Global Overcoverage Research Articles

Intermediate-Term Outcomes of Hip Arthroscopy for Femoroacetabular Impingement Syndrome in Patients With Global Versus Isolated Lateral Acetabular Overcoverage

Background: Previous studies evaluating the outcomes of hip arthroscopy for patients with global acetabular overcoverage and focal superolateral acetabular overcoverage suffer from short-term follow-up and inconsistent radiographic criteria when defining these subpopulations of patients with femoroacetabular impingement syndrome (FAIS). Purpose: To evaluate the intermediate-term postoperative outcomes for patients with FAIS in the setting of global acetabular overcoverage, lateral acetabular overcoverage, and normal acetabular coverage. Study Design: Cohort study; Level of evidence, 3. Methods: Patients undergoing hip arthroscopy for FAIS were enrolled in a prospective cohort study, and those with a minimum follow-up of 5 years were included in this analysis. Patients were grouped based on type of acetabular coverage: global overcoverage (lateral center-edge angle [LCEA] ≥40°, with coxa profunda), lateral overcoverage (LCEA ≥40°, without coxa profunda), and no overcoverage (LCEA <40°). Functional outcomes (modified Harris Hip Score and Nonarthritic Hip Score) and failure of primary hip arthroscopy were compared between groups. Results: In total, 94 patients (mean age, 41.9 ± 14.2 years) were included with a mean follow-up duration of 6.1 ± 0.9 years. Of these patients, 40.4% had no acetabular overcoverage, 36.2% had lateral overcoverage, and 23.4% had global overcoverage. There was no difference between groups with respect to percentage of patients who underwent reoperation for either revision arthroscopy or conversion to total hip arthroplasty (28.9% for the normal acetabular coverage group, 29.4% for the lateral overcoverage group, and 31.8% for the global overcoverage group; P = .971). Among patients for whom primary hip arthroscopy did not fail, there was no difference in 5-year functional outcomes between groups. Postoperative LCEA >40° (β = −13.3; 95% CI, –24.1 to −2.6; P = .016), female sex (β = −14.5; 95% CI, –22.7 to −6.2; P = .001), and higher body mass index (β = −1.9; 95% CI, –2.8 to −1.0; P < .001) were associated with worse intermediate-term hip function in terms of modified Harris Hip Score. Conclusion: There was no difference in functional outcomes or rate of reoperation at a minimum of 5 years postoperatively between those with global acetabular overcoverage, those with regional lateral overcoverage, and those with normal acetabular coverage. Provided that an appropriate acetabuloplasty is performed, there is no evidence to suggest that global acetabular overcoverage portends a worse prognosis than other FAIS subtypes.

Open and arthroscopic management of femoroacetabular impingement: a review of current concepts.

Femoroacetabular impingement (FAI) is a common femoral and/or acetabular abnormality that can cause progressive damage to the hip and osteoarthritis. FAI can be the result of femoral head/neck overgrowth, acetabular overgrowth or both femoral and acetabular abnormalities, resulting in a loss of native hip biomechanics and pain upon hip flexion and rotation. Radiographic evidence can include loss of sphericity of the femoral neck (cam impingement) and/or acetabular retroversion with focal or global overcoverage (pincer impingement). Operative intervention is indicated in symptomatic patients after failed conservative management with radiographic evidence of impingement and minimal arthritic changes of the hip, with the goal of restoring normal hip biomechanics and reducing pain. This is done by correcting the femoral head-neck relationship to the acetabulum through femoral and/or acetabular osteoplasty and treatment of concomitant hip pathology. In pincer impingement cases with small lunate surfaces, reverse periacetabular osteotomy is indicated as acetabular osteoplasty can decrease an already small articular surface. While surgical dislocation is regarded as the traditional gold standard, hip arthroscopy has become widely utilized in recent years. Studies comparing both open surgery and arthroscopy have shown comparable long-term pain reduction and improvements in clinical measures of hip function, as well as similar conversion rates to total hip arthroplasty. However, arthroscopy has trended toward earlier improvement, quicker recovery and faster return to sports. The purpose of this study was to review the recent literature on open and arthroscopic management of FAI.

An Assessment of Hip Strength, Patient Reported Outcomes, and Plasma Inflammatory Biomarkers After Surgical Correction for Symptomatic Femoroacetabular Impingement

Objectives:Patients with Femoroacetabular impingement (FAI) have been shown to have elevated circulating biomarkers of inflammation and cartilage catabolism, but little is known about whether corrective surgical intervention improves objective measures of hip strength and inflammation. This study measured several variables including pain, function, quality of life, symptoms, hip strength, and inflammatory and cartilage biomarkers in a cohort of subjects undergoing FAI surgery and postoperative (postop) rehabilitation. We hypothesized that surgical FAI repair and completion of a postop rehabilitation program will significantly improve patient reported outcomes (PROs), increase hip flexion and abduction strength measures, and decrease biomarkers of inflammation and cartilage degradation.Methods:This study was approved by the University of Michigan Medical School IRB (HUM00055335). Male and female patients aged 16-40 years of age, with symptomatic FAI diagnosed by concordant history, physical examination, and imaging findings were eligible for inclusion. Subjects who have undergone previous hip surgery, have a global overcoverage deformity, dysplasia, or degenerative chondral changes greater than Tonnis grade I were excluded. A single, fellowship trained, sports medicine orthopaedic surgeon performed all surgical procedures, and patients underwent a standardized postop rehabilitation program. HOOS questionnaires were assessed at each subject’s preoperative visit (preop), and at 2, 14, 26, and 52 weeks postop. Hip flexion, abduction, and extension were measured at each time point using a BioDex isokinetic dynamometer. High sensitivity C-reactive protein (HS-CRP) and cartilage oligomeric matrix protein (COMP) were measured in plasma using ELISAs. Differences between preop and postop time points were assessed using a mixed-effects model, and data are reported as mean±95% CI.Results:A total of 11 males and 6 females completed the study. Mean age of subjects was 25.2±3.8 years (range 16.0-38.0 years) and BMI of 24.2±2.0 kg/m2 (range 18.1-33.6 kg/m2). For most HOOS subscales, there was a decrease in score at 2 weeks postop, and by 14 weeks activities of daily living (ADL) improved by 18%, pain by 34%, quality of life by 69%, sport and recreation by 36%, and symptoms by 28% compared to preop values (Figure 1A-E). These improvements in HOOS subscales persisted for the duration of the study period (Figure 1A-E). No differences in hip flexion strength were observed, while extension was 20% and 31% significantly higher than preop values at 26 and 52 weeks, and for abduction patients were 34% stronger than preop values at 52 weeks. No differences in HS-CRP or COMP were observed (Figure 1F-J).Conclusion:In support of our hypothesis, we observed significant improvements in PROs of hip function, although changes in PROs preceded improvements in objective measures of hip extension and abduction strength. Despite improvements in other planes, no changes in hip flexion were observed. Plasma biomarkers of hip inflammation and cartilage turnover were not reduced by surgical intervention and rehabilitation. FAI surgery and postop rehabilitation is effective at treating pain, and improving patient reported quality of life and symptoms, with modest improvements in hip strength. However, the surgical correction of pathological hip anatomy and improvements in hip strength did not lead to significant differences in markers of inflammation or cartilage turnover.

Strategies in managing the labrum

The acetabular labrum plays a vital role in normal biomechanics of the hip joint. Both nociceptive and proprioceptive fibers are present in the labrum and their presence determines the rationale behind surgical labral treatments. In patients with femoroacetabular impingement (FAI) syndrome, a variety of labral injuries are observed. These may be the source of significant motion- and position-related hip and/or groin pain. However, there is a high prevalence of asymptomatic labral tear in the general and athletic population. Non-surgical treatment for symptomatic individuals includes education, activity modification, physical therapy, non-opioid oral medications, and injections. In the event of non-surgical treatment failure in non-arthritic and non-dysplastic individuals, surgical treatment includes labral repair and correction of cam, pincer, and subspine morphologies, and capsular management. Labral reconstruction is usually a revision procedure. However, in select primary cases (ossified labrum, global overcoverage pincer, irreparable tear), a reconstruction (or debridement) may be performed.

Are we failing in hip protrusio treatment?

In a recent article published in Clinical Orthopaedics and Related Research, Hanke and colleagues (1) reported the longest follow up trial available in the literature about the survivorship of hips with protrusio acetabuli treated with circumferential acetabular trimming through surgical hip dislocation. This group of patients was compared with a group of pincer type femoroacetabular impingement (FAI) without severe overcoverage. Severe pincer impingement (protrusio acetabuli) is an established cause of hip pain and osteoarthritis (OA): the acetabular roof is negatively tilted and typically deep with relative global overcoverage of the femoral head that overlaps the ilioischial line medially and protrudes in the true pelvis; therefore the size of the lunate surface is increased and leads to a pincer type FAI. Safe surgical hip dislocation described by Ganz et al .(2) with circumferential rim trimming and labral refixation or reconstruction is the current gold standard treatment for this acetabular morphology. Unfortunately this study underlines a poor expectation of survival in half of the hips with protrusio acetabuli compared with the control group according to Kaplan and Meier method’s endpoints (1): conversion to total hip arthroplasty (THA), radiographic progression of osteoarthritis, and Merle d’Aubigne-Postel score less than 15 points.

Arthroscopic treatment of global pincer-type femoroacetabular impingement.

Few studies have evaluated the role of hip arthroscopy in patients with coxa profunda. The purposes of this study are to (1) report functional hip outcomes after arthroscopic treatment of patients with femoroacetabular impingement (FAI) associated with radiographic coxa profunda and (2) evaluate factors associated with poor hip function at minimum 2years following surgery in this specific cohort. This retrospective review included patients with radiographic sign of coxa profunda who underwent hip arthroscopy to treat FAI. Preoperative and post-operative radiographs were reviewed to determine changes in lateral centre-edge angle (CEA), the presence and correction of Cam deformity, and Tönnis grade of osteoarthritis. Hip functional scores, including modified Harris Hip Score, Hip Outcome Score, and IHOT score, were obtained at a minimum of 2years following surgery. The study cohort included 46 patients with a mean preoperative CEA of 39.9 (±2.4)° which decreased to a mean of 30.8 (±1.8)° post-operatively. At a mean follow-up of 2.5years (±0.5), the mean mHHS and IHOT scores were 79.5 (±20.2) and of 69.7 (±28.3), respectively. Increased preoperative (p=0.02) and post-operative (p=0.001) Tönnis Osteoarthritis Grade was associated with a lower mHHS. Patients with coxa profunda can achieve similar functional scores to more traditional FAI cohorts after arthroscopic treatment. Baseline osteoarthritis is predictive of lower hip function after hip arthroscopy. This study demonstrates that patients with global over-coverage can benefit from hip arthroscopy and may influence surgeons to treat these patients with less invasive arthroscopic techniques which avoid the morbidity of open surgical procedures. Retrospective case series, Level IV.

Pelvic Incidence and Femoroacetabular Impingement - A Novel Relationship

Pelvic Incidence (PI) is a fixed anatomic parameter that plays an integral role in the sagittal balance of the spine and in maintaining stable posture while expending a minimum of energy - conus of economy. While PI has been studied in relation to the spine, PI has yet to be studied as it relates to disorders of the hip. We propose that abnormal PI is associated with femoroacetabular impingement (FAI). We performed a retrospective analysis of 50 consecutive patients (60 hips) who underwent hip arthroscopy for labral tears secondary to FAI. There were 31 women and 19 men. The average age was 33.1±8.7. All patient's underwent hip CT evaluation as well as plain radiographs. PI, acetabular version (AV) at a 3-o'clock position, alpha- angle, center-edge angle (CEA) and acetabular index (AI) were all measured. The PI was measured using scout lateral radiographs from the CT scan. Cam Impingement was defined as a bump on the head neck junction with an alpha-angle > 55°. Alpha angles were measured on all radiographs available as well as the oblique femoral head neck CT reformatted views and the largest number was used. Pincer Impingement was defined as global overcoverage with an AI < 0° or a CEA > 39° or as focal overcoverage/retroversion with an AV < 14°. The AI and the CEA were measured on AP x-rays. The AV was measured on the available CT imaging. Our cohort was compared to a historical control: Vialle et al. JBJS 2005. Vialle et al. measured spinopelvic measurements including PI on 300 asymptomatic patients (without spine or hip complaints). Student t-tests were used to compare all groups. Our mean PI was 50.8±11.3, less than the asymptomatic historical control (n=300) with a mean PI of 55.0±10.6 (p=0.01). Patients with global overcoverage (n=24) had a mean PI of 47.3±8.9, less than those without global overcoverage (n=36) with a mean PI of 53.2±12.3 (p=0.02). Patients with retroversion (n=23) had a mean PI of 45.6±9.9, less than those without retroversion (n=37) with a mean PI of 54.1±11.1 (p=0.003). Patients with cam impingement (n=39) had a mean PI of 51.1±9.8 compared to those without cam impingement with a mean PI of 49.6±14.0 (p=0.7). Pelvic incidence has been well described in the spine literature and has been shown to play an important role in spine pathology. The investigation of PI as it relates to the native hip is novel. Patients with labral tears due to FAI, particularly those with pincer impingement, have a smaller PI than an asymptomatic population. PI is the sum of sacral slope and pelvic tilt. Sacral slope and pelvic tilt change with position while PI is constant. With a smaller PI, the amount of change in sacral slope and pelvic tilt is limited. Thus, with a smaller pelvic incidence there is less range of motion between the lumbar spine and the pelvis around the hip joints. This restriction of movement and subsequent biomechanical adaptations may affect hip development, FAI, and resultant labral tears.

Radiographic Features Associated With Differing Impinging Hip Morphologies With Special Attention to Coxa Profunda

Combined with clinical examination and MRI, radiographs have been mainstays in the management femoroacetabular impingement (FAI). Because hip morphology often portends intraoperative damage, radiographic features should inform surgical management. We determined (1) the radiographic features of the various hip morphologies; (2) the prevalence of radiographic coxa profunda in each group; (3) the radiographic differences between hips with and without coxa profunda; and (4) its sensitivity and specificity as a measure of global acetabular overcoverage. We reviewed preoperative radiographs and operative notes of 144 hips that underwent surgical dislocation and correction for FAI between August 2002 and February 2011. Hips were divided into four FAI subtypes by radiographic analysis (cam, global overcoverage, retroversion, and combined) and three subtypes (cam, pincer, or combined) by intraarticular pathology. Standard radiographic measurements were performed, and we introduce a novel measurement that assesses femoral head coverage. We found differences in median Angle of Sharp, femoral head-neck angle, and median roof length (and its subset) among the FAI morphologies. The prevalence of radiographic coxa profunda was 48% in cam hips, 85% in global overcoverage hips, 66% in retroverted hips, and 32% in combined hips. The sensitivity and specificity of radiographic coxa profunda as a measure of global overcoverage was 75% (95% CI, 0.62-0.85) and 62% (95% CI, 0.51-0.73), respectively. We found major differences in radiographic measurements between FAI morphologies. Radiographic coxa profunda was poorly specific for global overcoverage. Measurement of roof length and ratio should be used to determine the morphology of the impinging hip. Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Radiographic Findings of Femoroacetabular Impingement in National Football League Combine Athletes Undergoing Radiographs for Previous Hip or Groin Pain

The purpose of this study was to investigate the prevalence of radiographic findings of femoroacetabular impingement (FAI) in elite football players with a history of hip pain or groin injury who underwent radiographs. We performed a retrospective review of athletes undergoing hip radiography at the National Football League Combine from 2007 to 2009. Radiographs were obtained in athletes with a history of hip pain or injury. Anteroposterior pelvis and frog-lateral radiographs were obtained in 123 hips (107 players) that met our inclusion criteria. Radiographic indicators of cam-type FAI (alpha angle, head-neck offset ratio) and pincer-type FAI (acetabular retroversion, center-edge angle, acetabular inclination) were recorded. Findings were correlated with clinical factors (previous groin/hip pain, position, race, and body mass index). The most common previous injuries included groin strain (n = 57) and sports hernia/abdominal strain (n = 21). Markers of cam- and/or pincer-type FAI were present in 94.3% of hips (116 of 123). Radiographic evidence of combined cam- and pincer-type FAI was the most common (61.8%, 76 hips), whereas isolated cam-type FAI (9.8%, 12 hips) and pincer-type FAI (22.8%, 28 hips) were less common. The most common deformities included acetabular retroversion (71.5%) and an abnormal alpha angle (61.8%). A body mass index greater than 35 was associated with the presence of global overcoverage (46.2% v 17.3%, P = .025). Radiographic indicators of FAI are very common among athletes evaluated at the National Football League Scouting Combine subjected to radiographic examination for the clinical suspicion of hip disease. Elite football athletes with significant or recurrent pain about the hip should be evaluated clinically and radiographically for FAI, because pain from FAI may be falsely attributed to or may be present in addition to other disorders. Level IV, therapeutic case series.

Femoroacetabular Impingement: Etiology and Surgical Concept

Osteoarthritis of the hip is one of the major causes of pain and disability in the developed world. Resulting therapeutic interventions and socioeconomic expenditures pose a considerable burden on health and social services. Based on experimental and clinical studies, including in situ inspection in consecutive adolescents and young adults undergoing surgical dislocations of the hip, we propose femoroacetabular impingement to cause early osteoarthritis in the nondysplastic hip; morphologic deviations of the acetabulum (regional or global overcoverage) and/or proximal femur with a decreased anterior head-neck offset may lead to repetitive trauma of the peripheral articular cartilage during flexion and internal rotation, particularly in individuals taking regular exercises. Frequently, this becomes symptomatic in the second and third decade of life in patients with an increased sportive activity. Based on predominance of the acetabular or femoral pathology, 2 different types of FAI, the pincer and the cam, are differentiated. Apart from these morphological alterations, a supraphysiological mobility and overuse can contribute to the FAI. The impingement concept has led to a new type of mainly intracapsular hip surgery aimed at improving clearance of the hip to avoid pathological contact.