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Hip osteoarthritis

123 citationsUpdated Sep 2026

Overview

Hip osteoarthritis is a prevalent condition that places significant demands on health services [4]. Clinical disease severity varies widely at the time of total hip replacement [5], and in advanced cases, clinical severity shows no correlation with radiographic severity [5]. The condition affects a broad demographic; approximately 22% of young patients undergoing hip arthroscopy receive a clinical diagnosis of hip osteoarthritis within two years [3]. Furthermore, multimorbid lumbar spinal stenosis co-occurs with hip osteoarthritis in people at a rate of 0 to 54% [33].

Management strategies range from non-operative interventions to surgical correction. Neuromuscular exercise has moderate effects in patients with severe hip osteoarthritis [2], while a six-week physiotherapist-led exercise and education intervention results in sustained significant improvements in pain severity and interference for patients awaiting arthroplasty [29]. Intra-articular corticosteroid injections provide large, clinically meaningful short-term pain relief and functional improvement, with benefits not reliably sustained beyond three months [15]. Viscosupplementation cannot be recommended as standard therapy for wider populations, and indications remain a highly individualised matter [6]. Patients treated with either platelet-rich plasma or hyaluronic acid injections can expect similarly beneficial short-term clinical outcomes [24], and a single injection of amniotic suspension allograft demonstrates promising results for pain relief and patient-reported outcomes in moderate hip osteoarthritis for up to one year [28].

Surgical intervention decisions rely on preoperative function and radiological osteoarthritis to determine when total hip arthroplasty will be most effective [76]. Findings question whether total hip arthroplasty should be prioritized only for patients with severe symptoms, a hypothesis requiring confirmation in a trial [17]. Patients who undergo total hip arthroplasty have impaired long-term self-reported physical quality of life and hip functionality but perform physically better than untreated patients with advanced hip osteoarthritis [26]. Hip arthroscopy outcomes are mixed; patients may have a lower rate of osteoarthritis progression and conversion to total hip arthroplasty compared to those initially treated nonoperatively [80], yet they have inferior results compared with those who did not undergo the procedure [1]. At a mean follow-up of 24.7 years, 14% of hips with femoroacetabular impingement without surgical intervention had symptomatic osteoarthritis and 4% underwent total hip arthroplasty [7]. No evidence exists on outcomes following non-operative management of femoroacetabular impingement with concomitant Tönnis Grade 2 or more hip osteoarthritis [31].

Anatomy & Pathophysiology

Bony Anatomy

The hip is a multiaxial joint formed by the articulation between the pelvis and femur, connecting the axial skeleton and the lower extremity [92]. The hemipelvis comprises three bones—the ilium, ischium, and pubis—which unite at the triradiate cartilage within the concave acetabulum [92]. The acetabulum consists of an articular crescent-moon-shaped lunate surface and a nonarticular central fossa that serves as the attachment point for the ligamentum teres [92]. Inferiorly, the acetabulum is incomplete, forming a notch through which vital blood vessels and nerves pass to supply the joint [92]. The femoral head forms two-thirds of a sphere, with a small depression at its center from which the ligamentum teres extends to connect to the acetabular notch [92].

The neck-shaft angle of the femur averages 125° [92], with a mean adult value of 130° ± 7° [99]. Normal version, defined as the head-neck angle in the frontal plane, averages 15 to 20° [92], while the mean anteversion of the femoral neck is 10° ± 7° [99]. The weakest area in the femoral neck is located in the Ward triangle [99]. The calcar femorale is a medial area of dense trabecular bone that transfers stress from the femoral shaft to the inferior portion of the femoral neck [99].

Soft Tissue Anatomy

The acetabular labrum is a fibrocartilaginous ring attached to the rim of the acetabulum that extends the articulating surface area and increases femoral head coverage [92]. Triangular in cross section, the labrum contributes to creating a pressurized seal of the central compartment of the hip during loading [92]. Only the external one-third of the labrum contains blood vessels, leaving the majority of the structure avascular and limiting its healing ability following injury [92]. The labrum is highly innervated, with the presence of both mechanoreceptors and nociceptors [92]. It is absent in the area of the inferior acetabular notch, where the transverse acetabular ligament serves as the continuation of the labrum [92].

The hip is surrounded by a dense fibrous capsule extending from the periphery of the acetabulum to the intertrochanteric line of the femoral neck [92]. Three main ligaments support the joint: * Iliofemoral ligament: Y-shaped and the thickest and strongest of the three main ligaments, it functions to limit external rotation, while its lateral arm limits extension of the joint [92]. * Ischiofemoral ligament: Extends from the ischial margin of the acetabulum to the greater trochanter of the femur and restricts internal rotation motion [92]. * Pubofemoral ligament: Extends from the obturator crest of the pubic bone to the femoral neck and acts to limit abduction of the joint [92].

Deep fibers from the iliofemoral, ischiofemoral, and pubofemoral ligaments merge to form the zona orbicularis, which circumvents the femoral neck [92]. The ligamentum teres originates in the cotyloid fossa and attaches on the fovea of the femoral head [94]. It transmits an arterial branch of the posterior division of the obturator artery to the femoral head, which is less significant in adults [89].

Muscular function around the hip is distributed among specific groups: * Flexors: The primary hip flexor muscles are the iliopsoas, rectus femoris, and sartorius muscles [98]. * Extensors: The gluteus maximus and hamstring muscles are the most important hip joint extensors [98]. * Abductors: The abductors of the hip are predominantly the gluteus medius and minimus muscles [98]. * External Rotators: These include the obturator internus and externus, superior and inferior gemelli, quadratus femoris, and piriformis muscles [98]. * Internal Rotators: The most consistent internal rotators of the hip joint are the gluteus medius and tensor fascia latae muscles [98].

Vascular Anatomy

In adulthood, the major blood supply to the femoral head is from the medial femoral circumflex and lateral epiphyseal arteries [102]. The medial femoral circumflex artery is the main blood supply to the femoral head and terminates in the posterior aspect of the extracapsular arterial ring [99]. The lateral femoral circumflex artery gives rise to the anterior aspect of the extracapsular arterial ring [99]. The ascending cervical arteries originate from the extracapsular arterial ring and are divided into four distinct groups: lateral, medial, posterior, and anterior [99]. The lateral group of ascending branches is the main blood supply to the femoral head [99]. The lateral epiphyseal artery penetrates the femoral head and is believed to be the dominant blood supply to the femoral head from the ascending cervical system [99]. Fractures that disrupt the ascending blood flow to the lateral epiphyseal vessel have an increased risk of osteonecrosis [99]. The artery of the ligamentum teres arises from either the obturator or medial femoral circumflex artery and does not provide sufficient blood supply to maintain the viability of the femoral head [99].

Pathophysiology

The primary changes of hip osteoarthritis include loss of articular cartilage, remodeling of subchondral bone, and formation of osteophytes [65]. The disease process usually involves all tissues that form the synovial joint, including the articular cartilage, subchondral bone, metaphyseal bone, synovium, ligaments, joint capsule, and muscles crossing the joint [65]. Despite its name implying an inflammatory process, inflammation is not a major component of osteoarthritis in most patients [65]. The etiology of hip osteoarthritis is multifactorial [65]. On a cellular level, osteoarthritis appears to be the result of deterioration in the ability of chondrocytes to maintain and restore articular cartilage [65]. Chondrocytes undergo age-related telomere erosion and increased expression of the senescence marker β-galactosidase, indicating that cell senescence is responsible for the age-related loss of chondrocyte function [65].

Subtle morphologic abnormalities around the hip, including femoroacetabular impingement (FAI) and acetabular dysplasia, may contribute to a mechanical process that results in articular cartilage damage and end-stage hip arthrosis [65]. FAI is abnormal bony contact between the rim of the acetabulum and the proximal femur during hip motion that can cause pain and damage to the acetabular labrum and articular cartilage [65]. * Cam impingement: Occurs when excessive bone is present at the junction of the femoral head and neck, resulting in decreased offset at the head-neck junction [65]. * Pincer impingement: Occurs when excessive bone is present along the rim of the acetabulum from an excessively deep socket or acetabular retroversion [65]. * Mixed impingement: Many cases of FAI involve a combination of cam and pincer impingement [65].

Increasing evidence suggests that FAI may be a major contributing factor to the development of hip osteoarthritis in many cases [65]. Acetabular dysplasia describes a shallow hip socket without frank dislocation of the femoral head but with varied degrees of superior lateral subluxation [65]. The shallow hip socket in acetabular dysplasia results in high articular cartilage contact stresses near the superolateral rim of the acetabulum, with concurrent labral tears and progressive lateral subluxation of the femoral head [65]. When there is loss of sphericity in the ball-and-socket joint, the articular surface is exposed to abnormal loads and contact forces leading to hyaline cartilage damage [155]. Common mechanical causes of hip osteoarthritis include developmental dysplasia of the hip (under-coverage), femoroacetabular impingement (over-coverage), and long-term consequences of Legg-Calvé-Perthes disease and slipped capital femoral epiphysis [155]. In post-traumatic osteoarthritis, there is loss of congruency of the articulating surface [155]. Non-mechanical causes of hip osteoarthritis include avascular necrosis of the femoral head, ankylosing spondylitis, inflammatory arthritis, and primary disorders of cartilage and the synovium [155].

Hip microinstability refers to the femoral head micromotion within the acetabulum, which is a prolonged phenomenon that leads to cartilage damage and eventually osteoarthritis of the hip [103]. Hip microinstability is often seen in athletes who require extreme range of motion, such as dancing [103]. Cam morphology primarily develops during adolescence and is strongly associated with athletic activity during this period [38]. Cam morphology has been associated with the development of hip osteoarthritis, while the association between pincer morphology and hip osteoarthritis is much less clear [54]. Severe pincer morphology is associated with incident hip osteoarthritis [194]. Femoroacetabular impingement syndrome in middle-aged individuals is strongly associated with the development of hip osteoarthritis within 10-year follow-up [36].

In a study of 730 hips treated with primary total hip arthroplasty in patients younger than 50 years, 55.5% had osteoarthritis [199]. Of the osteoarthritic hips in this study, 181 had developmental dysplasia of the hip, 32 had Perthes disease, 21 had slipped capital femoral epiphysis, and 6 had postsepsis [199]. In the study of osteoarthritic hips with unknown etiology in patients younger than 50 years, 78 had radiographic findings consistent with cam impingement, 10 with pincer impingement, and 40 with combined cam/pincer impingement [199]. Distinct transcriptome profiles for early and late stage hip degeneration have been identified along with key molecular contributors to the progression of hip osteoarthritis [87]. Elevated levels of TNF-α, IL-1β, and IL-6 have been found in the synovial tissue of patients with labral tear compared to hip osteoarthritis [193].

Individuals with mild-to-moderate hip osteoarthritis have lower limb muscle strength and volume deficits [27]. Early interventions to target muscle weakness and prevent the development of strength asymmetries that are characteristic of advanced hip osteoarthritis appear warranted [27]. Greater cross-sectional area of hip flexors might be associated with better quality of life in individuals with mild-to-moderate hip osteoarthritis [188]. Segmental electrical bioimpedance equipment can detect differences between limbs affected and unaffected by hip osteoarthritis [177]. Reduced gait velocity, reduced sagittal plane joint excursion, and a reduced hip flexion moment in the late stance phase of gait are evident in hip osteoarthritis patients with mild to moderate symptoms [123]. Subjects with end-stage hip osteoarthritis had 3.49 degrees less peak hip flexion and 8.82 degrees less extension angles [139]. Prior to total hip arthroplasty, individuals with hip osteoarthritis presented with an increased contralateral shift and forward displacement of the center of mass [48]. The reduced ability of flexion in the arthritic hip leads to posterior pelvic tilt in the relaxed-seated position, associated with compensatory increased lumbar flexion [151]. Spinal alignment and mobility should be considered when assessing risk and designing preventive intervention for radiographic progression of secondary hip osteoarthritis [77]. In patients with excessive hip adduction and pelvic tilt toward the swing limb during gait, gait modification may contribute to the reduction of hip joint loading [147]. The reversal gait profile is associated with hip osteoarthritis risk [51]. Besides more commonly reported spatiotemporal parameters, only upper body motion provided nonredundant and sensitive parameters representing gait adaptations in individuals with hip osteoarthritis [117]. There was no main effect of radiographic disease severity on hip kinematic variability in the sagittal or frontal plane in hip osteoarthritis [116]. Patients with hip osteoarthritis showed the poorest repeatability between gait recordings collected by different examiners, as compared to patients operated with a total hip arthroplasty and healthy controls [140].

The association between osteoarthritis and depression can be related to lack of exercise, loss of independence, and a heightened awareness of one’s physical aging [52]. Insomnia can result from the pain of osteoarthritis worsening with nocturnal nadirs in native cortisol production [52]. A 2018 study found that 53% of patients with osteoarthritis had insomnia symptoms and 66% had obstructive sleep apnea [52]. Pain and depression were associated with insomnia, while opioid use and depression were associated with obstructive sleep apnea [52]. The duration of sleep is strongly inversely correlated with osteoarthritis symptoms [52]. The chronic pain of osteoarthritis can lead to memory complaints, mood and anxiety disorders, multifocal pain, and fatigue [52].

Posttraumatic osteoarthritis can amount to 12% of symptomatic hip osteoarthritis [70]. In a review of 30 traumatic hip dislocations, those characterized as complex were more likely to develop osteoarthritis (4/9, 44%) or osteonecrosis (3/9, 33%) [70]. Retention of any intra-articular fragments after traumatic hip dislocation is associated with the development of posttraumatic osteoarthritis [70]. Rapidly progressive osteoarthritis of the hip is uncommon, more common in elderly women, and may be associated with intra-articular corticosteroid injections [70]. A 2018 study found a 21% rate of rapidly progressive osteoarthritis in patients who receive hip injections [70]. For a patient who recently developed Tönnis 1 degenerative change, the probability of undergoing total hip arthroplasty in 10 years based on hip morphology was approximately one in three for dysplasia of the hip and one in five for both femoroacetabular impingement and normal morphology hips [70]. The approximate probability at 20 years for a patient with Tönnis 1 degenerative change to undergo total hip arthroplasty was two in three for dysplasia of the hip and one in two for both femoroacetabular impingement and normal morphology hips [70]. Radiographic variables with negative prognostic value for hip osteoarthritis progression include femoral head lateralization greater than 8 mm, femoral head extrusion index greater than 0.2, acetabular depth-to-width index less than 0.3, lateral center-edge angle less than 25°, and Tönnis angle greater than 8° [70]. In a study of 367 patients undergoing total hip arthroplasty with no contralateral hip symptoms, Kaplan-Meier survivorship estimated that 41% of these patients develop symptoms at 10 years and 19% went on to total hip arthroplasty [70]. Reduced joint space, low center-edge angle, low head to neck ratio, and osteophytes are associated with the development of osteoarthritis over an average 11-year radiographic follow-up [70].

One in four people may develop symptomatic hip osteoarthritis in his or her lifetime [20]. The incidence of hip arthroplasty for primary osteoarthritis is increasing in 30- to 59-year-old patients [20]. Subclinical deformities of the hip are significant predictors of radiographic osteoarthritis and joint replacement in women [20]. The prevalence of predisposing deformity in osteoarthritic hip joints has been studied [20]. The relationship between body mass index and hip osteoarthritis has been established through systematic review and meta-analysis [20]. Body mass index affects clinical outcome post-operatively and at five years after primary unilateral hip replacement performed for osteoarthritis [20]. Intra-articular hip injection pain relief does not necessarily correlate with radiographic severity of osteoarthritis [20]. The natural history of radiographic hip osteoarthritis has been studied with 11-28 years of follow-up [20]. The prevalence of malformations of the hip joint is related to sex, groin pain, and risk of osteoarthritis [20]. Femoral head-neck junction deformity is related to osteoarthritis of the hip [20]. The incidence of contralateral total hip arthroplasty after index total hip arthroplasty for osteoarthritis has been documented [20]. Total hip replacement in morbidly obese patients with osteoarthritis has been studied in a prospectively matched study [20]. The mature athlete with hip arthritis presents a specific clinical challenge [20].

Classification

Radiographic Grading Systems

Hip osteoarthritis is categorized using the Kellgren-Lawrence or Tönnis classifications [22]. The Kellgren-Lawrence scale is widely recommended as a reliable radiologic classification for the hip [34] and is recommended for lower extremity osteoarthritis based on reliability data between radiologists and orthopaedic surgeons [81]. It is a 4-point grading system classified into doubtful, mild, moderate, and severe [22], with scores ranging from 0, representing healthy hips, to 4, representing end-stage OA [34]. Specifically, Kellgren-Lawrence Grade 0 indicates no features of osteoarthritis [184]. Grade 1 indicates doubtful osteoarthritis with questionable osteophytes or questionable joint space narrowing [184]. Grade 2 indicates minimal osteoarthritis with definitive small osteophytes and little or mild joint space narrowing [184]. Grade 3 indicates moderate osteoarthritis with definitive moderate osteophytes and joint space narrowing ≥50% [184]. Grade 4 indicates severe osteoarthritis with severely impaired joint space, cysts, and sclerosis of subchondral bone [184]. Scores 1, 2, and 3 represent mild, moderate, and moderate-severe OA, respectively [34].

The Tönnis classification is a 3-point grading system categorized into mild, moderate, and severe [22]. Tönnis Grade 0 demonstrates normal joint space with no arthritic changes [74]. Grade 1 shows slight joint space narrowing, increasing subchondral sclerosis of the acetabulum and/or femoral head, and mild osteophyte formation [74]. Grade 2 shows small cysts in the head or acetabulum, moderate joint-space narrowing, and moderate loss of sphericity of the femoral head [74]. Grade 3 demonstrates large cysts in the femoral head or acetabulum, severe joint-space narrowing or obliteration, and severe deformity of the femoral head [74].

The Kellgren-Lawrence and Tönnis classifications are more often used in the research setting than the clinical setting [22]. Radiographic and clinical severity do not necessarily correlate, particularly if radiographs are non-weight-bearing or if false-profile views are not included [22]. In advanced hip OA, clinical severity shows no correlation with radiographic severity [5].

Clinical and Diagnostic Considerations

No recommendation can be made regarding the use of hip injections for diagnosing hip OA [12]. The benefits of hip arthroscopy for patients with Tönnis grade 2 or greater hip osteoarthritis are ambiguous due to contradictory research and varying reliability of the Tönnis classification [136]. No evidence exists on outcomes following non-operative management of FAI with concomitant Tönnis Grade 2 or more OA of the hip [31].

Epidemiology and Prevalence

Hip osteoarthritis is a prevalent condition whose treatment will continue to place important demands on health services [4]. The prevalence of hip osteoarthritis was 1.96 times higher in women compared to men [63]. The age-standardized incidence, prevalence, and YLDs of global hip OA have been on the rise from 1992 to 2021, with predictions indicating that these metrics may continue to significantly increase in the future [176]. The prevalence of symptomatic hip OA in the United States is approximately 3% in adults aged ≥30 years [184]. The cumulative incidence of radiographic hip OA was found to be 9.3% in the Netherlands [184]. The cumulative incidence of patient self-reported hip OA was 5.8% in women and 3.8% in men in a Norwegian study [184].

Risk Factors and Associations

Abnormal femoral anteversion is associated with the development of hip osteoarthritis [34]. Associations between body mass index and hip osteoarthritis risk do not vary by sex, study design, or osteoarthritis definition [39]. Multiple genetic variants, including 5 novel loci, were associated with end-stage hip OA treated with primary THA [179]. No associations were found between mean pelvic incidence values or pelvic incidence categories and hip OA [174]. There is evidence that multimorbid lumbar spinal stenosis with knee or hip OA occurs in people at rates of 0 to 54%, although results are based on studies with high risk of bias and surgical populations [33].

Advanced and Emerging Classification Tools

Rapid destructive hip osteoarthritis represents an uncommon subset of arthrosis with rapid progression [14]. An interpretable machine learning approach for predicting and grading hip osteoarthritis using gait analysis demonstrated superior performance compared to other up-to-date methods, suggesting it can serve as a supplementary tool to the KL grading scale [47]. An artificial intelligence model for predicting the progression of hip osteoarthritis using plain radiographs and clinical data performed adequately and may be clinically applicable with additional datasets and validation [53]. Using dimension reduction and clustering algorithms, patients with hip FAI are separated into 5 clusters, each with a different risk for OA progression [159]. The identification of clinical phenotypes and prognostic factors for outcomes in pain and disability is a first step towards pre- and postoperative precision medicine for individuals with hip OA undergoing THA [25].

Clinical Presentation

History and Symptom Characteristics

Patients with hip osteoarthritis frequently present with activity-related groin pain that is exacerbated by hip flexion activities [23]. Anterior groin pain is most associated with intra-articular pathologies, which may include degenerative changes [180]. The onset of symptoms is often insidious or follows minor trauma [23], with many patients experiencing a gradual presentation over months or years rather than acute onset secondary to trauma [180]. Patients may experience difficulty with prolonged sitting, walking, running, or pivoting [23]. Mechanical symptoms secondary to labral and articular cartilage disease are common in this population [23]. In adolescent hip dysplasia, lateral hip pain is often the initial symptom, occurring later in the day as fatigue develops due to altered biomechanics [156]. Deep groin pain in adolescent hip dysplasia occurs later than lateral pain, is activity-related, and improves when activity restriction is instituted [156]. Patients with acetabular labral disease commonly present with groin pain that is worsened by prolonged sitting, walking, running, or pivoting [19].

Knee and hip pain within the last month was frequent among individuals aged 29–59 years [11]. Multiple known osteoarthritis risk factors were associated with the presence of knee and hip pain in individuals aged 29–59 years [11]. Two-thirds of people with hip and/or knee osteoarthritis in Portugal have poor management of their pain levels [43]. Patients with symptomatic hip osteoarthritis may present with insomnia and obstructive sleep apnea [97]. Characteristics associated with comorbid lumbar spinal stenosis symptoms in people with hip osteoarthritis can help identify co-occurring conditions to guide clinical decision-making [10]. Multimorbid lumbar spinal stenosis with hip osteoarthritis occurs in people, with prevalence estimates ranging from 0 to 54% [33].

Physical Examination

A thorough history is essential to differentiating between common causes of hip pain [21]. Assessing the onset, duration, and location of symptoms, along with factors that exacerbate or alleviate pain, is important for determining the cause of hip pain [180]. Identifying changes to activity type or training regime can help differentiate between conditions in patients with gradual onset hip pain [180]. Pain along the lateral thigh is often associated with greater trochanteric bursitis, iliotibial band syndrome, or abductor tendon tears or tendinitis [180]. Pain in the posterior region of the hip and pelvis can be the result of referred pain from the sacroiliac joint or low back [180].

Patients with hip osteoarthritis will exhibit restricted hip internal rotation in 90° of flexion [23]. The impingement test (flexion, adduction, internal rotation) elicits pain in patients with hip osteoarthritis, but the test is not specific for femoroacetabular impingement [23]. Clinical examination tests and imaging findings should be used to confirm a suspected clinical diagnosis of hip pathology [21]. Prior to total hip arthroplasty, individuals with hip osteoarthritis presented with an increased contralateral shift and forward displacement of the center of mass during the five times sit-to-stand test [48]. Functional movement compensations persist in individuals with hip osteoarthritis performing the five times sit-to-stand test 1 year after total hip arthroplasty [48].

Diagnostic Imaging and Classification

Conventional radiographs remain critical in the initial imaging evaluation of the hip for diagnosing osteoarthritis [22]. A complete hip series usually consists of an anterior-posterior pelvis, a centered AP hip, a lateral view (frog-leg, cross-table, Dunn 45° or 90°), and a false-profile (Lequesne) view [22]. Radiographic and clinical severity of hip osteoarthritis do not necessarily correlate, particularly if radiographs are non-weight-bearing or if false-profile views are not included [22].

Osteoarthritis of the hip can be categorized using the following classification systems: * Kellgren-Lawrence classification: A 4-point grading system classified into doubtful, mild, moderate, and severe [22]. Kellgren-Lawrence scores 1, 2, and 3 represent mild, moderate, and moderate-severe osteoarthritis, respectively [34]. * Tönnis classification: A 3-point grading system categorized into mild, moderate, and severe [22].

Ultrasonography can assess the anterior portions of the hip, including the joint capsule, acetabular labrum, portions of the femoral head articular cartilage, and bony contours [75]. It can also assess the joint space for effusions, synovial proliferation, and joint bodies [75]. Color Doppler ultrasonography can depict areas of synovial vascularization indicating active inflammation [75]. Joint effusions are diagnosed on ultrasonography when fluid distends the joint capsule greater than 7 mm, or when there is a greater than 1 mm side-to-side difference between hips [75]. Ultrasonography can assess for painful periarticular snapping of the hip attributable to internal causes (iliopsoas tendon complex) and external causes (iliotibial band over the greater trochanter) [75]. An interpretable machine learning approach using gait analysis can serve as a supplementary tool to the Kellgren-Lawrence grading scale for hip osteoarthritis detection and severity assessment [47]. Future clinical trials investigating the natural history and treatment of femoroacetabular impingement will require multimodal staging systems for hip osteoarthritis [9].

Risk Factors and Prevalence

Hip osteoarthritis is a prevalent condition whose treatment places important demands on health services [4]. Older age (≥ 70 years), female sex, large center-edge angle (≥ 40°), and acetabular dysplasia (center-edge angle < 20°) appeared to be significant risk factors of hip osteoarthritis [62]. Cam morphology is a risk factor for hip osteoarthritis, although the strength of this association varies widely across studies [38]. Radiographic evidence of femoroacetabular impingement is common in active patients with hip complaints [60]. Insurance status, income, and gender were associated with imaging and treatments performed in managing hip and knee osteoarthritis [66]. Consideration of sarcopenic obesity should be included in osteoarthritis patient assessments [68].

Diagnostic Procedures and Limitations

Limited evidence exists on the use of patient-reported outcomes as an integrated part of clinical practice for patients with hip and knee osteoarthritis [13]. The identification of clinical phenotypes and prognostic factors for outcomes in pain and disability is a step towards pre- and postoperative precision medicine for individuals with hip osteoarthritis undergoing total hip arthroplasty [25]. Screening patients with hip osteoarthritis for depression early in the disease course may contribute to better patient-reported pain, health-related quality of life, and satisfaction after future total hip arthroplasty [44]. The Dutch Lower Extremity Functional Scale is recommended as the outcome measure of choice to assess self-reported physical functioning in individuals with hip or knee osteoarthritis [124]. Range of motion and muscle strength measurements in patients with hip osteoarthritis have been evaluated for inter-rater reliability [108].

Investigations

Clinical Examination: A thorough clinical examination is required to establish a differential diagnosis for hip pain, as many hip conditions present with similar symptoms [21]. Clinical examination tests and imaging findings should be used to confirm a suspected clinical diagnosis [21]. The impingement test (flexion, adduction, internal rotation) elicits pain in patients with femoroacetabular impingement but is not specific for the condition [23]. Patients with femoroacetabular impingement exhibit restricted hip internal rotation in 90° of flexion [23]. No recommendation can be made regarding the use of anesthetic hip joint injections for diagnosing hip osteoarthritis [12]. Characteristics associated with comorbid lumbar spinal stenosis symptoms may help identify people with co-occurring lumbar spinal stenosis and hip osteoarthritis to guide clinical decision-making [10]. Knee/hip pain within the last month was frequent among individuals aged 29–59 years, and multiple known osteoarthritis risk factors were associated with the presence of knee/hip pain [11].

Plain radiography: Conventional radiographs remain critical in the initial imaging evaluation of the hip [22]. A complete hip series usually consists of an anterior-posterior pelvis, a centered anterior-posterior hip, a lateral view (frog-leg, cross-table, Dunn 45° or 90°), and a false-profile (Lequesne) view [22]. Radiographic and clinical severity do not necessarily correlate, particularly if the radiographs are non-weight-bearing or if false-profile views are not included [22]. The Dunn 45° view radiograph may be more accurate for determining the alpha angle measurement than CT or MRI [22]. The alpha angle is used to assess femoral head-neck junction morphology, with normal values generally considered less than 50°–55° [22]. Acetabular offset can be accurately determined on conventional radiographs in patients with primary hip osteoarthritis [86]. Radiographic findings appeared to correspond with functional status in former American-style football players with knee osteoarthritis but not hip osteoarthritis [175]. An artificial intelligence model using plain radiographs and clinical data performed adequately in predicting hip osteoarthritis progression and may be clinically applicable with additional datasets and validation [53]. A machine learning approach for predicting and grading hip osteoarthritis using gait analysis demonstrated superior performance compared to other up-to-date methods, suggesting it can serve as a supplementary tool to the Kellgren-Lawrence grading scale [47]. The novel HiSS categorization supported the use of pelvic tilt to potentially improve the ability to discern hip-spine syndrome types/pathologies in a subset of patients with hip osteoarthritis and spinal sagittal malalignment [40].

MRI: MRI is the modality of choice for patients suspected of soft tissue or intra-articular pathology, given its superior sensitivity and specificity [107]. Magnetic resonance arthrography is more appropriate than conventional MRI to determine injuries to the labrochondral structures and the ligamentum teres and to identify the presence of loose bodies and synovial chondromatosis [107]. The utility of magnetic resonance arthrography in the accurate detection and staging of articular cartilage lesions is reduced, with sensitivity reported to be less than 50% compared with arthroscopic findings [107]. 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 and were effective at detecting early changes to the articular cartilage surfaces of patients with hip dysplasia and femoroacetabular impingement [107]. Noncontrast 3T MRI and 1.5T magnetic resonance arthrography have similar accuracies for the evaluation of femoroacetabular impingement [111]. The accuracy of noncontrast 3T MRI for labral tears and acetabular cartilage lesions was 98% and 90%, respectively, when evaluated against hip arthroscopy [111]. Gadolinium-enhanced MRI arthrogram is useful when labral pathology is suspected, especially when associated with femoroacetabular impingement [119]. MRI may identify gluteus medius and gluteus minimus tears in patients with lateral hip pain and abductor weakness [119].

CT: 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 [107]. Measurements of femoral head coverage and acetabular and femoral impingement can also be performed reliably using CT images [107]. Three-dimensional CT with pelvic remodeling may be indicated for preoperative planning for reconstruction associated with dysplasia surgery, femoroacetabular impingement, posttraumatic arthritis, or other complex primary total hip arthroplasty [119].

Ultrasound: Ultrasonography can be an effective modality to identify musculotendinous disruptions, effusions associated with intra-articular pathology, or inflammatory conditions, such as bursitis [107]. Ultrasonography is also being increasingly used for targeted injections into muscles, tendons, or intra-articularly around the hip [107].

Other Considerations: Radiological features, specifically joint space narrowing, might be of importance for the decision of viscosupplementation in patients with hip osteoarthritis, though further confirmation by larger scale trials is needed [195]. At mean follow-up of 24.7 years, 14% of hips had symptomatic osteoarthritis and 4% underwent total hip arthroplasty in patients with femoroacetabular impingement without surgical intervention [7]. Subgroup analysis comparing operative versus nonoperative management for femoroacetabular impingement demonstrated a 32% reduction in the radiographic progression of osteoarthritis at long-term follow-up, though there were no significant differences in the risk of total hip arthroplasty [8]. Patients with hip osteoarthritis had inferior results compared with those who did not have hip osteoarthritis in the setting of hip arthroscopy [1]. Patients who exhibited rapidly progressive osteoarthritis before undergoing total hip arthroplasty showed worse patient-reported outcomes compared with those who did not have rapid progression [16]. Spinal pathology was significantly associated with both the development and progression of hip osteoarthritis [197]. Lumbosacral fusion increases the risk of hip osteoarthritis, particularly in patients with long-segment lumbosacral fusion [42]. Sagittal alignment and mobility of the thoracolumbar spine are associated with radiographic progression of secondary hip osteoarthritis [77]. Findings question whether total hip arthroplasty should be prioritized only for those patients who have severe hip osteoarthritis symptoms, but require confirmation in a trial [17].

Treatment

Non-Operative

Conservative management forms the initial line of defense for hip osteoarthritis. Non-narcotic medications, specifically NSAIDs, have strong evidence supporting their use in nonoperative management [131]. Weight loss may be beneficial for pain and function [131], while the use of a walking stick or other ambulatory aids assists in maintaining mobility and reducing pain [125, 133]. Activity modification, including the reduction of impact-loading exercises and avoidance of stairs, inclines, and squatting, is a standard component of nonoperative care [131]. Neuromuscular exercise has moderate effects in patients with severe hip OA [2], and a six-week physiotherapist-led exercise and education intervention resulted in sustained significant improvements in pain severity and interference in patients awaiting arthroplasty [29]. Evidence does not support the use of glucosamine sulfate [131], and there is no strong evidence to support the use of hyaluronate in the hip, which is not approved by the FDA for hip use in the United States [131].

Intra-articular corticosteroid injections are recommended as the most efficient agent for short-term pain relief and functional improvement [144]. These injections are safe and effective for up to three months, with a low risk of adverse events [61], and provide large, clinically meaningful short-term benefits that are not reliably sustained beyond three months [15]. They are efficacious in both immediate and delayed pain reduction within 12 weeks [72] and are more effective than saline injections for pain treatment and functional restoration [132]. The most common adverse event associated with intra-articular injection of cross-linked hyaluronic acid combined with triamcinolone hexacetonide for mild to moderate hip OA was transient hip pain [32]. Viscosupplementation cannot be recommended as standard therapy for wider populations, and indications remain a highly individualised matter [6].

Patients undergoing treatment with platelet-rich plasma (PRP) or hyaluronic acid (HA) injections can expect similarly beneficial short-term clinical outcomes [24]. However, the therapeutic effects of PRP and PRP+HA injections on pain and function lasted longer (6 months) than HA, and these interventions were superior to HA regarding performance, disability, and activities of daily living in the long run [64]. A single injection of amniotic suspension allograft (ASA) provides relief of pain and improvement in patient-reported outcomes for up to one year in patients with moderate hip OA, although the exact mechanism of action remains unknown [28]. Opioid medications should not play a role in the management of chronic OA symptoms, as their effect on arthritis pain and function is minimal and does not outweigh the risk of adverse events [52]. A randomized controlled trial comparing opioids to nonopioids showed no difference in function and worse pain intensity for the opioid group [52]. Preoperative opioid use correlates with higher postoperative narcotic usage and more difficult-to-control perioperative pain [52].

Characteristics associated with comorbid lumbar spinal stenosis symptoms in people with hip OA may help identify co-occurring conditions to guide clinical decision-making [10]. Limited evidence exists on the use of patient-reported outcomes (PROs) as an integrated part of clinical practice for patients with hip osteoarthritis [13]. Nonoperative OA hip patients were generally unreceptive to using smart technologies, with the exception of smartphone applications [181].

Operative

Indications: Before any major reconstruction of the hip is recommended, conservative measures including weight loss, nonopioid analgesics, reasonable activity modification, low-impact exercise, and ambulatory aids should be advised [69]. Surgery is justified if, despite conservative measures, pain at rest and pain with motion and weight bearing are severe enough to prevent the patient from working or carrying out activities of daily living [69]. Patients with limitation of motion, limp, or leg-length inequality with little or no hip pain are not candidates for total hip arthroplasty (THA) [69]. In adults with severe hip OA, total hip replacement reduced hip pain and improved self-reported hip function at 6 months compared with resistance training [129]. Clinical disease severity varies widely at the time of THA for osteoarthritis, and in advanced hip OA, clinical severity shows no correlation with radiographic severity [5]. Findings question whether THA should be prioritized only for patients who have severe hip OA symptoms, but this requires confirmation in a trial [17].

Surgical Approach / Technique: Total hip arthroplasty is a reliable surgical intervention for end-stage hip arthritis that has become safer over the past decade [79]. Femoral or periacetabular osteotomy should be considered for young patients with osteoarthritis if the joint is not grossly incongruous and satisfactory motion is present [69]. Hip resurfacing is an attractive option for young subjects under thirty years old [145]. There is some evidence that patients with femoroacetabular impingement syndrome (FAIS) who undergo hip arthroscopy may have a lower rate of progression of OA and conversion to THA compared to similar patients initially treated nonoperatively [80]. Subgroup analysis comparing operative versus nonoperative management for FAIS demonstrated a 32% reduction in the radiographic progression of osteoarthritis at long-term follow-up, though there were no significant differences in the risk of total hip arthroplasty [8]. At a mean follow-up of nearly 13 years, 7% of patients in the surgical group for FAIS experienced progression to THA, compared with 11% of the nonoperative control group [46]. Patients with hip OA had inferior results from hip arthroscopy compared with those who did not have hip OA [1]. Chronologic age in isolation is not an absolute contraindication to hip arthroscopy for FAI correction and labral preservation surgery [73]. At mean follow-up of 24.7 years, 14% of hips in patients with FAI without surgical intervention had symptomatic OA and 4% underwent THA [7].

Other Considerations: Patients with FAIS and concomitant hip OA of Tönnis grade 2 or greater benefit from operative management rather than nonoperative management if they are younger and/or have a normal BMI [158]. Patients with FAIS and concomitant hip OA of Tönnis grade 2 or greater are poor candidates for hip preservation surgery if they have severe joint space narrowing, Tönnis grade 3 hip OA, or a bilateral location of cartilage defects [158]. Tönnis grade 3 OA should be a contraindication for hip preservation surgery [158].

Hip arthrodesis is uncommonly used and can be used to treat advanced hip degeneration (often posttraumatic) in a very specific patient population [19]. Indications for hip arthrodesis include being younger than 30 years, high activity level, severe pain and stiffness, and normal adjacent joints [19]. Contraindications for hip arthrodesis include disease of the adjacent joints (lumbar spine, contralateral hip, ipsilateral knee), major limb-length discrepancy (>2.0 cm), and active infection [19]. The preferred position for hip arthrodesis is 25° to 30° of hip flexion, 0° to 5° of adduction, and 5° to 10° of external rotation [19]. Hip arthrodesis achieves lasting pain relief and satisfactory clinical results in most patients [19]. The survivorship of hip arthrodesis can be limited by symptomatic degenerative disease of the adjacent joints, with low back pain and osteoarthritis of the ipsilateral knee being the most common problems [19]. Conversion of hip fusion to total hip arthroplasty is occasionally needed, and good clinical results are seen in most patients following this conversion [19].

Absolute contraindications for THA include active infection of the hip joint or any other region and any unstable medical illnesses that would significantly increase the risk of morbidity or mortality [69]. Asymptomatic bacteriuria has not been associated with postoperative surgical site infections and should not be considered a contraindication for THA [69]. Insufficient evidence exists to establish the effectiveness of physiotherapy exercise following primary hip replacement for osteoarthritis [196].

Complications

Hip Arthroscopy

Patients with hip osteoarthritis experience inferior results following hip arthroscopy compared with those without the condition [1]. While subgroup analysis of femoroacetabular impingement management showed a 32% reduction in radiographic progression of osteoarthritis with operative treatment [8], there were no significant differences in the risk of total hip arthroplasty between operative and nonoperative groups [8]. At a mean follow-up of nearly 13 years, 7% of surgical patients progressed to total hip arthroplasty compared with 11% of nonoperative controls [46]. Persistent structural disease is the most common cause of repeat hip preservation surgery [135]. Reported complications include femoral neck fracture, abdominal compartment syndrome, acute iatrogenic dislocation, venous thromboembolic disease, and fatal pulmonary embolism [135]. Symptoms of nerve dysfunction are an under-reported complication [135]. Hip subluxation is a reported complication of arthroscopic debridement [135], while anterior dislocation occurs in patients with capsular laxity [135].

Total Hip Arthroplasty

Infection (PJI): Obesity increases the chance of infection due to mechanical wound problems related to thick subcutaneous fat and increases drainage duration, which is associated with higher periprosthetic infection rates [157]. Diabetes mellitus is an independent risk factor for infection [157], and poor perioperative glucose control is associated with higher rates of periprosthetic infection [157]. Preoperative hemoglobin A1c levels greater than 7 increase the risk of periprosthetic infection [157]. Patients with rheumatoid arthritis have an increased risk of late periprosthetic infection [65], as do patients with psoriatic arthritis [65].

Aseptic loosening: Some reports suggest that obesity may increase the chance of aseptic loosening after total hip arthroplasty [157].

Instability: Fixed spinal deformities may affect the functional positioning of the acetabular implant [157]. In patients with ankylosing spondylitis, the acetabular implant should be inserted in a more horizontal position with less anteversion to avoid anterior dislocation [157]. Dislocation occurred in 8% of arthroplasty patients in a multicenter study of 450 patients comparing internal fixation and arthroplasty for displaced femoral neck fractures [162].

Thromboembolism: Patients having total hip replacement for acute fracture had higher rates of mortality and pulmonary embolism compared with osteoarthritis patients [162].

Wound complications: Rates of hematoma formation were higher in patients having total hip replacement for acute fracture compared with osteoarthritis patients [162].

Other Considerations: Patients who have undergone total hip arthroplasty have impaired long-term self-reported physical quality of life and hip functionality but perform physically better than untreated patients with advanced hip osteoarthritis [26]. Younger patients with osteoarthritis are likely to return to high levels of activity, which may impact long-term wear-related implant survivorship [67]. Prolonged waiting time for total hip arthroplasty is a significant independent risk factor for reduced benefit after surgery [170], as prolonging the arthritic process may result in muscle atrophy, tissue contractures, and deterioration of general medical condition that may not be recoverable after surgery [170]. Preoperative quality of life status is a strong predictor of postoperative outcome following total hip arthroplasty [170]. The risk of complications in patients with acute femoral neck fractures is higher than in patients with osteoarthritis [162]. Rates of infection and dislocation were higher in patients having total hip replacement for acute fracture compared with osteoarthritis patients [162]. Fracture patients had a longer length of stay and discharge to a rehabilitation facility at all time periods compared with osteoarthritis patients [162]. Having a femoral neck fracture versus osteoarthritis was associated with greater rates of medical complications, longer hospitalization, discharge to inpatient care facility, and unplanned readmission [162]. A difference of greater than 9 to 10 mm in the atlantodens interval on flexion/extension views or space available for the cord less than 14 mm is associated with an increased risk of neurologic injury and usually requires surgical treatment [65]. An incidence of nonunion approaching 20% has been reported with conventional trochanteric osteotomy [65]. The most common adverse event for intra-articular injection of a cross-linked hyaluronic acid combined with triamcinolone hexacetonide was transient hip pain [32].

Hip Arthrodesis

The survivorship of hip arthrodesis can be limited by symptomatic degenerative disease of the adjacent joints [19]. Low back pain and osteoarthritis of the ipsilateral knee are the most common problems following hip arthrodesis [19]. Rehabilitation after conversion of hip fusion to total hip arthroplasty is prolonged because of profound hip abductor weakness and associated limp [19].

Disease Progression and Natural History

Rapidly progressive osteoarthritis of the hip may be associated with intra-articular corticosteroid injections [70]. The approximate probability of undergoing total hip arthroplasty at 20 years for a patient who recently developed Tönnis 1 degenerative change was two in three for dysplasia of the hip and one in two for both femoroacetabular impingement and normal morphology hips [70]. Kaplan-Meier survivorship estimated that 41% of patients with no contralateral hip symptoms develop symptoms at 10 years and 19% went on to total hip arthroplasty [70]. Reduced joint space, low center-edge angle, low head to neck ratio, and osteophytes are associated with development of osteoarthritis over an average 11-year radiographic follow-up [70]. Complex traumatic hip dislocations are more likely to develop osteoarthritis (44%) or osteonecrosis (33%) [70]. Retention of any intra-articular fragments after traumatic hip dislocation is associated with development of posttraumatic osteoarthritis [70]. A DDH family history is a risk factor for the progression of hip osteoarthritis [83]. Lumbosacral fusion increases the risk of hip osteoarthritis [42], and patients with long-segment lumbosacral fusion should be followed closely regarding hip osteoarthritis risk [42]. Multimorbid lumbar spinal stenosis with knee or hip osteoarthritis occurs in people at a rate of 0 to 54% [33]. Characteristics associated with comorbid lumbar spinal stenosis symptoms in people with knee or hip osteoarthritis may help to identify people with co-occurring conditions to guide clinical decision-making [10]. The incidence of depression among hip replacement patients in California between 2007 and 2010 increased 20%, affecting about 9% of patients [52]. A 2018 study examining sleep patterns for patients with osteoarthritis found 53% had insomnia symptoms and 66% had obstructive sleep apnea [52]. Chronic pain of osteoarthritis can lead to memory complaints, mood and anxiety disorders, multifocal pain, and fatigue [52]. In a 2014 Cochrane review, the effect of opioids in treating arthritis pain and improving function was minimal and did not outweigh the risk of adverse events or side effects [52]. A 2018 randomized controlled trial comparing opioids to nonopioids showed no difference in function and worse pain intensity for the opioid group [52]. Preoperative opioids correlate with higher postoperative narcotic usage and more difficult-to-control perioperative pain [52].

Recovery

Light activity (weeks): The provided evidence does not specify a typical week range for the resumption of desk work, driving, or light activities of daily living.

Full activity (months): The provided evidence does not specify a month range for the return to manual work, sport, or full range of motion and strength.

Complete recovery / outcome plateau (months): The provided evidence does not specify a month range for the stabilization of pain, strength, or final functional outcomes.

Rehabilitation protocol: A six-week physiotherapist-led exercise and education intervention resulted in sustained significant improvements in pain severity and interference in patients with hip or knee osteoarthritis awaiting arthroplasty [29]. The effects of neuromuscular exercise were moderate in patients with severe hip osteoarthritis [2].

Functional milestones: Patients who have undergone total hip arthroplasty exhibit impaired long-term self-reported physical quality of life and hip functionality [26]. Despite this impairment, these patients perform physically better than untreated patients with advanced hip osteoarthritis [26]. Pelvic tilt can vary depending on the time point of follow-up after total hip arthroplasty [30], and the primary diagnosis may impact pelvic tilt following the procedure [30].

Other Considerations: In non-operated individuals with hip osteoarthritis, no deterioration in gait parameters was evident at 6-7 year follow-up [187]. The only significant decline in functional status found at this interval was in passive hip flexion and adduction range of motion [187], while pain significantly improved [187]. Regarding natural history, at a mean follow-up of 24.7 years, 14% of hips with femoroacetabular impingement without surgical intervention had symptomatic osteoarthritis [7], and 4% underwent total hip arthroplasty [7]. At a mean follow-up of nearly 13 years, 7% of patients treated for symptomatic femoroacetabular impingement with hip arthroscopy experienced progression to total hip arthroplasty [46], compared to 11% of nonoperatively treated patients [46]. Distinct transcriptome profiles for early and late stage hip degeneration were identified along with key molecular contributors to the progression of hip osteoarthritis [87]. A family history of developmental dysplasia of the hip is a risk factor for the progression of hip osteoarthritis [83].

Intra-articular corticosteroid injections provide large, clinically meaningful short-term pain relief and functional improvement in hip osteoarthritis [15], with efficacy for immediate and delayed pain reduction within 12 weeks [72]. However, the benefits of these injections are not reliably sustained beyond three months [15]. The therapeutic effects of platelet-rich plasma and platelet-rich plasma plus hyaluronic acid injections for hip osteoarthritis lasted longer than hyaluronic acid alone, lasting 6 months [64]. Furthermore, the effects of platelet-rich plasma and platelet-rich plasma plus hyaluronic acid injections on patients' performance, disability, and activities of daily living were superior to hyaluronic acid in the long run [64]. A single injection of amniotic suspension allograft provides relief of pain and improvement in patient-reported outcomes for up to one year in patients with moderate hip osteoarthritis [28], although the exact mechanism of action remains unknown [28]. Leisure time physical activity showed no consistent overall relationship with the incidence of severe hip osteoarthritis defined as joint replacement due to osteoarthritis over 11 years [88]. Chronologic age in isolation is not an absolute contra-indication to hip arthroscopy [73]. Multiple known osteoarthritis risk factors are associated with the presence of knee or hip pain in individuals aged 29–59 years [11].

Key Evidence

• [L1] Patients with hip OA had inferior results compared with those who did not. [1] (10.1007/s11999-014-3943-9)
• [L2] While the effects were moderate in hip OA, they were only small in knee OA. [2] (10.3899/jrheum.130642)
• [L3] A clinical diagnosis of hip osteoarthritis was found in approximately 22% of young patients undergoing hip arthroscopy within 2 years. [3] (10.1186/s12891-019-2646-5)
• [L1] This study supports assertions that hip osteoarthritis is a prevalent condition whose treatment will continue to place important demands on health services, despite heterogeneity in study populations and diagnostic methods. [4] (10.1007/s11999-008-0625-5)
• [L2] Clinical disease severity varies widely at the time of total hip replacement for osteoarthritis, and in advanced hip OA clinical severity shows no correlation with radiographic severity. [5] (10.1186/1471-2474-10-19)
• [L1] However, it cannot be recommended as standard therapy in hip OA for wider populations, and therefore the indications remain a highly individualised matter. [6] (10.1007/s00402-007-0447-z)
• [L3] At mean follow-up of 24.7 years, 14% of hips had symptomatic OA and 4% underwent THA. [7] (10.1177/0363546520949179)
• [L4] Subgroup analysis comparing operative versus nonoperative management demonstrated a 32% reduction in the radiographic progression of osteoarthritis at long-term follow-up, though there were no significant differences in the risk of total hip arthroplasty. [8] (10.1177/23259671251326116)
• [L5] Future clinical trials investigating the natural history and treatment of femoroacetabular impingement will require multimodal staging systems for hip osteoarthritis because the optimal system will differ based on the size of the study population, the specific objective in question, and the time frame in which the investigator expects to see the specified end point. [9] (10.5435/00124635-201300001-00008)
• [L3] These characteristics may help to identify people with co-occurring LSS and knee or hip OA, which can be used to help guide clinical decision-making. [10] (10.1186/s12891-023-06356-3)
• [L4] Knee/hip pain within the last month was frequent among individuals aged 29–59 years, and multiple known osteoarthritis risk factors were associated with the presence of knee/hip pain. [11] (10.1186/s12891-018-2183-7)
• [L1] For clinical practice, no recommendation can be made regarding the use of hip injections for diagnosing hip OA. [12] (10.1016/j.arth.2013.12.008)
• [L2] Limited evidence on the use of PROs as an integrated part of clinical practice for patients with hip and knee osteoarthritis was found. [13] (10.1186/s12891-019-2620-2)
• [L4] Rapid destructive hip osteoarthritis represents an uncommon subset of arthrosis with rapid progression. [14] (10.1177/2325967120s00078)
• [L1] Intra-articular corticosteroid injections provides large, clinically meaningful short-term pain relief and functional improvement in hip OA, with benefits not reliably sustained beyond three months. [15] (10.1016/j.arth.2026.07.024)
• [L3] Patients who exhibited rapidly progressive osteoarthritis before undergoing total hip arthroplasty showed worse patient-reported outcomes compared with those who did not have rapid progression. [16] (10.1016/j.arth.2024.04.016)
• [L3] These findings question whether THA should be prioritized only for those patients who have severe hip OA symptoms, but require confirmation in a trial. [17] (10.1016/j.arth.2025.04.032)
• [L1] Patients undergoing treatment for hip OA with either PRP or HA injections can expect to experience similarly beneficial short-term clinical outcomes. [24] (10.1016/j.arthro.2021.11.005)
• [L4] The identification of clinical phenotypes and prognostic factors for outcomes in pain and disability will be a first step towards pre- and postoperative precision medicine for individuals with hip OA undergoing THA. [25] (10.1186/s12891-023-06326-9)
• [L3] Patients who had undergone total hip arthroplasty have impaired long-term self-reported physical quality of life and hip functionality but they still perform physically better than untreated patients with advanced hip osteoarthritis. [26] (10.1186/1471-2474-12-222)
• [L3] Early interventions to target muscle weakness and prevent the development of strength asymmetries that are characteristic of advanced hip OA appear warranted. [27] (10.1186/s12891-018-2230-4)
• [L4] This study demonstrates promising results for relief of pain and improvement in patient-reported outcomes with intra-articular ASA in patients with moderate osteoarthritis of the hip for up to one year, although the exact mechanism of action remains unknown. [28] (10.1016/j.arthro.2021.04.034)
• [L1] The intervention resulted in sustained significant improvements in pain severity and interference in patients with hip/knee osteoarthritis awaiting arthroplasty compared with a control group. [29] (10.1186/s12891-016-1088-6)
• [Paper] The authors acknowledge that pelvic tilt can vary depending on the time point of follow-up after total hip arthroplasty (THA) and that primary diagnosis may impact pelvic tilt, noting that over 90% of patients had a primary diagnosis of osteoarthritis. [30] (10.1007/s00586-014-3700-5)
• [L4] No evidence exists on outcomes following non-operative management of FAI with concomitant Tönnis Grade 2 or more OA of the hip. [31] (10.1007/s00167-022-07274-y)
• [L3] The most common adverse event was transient hip pain. [32] (10.1016/j.jisako.2024.100363)
• [L1] There is evidence that multimorbid LSS with knee or hip OA occurs in people (0 to 54%), although results are based on studies with high risk of bias and surgical populations. [33] (10.1186/s12891-022-05104-3)
• [L1] [34] (10.1016/j.asmr.2021.07.029)
• [L2] [36] (10.1136/bjsports-2024-108222)
• [L1] [38] (10.1136/bjsports-2025-110144)
• [L1] Associations between body mass index and hip osteoarthritis risk do not vary by sex, study design or osteoarthritis definition. [39] (10.1016/j.jbspin.2010.04.011)
• [L3] The novel HiSS categorization supported the use of pelvic tilt to potentially improve the ability to discern HiSS types/pathologies in a subset of patients with hip osteoarthritis and spinal sagittal malalignment. [40] (10.5435/jaaos-d-18-00295)
• [L3] Particularly patients with long-segment lumbosacral fusion should be followed closely regarding hip osteoarthritis risk. [42] (10.1186/s13018-023-03932-0)
• [L3] Two-thirds of people with hip and/or knee osteoarthritis in Portugal have poor management of their pain levels. [43] (10.1186/s12891-022-06110-1)
• [L3] Screening patients with hip OA for depression early in the disease course may contribute to better patient-reported pain, HRQoL, and satisfaction after future THA. [44] (10.1097/corr.0000000000002681)
• [L3] At a mean follow-up of nearly 13 years, 7% of patients of the surgical group experienced progression to THA, compared with 11% of the nonoperative control group. [46] (10.1177/03635465231188114)
• [L4] The results demonstrate superior performance compared to other up-to-date methods, suggesting that the proposed method can serve as a supplementary tool to the KL grading scale for hip OA detection and severity assessment in clinical practice. [47] (10.1186/s12891-025-08911-6)
• [L3] Prior to total hip arthroplasty, individuals with hip osteoarthritis presented with an increased contralateral shift and forward displacement of the center of mass. [48] (10.1186/s13018-020-01663-0)
• [L3] [51] (10.1016/j.arthro.2013.07.149)
• [L4] The proposed AI model performed adequately in predicting hip OA progression and may be clinically applicable with additional datasets and validation. [53] (10.1186/s12891-024-08034-4)
• [L2] Cam morphology has been associated with the development of hip osteoarthritis, while the association between pincer morphology and hip osteoarthritis is much less clear. [54] (10.2519/jospt.2018.7816)
• [L2] Radiographic evidence of FAI is common in active patients with hip complaints. [60] (10.1007/s11999-010-1233-8)
• [L5] Intra-articular corticosteroid injections are safe and effective at reducing pain and improving function for up to three months in patients with symptomatic hip OA, with a low risk of adverse events. [61] (10.1177/23259671211066966)
• [L3] Older age ( ≥ 70 years), female, large CEA ( ≥ 40 °), and acetabular dysplasia (CEA < 20 °) appeared to be significant risk factors of hip OA. [62] (10.1016/j.joca.2009.11.004)
• [L4] The prevalence of hip osteoarthritis was 1.96 times higher in women compared to men. [63] (10.1186/s12891-024-07513-y)
• [L1] Although all 3 interventions were associated with improvement of pain and function in patients with hip OA, the therapeutic effects of PRP and PRP+HA injections lasted longer (6 months), and the effects of these two interventions on patients' performance, disability, and ADL were superior to HA in the long run. [64] (10.1186/s12891-022-05787-8)
• [L3] Insurance status, income, and gender were also associated with imaging and treatments performed in managing hip and knee osteoarthritis. [66] (10.1016/j.arth.2022.02.019)
• [L3] Younger patients with osteoarthritis are likely to return to high levels of activity after surgery, which may impact long-term wear-related implant survivorship. [67] (10.1007/s11999-014-3952-8)
• [L4] Consideration of sarcopenic obesity should be included in osteoarthritis patient assessments. [68] (10.1186/s12891-018-2175-7)
• [L1] IAST was proved to be an efficacious therapy in both immediate and delay pain reduction for hip OA patients within 12 weeks. [72] (10.1155/2020/6320154)
• [L3] Chronologic age in isolation is not an absolute contra-indication to hip arthroscopy. [73] (10.1007/s00167-019-05520-4)
• [L2] Results suggest to focus on preoperative function and radiological osteoarthritis to decide when THA will be most effective. [76] (10.1186/s12891-016-1070-3)
• [L2] The findings suggest that spinal alignment and mobility should be considered when assessing risk and designing preventive intervention for radiographic progression of secondary hip OA. [77] (10.1016/j.joca.2017.12.005)
• [L1] There is some evidence that patients with FAIS who undergo hip arthroscopy may have a lower rate of progression of OA and conversion to THA compared to similar patients initially treated nonoperatively. [80] (10.1016/j.asmr.2025.101256)
• [L3] Based on our data, we recommend the Kellgren-Lawrence as the grading system for lower extremity osteoarthritis. [81] (10.1186/s13018-026-06695-6)
• [L3] A DDH family history is a risk factor for the progression of hip OA. [83] (10.1016/j.arth.2023.08.026)
• [L4] The study highlights the variability of acetabular anatomy in patients with primary OA, noting that acetabular offset can be accurately determined on conventional radiographs. [86] (10.1016/j.arth.2019.03.065)
• [L4] Distinct transcriptome profiles for early and late stage hip degeneration were identified along with key molecular contributors to the progression of hip OA. [87] (10.1016/j.arth.2022.03.013)
• [L2] In this population-based study of middle-aged men and women, leisure time physical activity showed no consistent overall relationship with incidence of severe knee or hip OA, defined as joint replacement due to OA, over 11 years. [88] (10.1186/1471-2474-13-73)
• [L3] [97] (10.1186/s12891-018-1993-y)
• [L4] [108] (10.1186/1471-2474-13-242)
• [L4] There was no main effect of radiographic disease severity on hip kinematic variability in the sagittal or frontal plane, and no significant differences in coordination of variability of segment couplings were observed. [116] (10.1002/jor.24609)
• [L3] Besides more commonly reported spatiotemporal parameters, only upper body motion provided nonredundant and sensitive parameters representing gait adaptations in individuals with hip OA. [117] (10.1186/s12891-021-04074-2)
• [L3] Reduced gait velocity, reduced sagittal plane joint excursion, and a reduced hip flexion moment in the late stance phase of gait were found to be evident already in hip osteoarthritis patients with mild to moderate symptoms, not eligible for total hip replacement. [123] (10.1186/1471-2474-13-258)
• [L3] Considering the LEFS' good psychometric qualities and ability to discriminate between pain and functioning, we recommend the LEFS as the outcome measure of choice to assess self-reported physical functioning in individuals with hip or knee osteoarthritis. [124] (10.1186/1471-2474-13-117)
• [L1] In adults with severe hip OA, THR reduced hip pain and improved self-reported hip function at 6 months compared with resistance training. [129] (10.2106/jbjs.25.00632)
• [L1] Evidence suggests that steroid injection is more effective than saline injection for the treatment of hip joint pain, and restoration of functional outcomes. [132] (10.1302/0301-620x.106b6.bjj-2023-1272.r1)
• [L5] The benefits of hip arthroscopy for patients with Tönnis grade 2 or greater hip osteoarthritis are ambiguous due to contradictory research and varying reliability of the Tönnis classification, necessitating shared decision-making between surgeon and patient. [136] (10.1016/j.arthro.2022.02.013)
• [L3] Subjects had 3.49 degrees less peak hip flexion and 8.82 degrees less extension angles. [139] (10.1002/jor.22772)
• [L4] Patients with hip osteoarthritis showed the poorest repeatability between gait recordings collected by different examiners, as compared to patients operated with a THA and healthy controls. [140] (10.1186/s12891-018-2145-0)
• [L1] CS injections are recommended as the most efficient agent in hip OA patients in the short term. [144] (10.1016/j.arthro.2019.09.043)
• [L3] The specific advantages of hip resurfacing make the procedure a very attractive option for young subjects. [145] (10.1007/s00264-012-1555-0)
• [L3] In patients with excessive hip adduction and pelvic tilt toward the swing limb during gait, gait modification may contribute to the reduction of hip joint loading. [147] (10.1186/s12891-019-3022-1)
• [L2] The reduced ability of flexion in the arthritic hip leads to posterior pelvic tilt in the relaxed-seated position, associated with compensatory increased lumbar flexion. [151] (10.1016/j.arth.2021.03.031)
• [L5] [158] (10.1016/j.arthro.2023.12.010)
• [L2] [159] (10.1177/23259671211050613)
• [L1] [170] (10.1097/01.blo.0000203477.19421.ed)
• [L3] No associations were found between mean PI values or PI categories and hip OA. [174] (10.1302/0301-620x.103b11.bjj-2021-0472.r1)
• [L3] Radiographic findings appeared to correspond with functional status in former ASF players with knee OA but not hip OA. [175] (10.1177/23259671261420422)
• [L2] The age-standardized incidence, prevalence, and YLDs of global hip OA have been on the rise from 1992 to 2021, with predictions indicating that these metrics may continue to significantly increase in the future. [176] (10.1186/s12891-025-09126-5)
• [L4] The segmental electrical bioimpedance equipment can detect differences between limbs affected and unaffected by hip osteoarthritis. [177] (10.1186/s12891-023-06541-4)
• [L2] Multiple genetic variants, including 5 novel loci, were associated with end-stage hip OA treated with primary THA. [179] (10.1016/j.arth.2023.05.006)
• [L4] Nonoperative OA hip patients were generally unreceptive to using smart technologies, with the exception of smartphone applications. [181] (10.1016/j.arth.2022.02.026)
• [L4] [184] (10.5435/00124635-201300001-00003)
• [L2] At 6-7 year follow-up, no deterioration in gait parameters was evident in non-operated individuals, and the only significant decline in functional status was found in passive hip flexion and adduction ROM, while pain significantly improved. [187] (10.2519/jospt.2015.5441)
• [L4] Greater cross-sectional area of hip flexors might be associated with better quality of life. [188] (10.1186/s12891-020-03348-5)
• [L4] [193] (10.1186/s12891-020-03888-w)
• [L2] [194] (10.1136/bjsports-2024-109595)
• [L4] This pilot study suggests that radiological features, specifically joint space narrowing, might be of importance for the decision of viscosupplementation in patients with hip osteoarthritis, though further confirmation by larger scale trials is needed. [195] (10.1186/s12891-016-1359-2)
• [L1] Insufficient evidence exists to establish the effectiveness of physiotherapy exercise following primary hip replacement for osteoarthritis. [196] (10.1186/1471-2474-10-98)
• [L3] Spinal pathology was significantly associated with both the development and progression of hip osteoarthritis (HOA). [197] (10.1016/j.arth.2026.05.058)
• [L3] [199] (10.1016/j.arth.2008.01.270)

See Also

• Total hip replacement
• Hip arthroscopy
• Femoroacetabular impingement
• Avascular necrosis of the femoral head
• Periacetabular osteotomy
• Hip resurfacing

References

[1] Hip Arthroscopy in the Setting of Hip Osteoarthritis: Systematic Review of Outcomes and Progression to Hip Arthroplasty. Clinical Orthopaedics & Related Research. 2015. DOI: 10.1007/s11999-014-3943-9

[2] Immediate Efficacy of Neuromuscular Exercise in Patients with Severe Osteoarthritis of the Hip or Knee: A Secondary Analysis from a Randomized Controlled Trial. The Journal of Rheumatology. 2014. DOI: 10.3899/jrheum.130642

[3] The two-year incidence of hip osteoarthritis after arthroscopic hip surgery for femoroacetabular impingement syndrome. BMC Musculoskeletal Disorders. 2019. DOI: 10.1186/s12891-019-2646-5

[4] Systematic Review of the Prevalence of Radiographic Primary Hip Osteoarthritis. Clinical Orthopaedics & Related Research. 2009. DOI: 10.1007/s11999-008-0625-5

[5] Variations in the pre-operative status of patients coming to primary hip replacement for osteoarthritis in European orthopaedic centres. BMC Musculoskeletal Disorders. 2009. DOI: 10.1186/1471-2474-10-19

[6] What is the evidence for viscosupplementation in the treatment of patients with hip osteoarthritis? Systematic review of the literature. Archives of Orthopaedic and Trauma Surgery. 2007. DOI: 10.1007/s00402-007-0447-z

[7] Risk Factors for Long-term Hip Osteoarthritis in Patients With Femoroacetabular Impingement Without Surgical Intervention. The American Journal of Sports Medicine. 2020. DOI: 10.1177/0363546520949179

[8] The Impact of Hip Arthroscopy on the Progression of Hip Osteoarthritis in Patients With Femoroacetabular Impingement Syndrome: A Systematic Review and Meta-analysis. Orthopaedic Journal of Sports Medicine. 2025. DOI: 10.1177/23259671251326116

[9] Staging of Hip Osteoarthritis for Clinical Trials on Femoroacetabular Impingement. Journal of the American Academy of Orthopaedic Surgeons. 2013. DOI: 10.5435/00124635-201300001-00008

[10] Characteristics associated with comorbid lumbar spinal stenosis symptoms in people with knee or hip osteoarthritis: an analysis of 9,136 good life with osteoArthritis in Denmark (GLA:D®) participants. BMC Musculoskeletal Disorders. 2023. DOI: 10.1186/s12891-023-06356-3

[11] Association of osteoarthritis risk factors with knee and hip pain in a population-based sample of 29–59 year olds in Denmark: a cross-sectional analysis. BMC Musculoskeletal Disorders. 2018. DOI: 10.1186/s12891-018-2183-7

[12] Is Anesthetic Hip Joint Injection Useful in Diagnosing Hip Osteoarthritis? A Meta-Analysis of Case Series. The Journal of Arthroplasty. 2014. DOI: 10.1016/j.arth.2013.12.008

[13] Implementing patient-reported outcomes in clinical decision-making within knee and hip osteoarthritis: an explorative review. BMC Musculoskeletal Disorders. 2019. DOI: 10.1186/s12891-019-2620-2

[14] Is This Rapid Destructive Hip Osteoarthritis ?. Orthopaedic Journal of Sports Medicine. 2020. DOI: 10.1177/2325967120s00078

[15] Efficacy of Intra-Articular Corticosteroid Injection for Hip Osteoarthritis: A Systematic Review with Meta-Analysis. The Journal of Arthroplasty. 2026. DOI: 10.1016/j.arth.2026.07.024

[16] Worse Patient-Reported Outcomes and Spino-Pelvic Parameters After Total Hip Arthroplasty for Rapidly Progressive Osteoarthritis of the Hip Compared to Osteoarthritis: A Propensity-Matched Cohort Study. The Journal of Arthroplasty. 2024. DOI: 10.1016/j.arth.2024.04.016

[17] Total Hip Arthroplasty versus Education and Exercise: A Secondary Analysis of Propensity Matched Data Comparing Outcomes Across Hip Osteoarthritis Symptom Severity. The Journal of Arthroplasty. 2025. DOI: 10.1016/j.arth.2025.04.032

[19] Aaos Comprehensive Orthopaedic Review 3. Nonarthroplasty Surgical Treatment of the Hip > IV. Hip Arthrodesis.

[20] Campbell S Operative Orthopaedics 4 Volume Set. COMBINED HIP ARTHROSCOPY AND LIMITED OPEN OSTEochondroplasty > OSTEOARTHRITIS.

[21] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy and Biomechanics, Evaluation, Clinical Examination, and Imaging of the Hip > Summary.

[22] Orthopaedic Knowledge Update Sports Medicine 6. Imaging of the Hip > Radiography.

[23] Aaos Comprehensive Orthopaedic Review 3. Nonarthroplasty Surgical Treatment of the Hip > I. Femoroacetabular Impingement.

[24] Platelet‐Rich Plasma Versus Hyaluronic Acid for Hip Osteoarthritis Yields Similarly Beneficial Short‐Term Clinical Outcomes: A Systematic Review and Meta‐analysis of Level I and II Randomized Controlled Trials. Arthroscopy. 2021. DOI: 10.1016/j.arthro.2021.11.005

[25] Clinical phenotypes and prognostic factors in persons with hip osteoarthritis undergoing total hip arthroplasty: protocol for a longitudinal prospective cohort study (HIPPROCLIPS). BMC Musculoskeletal Disorders. 2023. DOI: 10.1186/s12891-023-06326-9

[26] Quality of life and functionality after total hip arthroplasty: a long-term follow-up study. BMC Musculoskeletal Disorders. 2011. DOI: 10.1186/1471-2474-12-222

[27] Individuals with mild-to-moderate hip osteoarthritis have lower limb muscle strength and volume deficits. BMC Musculoskeletal Disorders. 2018. DOI: 10.1186/s12891-018-2230-4

[28] A Single Injection of Amniotic Suspension Allograft Is Safe and Effective for Treatment of Mild to Moderate Hip Osteoarthritis: A Prospective Study. Arthroscopy. 2021. DOI: 10.1016/j.arthro.2021.04.034

[29] Significant improvements in pain after a six-week physiotherapist-led exercise and education intervention, in patients with osteoarthritis awaiting arthroplasty, in South Africa: a randomised controlled trial. BMC Musculoskeletal Disorders. 2016. DOI: 10.1186/s12891-016-1088-6

[30] Characteristics of sagittal spine–pelvis–leg alignment in patients with severe hip osteoarthritis. European Spine Journal. 2014. DOI: 10.1007/s00586-014-3700-5

[31] No evidence exists on outcomes of non‐operative management in patients with femoroacetabular impingement and concomitant Tönnis Grade 2 or more hip osteoarthritis: a scoping review. Knee Surgery, Sports Traumatology, Arthroscopy. 2022. DOI: 10.1007/s00167-022-07274-y

[32] Intra-articular injection of a cross-linked hyaluronic acid combined with triamcinolone hexacetonide improves pain at six months in patients with mild to moderate hip osteoarthritis: A prospective observational study. Journal of ISAKOS. 2025. DOI: 10.1016/j.jisako.2024.100363

[33] Prevalence of multimorbid degenerative lumbar spinal stenosis with knee or hip osteoarthritis: a systematic review and meta-analysis. BMC Musculoskeletal Disorders. 2022. DOI: 10.1186/s12891-022-05104-3

[34] Abnormal Femoral Anteversion Is Associated With the Development of Hip Osteoarthritis: A Systematic Review and Meta‐Analysis. Arthroscopy, Sports Medicine, and Rehabilitation. 2021. DOI: 10.1016/j.asmr.2021.07.029

[36] Femoroacetabular impingement syndrome in middle-aged individuals is strongly associated with the development of hip osteoarthritis within 10-year follow-up: a prospective cohort study (CHECK). British Journal of Sports Medicine. 2024. DOI: 10.1136/bjsports-2024-108222

[38] Cam morphology and the risk of developing radiographic hip osteoarthritis within 8 years: an individual participant data meta-analysis of 23 886 hips from the world COACH consortium. British Journal of Sports Medicine. 2025. DOI: 10.1136/bjsports-2025-110144

[39] The relationship between body mass index and hip osteoarthritis: A systematic review and meta-analysis. Joint Bone Spine. 2011. DOI: 10.1016/j.jbspin.2010.04.011

[40] Radiographic Categorization of the Hip-spine Syndrome in the Setting of Hip Osteoarthritis and Sagittal Spinal Malalignment. Journal of the American Academy of Orthopaedic Surgeons. 2019. DOI: 10.5435/jaaos-d-18-00295

[42] Lumbosacral fusion increases the risk of hip osteoarthritis. Journal of Orthopaedic Surgery and Research. 2023. DOI: 10.1186/s13018-023-03932-0

[43] Prevalence of and factors associated with unmanageable pain levels in people with knee or hip osteoarthritis: a cross-sectional population-based study. BMC Musculoskeletal Disorders. 2023. DOI: 10.1186/s12891-022-06110-1

[44] What Factors Identified in Initial Osteoarthritis Management Are Associated With Poor Patient-reported Outcomes After THA? A Register-based Study. Clinical Orthopaedics & Related Research. 2023. DOI: 10.1097/corr.0000000000002681

[46] Progression of Osteoarthritis at Long-term Follow-up in Patients Treated for Symptomatic Femoroacetabular Impingement With Hip Arthroscopy Compared With Nonsurgically Treated Patients. The American Journal of Sports Medicine. 2023. DOI: 10.1177/03635465231188114

[47] An interpretable machine learning approach for predicting and grading hip osteoarthritis using gait analysis. BMC Musculoskeletal Disorders. 2025. DOI: 10.1186/s12891-025-08911-6

[48] Functional movement compensations persist in individuals with hip osteoarthritis performing the five times sit-to-stand test 1 year after total hip arthroplasty. Journal of Orthopaedic Surgery and Research. 2020. DOI: 10.1186/s13018-020-01663-0

[51] Paper #144: Can Gait Studies be Used to Predict Risk of Hip Osteoarthritis?. Arthroscopy. 2013. DOI: 10.1016/j.arthro.2013.07.149

[52] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. End-­Stage Hip Degeneration and Hip Reconstruction > Hip Osteoarthritis > Associated Conditions: Major Depression, Insomnia, Sleep Apnea, and Opioid Use.

[53] Development and accuracy of an artificial intelligence model for predicting the progression of hip osteoarthritis using plain radiographs and clinical data: a retrospective study. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-024-08034-4

[54] The Prevalence of Cam and Pincer Morphology and Its Association With Development of Hip Osteoarthritis. Journal of Orthopaedic & Sports Physical Therapy. 2018. DOI: 10.2519/jospt.2018.7816

[60] Radiographic Prevalence of Femoroacetabular Impingement in a Young Population with Hip Complaints Is High. Clinical Orthopaedics & Related Research. 2010. DOI: 10.1007/s11999-010-1233-8

[61] Arthroscopy Association of Canada Position Statement on Intra-articular Injections for Hip Osteoarthritis. Orthopaedic Journal of Sports Medicine. 2022. DOI: 10.1177/23259671211066966

[62] Hip osteoarthritis and risk factors in elderly Korean population. Osteoarthritis and Cartilage. 2010. DOI: 10.1016/j.joca.2009.11.004

[63] Annual epidemiological and health insurance disease burden of hip osteoarthritis in Hungary based on nationwide data. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-024-07513-y

[64] Comparison between the effects of ultrasound guided intra-articular injections of platelet-rich plasma (PRP), high molecular weight hyaluronic acid, and their combination in hip osteoarthritis: a randomized clinical trial. BMC Musculoskeletal Disorders. 2022. DOI: 10.1186/s12891-022-05787-8

[65] Aaos Comprehensive Orthopaedic Review 3. General Evaluation of the Hip Patient > III. Diagnostic Categories.

[66] Racial and Ethnic Disparities in the Imaging Workup and Treatment of Knee and Hip Osteoarthritis. The Journal of Arthroplasty. 2022. DOI: 10.1016/j.arth.2022.02.019

[67] Are Younger Patients Undergoing THA Appropriately Characterized as Active?. Clinical Orthopaedics & Related Research. 2015. DOI: 10.1007/s11999-014-3952-8

[68] The impact of sarcopenic obesity on knee and hip osteoarthritis: a scoping review. BMC Musculoskeletal Disorders. 2018. DOI: 10.1186/s12891-018-2175-7

[69] Campbell S Operative Orthopaedics 4 Volume Set. INDICATIONS AND CONTRAINDICATIONS FOR TOTAL HIP ARTHROPLASTY.

[70] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. End-­Stage Hip Degeneration and Hip Reconstruction > Hip Osteoarthritis > Natural History of Hip Osteoarthritis.

[72] Intra‐Articular Steroid Injection for Patients with Hip Osteoarthritis: A Systematic Review and Meta‐Analysis. BioMed Research International. 2020. DOI: 10.1155/2020/6320154

[73] Patients aged in their 70s do not have a high risk of progressive osteoarthritis following arthroscopic femoroacetabular impingement correction and labral preservation surgery. Knee Surgery, Sports Traumatology, Arthroscopy. 2019. DOI: 10.1007/s00167-019-05520-4

[74] Aaos Comprehensive Orthopaedic Review 3. Radiographic Evaluation of the Hip > V. Radiographic and MRI Parameters in the Setting of Osteoarthritis and Osteonecrosis.

[75] Orthopaedic Knowledge Update Sports Medicine 6. Imaging of the Hip > Ultrasonography.

[76] Preoperative predictors for outcomes after total hip replacement in patients with osteoarthritis: a systematic review. BMC Musculoskeletal Disorders. 2016. DOI: 10.1186/s12891-016-1070-3

[77] Sagittal alignment and mobility of the thoracolumbar spine are associated with radiographic progression of secondary hip osteoarthritis. Osteoarthritis and Cartilage. 2018. DOI: 10.1016/j.joca.2017.12.005

[79] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. End-­Stage Hip Degeneration and Hip Reconstruction > Summary.

[80] Hip Arthroscopy for Femoroacetabular Impingement Syndrome Reduces the Risk for Developing Hip Osteoarthritis: A Systematic Review. Arthroscopy, Sports Medicine, and Rehabilitation. 2025. DOI: 10.1016/j.asmr.2025.101256

[81] Reliability of radiographic knee and hip osteoarthritis classification between radiologists and orthopaedic surgeons. Journal of Orthopaedic Surgery and Research. 2026. DOI: 10.1186/s13018-026-06695-6

[83] Family History of Developmental Dysplasia of the Hip is a Risk Factor for the Progression of Hip Osteoarthritis. The Journal of Arthroplasty. 2024. DOI: 10.1016/j.arth.2023.08.026

[86] High Variability of Acetabular Offset in Primary Hip Osteoarthritis Influences Acetabular Reaming—A Computed Tomography–Based Anatomic Study. The Journal of Arthroplasty. 2019. DOI: 10.1016/j.arth.2019.03.065

[87] Otto Aufranc Award: Identification of Key Molecular Players in the Progression of Hip Osteoarthritis Through Transcriptomes and Epigenetics. The Journal of Arthroplasty. 2022. DOI: 10.1016/j.arth.2022.03.013

[88] Effect of leisure time physical activity on severe knee or hip osteoarthritis leading to total joint replacement: a population-based prospective cohort study. BMC Musculoskeletal Disorders. 2012. DOI: 10.1186/1471-2474-13-73

[89] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > 2. Arthrology > Hip (Fig. 2.49).

[92] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy and Biomechanics, Evaluation, Clinical Examination, and Imaging of the Hip > Osseous and Ligamentous Anatomy.

[94] Aaos Comprehensive Orthopaedic Review 3. Surgical Anatomy of the Hip > IV. Hip Capsule and Ligaments.

[97] Prevalence of and characteristics associated with insomnia and obstructive sleep apnea among veterans with knee and hip osteoarthritis. BMC Musculoskeletal Disorders. 2018. DOI: 10.1186/s12891-018-1993-y

[98] Aaos Comprehensive Orthopaedic Review 3. Surgical Anatomy of the Hip > V. Hip Joint Muscles.

[99] Aaos Comprehensive Orthopaedic Review 3. Fractures of the Hip > I. General Considerations.

[102] Aaos Comprehensive Orthopaedic Review 3. Surgical Anatomy of the Hip > VI. Neurovascular Structures Surrounding the Hip.

[103] Orthopaedic Knowledge Update Sports Medicine 6. Hip Microinstability > Introduction.

[107] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy and Biomechanics, Evaluation, Clinical Examination, and Imaging of the Hip > Imaging.

[108] Reproducibility of range of motion and muscle strength measurements in patients with hip osteoarthritis – an inter-rater study. BMC Musculoskeletal Disorders. 2012. DOI: 10.1186/1471-2474-13-242

[111] Orthopaedic Knowledge Update Sports Medicine 6. Imaging of the Hip > Annotated References.

[116] Hip joint kinematics and segment coordination variability according to pain and structural disease severity in hip osteoarthritis. Journal of Orthopaedic Research. 2020. DOI: 10.1002/jor.24609

[117] Independent and sensitive gait parameters for objective evaluation in knee and hip osteoarthritis using wearable sensors. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-021-04074-2

[119] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > SECTION 1 EVALUATION OF THE ADULT PATIENT WITH HIP PAIN.

[123] Sagittal plane gait characteristics in hip osteoarthritis patients with mild to moderate symptoms compared to healthy controls: a cross-sectional study. BMC Musculoskeletal Disorders. 2012. DOI: 10.1186/1471-2474-13-258

[124] The Dutch Lower Extremity Functional Scale was highly reliable, valid and responsive in individuals with hip/knee osteoarthritis: a validation study. BMC Musculoskeletal Disorders. 2012. DOI: 10.1186/1471-2474-13-117

[125] Apley And Solomon S Concise System Of Orthopaedics And Trauma. MAINSTAYS OF TREATMENT FOR HIP OA.

[129] In Adults with Severe Hip Osteoarthritis, Total Hip Replacement Reduced Hip Pain and Improved Self-Reported Hip Function at 6 Months Compared with Resistance Training. Journal of Bone and Joint Surgery. 2025. DOI: 10.2106/jbjs.25.00632

[131] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > SECTION 4 TREATMENT OF HIP ARTHRITIS.

[132] Clinical efficacy of multiple intra-articular injection for hip osteoarthritis. The Bone & Joint Journal. 2024. DOI: 10.1302/0301-620x.106b6.bjj-2023-1272.r1

[133] Apley And Solomon S Concise System Of Orthopaedics And Trauma. INFLAMMATORY ARTHRITIS OF THE HIP.

[135] Orthopaedic Knowledge Update Sports Medicine 6. Athletic Hip Injuries > Annotated References.

[136] Editorial Commentary: To Scope or Not to Scope a Patient With Tönnis Grade 2 Hip Osteoarthritis Remains Ambiguous. Arthroscopy. 2022. DOI: 10.1016/j.arthro.2022.02.013

[139] Relationship between physical impairments and movement patterns during gait in patients with end‐stage hip osteoarthritis. Journal of Orthopaedic Research. 2014. DOI: 10.1002/jor.22772

[140] Different reliability of instrumented gait analysis between patients with unilateral hip osteoarthritis, unilateral hip prosthesis and healthy controls. BMC Musculoskeletal Disorders. 2018. DOI: 10.1186/s12891-018-2145-0

[144] Different Intra‐articular Injections as Therapy for Hip Osteoarthritis: A Systematic Review and Network Meta‐analysis. Arthroscopy. 2020. DOI: 10.1016/j.arthro.2019.09.043

[145] Hip resurfacing in patients under thirty years old: an attractive option for young and active patients. International Orthopaedics. 2012. DOI: 10.1007/s00264-012-1555-0

[147] Gait kinematics of the hip, pelvis, and trunk associated with external hip adduction moment in patients with secondary hip osteoarthritis: toward determination of the key point in gait modification. BMC Musculoskeletal Disorders. 2020. DOI: 10.1186/s12891-019-3022-1

[151] Differences in Spinopelvic Characteristics Between Hip Osteoarthritis Patients and Controls. The Journal of Arthroplasty. 2021. DOI: 10.1016/j.arth.2021.03.031

[155] Apley And Solomon S Concise System Of Orthopaedics And Trauma. INTRA-ARTICULAR HIP PATHOLOGY – OSTEOARTHRITIS OF THE HIP JOINT.

[156] Orthopaedic Knowledge Update. Developmental Dysplasia of the Hip* > Adolescent HIP Dysplasia.

[157] Aaos Comprehensive Orthopaedic Review 3. General Evaluation of the Hip Patient > V. Comorbidities.

[158] Clinical Equipoise in the Management of Patients With Femoroacetabular Impingement Syndrome and Concomitant Tönnis Grade 2 Hip Osteoarthritis or Greater: An International Expert‐Panel Delphi Study. Arthroscopy. 2023. DOI: 10.1016/j.arthro.2023.12.010

[159] Automated Risk Stratification of Hip Osteoarthritis Development in Patients With Femoroacetabular Impingement Using an Unsupervised Clustering Algorithm: A Study From the Rochester Epidemiology Project. Orthopaedic Journal of Sports Medicine. 2021. DOI: 10.1177/23259671211050613

[162] Campbell S Operative Orthopaedics 4 Volume Set. SURGICAL PROBLEMS RELATIVE TO SPECIFIC HIP DISORDERS > TRAUMATIC AND POSTTRAUMATIC DISORDERS > ACUTE FEMORAL NECK FRACTURES.

[170] Delays Worsen Quality of Life Outcome of Primary Total Hip Arthroplasty. Clinical Orthopaedics & Related Research. 2006. DOI: 10.1097/01.blo.0000203477.19421.ed

[174] Pelvic incidence is not associated with the development of hip osteoarthritis. The Bone & Joint Journal. 2021. DOI: 10.1302/0301-620x.103b11.bjj-2021-0472.r1

[175] Factors Associated With Functional Outcomes in Former Professional American-Style Football Players With Symptomatic Knee and Hip Osteoarthritis. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/23259671261420422

[176] Global, regional, and national burden of hip osteoarthritis (1992–2021) and predictions of future disease burden trends: a systematic analysis of the global burden of disease study 2021. BMC Musculoskeletal Disorders. 2025. DOI: 10.1186/s12891-025-09126-5

[177] Segmental bioelectrical impedance analysis can detect differences between the affected and non-affected limbs in individuals with hip osteoarthritis. BMC Musculoskeletal Disorders. 2023. DOI: 10.1186/s12891-023-06541-4

[179] Genetic Risk Factors for End-Stage Hip Osteoarthritis Treated With Total Hip Arthroplasty: A Genome-wide Association Study. The Journal of Arthroplasty. 2023. DOI: 10.1016/j.arth.2023.05.006

[180] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy and Biomechanics, Evaluation, Clinical Examination, and Imaging of the Hip > Physical Examination.

[181] Patient Perceptions of Wearable and Smartphone Technologies for Remote Outcome Monitoring in Patients Who Have Hip Osteoarthritis or Arthroplasties. The Journal of Arthroplasty. 2022. DOI: 10.1016/j.arth.2022.02.026

[184] The Burden of Hip Osteoarthritis in the United States: Epidemiologic and Economic Considerations. Journal of the American Academy of Orthopaedic Surgeons. 2013. DOI: 10.5435/00124635-201300001-00003

[187] Gait Characteristics, Symptoms, and Function in Persons With Hip Osteoarthritis: A Longitudinal Study With 6 to 7 Years of Follow-up. Journal of Orthopaedic & Sports Physical Therapy. 2015. DOI: 10.2519/jospt.2015.5441

[188] Association between hip muscle cross-sectional area and hip pain and function in individuals with mild-to-moderate hip osteoarthritis: a cross-sectional study. BMC Musculoskeletal Disorders. 2020. DOI: 10.1186/s12891-020-03348-5

[193] Elevated levels of TNF-α, IL-1β and IL-6 in the synovial tissue of patients with labral tear: a comparative study with hip osteoarthritis. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-020-03888-w

[194] Severe pincer morphology is associated with incident hip osteoarthritis: prospective individual participant data from 18 935 hips from the World COACH consortium. British Journal of Sports Medicine. 2025. DOI: 10.1136/bjsports-2024-109595

[195] Predictors of response to viscosupplementation in patients with hip osteoarthritis: results of a prospective, observational, multicentre, open-label, pilot study. BMC Musculoskeletal Disorders. 2017. DOI: 10.1186/s12891-016-1359-2

[196] Effectiveness of physiotherapy exercise following hip arthroplasty for osteoarthritis: a systematic review of clinical trials. BMC Musculoskeletal Disorders. 2009. DOI: 10.1186/1471-2474-10-98

[197] Differential Effects of Degenerative Spine Disease and Spinal Fusion on the Risk and Progression of Hip Osteoarthritis: A Nationwide Time-Varying Cohort Study. The Journal of Arthroplasty. 2026. DOI: 10.1016/j.arth.2026.05.058

[199] Defining The Etiologies Of Premature Hip Joint Degeneration: Do Impingement Disorders Have A Role?. The Journal of Arthroplasty. 2008. DOI: 10.1016/j.arth.2008.01.270