Pelvic tilt after Bernese periacetabular osteotomy-a long-term follow-up study.

Patients with developmental dysplasia of the hip (DDH) are believed to present with increased anterior pelvic tilt to compensate for reduced anterior femoral head coverage. If true, pelvic tilt in dysplastic patients should be high preoperatively and decrease after correction with periacetabular osteotomy (PAO). To date, the evolution of pelvic tilt in long-term follow-up after PAO has not been reported. We therefore asked the following questions: (i) is there a difference in pelvic tilt between patients with DDH and an asymptomatic control group? (ii) How does pelvic tilt evolve during long-term follow-up after Bernese PAO compared with before surgery? This study is a therapeutic study with the level of evidence III. We retrospectively compared preoperative pelvic tilt in 64 dysplastic patients (71 hips) with an asymptomatic control group of 20 patients (20 hips). In addition, immediate postoperative and long-term follow-up (at 18 ± 8 [range 7-34 years) pelvic tilt was assessed and compared. Dysplastic patients had a significantly higher mean preoperative pelvic tilt than controls [2.3 ± 5.3° (-11.2° to 16.4°) versus 1.1 ± 3.0° (-4.9 to 5.9), P = 0.006]. Mean pelvic tilt postoperatively was 1.5 ± 5.3° (-11.2 to 17.0º, P = 0.221) and at long-term follow-up was 0.4 ± 5.7° (range -9.9° to 20.9°, P = 0.002). Dysplastic hips undergoing PAO show a statistically significant decrease in pelvic tilt during long-term follow-up. However, given the large interindividual variability in pelvic tilt, the observed differences may not achieve clinical significance.

Image-Less THA Cup Navigation in Clinical Routine Setup: Individual Adjustments, Accuracy, Precision, and Robustness.

Background and Objectives: Even after the 'death' of Lewinnek's safe zone, the orientation of the prosthetic cup in total hip arthroplasty is crucial for success. Accurate cup placement can be achieved with surgical navigation systems. The literature lacks study cohorts with large numbers of hips because postoperative computer tomography is required for the reproducible evaluation of the acetabular component position. To overcome this limitation, we used a validated software program, HipMatch, to accurately assess the cup orientation based on an anterior-posterior pelvic X-ray. The aim of this study were to (1) determine the intraoperative 'individual adjustment' of the cup positioning compared to the widely suggested target values of 40° of inclination and 15° of anteversion, and evaluate the (2) 'accuracy', (3) 'precision', and (4) robustness, regarding systematic errors, of an image-free navigation system in routine clinical use. Material and Methods: We performed a retrospective, accuracy study in a single surgeon case series of 367 navigated primary total hip arthroplasties (PiGalileoTM, Smith+Nephew) through an anterolateral approach performed between January 2011 and August 2018. The individual adjustments were defined as the differences between the target cup orientation (40° of inclination, 15° of anteversion) and the intraoperative registration with the navigation software. The accuracy was the difference between the intraoperative captured cup orientation and the actual postoperative cup orientation determined by HipMatch. The precision was analyzed by the standard deviation of the difference between the intraoperative registered and the actual cup orientation. The outliers were detected using the Tukey method. Results: Compared to the target value (40° inclination, 15° anteversion), the individual adjustments showed that the cups are impacted in higher inclination (mean 3.2° ± 1.6°, range, (−2)−18°) and higher anteversion (mean 5.0° ± 7.0°, range, (−15)−23°) (p < 0.001). The accuracy of the navigated cup placement was −1.7° ± 3.0°, ((−15)−11°) for inclination, and −4.9° ± 6.2° ((−28)−18°) for anteversion (p < 0.001). Precision of the system was higher for inclination (standard deviation SD 3.0°) compared to anteversion (SD 6.2°) (p < 0.001). We found no difference in the prevalence of outliers for inclination (1.9% (7 out of 367)) compared to anteversion (1.63% (6 out of 367), p = 0.78). The Bland-Altman analysis showed that the differences between the intraoperatively captured final position and the postoperatively determined actual position were spread evenly and randomly for inclination and anteversion. Conclusion: The evaluation of an image-less navigation system in this large study cohort provides accurate and reliable intraoperative feedback. The accuracy and the precision were inferior compared to CT-based navigation systems particularly regarding the anteversion. However the assessed values are certainly within a clinically acceptable range. This use of image-less navigation offers an additional tool to address challenging hip prothesis in the context of the hip−spine relationship to achieve adequate placement of the acetabular components with a minimum of outliers.

The New Bern Chondrolabral Classification Is Reliable and Reproducible.

BACKGROUND: Several classification systems have been used to describe early lesions of hip cartilage and the acetabular labrum in young adults with hip pain. Some of them were introduced before the concept of femoroacetabular impingement was proposed. Others were developed for other joints (such as the patellofemoral joint). However, these often demonstrate inadequate reliability, and they do not characterize all possible lesions. Therefore, we developed a novel classification system. QUESTION/PURPOSE: We asked: What is the (1) intraobserver reliability, (2) interobserver reproducibility, and (3) percentage of nonclassifiable lesions of the new classification system for damage to the hip cartilage and labrum compared with six established classification systems for chondral lesions (Beck et al. [4], Konan et al. [10], Outerbridge et al. [14]) and labral lesions (Beck et al. [3], Lage et al. [12], Peters and Erickson [15])? METHODS: We performed a validation study of a new classification system of early chondrolabral degeneration lesions based on intraoperative video documentation taken during surgical hip dislocations for joint-preserving surgery in 57 hips (56 patients) performed by one surgeon with standard video documentation of intraarticular lesions. The exclusion criteria were low-quality videos, inadequate exposure angles, traumatic lesions, and incomplete radiographic documentation. This left 42 hips (41 patients) for the blinded and randomized analysis of six raters, including those with cam-pincer-type femoroacetabular impingement (FAI) (19 hips in 18 patients), isolated cam-type FAI (10 hips), extraarticular FAI due to femoral anteversion (seven hips), isolated pincer-type FAI (two hips), focal avascular necrosis (two hips), localized pigmented villonodular synovitis (one hip), and acetabular dysplasia as a sequelae of Perthes disease (one hip). The raters had various degrees of experience in hip surgery: Three were board-certified orthopaedic fellows and three were orthopaedic residents, in whom we chose to prove the general usability of the classification systems in less experienced readers. Every rater was given the original publication of all existing classification systems and a visual guide of the new Bern classification system. Every rater classified the lesions according the existing classifications (cartilage: Beck et al. [4], Konan et al. [10], and Outerbridge et al. [14]; labrum: Beck et al. [3], Peters and Erickson [15], and Lage et al. [12]) and our new Bern chondrolabral classification system. The intraclass correlation coefficient with 95% confidence interval was used to assess the intraobserver reliability and interobserver reproducibility. The percentage of nonclassifiable lesions was calculated as an absolute number and percentage. RESULTS: The intraobserver intercorrelation coefficients (ICCs) for cartilage lesions were as follows: the Bern classification system (0.68 [95% CI 0.61 to 0.70]), Beck (0.44 [95% CI 0.34 to 0.54]), Konan (0.39 [95% CI 0.29 to 0.49]), and the Outerbridge classification (0.57 [95% CI 0.48 to 0.65]). For labral lesions, the ICCs were as follows: the Bern classification (0.70 [95% CI 0.63 to 0.76]), Peters (0.42 [95% CI 0.31 to 0.51]), Lage (0.26 [95% CI 0.15 to 0.38]), and Beck (0.59 [95% CI 0.51 to 0.67]). The interobserver ICCs for cartilage were as follows: the Bern classification system (0.63 [95% CI 0.51 to 0.75), the Outerbridge (0.14 [95% CI 0.04 to 0.28]), Konan (0.58 [95% CI 0.40 to 0.76]), and Beck (0.52 [95% CI 0.39 to 0.66]). For labral lesions, the ICCs were as follows: the Bern classification (0.61 [95% CI 0.49 to 0.74]), Beck (0.31 [95% CI 0.19 to 0.46]), Peters (0.28 [95% CI 0.16 to 0.44]), and Lage (0.20 [95% CI 0.09 to 0.35]). The percentage of nonclassifiable cartilage lesions was 0% for the Bern, 0.04% for Beck, 17% for Konan, and 25% for the Outerbridge classification. The percentage of nonclassifiable labral lesions was 0% for Bern and Beck, 4% for Peters, and 25% for Lage. CONCLUSION: We have observed some shortcomings with currently used classification systems for hip pathology, and the new classification system we developed seems to have improved the intraobserver reliability compared with the Beck and Konan classifications in cartilage lesions and with the Peters and Lage classifications in labral lesions. The interrater reproducibility of the Bern classification seems to have improved in cartilage lesions compared with the Outerbridge classification and in labral lesions compared with the Beck, Peters, and Lage classifications. The Bern classification identified all present cartilage and labral lesions. It provides a solid clinical basis for accurate descriptions of early degenerative hip lesions independent of etiology, and it is reproducible enough to use in the reporting of clinical research. Further studies need to replicate our findings in the hands of nondevelopers and should focus on the prognostic value of this classification and its utility in guiding surgical indications. LEVEL OF EVIDENCE: Level II, diagnostic study.

The crescent sign-a predictor of hip instability in magnetic resonance arthrography.

Currently, much is debated on the optimal treatment of borderline hips, being in the continuum between stable and unstable hips. The diagnosis of stability is often difficult but is a prerequisite for further treatment. Analysis includes a variety of radiographic parameters. We observed that unstable hips often had a crescent-like gadolinium collection in the postero-inferior joint space. We therefore questioned if the 'crescent sign' could be an indicator for hip instability? A retrospective comparative study was conducted including 56 hips in the instability group (treated with PAO) and 70 hips with femoroacetabular impingement (FAI) as control group. Based on standard radiographic parameters and magnetic resonance imaging (MRI), the association between hip instability and the 'crescent sign' was analyzed. For univariate group comparisons, the non-parametric Wilcoxon two sample test was used. Association between discrete variables was examined by means of chi-square tests. To examine predictive variables, logistic regression models were carried out. Most hips with a crescent sign belong to the instability group. A crescent sign has a sensitivity of 73.3% and specificity of 93% for instability. Based on our results, the crescent sign is a factor that is more prevalent in unstable hips. However, its absence does not exclude instability of the hip. If present, the specificity speaks strongly in favor for instability of the hip.

Location of Intra- and Extra-articular Hip Impingement Is Different in Patients With Pincer-Type and Mixed-Type Femoroacetabular Impingement Due to Acetabular Retroversion or Protrusio Acetabuli on 3D CT-Based Impingement Simulation.

BACKGROUND: Diagnosis and surgical treatment of hips with different types of pincer femoroacetabular impingement (FAI), such as protrusio acetabuli and acetabular retroversion, remain controversial because actual 3-dimensional (3D) acetabular coverage and location of impingement cannot be studied via standard 2-dimensional imaging. It remains unclear whether pincer hips exhibit intra- or extra-articular FAI. PURPOSE: (1) To determine the 3D femoral head coverage in these subgroups of pincer FAI, (2) determine the impingement-free range of motion (ROM) through use of osseous models based on 3D-computed tomography (CT) scans, and (3) determine the osseous intra-and extra-articular 3D impingement zones by use of 3D impingement simulation. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: This is a retrospective, comparative, controlled study involving 70 hips in 50 patients. There were 24 patients (44 hips) with symptomatic pincer-type or mixed-type FAI and 26 patients (26 hips) with normal hips. Surface models based on 3D-CT scans were reconstructed and compared for hips with acetabular retroversion (30 hips), hips with protrusio acetabuli (14 hips), and normal asymptomatic hips (26 hips). Impingement-free ROM and location of impingement were determined for all hips through use of validated 3D collision detection software based on CT-based 3D models. No abnormal morphologic features of the anterior iliac inferior spine were detected. RESULTS: (1) Mean total femoral head coverage was significantly (P < .001) increased in hips with protrusio acetabuli (92% ± 7%) and acetabular retroversion (71% ± 5%) compared with normal hips (66% ± 6%). (2) Mean flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (104°± 9°) and acetabular retroversion (116°± 6°) compared with normal hips (125°± 13°). Mean internal rotation in 90° of flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (16°± 12°) compared with normal hips (35°± 13°). (3) The prevalence of extra-articular subspine impingement was significantly (P < .001) higher in hips with acetabular retroversion (87%) compared with hips with protrusio acetabuli (14%) and normal hips (0%) and was combined with intra-articular impingement. The location of anterior impingement differed significantly (P < .001) between hips with protrusio acetabuli and normal hips. CONCLUSION: Using CT-based 3D hip models, we found that hips with pincer-type and mixed-type FAI have significantly larger femoral head coverage and different osseous ROM and location of impingement compared with normal hips. Additionally, intra- and extra-articular subspine impingement was detected predominantly in hips with acetabular retroversion. Acetabular rim trimming during hip arthroscopy or open surgical hip dislocation should be performed with caution for these hips. Patient-specific analysis of location of impingement using 3D-CT could theoretically improve diagnosis and planning of surgical treatment.

Periacetabular Osteotomy Provides Higher Survivorship Than Rim Trimming for Acetabular Retroversion.

BACKGROUND: Acetabular retroversion can cause impaction-type femoroacetabular impingement leading to hip pain and osteoarthritis. It can be treated by anteverting periacetabular osteotomy (PAO) or acetabular rim trimming with refixation of the labrum. There is increasing evidence that acetabular retroversion is a rotational abnormality of the entire hemipelvis and not a focal overgrowth of the anterior acetabular wall, which favors an anteverting PAO. However, it is unknown if this larger procedure would be beneficial in terms of survivorship and Merle d'Aubigné scores in a midterm followup compared with rim trimming. QUESTIONS/PURPOSES: We asked if anteverting PAO results in increased survivorship of the hip compared with rim trimming through a surgical hip dislocation in patients with symptomatic acetabular retroversion. METHODS: We performed a retrospective, comparative study evaluating the midterm survivorship of two matched patient groups with symptomatic acetabular retroversion undergoing either anteverting PAO or acetabular rim trimming through a surgical hip dislocation. Acetabular retroversion was defined by a concomitantly present positive crossover, posterior wall, and ischial spine sign. A total of 279 hips underwent a surgical intervention for acetabular retroversion at our center between 1997 and 2012 (166 periacetabular osteotomies, 113 rim trimmings through surgical hip dislocation). A total of 99 patients (60%) were excluded from the PAO group and 56 patients (50%) from the rim trimming group because they had any of several prespecified conditions (eg, dysplasia or pediatric conditions 61 [37%] for the PAO group and two [2%] for the rim trimming group), matching (10 [6%]/10 [9%] hips), deficient records (10 [6%]/13 [12%] hips), or the patient declined or was lost to followup (18 [11%]/31 [27%] hips). This left 67 hips (57 patients) that underwent anteverting PAO and 57 hips (52 patients) that had acetabular rim trimming. The two groups did not differ in terms of age, sex, body mass index, preoperative ROM, preoperative Merle d'Aubigné-Postel score, radiographic morphology of the acetabulum (except total and anterior acetabular coverage), alpha angle, Tönnis grade of osteoarthritis, and labral and chondral lesions on the preoperative MRI. During the period in question, we generally performed PAO from 1997 to 2003. With the availability of surgical hip dislocation and labral refixation, we generally performed rim trimming from 2004 to 2010. With growing knowledge of the underlying pathomorphology, anteverting PAOs became more common again around 2007 to 2008. A minimum followup of 2 years was required for this study. Failures were included at any time. The median followup for the anteverting PAO group was 9.5 years (range, 2-17.4 years) and 6.8 years (range, 2.2-10.5 years) for the rim trimming group (p < 0.001). Kaplan-Meier survivorship analysis was performed using the following endpoints at 5 and 10 years: THA, radiographic progression of osteoarthritis by one Tönnis grade, and/or Merle d'Aubigné-Postel score < 15 points. RESULTS: Although the 5-year survivorship of the two groups was not different with the numbers available (86% [95% confidence interval {CI}, 76%-94%] for anteverting PAO versus 86% [95% CI, 76%-96%] for acetabular rim trimming), we found increased survivorship at 10 years in hips undergoing anteverting PAO for acetabular retroversion (79% [95% CI, 68%-90%]) compared with acetabular rim trimming (23% [95% CI, 6%-40%]) at 10 years (p < 0.001). The drop in the survivorship curve for the acetabular rim trimming through surgical hip dislocation group started at Year 6. The main reason for failure was a decreased Merle d'Aubigné score. CONCLUSIONS: Anteverting PAO may be the more appropriate treatment for hips with substantial acetabular retroversion. This may be the result of reduction of an already smaller lunate surface of hips with acetabular retroversion through rim trimming. However, rim trimming may still benefit hips with acetabular retroversion in which only one or two of the three signs are positive. Future randomized studies should compare these treatments. LEVEL OF EVIDENCE: Level III, therapeutic study.

Hips With Protrusio Acetabuli Are at Increased Risk for Failure After Femoroacetabular Impingement Surgery: A 10-year Followup.

BACKGROUND: Protrusio acetabuli is a rare anatomic pattern of the hip in which the femoral head protrudes into the true pelvis. The increased depth of the hip and the excessive size of the lunate surface typically lead to severe pincer-type femoroacetabular impingement (FAI); however, to our knowledge, there are no published mid- or long-term studies on results of circumferential acetabular rim trimming through a surgical hip dislocation for patients with this condition. QUESTIONS/PURPOSES: (1) What is the 10-year survivorship of the hips treated with circumferential rim trimming through a surgical hip dislocation compared with a control group of hips that underwent surgery for pincer FAI but that did not have protrusio acetabuli? (2) What are the factors that were associated with a decreased likelihood of survivorship in those hips with the following endpoints: total hip arthroplasty, Merle d'Aubigné score of less than 15, and/or radiographic progression of osteoarthritis (OA)? (3) Does the radiographic pattern of degeneration differ between the two groups? METHODS: We performed a case-control study comparing two groups: a protrusio group (32 patients [39 hips]) and a control group (66 patients [86 hips]). The control group consisted of hips treated with a surgical hip dislocation for pincer FAI and did not include hips with a positive protrusio sign or a lateral center-edge angle > 39°. The study group did not differ from the control group regarding the preoperative Tönnis OA score, age, and body mass index. However, the study group had more women, decreased mean height and weight, and lower preoperative Merle d'Aubigné-Postel scores, which were inherent differences at the time of first presentation. During the period in question, the indication for performing these procedures was a painfully restricted range of motion in flexion and internal rotation (positive impingement sign). The mean followup of the protrusio group (9 ± 5 years [range, 2-18 years]) did not differ from the control group (11 ± 1 years [range, 10-13 years], p = 0.109). At the respective minimum followup intervals in the underlying database from which cases and control subjects were drawn, followup was 100% for patients with protrusion who underwent FAI surgery and 97% for patients with FAI who underwent surgery for other anatomic patterns (three of 86 hips). We assessed the Merle d'Aubigné-Postel score, Harris hip score, WOMAC, and UCLA activity score at latest followup. A Kaplan-Meier survivorship analysis of the hip was calculated if any of the following endpoints for both groups occurred: conversion to total hip arthroplasty, a Merle d'Aubigné-Postel score < 15, and/or radiographic progression of OA. Differences in survivorship were analyzed using the log-rank test. RESULTS: At 10-year followup, we found a decreased survivorship of the hip for the protrusio group (51% [95% confidence interval {CI}, 34%-67%]) compared with the control group (83% [95% CI, 75%-91%], p < 0.001) with one or more of the endpoints stated. We found four multivariate factors associated with a decreased likelihood of survival of the native hip according to the mentioned endpoints: body mass index > 25 kg/m(2) (adjusted hazard ratio, 6.4; 95% CI, 5.2-8.1; p = 0.009), a preoperative Tönnis OA score ≥ 1 (13.3; 95% CI, 11.8-14.9; p = 0.001), a postoperative lateral center-edge angle > 40° (4.2; 95% CI, 2.8-5.6; p = 0.042), and a postoperative posterior coverage > 56% (6.0; 95% CI, 4.3-7.6; p = 0.037). Preoperatively, joint space narrowing and osteophytes were more frequent posteroinferior (joint space narrowing 18% versus 2%, p = 0.008; osteophytes 21% versus 4%, p = 0.007), medial (joint space narrowing 33% versus 5%, p < 0.001) and  anterior (osteophytes 15% versus 1%, p = 0.004) in the protrusio compared with the control group. After correction in hips with protrusio, progression of joint space narrowing (from 6% to 45%, p = 0.001) and osteophyte formation (from 15% to 52%, p = 0.002) was most pronounced laterally. CONCLUSIONS: At 10 years, in 51% of all hips undergoing open acetabular rim trimming for protrusio acetabuli, the hip can be preserved without further radiographic degeneration and a Merle d'Aubigné score > 15. Even with the lack of a control group with nonoperative treatment, isolated rim trimming may not entirely resolve the pathomorphology in protrusio hips given the clearly inferior results compared with surgical hip dislocation for FAI without severe overcoverage. LEVEL OF EVIDENCE: Level III, therapeutic study.

Head reduction osteotomy with additional containment surgery improves sphericity and containment and reduces pain in Legg-Calvé-Perthes disease.

BACKGROUND: Severe femoral head deformities in the frontal plane such as hips with Legg-Calvé-Perthes disease (LCPD) are not contained by the acetabulum and result in hinged abduction and impingement. These rare deformities cannot be addressed by resection, which would endanger head vascularity. Femoral head reduction osteotomy allows for reshaping of the femoral head with the goal of improving head sphericity, containment, and hip function. QUESTIONS/PURPOSES: Among hips with severe asphericity of the femoral head, does femoral head reduction osteotomy result in (1) improved head sphericity and containment; (2) pain relief and improved hip function; and (3) subsequent reoperations or complications? METHODS: Over a 10-year period, we performed femoral head reduction osteotomies in 11 patients (11 hips) with severe head asphericities resulting from LCPD (10 hips) or disturbance of epiphyseal perfusion after conservative treatment of developmental dysplasia (one hip). Five of 11 hips had concomitant acetabular containment surgery including two triple osteotomies, two periacetabular osteotomies (PAOs), and one Colonna procedure. Patients were reviewed at a mean of 5 years (range, 1-10 years), and none was lost to followup. Mean patient age at the time of head reduction osteotomy was 13 years (range, 7-23 years). We obtained the sphericity index (defined as the ratio of the minor to the major axis of the ellipse drawn to best fit the femoral head articular surface on conventional anteroposterior pelvic radiographs) to assess head sphericity. Containment was assessed evaluating the proportion of patients with an intact Shenton's line, the extrusion index, and the lateral center-edge (LCE) angle. Merle d'Aubigné-Postel score and range of motion (flexion, internal/external rotation in 90° of flexion) were assessed to measure pain and function. Complications and reoperations were identified by chart review. RESULTS: At latest followup, femoral head sphericity (72%; range, 64%-81% preoperatively versus 85%; range, 73%-96% postoperatively; p = 0.004), extrusion index (47%; range, 25%-60% versus 20%; range, 3%-58%; p = 0.006), and LCE angle (1°; range, -10° to 16° versus 26°; range, 4°-40°; p = 0.0064) were improved compared with preoperatively. With the limited number of hips available, the proportion of an intact Shenton's line (64% versus 100%; p = 0.087) and the overall Merle d'Aubigné-Postel score (14.5; range, 12-16 versus 15.7; range, 12-18; p = 0.072) remained unchanged at latest followup. The Merle d'Aubigné-Postel pain subscore improved (3.5; range, 1-5 versus 5.0; range, 3-6; p = 0.026). Range of motion was not observed to have improved with the numbers available (p ranging from 0.513 to 0.778). In addition to hardware removal in two hips, subsequent surgery was performed in five of 11 hips to improve containment after a mean interval of 2.3 years (range, 0.2-7.5 years). Of those, two hips had triple osteotomy, one hip a combined triple and valgus intertrochanteric osteotomy, one hip an intertrochanteric varus osteotomy, and one hip a PAO with a separate valgus intertrochanteric osteotomy. No avascular necrosis of the femoral head occurred. CONCLUSIONS: Femoral head reduction osteotomy can improve femoral head sphericity. Improved head containment in these hips with an often dysplastic acetabulum requires additional acetabular containment surgery, ideally performed concomitantly. This can result in reduced pain and avascular necrosis seems to be rare. With the number of patients available, function did not improve. Therefore, future studies should use more precise instruments to evaluate clinical outcome and include longer followup to confirm joint preservation.

Eighty percent of patients with surgical hip dislocation for femoroacetabular impingement have a good clinical result without osteoarthritis progression at 10 years.

BACKGROUND: We previously reported the 5-year followup of hips with femoroacetabular impingement (FAI) that underwent surgical hip dislocation with trimming of the head-neck junction and/or acetabulum including reattachment of the labrum. The goal of this study was to report a concise followup of these patients at a minimum 10 years. QUESTIONS/PURPOSES: We asked if these patients had (1) improved hip pain and function; we then determined (2) the 10-year survival rate and (3) calculated factors predicting failure. METHODS: Between July 2001 and March 2003, we performed surgical hip dislocation and femoral neck osteoplasty and/or acetabular rim trimming with labral reattachment in 75 patients (97 hips). Of those, 72 patients (93 hips [96%]) were available for followup at a minimum of 10 years (mean, 11 years; range, 10-13 years). We used the anterior impingement test to assess pain and the Merle d'Aubigné-Postel score to assess function. Survivorship calculation was performed using the method of Kaplan and Meier and any of the following factors as a definition of failure: conversion to total hip arthroplasty (THA), radiographic evidence of worsening osteoarthritis (OA), or a Merle d'Aubigné-Postel score less than 15. Predictive factors for any of these failures were calculated using the Cox regression analysis. RESULTS: At 10-year followup, the prevalence of a positive impingement test decreased from preoperative 95% to 38% (p < 0.001) and the Merle d'Aubigné-Postel score increased from preoperative 15.3 ± 1.4 (range, 9-17) to 16.9 ± 1.3 (12-18; p < 0.001). Survivorship of these procedures for any of the defined failures was 80% (95% confidence interval, 72%-88%). The strongest predictors of failure were age > 40 years (hazard ratio with 95% confidence interval, 5.9 [4.8-7.1], p = 0.002), body mass index > 30 kg/m(2) (5.5 [3.9-7.2], p = 0.041), a lateral center-edge angle < 22° or > 32° (5.4 [4.2-6.6], p = 0.006), and a posterior acetabular coverage < 34% (4.8 [3.7-5.6], p = 0.006). CONCLUSIONS: At 10-year followup, 80% of patients with FAI treated with surgical hip dislocation, osteoplasty, and labral reattachment had not progressed to THA, developed worsening OA, or had a Merle d'Aubigné-Postel score of less than 15. Radiographic predictors for failure were related to over- and undertreatment of acetabular rim trimming.

Periacetabular osteotomy restores the typically excessive range of motion in dysplastic hips with a spherical head.

BACKGROUND: Residual acetabular dysplasia is seen in combination with femoral pathomorphologies including an aspherical femoral head and valgus neck-shaft angle with high antetorsion. It is unclear how these femoral pathomorphologies affect range of motion (ROM) and impingement zones after periacetabular osteotomy. QUESTIONS/PURPOSES: (1) Does periacetabular osteotomy (PAO) restore the typically excessive ROM in dysplastic hips compared with normal hips; (2) how do impingement locations differ in dysplastic hips before and after PAO compared with normal hips; (3) does a concomitant cam-type morphology adversely affect internal rotation; and (4) does a concomitant varus-derotation intertrochanteric osteotomy (IO) affect external rotation? METHODS: Between January 1999 and March 2002, we performed 200 PAOs for dysplasia; of those, 27 hips (14%) met prespecified study inclusion criteria, including availability of a pre- and postoperative CT scan that included the hip and the distal femur. In general, we obtained those scans to evaluate the pre- and postoperative acetabular and femoral morphology, the degree of acetabular reorientation, and healing of the osteotomies. Three-dimensional surface models based on CT scans of 27 hips before and after PAO and 19 normal hips were created. Normal hips were obtained from a population of CT-based computer-assisted THAs using the contralateral hip after exclusion of symptomatic hips or hips with abnormal radiographic anatomy. Using validated and computerized methods, we then determined ROM (flexion/extension, internal- [IR]/external rotation [ER], adduction/abduction) and two motion patterns including the anterior (IR in flexion) and posterior (ER in extension) impingement tests. The computed impingement locations were assigned to anatomical locations of the pelvis and the femur. ROM was calculated separately for hips with (n = 13) and without (n = 14) a cam-type morphology and PAOs with (n = 9) and without (n = 18) a concomitant IO. A post hoc power analysis based on the primary research question with an alpha of 0.05 and a beta error of 0.20 revealed a minimal detectable difference of 4.6° of flexion. RESULTS: After PAO, flexion, IR, and adduction/abduction did not differ from the nondysplastic control hips with the numbers available (p ranging from 0.061 to 0.867). Extension was decreased (19° ± 15°; range, -18° to 30° versus 28° ± 3°; range, 19°-30°; p = 0.017) and ER in 0° flexion was increased (25° ± 18°; range, -10° to 41° versus 38° ± 7°; range, 17°-41°; p = 0.002). Dysplastic hips had a higher prevalence of extraarticular impingement at the anteroinferior iliac spine compared with normal hips (48% [13 of 27 hips] versus 5% [one of 19 hips], p = 0.002). A PAO increased the prevalence of impingement for the femoral head from 30% (eight of 27 hips) preoperatively to 59% (16 of 27 hips) postoperatively (p = 0.027). IR in flexion was decreased in hips with a cam-type deformity compared with those with a spherical femoral head (p values from 0.002 to 0.047 for 95°-120° of flexion). A concomitant IO led to a normalization of ER in extension (eg, 37° ± 7° [range, 21°-41°] of ER in 0° of flexion in hips with concomitant IO compared with 38° ± 7° [range, 17°-41°] in nondysplastic control hips; p = 0.777). CONCLUSIONS: Using computer simulation of hip ROM, we could show that the PAO has the potential to restore the typically excessive ROM in dysplastic hips. However, a PAO can increase the prevalence of secondary intraarticular impingement of the aspherical femoral head and extraarticular impingement of the anteroinferior iliac spines in flexion and internal rotation. A cam-type morphology can result in anterior impingement with restriction of IR. Additionally, a valgus hip with high antetorsion can result in posterior impingement with decreased ER in extension, which can be normalized with a varus derotation IO of the femur. However, indication of an additional IO needs to be weighed against its inherent morbidity and possible complications. The results are based on a limited number of hips with a pre- and postoperative CT scan after PAO. Future prospective studies are needed to verify the current results based on computer simulation and to test their clinical importance.