88]. The higher the hip center, the more bone coverage is gained, but this decreases the range of hip flexion and internal rotation [100]. In patients with hip dysplasia, a smaller weightbearing area results in higher contact stresses, resulting in cartilage breakdown [101]. Long-term exposure to elevated cartilage contact stresses may affect joint morphology, making hips less amenable to joint-preservation procedures such as periacetabular osteotomy [84]. The degree of acetabular correction in the coronal plane where joint contact pressure is minimized varies among patients [99]. Higher degrees of fragment reorientation in abduction and extension limit the ability to achieve the intended improvement in overall hip biomechanics, especially in reverse periacetabular osteotomy for acetabular retroversion or protrusio acetabuli [80].

Rotational acetabular osteotomy is more effective in relieving hip joint stress compared with shelf procedure and Chiari osteotomy [81]. Reorientation of the acetabulum reduces stress at the acetabular rim and shifts the os acetabuli out of the stress region, allowing union of the bony fragment with the acetabulum [93]. Different combinations of acetabular rotations can result in large variations in femoral head coverage and hip motion [90]. No single combination of acetabular rotations is applicable to all cases for optimizing femoral head coverage and range of motion [90]. The percentage of femoral head coverage determined by center of gravity strongly correlated with segmented acetabular subtended angles and likely reflected true values [91]. Computer-assisted analysis of young adult hip radiographs generally demonstrates substantial to excellent levels of interobserver reliability for most parameters [96].

Pathophysiology and Natural History

Progression of arthritis after periacetabular osteotomy is related directly to the extent of arthritis present at the time of the procedure [21]. There is a significant association between advanced osteoarthritis and an unsatisfactory clinical outcome after periacetabular osteotomy [21]. Anatomic aberrations of the proximal femur resulting from underlying disease or previous surgeries may predispose patients to femoroacetabular impingement [21]. High-level sport and combat sports are major risk factors for mechanical hip pathology in young adults [86]. A familial history of hip pathology is confirmed as a risk factor for mechanical hip pathology in young adults [86].

Additional studies are needed to determine protective or adaptive factors in patients with abnormal anatomy who do not develop early osteoarthritis [76]. Additional studies are needed to determine whether joint preserving hip surgery extends the life of the native hip joint [76]. Thorough patient evaluation with detailed characterization of structural hip anatomy and articular cartilage integrity are critical to the selection of proper surgical intervention and successful patient outcome [78]. Patients with evidence of abnormal hip morphologies may not benefit from hip arthroscopy and isolated treatment of the labrum, which may accelerate the process of arthritis in some patients [105]. Standardisation of the modes of failure may help identify the best practice for joint-preserving surgery of the hip [83].

Obesity and heterotopic ossification formation are independent predictors of persistent hip dysfunction after periacetabular osteotomy [108]. Preoperative age older than 35 and fair or poor joint congruence have been reported to be independent factors predictive of failure of periacetabular osteotomy [107]. When preoperative age is older than 35 and joint congruence is fair or poor, the chance of resultant severe pain or conversion to total hip replacement reached 95% [107]. The problem in patients with hip dysplasia is one of abnormal loading, where a smaller weightbearing area results in higher contact stresses leading to cartilage breakdown [101].

Classification

Instability-Based Framework: A diagnostic framework categorizes symptomatic dysplastic hips into three groups based on the primary direction of instability: anterior, posterior, and global [127].

Morphologic Subtypes: Recognition of distinct morphologic subtypes of acetabular deficiency is essential for diagnostic and surgical treatment considerations. Identifying these subtypes optimizes acetabular correction and helps avoid femoroacetabular impingement [36].

Other Considerations: The standard radiographic classification of 'borderline dysplastic' (LCEA 20° and <25°) and 'dysplastic' (LCEA <20°) is unreliable with respect to stability [30]. Computed tomography-based three-dimensional analyses demonstrate similarities in anterosuperior acetabular coverage between acetabular dysplasia and borderline dysplasia [133]. Prominent anterior inferior iliac spine morphologies are common in patients with acetabular dysplasia undergoing periacetabular osteotomy [132]. The morphology of the anterior inferior iliac spine in patients with symptomatic dysplasia may aid preoperative planning, surgical technique, and evaluation of postoperative issues after periacetabular osteotomy [132].

Clinical Presentation

Demographics and Onset

Symptomatic acetabular dysplasia in skeletally mature patients presents with a female predominance of 72% and a mean age of 24 years [98]. The initial clinical presentation is insidious in 97% of hips [98]. Patients with borderline hip dysplasia demonstrate worse preoperative patient-reported outcome measures than those with frank dysplasia [120].

Pain Characteristics

Activity-related hip pain is present in 88% of patients with symptomatic acetabular dysplasia [98]. Moderate-to-severe pain on a daily basis is associated with 77% of symptomatic hips [98]. Pain is most commonly localized to the groin in 72% of cases [98] and to the lateral aspect of the hip in 66% of cases [98]. Activity restriction diminishes hip pain in 75% of cases [98].

Physical Examination Findings

A positive impingement sign is present in 97% of hips with symptomatic acetabular dysplasia [98]. A limp is associated with 48% of affected hips [98], while a positive Trendelenburg sign is present in 38% [98].

Radiographic and Morphologic Features

Acetabular dysplasia is defined by a lateral center-edge angle less than 25° [35]. In the context of symptomatic presentation with hip pain for more than 3 months that interferes with daily function, it is defined by a lateral center-edge angle less than 20° [41]. Three distinct morphologic subtypes of acetabular deficiency are common in young adult patients with acetabular dysplasia [36]. Radiological evidence of symptomatic femoroacetabular impingement is not uncommon in patients with hip pain, with cam deformity findings being the most common [48]. Acetabular and femoral osseous abnormalities are commonly associated with labral tears [123].

Associated Pathology and Comorbidities

Acetabular dysplasia is recognized as a cause of early degenerative hip osteoarthritis [98]. Patients with a history of periacetabular osteotomy were more likely to deliver future children by cesarean section [12].

Investigations

Plain radiography: Conventional radiographs serve as the initial imaging modality for developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) [56]. A complete hip series comprises an anterior-posterior (AP) pelvis, a centered AP hip, a lateral view (frog-leg, cross-table, Dunn 45° or 90°), and a false-profile (Lequesne) view [63]. Standard AP radiographs examine bony architecture, joint space narrowing, bone quality changes, and femoral head coverage [62]. Acetabular morphology is assessed on AP pelvis radiographs for overcoverage and undercoverage [63]. The "crossover" sign indicates acetabular retroversion related to lateralization of the anterior acetabular wall relative to the posterior acetabular wall; however, an optimal AP pelvis image is required, as pelvic tilt or rotation may lead to false-positive and false-negative results [63]. For neutral pelvic tilt, the sacrococcygeal joint should be between 3 and 5 cm above the superior border of the symphysis pubis [63]. The ilioischial line and acetabular fossa contour are assessed, with coxa profunda diagnosed when the fossa line touches or is medial to the ilioischial line [63]. The femoral head extrusion index is defined by the length of the femoral head beyond the acetabulum as a percentage of the total horizontal width of the femoral head, with values greater than 25% considered abnormal [63]. The Tönnis angle is defined by the angle of the acetabular sourcil and a line parallel to the transverse pelvis axis, with angles between 0° and 10° considered normal [63]. The lateral center-edge angle of Wiberg is the angle between a line from the center of the femoral head perpendicular to the transverse pelvis axis and a second line from the center of the femoral head to the superolateral most point of the acetabulum [63]. Center-edge angles of 20°–40° are considered normal, while angles from 20° to 25° are considered borderline [63]. The Dunn view and frog leg view are appropriate to measure the alpha angle to determine the presence of impingement [62]. Some studies have shown that radiographs, in particular the Dunn 45° view, may be more accurate for determining the alpha angle measurement than CT or MRI [63]. The femoral head-neck junction morphology is often assessed using the alpha angle [63]. The windshield wiper sign is a radiographic instability sign visible on plain radiographs that predicts hip instability and allows for the planning of combined arthroscopic cartilage therapy and periacetabular osteotomy [125]. Radiographic reference values for acetabular under- and overcoverage may be used for radiographic evaluation of symptomatic hips, may offer possible predictors for surgical outcomes, and serve to guide clinical decision-making [143].

CT: Computed tomography overcomes the limitations of radiography by providing three-dimensional assessment of bony morphology and, to some degree, assessment of soft-tissue abnormalities [56]. CT scans are effective for examining cortical and cancellous bone and can be used to create three-dimensional reconstructions of the hip for use in surgical planning [62]. Measurements of femoral head coverage and acetabular and femoral impingement can be performed reliably using CT images [62]. Low-dose CT with three-dimensional reformats is particularly useful in surgical planning of complex or borderline deformities [68]. The multiplanar and 3D capabilities of CT make it an invaluable tool for assessing bone morphology, but at higher cost and radiation dose [66]. 3D volume renderings are useful to aid in preoperative planning in FAI and subspine impingement [66].

MRI: The soft-tissue contrast of MRI is superior to other imaging modalities in assessing both intra-articular and extra-articular hip pathology [56]. For patients suspected of soft tissue or intra-articular pathology, MRI is the modality of choice, given its superior sensitivity and specificity [62]. Conventional MRI is effective at identifying osteochondral injuries, musculotendinous pathologies, and inflammation [62]. Magnetic resonance arthrography (MRA) is more appropriate to determine injuries to the labrochondral structures and the ligamentum teres and identify the presence of loose bodies and synovial chondromatosis [62]. In the accurate detection and staging of articular cartilage lesions, the utility of MRA is reduced, with sensitivity reported to be less than 50% compared with arthroscopic findings [62]. Recent advances in MRI imaging techniques, such as delayed gadolinium-enhanced MR imaging and T2 mapping, allow for a more in-depth analysis of the structure of articular cartilage [62]. Delayed gadolinium-enhanced MR imaging and T2 mapping were effective at detecting early changes to the articular cartilage surfaces of patients with hip dysplasia and femoroacetabular impingement [62]. MRI provides information regarding the integrity of the acetabular labrum and articular cartilage, as well as the anatomy of the proximal femur and the version of the acetabulum and femur [68]. The sensitivity of MRI to acetabular rim chondral lesions is limited [68]. Noncontrast MRI at 3T is generally adequate for diagnosing intra-articular pathology [66]. If 3T imaging is unavailable, MRA can be considered at 1.5T for increased diagnostic accuracy [66]. MRI is helpful in identifying femoral neck stress fracture in athletes and predicting patients that may require surgical intervention [66]. Preoperative MRI evaluation of femoral anteversion is recommended as essential rather than adjunctive [142]. Coronal femoroacetabular distance and limbus thickness on post-reduction MRI help predict hips that will have residual acetabular dysplasia in the long term after closed or open reduction [141].

Ultrasonography: Ultrasonography provides real-time dynamic assessment of the hip and is useful in diagnosing soft-tissue abnormalities about the hip joint [56]. Ultrasonography is particularly useful in providing real-time guidance during diagnostic and therapeutic procedures [56]. Although ultrasonography is a valuable tool to examine pediatric hip conditions, its utility in evaluating the adult hip is limited [62]. Ultrasonography can be an effective modality to identify musculotendinous disruptions, effusions associated with intra-articular pathology, or inflammatory conditions, such as bursitis [62]. Ultrasonography is increasingly used for targeted injections into muscles, tendons, or intra-articularly around the hip [62]. Ultrasonography shows nonossified structures such as the femoral head and is useful to diagnose hip dysplasia and dislocation [67]. Ultrasonography provides dynamic assessment of structures such as tendon and nerve subluxation [67]. Ultrasonography cannot image inside bone because bone cortex reflects almost all sound waves [67]. Internal joint structures are not well visualized by ultrasonography unless they are in a superficial location [67].

Other Considerations: A thorough understanding of normal anatomy and biomechanics is necessary to identify pathology and determine the appropriate course of treatment [55]. Because many hip conditions present with similar symptoms, a comprehensive clinical examination is required to determine a differential diagnosis [55]. Findings from imaging studies should complement clinical examination findings to provide the most accurate diagnosis [55]. A thorough history is essential to differentiating between common causes of hip pain [55]. Clinical examination tests and imaging findings should be used to confirm a suspected clinical diagnosis [55]. Patients with FAI will exhibit restricted hip internal rotation in 90° of flexion [68]. The impingement test (flexion, adduction, internal rotation) will elicit pain in patients with FAI, but the test is not specific for FAI [68]. Surgeons should not ignore posterior hip or gluteal pain or discomfort after periacetabular osteotomy as it could originate from ischiofemoral impingement, and a proper investigation and clinical assessment can help define the source of pain [32]. The authors encourage thorough preoperative evaluation of radiographs and advanced imaging for all patients being considered for hip arthroscopy [49]. Radiological evidence of symptomatic femoroacetabular impingement was not uncommon in Japanese patients with hip pain, with cam deformity findings being the most common [48]. Osteoarthritis of the hip can be categorized using the Kellgren-Lawrence or Tönnis classifications [63]. The Kellgren-Lawrence classification is a 4-point grading system classified into doubtful, mild, moderate, and severe [63]. The Tönnis classification is a 3-point grading system categorized into mild, moderate, and severe [63]. Radiographic and clinical severity do not necessarily correlate, particularly if the radiographs are non-weight-bearing or if false-profile views are not included [63].

Treatment

Non-Operative

The provided evidence does not detail specific conservative management protocols such as weight loss, physical therapy, NSAIDs, or injections. However, patients with prior nonoperative or operative treatment for dysplasia of the hip can be counseled on the potential for increased complications and incomplete correction but should be encouraged that they are likely to have good pain relief and function after periacetabular osteotomy [22].

Operative

Indications: Periacetabular osteotomy remains an option for patients older than 40 years, providing excellent quality of life outcomes in a high percentage of this demographic, though it should only be performed in highly selected cases [5]. Instability-driven symptoms in patients with borderline hip dysplasia primarily indicate periacetabular osteotomy [122]. Specific patient subgroups who do not do well with hip arthroscopy alone should be considered for initial treatment with periacetabular osteotomy [27].

Surgical Approach / Technique: The Bernese periacetabular osteotomy is currently favored for restoring pelvic anatomy with good correction and minimal secondary deformity [40]. Isolated lateral rotation of the acetabular fragment should be the predominant direction of correction during the procedure [14]. The oblique inguinal incision for the anterior approach allows healing of surgical wounds without dehiscence or hypertrophic changes by respecting tension lines [85]. A curved periacetabular osteotomy modification aims to reduce postoperative complications through the use of a minimally invasive exposure and a spherical osteotomy of the acetabulum [43]. Preservation of the intact posterior column in the Bernese technique may be responsible for persistent technical difficulties and serves no useful purpose beyond vanity, suggesting that modifying the posterior column cut plane or using alternative techniques like the Birmingham Interlocking Pelvic Osteotomy may improve outcomes [50].

Adjuncts: The combined procedure of periacetabular osteotomy and femoral head-neck junction osteochondroplasty provides effective correction of associated femoral head-neck deformities and produces similar early functional outcomes when compared with isolated periacetabular osteotomy [8]. Arthroscopy provides a powerful tool to successfully treat intra-articular hip pathology secondary to dysplasia while improving the bony coverage/alignment with periacetabular osteotomy; through a specialized team approach, all relevant pathology can be addressed and successful outcomes achieved [28]. Periacetabular osteotomy with arthroscopic labral repair successfully managed a case of failed hip arthroscopy due to iatrogenic aggravation of hip dysplasia, preserving function to a hip with dysplasia [34].

Other Considerations: The risk from chemoprophylaxis and the development of hematoma may be greater than the risk of clinically important venous thromboembolism in patients undergoing periacetabular osteotomy [42]. Among the scores analyzed, the HOOS appears to be the most appropriate measure of patient-reported outcome in patients undergoing periacetabular osteotomy [7]. Activity levels and hip function improved after periacetabular osteotomy in patients with borderline hip dysplasia, and participation in high-impact sports was maintained postoperatively [25]. One-third of hips after periacetabular osteotomy survive 30 years with good clinical results, no progression of arthritis, or conversion to total hip arthroplasty [20]. Previous Bernese periacetabular osteotomy does not compromise the results of total hip arthroplasty [21]. In cases with large preoperative bone defects, the acetabular component was placed more superiorly in the periacetabular osteotomy group, which did not appear to affect long-term (10 year) implant survivorship [53].

Complications

General Complication Rates: For surgeons experienced with periacetabular osteotomy, the procedure carries a 5.9% risk of grade-III or IV complications beyond the learning curve [11], although complications may be expected in as many as 15% of cases following Bernese periacetabular osteotomy [17]. In a structured-mentorship program for a low-volume surgeon, 41 periacetabular osteotomies had a postoperative complication within the first 12 months of surgery [139]. The incidence of postoperative complications and revision surgery was not different between total hip arthroplasty and periacetabular osteotomy groups [153]. Patients with prior nonoperative or operative treatment for dysplasia of the hip can be counseled on the potential for increased complications and incomplete correction after periacetabular osteotomy [22]. In a series of 37 patients undergoing reverse periacetabular osteotomy, the complication rate was 19% [137]. In a series of 33 hips in teenagers, 9 hips (27%) presented with complications or symptoms, while 24 hips (73%) had no post-operative clinical or radiographic issues [130].

Nonunion and Healing: The proportion of nonunion at a minimum of 12 months after periacetabular osteotomy was 8% [52]. At the 6-month visit, 45% (96 of 215) of patients had complete radiographic healing of all osteotomy sites, while 55% (119 of 215) had not healed completely [52]. At approximately 1 year postoperatively, 92% (225 of 245) of patients demonstrated complete radiographic healing of all osteotomy sites [52]. In a series of teenagers, the most common minor complication was nonunion at an osteotomy site, occurring in 4 hips (12%) at the superior pubic ramus [130]. All patients with nonunion of the superior pubic ramus in the teenage series were completely asymptomatic [130]. In a structured-mentorship program, two ischial nonunions caused painful pubic stress fractures that eventually settled [139].

Nerve Injury: Transient lateral femoral cutaneous nerve numbness occurred in 3 hips (9%) in a series of teenagers [130]. All cases of transient lateral femoral cutaneous nerve numbness in the teenage series were asymptomatic and did not require further intervention [130]. In a structured-mentorship program, one temporary femoral nerve palsy occurred as a Grade II complication [139]. In a structured-mentorship program, one temporary partial sciatic nerve palsy occurred in association with a posterior column fracture as a Grade II complication [139]. Both nerve injuries in the structured-mentorship program fully recovered within 3 months [139]. In a series of combined hip arthroscopy and periacetabular osteotomy, a partial sciatic nerve palsy developed in 1 patient and resolved on postoperative day 3 [147]. Femoral nerve palsy is particularly concerning in reverse periacetabular osteotomy because of abduction of the acetabular fragment that results in intrapelvic prominence and potential femoral nerve irritation [137]. Five patients had dysaesthesias in the distribution of the lateral femoral cutaneous nerve following Salter innominate osteotomy [134].

Wound and Infection: In a series of teenagers, superficial stitch abscess occurred in 1 hip (3%) [130]. In a structured-mentorship program, three superficial wound infections were treated using antibiotics [139]. In a structured-mentorship program, one wound infection was treated with irrigation and débridement as a Grade III complication [139]. In a series of combined hip arthroscopy and periacetabular osteotomy, 1 patient developed a superficial wound infection treated successfully with oral antibiotics [147]. In a series of combined hip arthroscopy and periacetabular osteotomy, 1 patient developed proximal wound dehiscence and possible infection requiring a return to the operating room for irrigation and debridement [147]. Extensive dissection of the abductors from the outer aspect of the pelvis to complete an iliac osteotomy may cause ischemic insult to the functional integrity of the muscle [43]. Dissection of the gluteus muscles allows a considerable rate of postoperative complications, such as delayed wound healing and superficial infection [43].

Fractures: In a structured-mentorship program, eight isolated posterior column fractures united uneventfully [139]. In a series of combined hip arthroscopy and periacetabular osteotomy, 1 patient had a known intraoperative posterior column fracture [147]. Stress fracture of the inferior pubic ramus was found incidentally on a routine follow-up examination in 2 patients (6%) in a series of teenagers [130]. All stress fractures of the inferior pubic ramus in the teenage series were asymptomatic and did not require further intervention [130]. One patient undergoing Salter innominate osteotomy underwent re-operation 2 weeks after the first operation because a fall led to dislocation of the osteotomy and loss of correction [134].

Thromboembolism: In a series of combined hip arthroscopy and periacetabular osteotomy, a pulmonary embolism developed in 1 patient after noncompliance with the discontinuation of oral contraceptive medication [147].

Heterotopic Ossification: The most common complication in a series of reverse periacetabular osteotomy was heterotopic ossification resulting in surgical resection [137].

Hernia: Incisional hernia is a rare complication (0.2% incidence) after periacetabular osteotomy [138]. Risk factors for incisional hernia after periacetabular osteotomy include obesity, weak abdominal muscles, and increased intraabdominal pressure [138].

Obstetric Complications: The increased likelihood of cesarean section in patients with a history of periacetabular osteotomy could be attributable to obstetrician preference [12].

Hardware and Fixation Issues: In a structured-mentorship program, one patient underwent removal of an irritating anterosuperior iliac spine (ASIS) screw as a Grade III complication [139]. In a structured-mentorship program, one patient underwent refixation for delayed union as a Grade III complication [139]. In a structured-mentorship program, one patient underwent revision correction and fixation of the periacetabular osteotomy as a Grade III complication [139].

Blood Loss: The mean estimated blood loss in a series of combined hip arthroscopy and periacetabular osteotomy was 1,064 mL (range, 300 to 2,000 mL) [147].

Recovery

Functional Outcomes and Pain Relief: Periacetabular osteotomy provides excellent quality of life outcomes in a high percentage of patients, though it should only be performed in highly selected cases [5]. Satisfactory clinical and radiographic results are achievable after curved periacetabular osteotomy in patients fifty years of age or older with Tönnis grade-1 or 2 osteoarthritis of the hip secondary to developmental dysplasia [23]. Patients with prior nonoperative or operative treatment for dysplasia of the hip are likely to have good pain relief and function after periacetabular osteotomy [22]. Single-stage combined hip arthroscopy with periacetabular osteotomy for patients with symptomatic hip dysplasia results in improvement in patient-reported outcomes and arthroplasty free survivorship of 92% at median 2.5 year follow-up [26]. Combined surgical dislocation and periacetabular osteotomy provided clinical improvement and intermediate-term survivorship of 85% at 10 years for patients with complex residual Legg-Calvé-Perthes deformities [38]. The novel minimally invasive spherical periacetabular osteotomy (SPO) using patient-specific preoperative planning is a feasible technique with short-term results showing significant radiographic correction and clinical improvement [54].

Activity and Sports Participation: Overall, activity levels and hip function improved after periacetabular osteotomy, and although more patients engaged in low-impact sports, participation in high-impact sports was maintained postoperatively [25]. The majority (71%) of active patients with hip dysplasia return to presurgical or higher activity levels after open hip preservation surgery with the periacetabular osteotomy [39].

Complications and Safety: The novel minimally invasive spherical periacetabular osteotomy (SPO) is associated with a high rate of transient lateral femoral cutaneous nerve palsy [54].

Patient-Reported Outcomes and Decision-Making: The study underscores the need for more consistent and effective shared decision-making in periacetabular osteotomy decision-making, highlighting gaps in addressing patients' complex information needs and the necessity for improved training and decision-support tools [151].

Specific Clinical Considerations: This combined procedure provides effective correction of associated femoral head-neck deformities and produces similar early functional outcomes when compared with isolated periacetabular osteotomy [8].

Key Evidence

• [L4] Periacetabular osteotomy provides pain relief and improved hip function in most patients over short- to midterm followup. [1] (10.1007/s11999-009-0842-6)
• [L5] Refinements in the periacetabular osteotomy technique and perioperative management have markedly improved the clinical outcomes and recovery in these patients. [2] (10.1016/j.arth.2017.02.015)
• [L4] Acetabular rim trimming (ART) and periacetabular osteotomy (PAO) are the best described surgical options for the treatment of AR. [3] (10.1302/2058-5241.3.180015)
• [L4] Optimal combined anteversion should be considered during periacetabular osteotomy. [4] (10.1007/s11999-015-4373-z)
• [L3] However, periacetabular osteotomy still provided excellent quality of life outcomes in a high percentage of patients, though it should only be performed in highly selected cases. [5] (10.1016/j.arth.2007.08.015)
• [L4] Periacetabular osteotomy used as a salvage procedure for patients with hip instability recalcitrant to prior arthroscopy demonstrated substantial improvement in patient-reported outcome measures and radiographic correction of acetabular coverage. [6] (10.2106/jbjs.20.00087)
• [L3] Among the scores analyzed, the HOOS appears to be the most appropriate measure of patient-reported outcome in patients undergoing periacetabular osteotomy. [7] (10.2106/jbjs.18.00185)
• [L3] This combined procedure provides effective correction of associated femoral head-neck deformities and produces similar early functional outcomes when compared with isolated periacetabular osteotomy. [8] (10.2106/jbjs.k.01038)
• [L3] Elevation of hip joint centers as much as 10 mm is one therapeutic option in the case of severe acetabular defects following total hip arthroplasty after periacetabular osteotomy. [9] (10.1007/s00402-019-03174-y)
• [L2] The Bernese periacetabular osteotomy is able to result in favourable midto long-term outcomes conditional on a stringent patient selection criteria. [10] (10.1016/j.otsr.2022.103283)
• [L4] For surgeons experienced with the periacetabular osteotomy, it is a safe procedure but is associated with a 5.9% risk of grade-III or IV complications beyond the learning curve. [11] (10.2106/jbjs.n.00113)
• [L4] However, we did note that patients with a history of periacetabular osteotomy were more likely to deliver future children by cesarean section, which could be attributable to obstetrician preference. [12] (10.1097/corr.0000000000000921)
• [Paper] When performed by an experienced surgeon, the addition of arthroscopy before periacetabular osteotomy can be done safely and does not increase the complication rate. [13] (10.1016/j.eats.2019.08.015)
• [L5] Isolated lateral rotation of the acetabular fragment should be the predominant direction of correction during periacetabular osteotomy. [14] (10.1007/s00402-020-03632-y)
• [L3] The preoperative presence of acetabular cysts did not influence the results of periacetabular osteotomy. [15] (10.1097/01.blo.0000229370.88479.76)
• [L3] Periacetabular osteotomy is an effective technique for treating symptomatic developmental dysplasia of the hip and can maintain the natural hip at least 19 years in selected patients. [16] (10.1007/s11999-008-0242-3)
• [L2] The Bernese periacetabular osteotomy can be effective for the treatment of painful hip dysplasia, but complications may be expected in as many as 15% of cases. [17] (10.2106/jbjs.j.00646)
• [L3] Sufficient acetabular reorientation, such as periacetabular rotational osteotomy, with concomitant arthroscopic debridement showed successful long-term outcomes for acetabular dysplasia in adults. [18] (10.1016/j.arth.2020.05.045)
• [L3] Periacetabular osteotomy is an effective technique to treat symptomatic hip dysplasia in selected and young patients with closed triradiate cartilage. [20] (10.1007/s11999-016-5169-5)
• [L4] [21] (10.1097/01.blo.0000128287.98083.63)
• [L5] Patients with prior nonoperative or operative treatment for dysplasia of the hip can be counseled on the potential for increased complications and incomplete correction but should be encouraged that they are likely to have good pain relief and function after periacetabular osteotomy. [22] (10.1097/corr.0000000000003200)
• [L2] Satisfactory results can be obtained clinically and radiographically after curved periacetabular osteotomy in patients fifty years of age or older with Tönnis grade-1 or 2 osteoarthritis of the hip secondary to developmental dysplasia. [23] (10.2106/jbjs.j.01126)
• [L3] We believe that THA is a reasonable surgical intervention for symptomatic dysplasia patients who have mild arthritis and do not qualify for periacetabular osteotomy. [24] (10.1016/j.arth.2024.04.060)
• [L4] Overall, activity levels and hip function improved after periacetabular osteotomy, and although more patients engaged in low-impact sports, participation in high-impact sports was maintained postoperatively. [25] (10.1177/03635465231217736)
• [L4] Single-stage combined hip arthroscopy with periacetabular osteotomy for patients with symptomatic hip dysplasia results in improvement in PROs and arthroplasty free survivorship of 92% at median 2.5 year follow-up. [26] (10.1016/j.arthro.2023.06.034)
• [Letter] While both hip arthroscopy and periacetabular osteotomy offer potential benefits for patients with borderline hip dysplasia, the authors argue for moving beyond generalized results to identify specific patient subgroups who do not do well with hip arthroscopy alone and should be considered for initial treatment with periacetabular osteotomy. [27] (10.1016/j.arthro.2025.01.057)
• [L5] Arthroscopy provides a powerful tool to successfully treat intra-articular hip pathology secondary to dysplasia while improving the bony coverage/alignment with periacetabular osteotomy; through a specialized team approach, all relevant pathology can be addressed and successful outcomes achieved. [28] (10.1016/j.arthro.2018.11.042)
• [L5] The combination of hip arthroscopy and periacetabular osteotomy is safe and effective, but clearer definitions for labral pathology and indications for repair or debridement are required. [29] (10.1016/j.arthro.2025.01.002)
• [L3] [30] (10.1007/s11999-016-5137-0)
• [L5] Surgeons should not ignore posterior hip or gluteal pain or discomfort after periacetabular osteotomy as it could originate from ischiofemoral impingement, and a proper investigation and clinical assessment can help define the source of pain. [32] (10.1097/corr.0000000000002226)
• [L4] This case demonstrates a failure of hip arthroscopy to appropriately address underlying dysplasia but was successfully managed with periacetabular osteotomy to correctly address the deficiency in acetabular coverage, preserving function to a hip with dysplasia. [34] (10.1007/s00167-013-2540-x)
• [L3] [35] (10.1097/corr.0000000000000566)
• [L4] Recognition of these distinct morphologic subtypes is important for diagnostic and surgical treatment considerations to optimize acetabular correction and avoid femoroacetabular impingement. [36] (10.1007/s11999-016-5150-3)
• [L3] Combined surgical dislocation and periacetabular osteotomy provided clinical improvement and intermediate-term survivorship of 85% at 10 years for patients with complex residual Legg-Calvé-Perthes deformities. [38] (10.2106/jbjs.21.00132)
• [L4] The majority (71%) of active patients with hip dysplasia return to presurgical or higher activity levels after open hip preservation surgery with the periacetabular osteotomy. [39] (10.1177/0363546514535906)
• [L4] The Bernese periacetabular osteotomy is currently favored for restoring pelvic anatomy with good correction and minimal secondary deformity. [40] (10.5435/00124635-200209000-00004)
• [L4] [41] (10.1097/corr.0000000000001599)
• [L4] The risk from chemoprophylaxis and the development of hematoma may be greater than the risk of clinically important venous thromboembolism in patients undergoing periacetabular osteotomy. [42] (10.2106/jbjs.j.01769)
• [L4] [43] (10.1097/01.blo.0000153281.75265.1d)
• [L4] Radiological evidence of symptomatic femoroacetabular impingement was not uncommon in these Japanese patients with hip pain, with cam deformity findings being the most common. [48] (10.1302/0301-620x.96b2.32680)
• [L5] The authors encourage thorough preoperative evaluation of radiographs and advanced imaging for all patients being considered for hip arthroscopy. [49] (10.5435/jaaos-d-16-00231)
• [L5] This CORR Insights commentary argues that preservation of the intact posterior column in the Bernese periacetabular osteotomy may be responsible for persistent technical difficulties and serves no useful purpose beyond vanity, suggesting that modifying the posterior column cut plane or using alternative techniques like the Birmingham Interlocking Pelvic Osteotomy may improve outcomes. [50] (10.1097/corr.0000000000000704)
• [L5] [51] (10.1097/corr.0000000000000581)
• [L3] [52] (10.1097/corr.0000000000001296)
• [L3] In cases with large preoperative bone defects, the acetabular component was placed more superiorly in the PAO group, which did not appear to affect long-term (10 year) implant survivorship. [53] (10.1016/j.arth.2025.07.063)
• [L4] The novel minimally invasive spherical periacetabular osteotomy (SPO) using patient-specific preoperative planning is a feasible technique with short-term results showing significant radiographic correction and clinical improvement, despite a high rate of transient lateral femoral cutaneous nerve palsy. [54] (10.2106/jbjs.20.00940)
• [L3] The associations with PROMs detected in the current study suggest that muscle-induced biomechanics may have wide-reaching effects not only on loads within the hip, but also on patients' perceptions of their health and function. [57] (10.1097/corr.0000000000002728)
• [L5] A patient's age and hip shape are important factors contributing to the resulting hip mechanics, although the interplay between those mechanical factors and patient-reported outcomes of pain are unclear. [61] (10.1097/corr.0000000000000621)
• [L5] Individual and postural variations in physiologic pelvic tilt affect joint contact pressure in the hip. [72] (10.1097/corr.0000000000001737)
• [L4] Increased cam morphology remained a significant contributor to reduced internal rotation but did not affect hip flexion. [73] (10.1016/j.arthro.2020.02.044)
• [L3] Weightbearing postural radiographs are crucial for understanding hip biomechanics in hip dysplasia and refining surgical corrections during PAO. [74] (10.1177/23259671251319994)
• [L3] Hips with lower anteversion or a larger difference between anatomic and functional anteversion were more likely to be symptomatic. [75] (10.1097/corr.0000000000002768)
• [L4] Additional studies are needed to determine protective or adaptive factors in patients with abnormal anatomy who do not develop early OA and to determine whether joint preserving hip surgery extends the life of the native hip joint. [76] (10.5435/jaaos-d-16-00532)
• [L5] Hip dysplasia is a pathoanatomic osseous morphology associated with hip instability that may, in part, be due to hip capsular thickness. [77] (10.1016/j.arthro.2024.07.012)
• [L4] Thorough patient evaluation with detailed characterization of structural hip anatomy and articular cartilage integrity are critical to the selection of proper surgical intervention and successful patient outcome. [78] (10.1007/s11999-013-3015-6)
• [L5] This finding is more pronounced with higher degrees of fragment reorientation in abduction and extension; it becomes especially pronounced in reverse PAO for acetabular retroversion or protrusio acetabuli, and might limit the ability to achieve the intended improvement in overall hip biomechanics. [80] (10.2106/jbjs.21.00454)
• [L5] From biomechanics points, RAO was more effective in relieving hip joint stress compared with shelf procedure and Chiari osteotomy. [81] (10.1186/1471-2474-15-47)
• [L3] Standardisation of the modes of failure may help identify the best practice for joint-preserving surgery of the hip. [83] (10.1302/0301-620x.99b3.bjj-2016-0268.r1)
• [L5] Long-term exposure to elevated cartilage contact stresses may affect joint morphology, making hips in these individuals less amenable to joint-preservation procedures such as PAO. [84] (10.1097/corr.0000000000000715)
• [L4] Oblique inguinal incision for the anterior approach in Bernese periacetabular osteotomy is a technique that allows healing of surgical wounds without dehiscence or hypertrophic changes by respecting tension lines. [85] (10.5435/jaaosglobal-d-17-00061)
• [L4] High-level sport and combat sports are major risk factors for mechanical hip pathology in young adults, and a familial history of hip pathology is confirmed. [86] (10.1016/j.otsr.2010.09.005)
• [L5] PAO caused reductions in hip abduction and internal rotation but greater increases in hip adduction and external rotation. [88] (10.2106/jbjs.21.00405)
• [L4] Different combinations of acetabular rotations can result in large variations in femoral head coverage and hip motion, and no single combination is applicable to all cases. [90] (10.1016/j.arth.2025.04.016)
• [L2] The %FHC determined by CG strongly correlated with segmented acetabular subtended angles and thus more likely reflected true values. [91] (10.1177/03635465221109240)
• [L4] The report supports the biomechanical principle that reorientation of the acetabulum reduces stress at the acetabular rim, shifts the os acetabuli out of the stress region, and allows union of the bony fragment with the acetabulum. [93] (10.1007/s00402-002-0431-6)
• [L5] This CORR Insights article is a commentary on a study by Wu et al. and does not present original data; it highlights that muscle-induced biomechanical variables in patients with developmental dysplasia of the hip (DDH) were associated with worse function and pain outcomes, suggesting these variables can better predict prognosis than bony anatomy alone. [94] (10.1097/corr.0000000000002787)
• [L3] A computer-assisted analysis of young adult hip radiographs generally demonstrates substantial to excellent levels of interobserver reliability for most parameters. [96] (10.1177/0363546514542797)
• [L4] [98] (10.2106/jbjs.j.01735)
• [L5] The degree of acetabular correction in the coronal plane where joint contact pressure is minimized varied among patients. [99] (10.1186/s12891-022-05005-5)
• [L5] The higher hip center gained more bone coverage but decreased the range of hip flexion and internal rotation. [100] (10.1016/j.arth.2016.03.014)
• [L5] The current evidence suggests that in patients with hip dysplasia, the problem is one of abnormal loading (a smaller weightbearing area results in higher contact stresses in those areas, resulting in cartilage breakdown). [101] (10.1097/corr.0000000000000364)
• [L3] Concomitant lumbopelvic deformity affecting the hip joint morphology could aggravate clinical symptoms leading to earlier presentation in patients undergoing PAO. [102] (10.1002/ksa.12587)
• [L5] The 3 primary factors involved with preservation of the hip joint are femoroacetabular impingement (FAI), hip dysplasia, and femoral torsion abnormalities. [104] (10.1016/j.arthro.2024.04.002)
• [L4] Patients with evidence of abnormal hip morphologies may not benefit from hip arthroscopy and isolated treatment of the labrum; in fact, the latter may accelerate the process of arthritis in some patients. [105] (10.1016/j.arth.2009.05.021)
• [L4] In addition, we found that obesity and HO formation were independent predictors of persistent hip dysfunction. [108] (10.5435/jaaos-d-21-00535)
• [L3] Patients with borderline hip dysplasia (BHD) demonstrated worse preoperative patient-reported outcome measures (PROMs) than those with frank dysplasia but experienced substantial improvement after periacetabular osteotomy (PAO). [120] (10.1016/j.jisako.2026.101166)
• [L5] Hip arthroscopy for borderline hip dysplasia has a role with narrow indications, particularly in revision settings where the root cause of failure must be identified; instability-driven symptoms primarily indicate periacetabular osteotomy. [122] (10.1016/j.arthro.2024.06.026)
• [L2] Acetabular and femoral osseous abnormalities commonly are associated with labral tears, and recognition of these abnormalities is important to optimize surgical treatment of patients with symptomatic labral disease. [123] (10.1097/01.blo.0000181147.86058.74)
• [L5] The windshield wiper sign is a new radiographic instability sign visible on plain radiographs, MRI, and arthroscopy that predicts hip instability and allows for the planning of combined arthroscopic cartilage therapy and periacetabular osteotomy. [125] (10.1016/j.arthro.2024.06.003)
• [L5] The authors propose a diagnostic framework that groups symptomatic dysplastic hips into one of 3 categories based on the primary direction of instability: anterior, posterior, and global, to aid clinicians in developing a differential diagnosis and planning appropriate surgical management. [127] (10.1016/j.arth.2017.02.067)
• [L4] [130] (10.1007/s00264-015-2973-6)
• [L4] [132] (10.1097/corr.0000000000001547)
• [L3] [133] (10.1016/j.arthro.2020.05.049)
• [L4] [134] (10.1007/s004020050387)
• [L4] [137] (10.1097/corr.0000000000001549)
• [L4] Incisional hernia is a rare complication (0.2% incidence) after periacetabular osteotomy, with risk factors including obesity, weak abdominal muscles, and increased intraabdominal pressure. [138] (10.1097/01.blo.0000130203.28818.da)
• [L4] [139] (10.1097/corr.0000000000000571)
• [L4] Coronal femoroacetabular distance and limbus thickness on post-reduction MRI help predict hips that will have residual acetabular dysplasia in the long term after closed or open reduction. [141] (10.2106/jbjs.23.00333)
• [L4] Preoperative MRI evaluation of femoral anteversion is recommended as essential rather than adjunctive. [142] (10.1007/s00402-009-1020-8)
• [L3] They may be used for radiographic evaluation of symptomatic hips, may offer possible predictors for surgical outcomes, and serve to guide clinical decision-making. [143] (10.1007/s11999-014-4038-3)
• [L4] [147] (10.1016/j.arthro.2015.06.002)
• [L5] [148] (10.5435/jaaos-d-24-00340)
• [L3] [149] (10.1007/s00167-014-3297-6)
• [L5] The study underscores the need for more consistent and effective shared decision-making in periacetabular osteotomy decision-making, highlighting gaps in addressing patients' complex information needs and the necessity for improved training and decision-support tools. [151] (10.1097/corr.0000000000003223)
• [L1] The incidence of postoperative complications and revision surgery was not different between THA and PAO groups. [153] (10.1016/j.otsr.2020.08.012)

See Also

• Hip arthroscopy
• Femoroacetabular impingement
• Total hip replacement
• Hip osteoarthritis

References

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