Search

Background: Femoral version deformities have recently been identified as a major contributor to femoroacetabular impingement (FAI). An in-depth understanding of the specific labral damage patterns caused by femoral version deformities may help to understand the underlying pathomorphologies in symptomatic patients and select the appropriate surgical treatment., Questions/purposes: We asked: (1) Is there a correlation between femoral version and the mean cross-sectional area of the acetabular labrum? (2) Is there a difference in the location of lesions of the acetabular labrum between hips with increased femoral version and hips with decreased femoral version? (3) Is there a difference in the pattern of lesions of the acetabular labrum between hips with increased femoral version and hips with decreased femoral version?, Methods: This was a retrospective, comparative study. Between November 2009 and September 2016, we evaluated 640 hips with FAI. We considered patients with complete diagnostic imaging including magnetic resonance arthrography (MRA) of the affected hip with radial slices of the proximal femur and axial imaging of the distal femoral condyles (allowing for calculation of femoral version) as eligible. Based on that, 97% (620 of 640 hips) were eligible; a further 77% (491 of 640 hips) were excluded because they had either normal femoral version (384 hips), incomplete imaging (20 hips), a lateral center-edge angle < 22° (43 hips) or > 39° (16 hips), age > 50 years (8 hips), or a history of pediatric hip disease (20 hips), leaving 20% (129 of 640 hips) of patients with a mean age of 27 ± 9 years for analysis, and 61% (79 of 129 hips) were female. Patients were assigned to either the increased (> 30°) or decreased (< 5°) femoral version group. The labral cross-sectional area was measured on radial MR images in all patients. The location-dependent labral cross-sectional area, presence of labral tears, and labral tear patterns were assessed using the acetabular clockface system and compared among groups., Results: In hips with increased femoral version, the labrum was normal in size (21 ± 6 mm 2 [95% confidence interval 20 to 23 mm 2 ]), whereas hips with decreased femoral version showed labral hypotrophy (14 ± 4 mm 2 [95% CI 13 to 15 mm 2 ]; p < 0.01). In hips with increased femoral version, labral tears were located more anteriorly (median 1:30 versus 12:00; p < 0.01). Hips with increased femoral version exhibited damage of the anterior labrum with more intrasubstance tears anterosuperiorly (17% [222 of 1322] versus 9% [93 of 1084]; p < 0.01) and partial tears anteroinferiorly (22% [36 of 165] versus 6% [8 of 126]; p < 0.01). Hips with decreased femoral version showed superior labral damage consisting primarily of partial labral tears., Conclusion: In the evaluation of patients with FAI, the term "labral tear" is not accurate enough to describe labral pathology. Based on high-quality radial MR images, surgeons should always evaluate the combination of labral tear location and labral tear pattern, because these may provide insight into associated femoral version abnormalities, which can inform appropriate surgical treatment. Future studies should examine symptomatic patients with normal femoral version, as well as an asymptomatic control group, to describe the effect of femoral version on labral morphology across the entire spectrum of pathomorphologies., Level of Evidence: Level III, prognostic study., Competing Interests: Each author certifies that there are no funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article related to the author or any immediate family members. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Association of Bone and Joint Surgeons.)

Aims: The aim of this study was to investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies. We asked: is there a difference in APP-PT between young symptomatic patients being evaluated for joint preservation surgery and an asymptomatic control group? Does APP-PT vary among distinct acetabular and femoral pathomorphologies? And does APP-PT differ in symptomatic hips based on demographic factors?, Methods: This was an institutional review board-approved, single-centre, retrospective, case-control, comparative study, which included 388 symptomatic hips in 357 patients who presented to our tertiary centre for joint preservation between January 2011 and December 2015. Their mean age was 26 years (SD 2; 23 to 29) and 50% were female. They were allocated to 12 different morphological subgroups. The study group was compared with a control group of 20 asymptomatic hips in 20 patients. APP-PT was assessed in all patients based on supine anteroposterior pelvic radiographs using validated HipRecon software. Values in the two groups were compared using an independent-samples t -test. Multiple regression analysis was performed to examine the influences of diagnoses and demographic factors on APP-PT. The minimal clinically important difference (MCID) for APP-PT was defined as > 1 SD., Results: There were no significant differences in APP-PT between the control group and the overall group (1.1° (SD 3.0°; -4.9° to 5.9°) vs 1.8° (SD 3.4°; -6.9° to 13.2°); p = 0.323). Acetabular retroversion and overcoverage groups showed higher mean APP-PTs compared with the control group (p = 0.001 and p = 0.014) and were the only diagnoses with a significant influence on APP-PT in the stepwise multiple regression analysis. All differences were below the MCID. The age, sex, height, weight, and BMI showed no influence on APP-PT., Conclusion: APP-PT showed no radiologically significant variation across different pathomorphologies of the hip in patients being assessed for joint-preserving surgery., Competing Interests: A. F. Heimann reports funding from the HFR Fribourg Hospital Research Fund, related to this article., (© 2024 Heimann et al.)

Background: Acetabular retroversion is observed frequently in healed Legg-Calvé-Perthes disease (LCPD). Currently, it is unknown at which stage and with what prevalence retroversion occurs because in non-ossified hips, retroversion cannot be measured with standard radiographic parameters., Methods: In a retrospective, observational study; we examined pelvic radiographs in children with LCPD the time point of occurrence of acetabular retroversion and calculated predictive factors for retroversion. Between 2004 and 2017, we included 55 children with a mean age of 5.7 ± 2.4 years at diagnosis. The mean radiographic follow-up was 7.0 ± 4.4 years. We used two new radiographic parameters which allow assessment of acetabular version in non-ossified hips: the pelvic width index and the ilioischial angle. They are based on the fact that the pelvic morphology differs depending on the acetabular version. These parameters were compared among the four Waldenström stages and to the contralateral side. Logistic regression analysis was performed to determine predictive factors for acetabular retroversion., Results: Both parameters differed significantly among the stages of Waldenström (p < 0.003 und 0.038, respectively). A more retroverted acetabulum was found in stage II and III (prevalence ranging from 54 to 56%) compared to stage I and IV (prevalence ranging from 23 to 39%). In hips of the contralateral side without LCPD, the prevalence of acetabular retroversion was 0% in all stages for both parameters. Predictive factors for retroversion were younger age at stage II and IV, collapse of the lateral pillar in stage II or a non-dysplastic hip., Conclusions: This is the first study evaluating acetabular version in children with LCPD from early stage to healing. In the developing hip, LCPD may result in acetabular retroversion and is most prevalent in the fragmentation (stage II) and early healing stage (stage III). Partial correction of acetabular retroversion can occur after healing. This has a potential clinical impact on the timing and type of surgical correction, especially in pelvic osteotomies for correction of acetabular version., Level of Evidence: Level III, retrospective observational study., (© 2022. The Author(s).)

Background: Geriatric acetabular fractures are becoming more common due to demographic changes. Compared with proximal femoral fractures, surgical treatment is more complex and often does not allow full-weight-bearing. The aims of this study were to compare operatively treated acetabular and proximal femoral fractures with regard to (1) cumulative 1-year mortality, (2) perioperative complications, and (3) predictive factors associated with a higher 1-year mortality., Methods: This institutional review board-approved comparative study included 486 consecutive surgically treated elderly patients (136 acetabular and 350 proximal femoral fractures). After matching, 2 comparable groups of 129 acetabular and 129 proximal femoral fractures were analyzed. Cumulative 1-year mortality was evaluated through Kaplan-Meier survivorship analysis, and perioperative complications were documented and graded. After confirming that the proportionality assumption was met, Cox proportional hazard modeling was conducted to identify factors associated with increased 1-year mortality., Results: The acetabular fracture group had a significantly lower cumulative 1-year mortality before matching (18% compared with 33% for proximal femoral fractures, log-rank p = 0.001) and after matching (18% compared with 36%, log-rank p = 0.005). Nevertheless, it had a significantly higher overall perioperative complication rate (68% compared with 48%, p < 0.001). In our multivariable Cox regression analysis, older age, perioperative blood loss of >1 L, and wheelchair mobilization were associated with lower survival rates after acetabular fracture surgery. Older age and a higher 5-item modified frailty index were associated with a higher 1-year mortality rate after proximal femoral fractures, whereas postoperative full weight-bearing was protective., Conclusions: Despite the complexity of operative treatment and a higher complication rate after acetabular fractures in the elderly, the 1-year mortality rate is lower than that after operative treatment of proximal femoral fractures, even after adjustment for comorbidities., Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: The authors indicated that no external funding was received for any aspect of this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/G511)., (Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.)

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., Competing Interests: Each author certifies that neither he nor she, nor any member of his or her immediate family, has funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2021 by the Association of Bone and Joint Surgeons.)

Background: Assessment of AP acetabular coverage is crucial for choosing the right surgery indication and for obtaining a good outcome after hip-preserving surgery. The quantification of anterior and posterior coverage is challenging and requires either other conventional projections, CT, MRI, or special measurement software, which is cumbersome, not widely available and implies additional radiation. We introduce the "rule of thirds" as a promising alternative to provide a more applicable and easy method to detect an excessive or deficient AP coverage. This method attributes the intersection point of the anterior (posterior) wall to thirds of the femoral head radius (diameter), the medial third suggesting deficient and the lateral third excessive coverage., Question/purpose: What is the validity (area under the curve [AUC], sensitivity, specificity, positive/negative likelihood ratios [LR(+)/LR(-)], positive/negative predictive values [PPV, NPV]) for the rule of thirds to detect (1) excessive and (2) deficient anterior and posterior coverages compared with previously established radiographic values of under-/overcoverage using Hip2Norm as the gold standard?, Methods: We retrospectively evaluated all consecutive patients between 2003 and 2015 from our institutional database who were referred to our hospital for hip pain and were potentially eligible for joint-preserving hip surgery. We divided the study group into six specific subgroups based on the respective acetabular pathomorphology to cover the entire range of anterior and posterior femoral coverage (dysplasia, overcoverage, severe overcoverage, excessive acetabular anteversion, acetabular retroversion, total acetabular retroversion). From this patient cohort, 161 hips were randomly selected for analysis. Anterior and posterior coverage was determined with Hip2Norm, a validated computer software program for evaluating acetabular morphology. The anterior and posterior wall indices were measured on standardized AP pelvis radiographs, and the rule of thirds was applied by one observer., Results: The detection of excessive anterior and posterior acetabular wall using the rule of thirds revealed an AUC of 0.945 and 0.933, respectively. Also the detection of a deficient anterior and posterior acetabular wall by applying the rule of thirds revealed an AUC of 0.962 and 0.876, respectively. For both excessive and deficient anterior and posterior acetabular coverage, we found high specificities and PPVs but low sensitivities and NPVs., Conclusion: We found a high probability for an excessive (deficient) acetabular wall when this intersection point lies in the lateral (medial) third, which would qualify for surgical correction. On the other hand, if this point is not in the lateral (medial) third, an excessive (deficient) acetabular wall cannot be categorically excluded. Thus, the rule of thirds is very specific but not as sensitive as we had expected., Level of Evidence: Level II, diagnostic study., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request. Each author certifies that neither he nor she, nor any member of his or her immediate family, has funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article., (Copyright © 2020 by the Association of Bone and Joint Surgeons.)

Background: Periacetabular osteotomy (PAO) has been shown to be a valuable option for delaying the onset of osteoarthritis in patients with hip dysplasia. Published studies at 30 years of follow-up found that postoperative anterior overcoverage and posterior undercoverage were associated with early conversion to THA. The anterior and posterior wall indices are practical tools for assessing AP coverage on standard AP radiographs of the pelvis pre-, intra-, and postoperatively. However, no study that we know of has evaluated the relationship between the postoperative anterior and posterior wall indices and survivorship free from arthroplasty., Questions/purposes: In a study including patients after PAO for developmental dysplasia of the hip (DDH), we evaluated whether the acetabular wall index is associated with conversion to THA in the long-term after PAO. We asked: (1) Is an abnormal postoperative anterior wall index associated with conversion to THA after PAO? (2) Is an abnormal postoperative posterior wall index associated with conversion to THA after PAO? (3) Are there other factors associated with joint replacement after PAO?, Methods: This retrospective study involved pooling data of PAO for DDH from two previously published sources. The first series (1984-1987) comprised the very first 75 PAOs for symptomatic DDH performed at the inventor's institution. The second (1997-2000) comprised a series of PAOs for symptomatic DDH completed at the same institution 10 years later. No patient was lost to follow-up. Fifty hips (44 patients) were excluded for predefined reasons (previous surgery, substantial femoral pathomorphologies, poor-quality radiographs), leaving 115 hips (102 patients, mean age 29 ± 11 years, 28% male) for analysis with a mean follow-up of 22 ± 6 years. One observer not involved in patient treatment digitally measured the anterior and posterior wall indices on postoperative AP pelvic radiographs of all patients. All patients were contacted by mail or telephone to confirm any conversion to THA and the timing of that procedure relative to the index procedure. We performed univariate and multivariate Cox regression analyses using conversion to THA as our endpoint to determine whether the anterior and posterior wall indices are associated with prosthetic replacement in the long-term after PAO. Thirty-one percent (36 of 115) of hips were converted to THA within a mean of 15 ± 7 years until failure. The mean follow-up duration of the remaining patients was 22 ± 6 years., Results: A deficient anterior wall index was associated with conversion THA in the long-term after PAO (adjusted hazard ratio 10 [95% CI 3.6 to 27.9]; p < 0.001). Although observed in the univariate analysis, we could not find a multivariate association between the posterior wall index and a higher conversion rate to THA. Grade 0 Tönnis osteoarthritis was associated with joint preservation (adjusted HR 0.2 [95% CI 0.07 to 0.47]; p = 0.005). Tönnis osteoarthritis Grades 2 and 3 were associated with conversion to THA (adjusted HR 2.3 [95% CI 0.9 to 5.7]; p = 0.08)., Conclusion: A deficient anterior wall index is associated with a decreased survivorship of the native hip in the long-term after PAO. Intraoperatively, in addition to following established radiographical guidelines, the acetabular wall indices should be measured systematically to ascertain optimal acetabular fragment version to increase the likelihood of reconstructive survival after PAO for DDH., Level of Evidence: Level III, therapeutic study., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request. Each author certifies that neither he nor she, nor any member of his or her immediate family, has funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article., (Copyright © 2021 by the Association of Bone and Joint Surgeons.)

Objective: To develop a hybrid augmented marker-based navigation system for acetabular reorientation during peri-acetabular osteotomy (PAO)., Methods: The system consists of a tracking unit attached to the patient's pelvis, augmented marker attached to the acetabular fragment and a host computer to do all the computations and visualization. The augmented marker is comprised of an external planar Aruco marker facing toward the tracking unit and an internal inertial measurement unit (IMU) to measure its orientation. The orientation output from the IMU is sent to the host computer. The tracking unit streams a live video of the augmented marker to the host computer, where the planar marker is detected and its pose is estimated. A Kalman filter-based sensor fusion combines the output from marker tracking and the IMU. We validated the proposed system using a plastic bone study and a cadaver study. Every time, we compared the inclination and anteversion values measured by the proposed system to those from a previously developed optical tracking-based navigation system., Results: Mean absolute differences for inclination and anteversion were 1.34 ([Formula: see text]) and 1.21 ([Formula: see text])[Formula: see text], respectively, for the cadaver study. Mean absolute differences were 1.63 ([Formula: see text]) and 1.55 ([Formula: see text])[Formula: see text] for inclination and anteversion for the plastic bone study. In both validation studies, very strong correlations were observed., Conclusion: We successfully demonstrated the feasibility of our system to measure the acetabular orientation during PAO.

Background: Variations in femoral and acetabular version are becoming increasingly recognized as contributing factors to the development of hip pain in patients with femoroacetabular impingement (FAI) and hip dysplasia. It is still unknown what the true prevalence of these rotational abnormalities is in this patient population., Purpose: To determine (1) the prevalence of femoral version abnormalities in symptomatic hips with FAI and hip dysplasia, (2) the prevalence of combined abnormalities of femoral and acetabular version in these patients, and (3) which specific hip morphologies are associated with abnormalities of femoral version., Study Design: Cross-sectional study; Level of evidence, 3., Methods: A total of 462 symptomatic patients (538 hips) were included who had hip pain attributed to FAI or hip dysplasia and who presented to our tertiary referral center for hip preservation surgery between 2011 and 2015. We retrospectively examined femoral and acetabular version among 11 subgroups with predefined hip morphologies and compared findings with a control group. The allocation to each subgroup was based on morphologic reference values for femoral head coverage, lateral center edge angle, alpha angle, and neck-shaft angle calculated on plain radiographs., Results: Of the 538 hips included, 52% were found to have abnormal femoral version; severe abnormalities were found in 17%. Severely decreased femoral version (<0°) was found in 5%; moderately decreased femoral version (0°-10°), in 17%; moderately increased femoral version (26°-35°), in 18%; and severely increased femoral version (>35°), in 12%. The most frequent abnormal combination was increased femoral version combined with normal acetabular version (22%). We found significantly lower mean femoral version for the cam-type FAI group (15°) and significantly higher mean femoral version for the Perthes hips (32°; ie, Legg-Calvé-Perthes disease) as compared with the control group (22°). The mean femoral version of the study group was 19°; for male patients, 15°; and for female patients, 22°., Conclusion: Abnormalities in femoral version are highly prevalent in patients with hip pain who are eligible for hip preservation surgery, and severe abnormalities are prevalent in 1 of 6 patients (17%). Based on these results, the evaluation of young patients with hip pain should always include an assessment of femoral version and acetabular version to best decide what treatment approach should be undertaken to optimize outcomes.

We developed and validated a small, easy to use and cost-effective augmented marker-based hybrid navigation system for peri-acetabular osteotomy (PAO) surgery. The hybrid system consists of a tracking unit directly placed on the patient's pelvis, an augmented marker with an integrated inertial measurement unit ('MU) attached to the patient's acetabular fragment and the host computer. The tracking unit sends a live video stream of the marker to the host computer where the marker's pose is estimated. The augmented marker with the 'MU sends its pose estimate to the host computer where we apply sensor fusion to compute the final marker pose estimate. The host computer then tracks the orientation of the acetabular fragment during peri-acetabular osteotomy surgery. Anatomy registration is done using a previously developed registration device. A Kalman filter-based sensor fusion was added to complete the system. A plastic bone study was performed for validation between an optical tracking-based navigation system and our proposed system. Mean absolute difference for inclination and anteversion was 1.63 degrees and 1.55 degrees, respectively. The results show that our system is able to accurately measure the orientation of the acetabular fragment.

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.

Background: Since its first description in 1984, periacetabular osteotomy (PAO) has become an accepted treatment for hip dysplasia. The 30-year survivorship with this procedure has not been reported. Because these patients are often very young at the time of surgery, long-term followup and identification of factors associated with poor outcome could help to improve patient selection., Questions/purposes: Looking at the initial group of patients with hip dysplasia undergoing PAO at the originator's institution, we asked: (1) What is the cumulative 30-year survival rate free from conversion to THA, radiographic progression of osteoarthritis, and/or a Merle d'Aubigné-Postel score < 15? (2) Did hip function improve and pain decrease? (3) Did radiographic osteoarthritis progress? (4) What are the factors associated with one or more of the three endpoints: THA, radiographic progression of osteoarthritis, and/or Merle d'Aubigné-Postel score < 15?, Methods: We retrospectively evaluated the first 63 patients (75 hips) who underwent PAO for hip dysplasia between 1984 and 1987. At that time, hip dysplasia was the only indication for PAO and no patients with acetabular retroversion, the second indication for a PAO performed today, were included. During that period, no other surgical treatment for hip dysplasia in patients with closed triradiate cartilage was performed. Advanced osteoarthritis (≥ Grade 2 according to Tönnis) was present preoperatively in 18 hips (24%) and 22 patients (23 hips [31%]) had previous femoral and/or acetabular surgery. Thirty-nine patients (42 hips [56%]) were converted to a THA and one patient (one hip [1%]) had hip fusion at latest followup. Two patients (three hips [4%]) died from a cause unrelated to surgery 6 and 16 years after surgery with an uneventful followup. From the remaining 21 patients (29 hips), the mean followup was 29 years (range, 27-32 years). Of those, five patients (six hips [8%]) did not return for the most recent followup and only a questionnaire was available. The cumulative survivorship of the hip according to Kaplan-Meier was calculated if any of the three endpoints, including conversion to THA, progression of osteoarthritis by at least one grade according to Tönnis, and/or a Merle d'Aubigné-Postel score < 15, occurred. Hip pain and function were assessed with Merle d'Aubigné-Postel score, Harris hip score, limp, and anterior and posterior impingement tests. Progression of radiographic osteoarthritis was assessed with Tönnis grades. A Cox regression model was used to calculate factors associated with the previously defined endpoints., Results: The cumulative survivorship free from conversion to THA, radiographic progression of osteoarthritis, and/or Merle d'Aubigné-Postel score < 15 was 29% (95% confidence interval, 17%-42%) at 30 years. No improvement was found for either the Merle d'Aubigné-Postel (15 ± 2 versus 16 ± 2, p = 0.144) or Harris hip score (83 ± 11 versus 85 ± 17, p = 0.602). The percentage of a positive anterior impingement test (39% versus 14%, p = 0.005) decreased at 30-year followup, whereas the percentage of a positive posterior impingement test (14% versus 3%, p = 0.592) did not decrease. The percentage of positive limp decreased from preoperatively 66% to 18% at 30-year followup (p < 0.001). Mean osteoarthritis grade (Tönnis) increased from preoperatively 0.8 ± 1 (0-3) to 2.1 ± 1 (0-3) at 30-year followup (p < 0.001). Ten factors associated with poor outcome defined as THA, radiographic progression of osteoarthritis, and/or Merle d'Aubigné-Postel score < 15 were found: preoperative age > 40 years (hazard ratio [HR] 4.3 [3.7-4.9]), a preoperative Merle d'Aubigné-Postel score < 15 (HR 4.1 [3.5-4.6]), a preoperative Harris hip score < 70 (HR 5.8 [5.2-6.4]), preoperative limp (HR 1.7 [1.4-1.9]), presence of a preoperative positive anterior impingement test (HR 3.6 [3.1-4.2]), presence of a preoperative positive posterior impingement test (HR 2.5 [1.7-3.2]), a preoperative internal rotation of < 20° (HR 4.3 [3.7-4.9]), a preoperative Tönnis Grade > 1 (HR 5.7 [5.0-6.4]), a postoperative anterior coverage > 27% (HR 3.2 [2.5-3.9]), and a postoperative acetabular retroversion (HR 4.8 [3.4-6.3])., Conclusions: Thirty years postoperatively, 29% of hips undergoing PAO for hip dysplasia can be preserved, but more than 70% will develop progressive osteoarthritis, pain, and/or undergo THA. Periacetabular osteotomy is an effective technique to treat symptomatic hip dysplasia in selected and young patients with closed triradiate cartilage. Hips with advanced joint degeneration (osteoarthritis Tönnis Grade ≥ 2) should not be treated with PAO. Postoperative anterior acetabular overcoverage or postoperative acetabular retroversion were associated with decreased joint survival., Level of Evidence: Level III, therapeutic study.

Background: Since the importance of an intact labrum for normal hip function has been shown, labral reattachment has become the standard method for open or arthroscopic treatment of hips with femoroacetabular impingement (FAI). However, no long-term clinical results exist evaluating the effect of labral reattachment. A 2-year followup comparing open surgical treatment of FAI with labral resection versus reattachment was previously performed at our clinic. The goal of this study was to report a concise followup of these patients at a minimum of 10 years., Questions/purposes: We asked if patients undergoing surgical hip dislocation for the treatment of mixed-type FAI with labral reattachment compared with labral resection had (1) improved hip pain and function based on the Merle d'Aubigné-Postel score; and (2) improved survival at 10-year followup., Methods: Between June 1999 and July 2002, we performed surgical hip dislocation with femoral neck osteoplasty and acetabular rim trimming in 52 patients (60 hips) with mixed-type FAI. In the first 20 patients (25 hips) until June 2001, a torn labrum or a detached labrum in the area of acetabular rim resection was resected. In the next 32 patients (35 hips), reattachment of the labrum was performed. The same indications were used to perform both procedures during the periods in question. Of the 20 patients (25 hips) in the first group, 19 patients (95%) (24 hips [96%]) were available for clinical and/or radiographic followup at a minimum of 10 years (mean, 13 years; range, 12-14 years). Of the 32 patients (35 hips) in the second group, 29 patients (91%) (32 hips [91%]) were available for clinical and/or radiographic followup at a minimum of 10 years (mean, 12 years; range, 10-13 years). We used the anterior impingement test to assess pain. Function was assessed using the Merle d'Aubigné- Postel score and ROM. Survivorship calculation was performed using the method of Kaplan-Meier with failure defined as conversion to THA, progression of osteoarthritis (of one grade or more on the Tönnis score), and a Merle d'Aubigné-Postel score < 15., Results: At the 10-year followup, hip pain in hips with labral reattachment was slightly improved for the postoperative Merle d'Aubigné-Postel pain subscore (5.0 ± 1.0 [3-6] versus 3.9 ± 1.7 [0-6]; p = 0.017). No difference existed for the prevalence of hip pain assessed using the anterior impingement test with the numbers available (resection group 52% [11 of 21 hips] versus reattachment group 27% [eight of 30 hips]; odds ratio, 3.03; 95% confidence interval [CI], 0.93-9.83; p = 0.062). Function was slightly better in the reattachment group for the overall Merle d'Aubigné-Postel score (16.7 ± 1.5 [13-18] versus 15.3 ± 2.4 [9-18]; p = 0.028) and hip abduction (45° ± 13° [range, 30°-70°] versus 38° ± 8° [range, 25°-45°]; p = 0.001). Hips with labral reattachment showed a better survival rate at 10 years than did hips that underwent labral resection (78%; 95% CI, 64%-92% versus 46%, 95% CI, 26%-66%; p = 0.009) with the endpoints defined as conversion to THA, progression of osteoarthritis, and a Merle d'Aubigné-Postel score < 15. With isolated endpoints, survival at 10 years was increased for labral reattachment and the endpoint Merle d'Aubigné score < 15 (83%, 95% CI, 70%-97% versus 48%, 95% CI, 28%-69%; p = 0.009) but did not differ for progression of osteoarthritis (83%, 95% CI, 68%-97% versus 81%, 95% CI, 63%-98%; p = 0.957) or conversion to THA (94%, 95% CI, 86%-100% versus 87%, 95% CI, 74%-100%; p = 0.366)., Conclusions: The current results suggest the importance of preserving the labrum and show that resection may put the hip at risk for early deterioration. At 10-year followup, hips with labral reattachment less frequently had a decreased Merle d'Aubigné score but no effect on progression of osteoarthritis or conversion to THA could be shown., Level of Evidence: Level III, therapeutic study.

Background: In recent years, surgical treatment of symptomatic femoroacetabular impingement (FAI) has been increasingly performed using arthroscopy. Bony pathomorphologies and damage to the labrum as well as cartilage defects can be addressed with comparable results to open surgery with overall less surgery-related complications. Despite the increasing importance of hip arthroscopy, however, reports on midterm clinical and radiographic outcomes and comparison to open surgical hip dislocation are scarce., Questions/purposes: (1) What are the clinical and radiographic outcomes at a mean 7-year followup; (2) what is the cumulative 7-year survivorship, using the endpoints of THA, progression of osteoarthritis according to Tönnis, or poor clinical outcome with a Merle d'Aubigné score of less than 15 points, of hips with symptomatic FAI treated arthroscopically; and (3) what factors were associated with revision surgery?, Methods: Between 2003 and 2008 we performed a total of 62 arthroscopic procedures (60 patients) for FAI. For the same indication, we also performed 571 surgical hip dislocations during that time. Standardized treatment was femoral offset correction, acetabular rim trimming, or both and treatment of labral or chondral defects. An arthroscopic approach was generally used if the pathomorphology was located in the anterosuperior quadrant of the hip and was gradually used for more complex cases. We excluded 10 hips (10 patients) in which the standardized treatment was not achieved and no offset correction or acetabular rim trimming was performed. Of the remaining 52 hips (50 patients), 39 hips underwent isolated femoral offset correction, four hips isolated acetabular rim trimming, and nine hips both procedures. At a mean followup of 7 years (range, 5-11 years), the Merle d'Aubigné clinical score was obtained and plain radiographs were examined (Tönnis grade, heterotopic ossification, lateral center-edge [LCE] angle, acetabular index [AI], extrusion index, alpha angle, and pistol grip deformity). Cumulative survivorship was calculated according to Kaplan-Meier using conversion to THA, progression of osteoarthritis (one or more Tönnis grades), or poor clinical outcome (Merle d'Aubigné score < 15 points) as endpoints. Cox regression analysis was used to identify univariate factors associated with revision surgery., Results: At last followup we detected a significant but possibly not clinically relevant increase in Merle d'Aubigné scores from preoperative levels to latest followup (14 ± 1 versus 16 ± 2, mean difference 2 points with a 95% confidence interval [95% CI] -3 to 7, p < 0.001). Six hips showed progression of osteoarthritis. Cumulative survivorship (hips free from conversion to THA, progression of osteoarthritis, or poor clinical outcome) of hips treated with hip arthroscopy for FAI at a mean followup of 7 years was 81% (95% CI, 68%-95%). Two patients (two hips, 4%) underwent THA at 7 and 9 years, respectively. An increased preoperative acetabular coverage (LCE angle, AI), increased offset in the superior portion of the femoral neck (pistol grip deformity), and a remaining pistol grip deformity postoperatively were associated with revision surgery. Any treatment of the labrum did not influence the outcome. Factors associated with failure could not be identified., Conclusions: In this series of patients with arthroscopic treatment of symptomatic FAI, hip arthroscopy resulted in an intact hip without progression of osteoarthritis and with a Merle d'Aubigné score of ≥ 15 points in 81% of patients at 7-year followup. Increased acetabular coverage and femoral pistol grip deformity were risk factors for revision surgery., Level of Evidence: Level IV, therapeutic study.

Background: Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) allows an objective, noninvasive, and longitudinal quantification of biochemical cartilage properties. Although dGEMRIC has been used to monitor the course of cartilage degeneration after periacetabular osteotomy (PAO) for correction of hip dysplasia, such longitudinal data are currently lacking for femoroacetabular impingement (FAI)., Questions/purposes: (1) How does the mean acetabular and femoral dGEMRIC index change after surgery for FAI at 1-year followup compared with a similar group of patients with FAI treated without surgery? (2) Does the regional distribution of the acetabular and femoral dGEMRIC index change for the two groups over time? (3) Is there a correlation between the baseline dGEMRIC index and the change of patient-reported outcome measures (PROMs) at 1-year followup? (4) Among those treated surgically, can dGEMRIC indices distinguish between intact and degenerated cartilage?, Methods: We performed a prospective, comparative, nonrandomized, longitudinal study. At the time of enrollment, the patients' decision whether to undergo surgery or choose nonoperative treatment was not made yet. Thirty-nine patients (40 hips) who underwent either joint-preserving surgery for FAI (20 hips) or nonoperative treatment (20 hips) were included. The two groups did not differ regarding Tönnis osteoarthritis score, preoperative PROMs, or baseline dGEMRIC indices. There were more women (60% versus 30%, p = 0.003) in the nonoperative group and patients were older (36 ± 8 years versus 30 ± 8 years, p = 0.026) and had lower alpha angles (65° ± 10° versus 73° ± 12°, p = 0.022) compared with the operative group. We used a 3.0-T scanner and a three-dimensional dual flip-angle gradient-echo technique for the dGEMRIC technique for the baseline and the 1-year followup measurements. dGEMRIC indices of femoral and acetabular cartilage were measured separately on the initial and followup radial dGEMRIC reformats in direct comparison with morphologic radial images. Regions of interest were placed manually peripherally and centrally within the cartilage based on anatomic landmarks at the clockface positions. The WOMAC, the Hip disability and Osteoarthritis Outcome Score, and the modified Harris hip score were used as PROMs. Among those treated surgically, the intraoperative damage according to the Beck grading was recorded and compared with the baseline dGEMRIC indices., Results: Although both the operative and the nonoperative groups experienced decreased dGEMRIC indices, the declines were more pronounced in the operative group (-96 ± 112 ms versus -16 ± 101 ms on the acetabular side and -96 ± 123 ms versus -21 ± 83 ms on the femoral side in the operative and nonoperative groups, respectively; p < 0.001 for both). Patients undergoing hip arthroscopy and surgical hip dislocation experienced decreased dGEMRIC indices; the decline in femoral dGEMRIC indices was more pronounced in hips after surgical hip dislocation (-120 ± 137 ms versus -61 ± 89 ms, p = 0.002). In the operative group a decline in dGEMRIC indices was observed in 43 of 44 regions over time. In the nonoperative group a decline in dGEMRIC indices was observed in four of 44 regions over time. The strongest correlation among patients treated surgically was found between the change in WOMAC and baseline dGEMRIC indices for the entire joint (R = 0.788, p < 0.001). Among those treated nonoperatively, no correlation between baseline dGEMRIC indices and change in PROMs was found. In the posterosuperior quadrant, the dGEMRIC index was higher for patients with intact cartilage compared with hips with chondral lesions (592 ± 203 ms versus 444 ± 205 ms, p < 0.001)., Conclusions: We found a decline in acetabular, femoral, and regional dGEMRIC indices for the surgically treated group at 1-year followup despite an improvement in all PROMs. We observed a similar but less pronounced decrease in the dGEMRIC index in symptomatic patients without surgical treatment indicating continuous cartilage degeneration. Although treatment of FAI is intended to alter the forces acting across the hip by eliminating impingement, its effects on cartilage biology are not clear. dGEMRIC provides a noninvasive method of assessing these effects. Longer term studies will be needed to determine whether the matrix changes of the bradytrophic cartilage seen here are permanent or clinically important., Level of Evidence: Level II, therapeutic study.

Background: Magnetic resonance arthrogram (MRA) with radial cuts is presently the best available preoperative imaging study to evaluate chondrolabral lesions in the setting of femoroacetabular impingement (FAI). Existing followup studies for surgical treatment of FAI have evaluated predictors of treatment failure based on preoperative clinical examination, intraoperative findings, and conventional radiography. However, to our knowledge, no study has examined whether any preoperative findings on MRA images might be associated with failure of surgical treatment of FAI in the long term., Questions/purposes: The purposes of this study were (1) to identify the preoperative MRA findings that are associated with conversion to THA, any progression of osteoarthritis, and/or a Harris hip score of < 80 points after acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through a surgical hip dislocation (SHD) for FAI at a minimum 10-year followup; and (2) identify the age of patients with symptomatic FAI when these secondary degenerative findings were detected on preoperative radial MRAs., Methods: We retrospectively studied 121 patients (146 hips) who underwent acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through SHD for symptomatic anterior FAI between July 2001 and March 2003. We excluded 35 patients (37 hips) with secondary FAI after previous surgery and 11 patients (12 hips) with Legg-Calvé-Perthes disease. All patients underwent preoperative MRA to further specify chondrolabral lesions except in 19 patients (32 hips) including 17 patients (20 hips) who presented with an MRI from an external institution taken with a different protocol, 10 patients with no preoperative MRA because the patients had already been operated on the contralateral side with a similar appearance, and two patients (two hips) refused MRA because of claustrophobia. This resulted in 56 patients (65 hips) with idiopathic FAI and a preoperative MRA. Of those, three patients (three hips) did not have minimal 10-year followup (one patient died; two hips with followup between 5 and 6 years). The remaining patients were evaluated clinically and radiographically at a mean followup of 11 years (range, 10-13 years). Thirteen pathologic radiographic findings on the preoperative MRA were evaluated for an association with the following endpoints using Cox regression analysis: conversion to THA, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80. The age of the patient when each degenerative pattern was found on the preoperative MRA was recorded., Results: The following MRI findings were associated with one or more of our predefined failure endpoints: cartilage damage exceeding 60° of the circumference had a hazard ratio (HR) of 4.6 (95% confidence interval [CI], 3.6-5.6; p = 0.003) compared with a damage of less than 60°, presence of an acetabular rim cyst had a HR of 4.1 (95% CI, 3.1-5.2; p = 0.008) compared with hips without these cysts, and presence of a sabertooth osteophyte had a HR of 3.2 (95% CI, 2.3-4.2; p = 0.013) compared with hips without a sabertooth osteophyte. The degenerative pattern associated with the youngest patient age when detected on preoperative MRA was the sabertooth osteophyte (lower quartile 27 years) followed by cartilage damage exceeding 60° of the circumference (28 years) and the presence of an acetabular rim bone cyst (31 years)., Conclusions: Preoperative MRAs with radial cuts reveal important findings that may be associated with future failure of surgical treatment for FAI. Most of these factors are not visible on conventional radiographs or standard hip MRIs. Preoperative MRA evaluation is therefore strongly recommended on a routine basis for patients undergoing these procedures. Findings associated with conversion to arthroplasty, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80 points should be incorporated into the decision-making process in patients being evaluated for joint-preserving hip surgery., Level of Evidence: Level III, therapeutic study.

Purpose: To compare quantitative measurements of acetabular morphology obtained using intraoperative fluoroscopy, to standardized anteroposterior (AP) pelvis radiographs., Methods: Ten dried human pelvis specimens (20 hips) were imaged using hip-centered fluoroscopy and standardized AP pelvis radiographs. Each hip was evaluated for acetabular version and coverage, including lateral center edge (LCE) angle, acetabular index (AI), total anterior and posterior coverage, and crossover sign., Results: No statistically significant differences existed between the mean LCE angle (fluoroscopy 36.5° ± 8.3° v plain films 36.1° ± 7.9°, P = .59), acetabular index (0.6° ± 8.6° v 0.2° ± 7.1°, P = .61), ACM angle (44.0° ± 2.6° v 44.1° ± 3.8°, P = .89), Sharp's angle (31.8° ± 5.7° v 32.4° ± 3.9°, P = .44), and the total femoral coverage (80.9% ± 6.4% v 80.7% ± 7.5%, P = .83). Conversely, total anterior coverage (30.7% ± 8.5% v 33.3% ± 8.2%, P < .0001) appeared significantly decreased and the total posterior coverage (54.1% ± 6.9% v 49.1% ± 7.8%, P < .0001) appeared significantly increased in fluoroscopy compared with plain film radiographs. Fluoroscopy also failed to identify the presence of a crossover sign in 30% and underestimated the retroversion index (9% ± 16%, v 13% ± 16%, P = .016)., Conclusions: The values for the LCE angle and AI determined by hip-centered fluoroscopy did not differ from those obtained by standardized AP plain film radiography. However, fluoroscopy leads to a more anteverted projection of the acetabulum with significantly decreased total anterior coverage, significantly increased total posterior coverage, and underestimated signs of retroversion compared with standardized AP pelvis radiography., Clinical Relevance: This study shows reliable LCE and AI angles but significant differences in the projected anteversion of the acetabulum between standardized AP pelvis radiography and hip-centered fluoroscopy., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Background: In some hips with cam-type femoroacetabular impingement (FAI), we observed a morphology resembling a more subtle form of slipped capital femoral epiphysis (SCFE). Theoretically, the morphology in these hips should differ from hips with a primary cam-type deformity., Questions/purposes: We asked if (1) head-neck offset; (2) epiphyseal angle; and (3) tilt angle differ among hips with a slip-like morphology, idiopathic cam, hips after in situ pinning of SCFE, and normal hips; and (4) what is the prevalence of a slip-like morphology among cam-type hips?, Methods: We retrospectively compared the three-dimensional anatomy of hips with a slip-like morphology (29 hips), in situ pinning for SCFE (eight hips), idiopathic cam deformity (171 hips), and 30 normal hips using radial MRI arthrography. Normal hips were derived from 17 asymptomatic volunteers. All other hips were recruited from a series of 277 hips (243 patients) seen at a specialized academic hip center between 2006 and 2010. Forty-one hips with isolated pincer deformity were excluded. Thirty-six of 236 hips had a known cause of cam impingement (secondary cam), including eight hips after in situ pinning of SCFE (postslip group). The 200 hips with a primary cam were separated in hips with a slip-like morphology (combination of positive fovea sign [if the neck axis did not intersect with the fovea capitis] and a tilt angle [between the neck axis and perpendicular to the basis of the epiphysis] exceeding 4°) and hips with an idiopathic cam. We evaluated offset ratio, epiphyseal angle (angle between the neck axis and line connecting the center of the femoral head and the point where the physis meets the articular surface), and tilt angle circumferentially around the femoral head-neck axis. Prevalence of slip-like morphology was determined based on the total of 236 hips with cam deformities., Results: Offset ratio was decreased anterosuperiorly in idiopathic cam, slip-like, and postslip (eg, 1 o'clock position with a mean offset ranging from 0.00 to 0.14; p < 0.001 for all groups) compared with normal hips (0.25 ± 0.06 [95% confidence interval, 0.13-0.37]) and increased posteroinferiorly in slip-like (eg, 8 o'clock position, 0.5 ± 0.09 [0.32-0.68]; p < 0.001) and postslip groups (0.55 ± 0.12 [0.32-0.78]; p < 0.001) and did not differ in idiopathic cam (0.32 ± 0.09 [0.15-0.49]; p = 0.323) compared with normal (0.31 ± 0.07 [0.18-0.44]) groups. Epiphyseal angle was increased anterosuperiorly in the slip-like (eg, 1 o'clock position, 70° ± 9° [51°-88°]; p < 0.001) and postslip groups (75° ± 13° [49°-100°]; p = 0.008) and decreased in idiopathic cam (50° ± 8° [35°-65°]; p < 0.001) compared with normal hips (58° ± 8° [43°-74°]). Posteroinferiorly, epiphyseal angle was decreased in slip-like (eg, 8 o'clock position, 54° ± 10° [34°-74°]; p < 0.001) and postslip (44° ± 11° [23°-65°]; p < 0.001) groups and did not differ in idiopathic cam (76° ± 8° [61°-91°]; p = 0.099) compared with normal (73° ± 7° [59°-88°]) groups. Tilt angle increased in slip-like (eg, 2/8 o'clock position, 14° ± 8° [-1° to 30°]; p < 0.001) and postslip hips (29° ± 10° [9°-48°]; p < 0.001) and decreased in hips with idiopathic cam (-7° ± 5° [-17° to 4°]; p < 0.001) compared with normal (-1° ± 5° [-10° to 8°]) hips. The prevalence of a slip-like morphology was 12%., Conclusions: The slip-like morphology is the second most frequent pathomorphology in hips with primary cam deformity. MRI arthrography of the hip allows identifying a slip-like morphology, which resembles hips after in situ pinning of SCFE and distinctly differs from hips with idiopathic cam. These results support previous studies reporting that SCFE might be a risk factor for cam-type FAI.

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.

Background: Cam-type femoroacetabular impingement (FAI) resulting from an abnormal nonspherical femoral head shape leads to chondrolabral damage and is considered a cause of early osteoarthritis. A previously developed experimental ovine FAI model induces a cam-type impingement that results in localized chondrolabral damage, replicating the patterns found in the human hip. Biochemical MRI modalities such as T2 and T2* may allow for evaluation of the cartilage biochemistry long before cartilage loss occurs and, for that reason, may be a worthwhile avenue of inquiry., Questions/purposes: We asked: (1) Does the histological grading of degenerated cartilage correlate with T2 or T2* values in this ovine FAI model? (2) How accurately can zones of degenerated cartilage be predicted with T2 or T2* MRI in this model?, Methods: A cam-type FAI was induced in eight Swiss alpine sheep by performing a closing wedge intertrochanteric varus osteotomy. After ambulation of 10 to 14 weeks, the sheep were euthanized and a 3-T MRI of the hip was performed. T2 and T2* values were measured at six locations on the acetabulum and compared with the histological damage pattern using the Mankin score. This is an established histological scoring system to quantify cartilage degeneration. Both T2 and T2* values are determined by cartilage water content and its collagen fiber network. Of those, the T2* mapping is a more modern sequence with technical advantages (eg, shorter acquisition time). Correlation of the Mankin score and the T2 and T2* values, respectively, was evaluated using the Spearman's rank correlation coefficient. We used a hierarchical cluster analysis to calculate the positive and negative predictive values of T2 and T2* to predict advanced cartilage degeneration (Mankin ≥ 3)., Results: We found a negative correlation between the Mankin score and both the T2 (p < 0.001, r = -0.79) and T2* values (p < 0.001, r = -0.90). For the T2 MRI technique, we found a positive predictive value of 100% (95% confidence interval [CI], 79%-100%) and a negative predictive value of 84% (95% CI, 67%-95%). For the T2* technique, we found a positive predictive value of 100% (95% CI, 79%-100%) and a negative predictive value of 94% (95% CI, 79%-99%)., Conclusions: T2 and T2* MRI modalities can reliably detect early cartilage degeneration in the experimental ovine FAI model., Clinical Relevance: T2 and T2* MRI modalities have the potential to allow for monitoring the natural course of osteoarthrosis noninvasively and to evaluate the results of surgical treatments targeted to joint preservation.

Background: Both acetabular undercoverage (hip dysplasia) and overcoverage (pincer-type femoroacetabular impingement) can result in hip osteoarthritis. In contrast to undercoverage, there is a lack of information on radiographic reference values for excessive acetabular coverage., Questions/purposes: (1) How do common radiographic hip parameters differ in hips with a deficient or an excessive acetabulum in relation to a control group; and (2) what are the reference values determined from these data for acetabular under- and overcoverage?, Methods: We retrospectively compared 11 radiographic parameters describing the radiographic acetabular anatomy among hip dysplasia (26 hips undergoing periacetabular osteotomy), control hips (21 hips, requiring no rim trimming during surgical hip dislocation), hips with overcoverage (14 hips, requiring rim trimming during surgical hip dislocation), and hips with severe overcoverage (25 hips, defined as having acetabular protrusio). The hips were selected from a patient cohort of a total of 593 hips. Radiographic parameters were assessed with computerized methods on anteroposterior pelvic radiographs and corrected for neutral pelvic orientation with the help of a true lateral radiograph., Results: All parameters except the crossover sign differed among the four study groups. From dysplasia through control and overcoverage, the lateral center-edge angle, acetabular arc, and anteroposterior/craniocaudal coverage increased. In contrast, the medial center-edge angle, extrusion/acetabular index, Sharp angle, and prevalence of the posterior wall sign decreased. The following reference values were found: lateral center-edge angle 23° to 33°, medial center-edge angle 35° to 44°, acetabular arc 61° to 65°, extrusion index 17% to 27%, acetabular index 3° to 13°, Sharp angle 38° to 42°, negative crossover sign, positive posterior wall sign, anterior femoral head coverage 15% to 26%, posterior femoral head coverage 36% to 47%, and craniocaudal coverage 70% to 83%., Conclusions: These acetabular reference values define excessive and deficient coverage. They may be used for radiographic evaluation of symptomatic hips, may offer possible predictors for surgical outcomes, and serve to guide clinical decision-making.

Background: Acetabular retroversion is associated with pincer-type femoroacetabular impingement and can lead to hip osteoarthritis. We report the ten-year results of a previously described patient cohort that had corrective periacetabular osteotomy for the treatment of symptomatic acetabular retroversion., Methods: Clinical and radiographic parameters were assessed preoperatively and at two and ten years postoperatively. A Kaplan-Meier survivorship analysis of the twenty-two patients (twenty-nine hips) with a mean follow-up (and standard deviation) of 11 ± 1 years (range, nine to twelve years) was performed. In addition, a univariate Cox regression analysis was done with conversion to total hip arthroplasty as the primary end point and progression of the osteoarthritis, a fair or poor result according to the Merle d'Aubigné score, or the need for revision surgery as the secondary end points., Results: The mean Merle d'Aubigné score improved significantly from 14 ± 1.4 points (range, 12 to 17 points) preoperatively to 16.9 ± 0.9 points (range, 15 to 18 points) at ten years (p < 0.001). There were also significant improvements with regard to hip flexion (p = 0.003), internal rotation (p = 0.003), and adduction (p = 0.002) compared with the preoperative status. No significant increase of the mean Tönnis osteoarthritis score was seen at ten years (p = 0.06). The cumulative ten-year survivorship, with conversion to a total hip arthroplasty as the primary end point, was 100%. The cumulative ten-year survivorship in achievement of one of the secondary end points was 71% (95% confidence interval, 54% to 88%). Predictors for poor outcome were the lack of femoral offset creation and overcorrection of the acetabular version resulting in excessive anteversion., Conclusions: Anteverting periacetabular osteotomy for acetabular retroversion leads to favorable long-term results with preservation of the native hip at a mean of ten years. Overcorrection resulting in excessive anteversion of the hip and omitting concomitant offset creation of the femoral head-neck junction are associated with an unfavorable outcome., (Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.)

Acetabular retroversion following acetabular osteotomy in hips with dysplasia can negatively effect the outcome. Total retroversion, where the entire anterior rim is lateral to the posterior rim, is rare and can easily be missed on pelvic radiographs due to the lack of a crossover sign. We evaluated the clinical and radiographic presentation, the surgical management, and the outcome of hips with total acetabular retroversion. We retrospectively reviewed 26 patients (26 hips) with total retroversion following 15 periacetabular osteotomies (PAO), 10 triple type, and one Salter osteotomy. We obtained range of motion (ROM), anterior impingement test, Drehmann's sign, Merle d’Aubigné-Postel score, and Tönnis score for osteoarthrosis. Corrective surgery included 19 revision PAOs and seven total hip arthroplasties (THA). The mean follow-up was 4.7 ± 4.2 (range 0.5-13.8) years. Patients presented with a restricted ROM (flexion and internal rotation), a positive anterior impingement test, a positive Drehmann's sign, and a decreased Merle d'Aubigné-Postel score due to pain. Corrective surgery was performed after mean of 7 ± 5 (1-15) years. Complications for revision PAO and THA occurred in 37% and 29%, respectively. At follow-up, the Merle d'Aubigné-Postel score improved for both revision PAOs and THAs. The prevalence of a positive anterior impingement test and Drehmann's sign decreased for revision PAOs. There was a tendency for progression of OA in hips with revision PAO. Iatrogenic total acetabular retroversion following reorientation is a disabling condition for the patients. Corrective surgery including revision PAO and THA results in improved clinical outcome. However, these procedures are technically challenging and associated with high complication rates.

Background: Although periacetabular osteotomy (PAO) for developmental dysplasia of the hip (DDH) provides conceptual advantages compared with other osteotomies and reportedly is associated with joint survivorship of 60% at 20 years, the beneficial effect of proper acetabular reorientation with concomitant arthrotomy and creation of femoral head-neck offset on 10-year hip survivorship remains unclear., Questions/purposes: We asked the following questions: (1) Does the 10-year survivorship of the hip after PAO improve with proper acetabular reorientation and a spherical femoral head; (2) does the Merle d'Aubigné-Postel score improve; (3) can the progression of osteoarthritis (OA) be slowed; and (4) what factors predict conversion to THA, progression of OA, or a Merle d'Aubigné-Postel score less than 15 points?, Methods: We retrospectively reviewed 147 patients who underwent 165 PAOs for DDH with two matched groups: Group I (proper reorientation and spherical femoral head) and Group II (improper reorientation and aspherical femoral head). We compared the Kaplan-Meier survivorship, Merle d'Aubigné-Postel scores, and progression of OA in both groups. A Cox regression analysis (end points: THA, OA progression, or Merle d'Aubigné-Postel score less than 15) was performed to detect factors predicting failure. The minimum followup was 10 years (median, 11 years; range, 10-14 years)., Results: An increased survivorship was found in Group I. The Merle d'Aubigné-Postel score did not differ. Progression of OA in Group I was slower than in Group II. Factors predicting failure included greater age, lower preoperative Merle d'Aubigné-Postel score, and the presence of a Trendelenburg sign, aspherical head, OA, subluxation, postoperative acetabular retroversion, excessive acetabular anteversion, and undercoverage., Conclusions: Proper acetabular reorientation and the creation of a spherical femoral head improve long-term survivorship and decelerate OA progression in patients with DDH.

Sheep hips have a natural non-spherical femoral head similar to a cam-type deformity in human beings. By performing an intertrochanteric varus osteotomy, cam-type femoro-acetabular impingement (FAI) during flexion can be created. We tested the hypotheses that macroscopic lesions of the articular cartilage and an increased Mankin score (MS) can be reproduced by an experimentally induced cam-type FAI in this ovine in vivo model. Furthermore, we hypothesized that the MS increases with longer ambulatory periods. Sixteen sheep underwent unilateral intertrochanteric varus osteotomy of the hip with the non-operated hip as a control. Four sheep were sacrificed after 14, 22, 30, and 38-weeks postoperatively. We evaluated macroscopic chondrolabral alterations, and recorded the MS, based on histochemical staining, for each ambulatory period. A significantly higher prevalence of macroscopic chondrolabral lesions was found in the impingement zone of the operated hips. The MS was significantly higher in the acetabular/femoral cartilage of the operated hips. Furthermore, these scores increased as the length of the ambulatory period increased. Cam-type FAI can be induced in an ovine in vivo model. Localized chondrolabral degeneration of the hip, similar to that seen in humans (Tannast et al., Clin Orthop Relat Res 2008; 466: 273-280; Beck et al., J Bone Joint Surg Br 2005; 87: 1012-1018), can be reproduced. This experimental sheep model can be used to study cam-type FAI., (Copyright © 2012 Orthopaedic Research Society.)

Background: Understanding acetabular pathomorphology is necessary to correctly treat patients with hip complaints. Existing radiographic parameters classify acetabular coverage as deficient, normal, or excessive but fail to quantify contributions of anterior and posterior wall coverage. A simple, reproducible, and valid measurement of anterior and posterior wall coverage in patients with hip pain would be a clinically useful tool., Questions/purposes: We (1) introduce the anterior wall index (AWI) and posterior wall index (PWI), (2) report the intra- and interobserver reliability of these measurements, and (3) validate these measurements against an established computer model., Methods: We retrospectively reviewed 87 hips (63 patients) with symptomatic hip disease. A validated computer model was used to determine total anterior and posterior acetabular coverage (TAC and TPC) on an AP pelvis radiograph. Two independent observers measured the AWI and PWI on each film, and the intraclass correlation coefficient (ICC) was calculated. Pearson correlation was used to determine the strength of linear dependence between our measurements and the computer model., Results: Intra- and interobserver ICCs were 0.94 and 0.99 for the AWI and 0.81 and 0.97 for the PWI. For validation against the computer model, Pearson r values were 0.837 (AWI versus TAC) and 0.895 (PWI versus TPC). Mean AWI and PWI were 0.28 and 0.81 for dysplastic hips, 0.41 and 0.91 for normal hips, 0.61 and 1.15 for hips with a deep acetabulum., Conclusions: Our data suggest these measures will be helpful in evaluating anterior and posterior coverage before and after surgery but need to be evaluated in asymptomatic individuals without hip abnormalities to establish normal ranges., Level of Evidence: Level III, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.

Background: The aims of the study were (1) to determine the cumulative two to twenty-year survivorship of the hip after open reduction and internal fixation of displaced acetabular fractures, (2) to identify factors predicting conversion to total hip arthroplasty or hip arthrodesis, and (3) to create a predictive model that calculates an individual's probability of early need for total hip arthroplasty or hip arthrodesis., Methods: Eight hundred and sixteen acetabular fractures treated with open reduction and internal fixation by one surgeon over a twenty-six-year period were analyzed. Cumulative two to twenty-year Kaplan-Meier survivorship analyses of the hip, including best and worst-case scenarios, were performed with total hip arthroplasty or hip arthrodesis as the end point. Univariate and multivariate Cox regression analyses were performed to identify negative predictors, which were then used to construct a nomogram for predicting an individual's probability of needing an early total hip arthroplasty., Results: The cumulative twenty-year survivorship of the 816 hips available for follow-up was 79% at twenty years. The best and worst-case scenarios corresponded to cumulative twenty-year survivorship of 86% and 52%, respectively. Significant independent negative predictors were nonanatomical fracture reduction, an age of more than forty years, anterior hip dislocation, postoperative incongruence of the acetabular roof, involvement of the posterior acetabular wall, acetabular impaction, a femoral head cartilage lesion, initial displacement of the articular surface of ≥ 20 mm, and utilization of the extended iliofemoral approach., Conclusions: Open reduction and internal fixation of displaced acetabular fractures was able to successfully prevent the need for subsequent total hip arthroplasty within twenty years in 79% of the patients. The results represent benchmark comparative data for any future and past studies on the outcome of surgical fixation of acetabular fractures.

Background: The evidence supporting continued use of shelf acetabuloplasty in Legg-Calvé-Perthes disease (LCPD) is not well-defined, and there is controversy regarding the long-term benefits related to clinical and functional improvement., Questions/purposes: Our goals were to determine whether shelf arthroplasty for LCPD (1) prevents the onset of early osteoarthritis; (2) improves pain, ROM, activity, and functional outcomes; (3) maintains or improves femoral head containment, sphericity, and congruency; (4) changes the acetabular index; and (5) is associated with a low rate of complications., Methods: We performed a systematic review of the medical literature from 1966 to 2009 using the search terms Perthes, shelf procedure, and acetabuloplasty. We excluded reports using multiple/combined treatment methods and those not clearly stratifying outcomes. Thirteen studies met the criteria. There were no Level I studies, one Level II prognostic study, five Level III therapeutic studies, and seven Level IV studies. Mean followup ranged from 2.6 to 17.9 years., Results: Only one study reported progression to early osteoarthritis in one patient. We found no evidence for improvement in ROM and continued pain relief at long-term followup. Mean decrease in lateral subluxation ratio was 13% to 30%, demonstrating an improvement in femoral head containment. Mean acetabular cover percentage improved 16% to 38%, and mean acetabular and center-edge angles improved 4° to 14° and 8° to 33°, respectively. There were no reports of any major complications after the procedure., Conclusions: While radiographic measurements indicate improved coverage of the femoral head after shelf acetabuloplasty for LCPD, available evidence does not document the procedure prevents early onset of osteoarthritis or improves long-term function.

Objectives: To classify the fracture patterns of gunshot wounds to the acetabulum; identify the associated injuries and complications; determine the predictors of poor outcome and deep infection; and propose a treatment algorithm based on the results., Design: Retrospective review of two trauma registry databases over a 13-year period., Setting: Multicenter study., Patients: Thirty-nine gunshot wounds to the acetabulum (38 patients)., Intervention: Treatment strategy was based on infection control by treating bowel and bladder injury, presence/absence of intra-articular lead, pattern, and stability of the fracture., Main Outcome Measurements: Merle d'Aubigné score, rate of failures, and complications. Multivariate logistic regression analysis to detect predictors of poor outcome and deep infection., Results: There were 32 simple (82%) and seven (18%) associated fracture patterns. Bowel injuries were the most common associated injures. There was a 54% major complication rate. Significant predictors of poor outcome were high-velocity missile, involvement of the acetabular dome, abdominal injury, nerve injury, vascular injury, and male gender. Significant factors associated with deep infection were presence of a bowel injury with primary anastomosis of the bowel and an associated fracture pattern., Conclusions: The Letournel classification system can be applied to describe these injuries. The successful treatment of the bowel injury directly correlates to infection control. Diverting colostomy is associated with a reduction of the infection rate. Overall, gunshot wounds to the acetabulum are catastrophic injuries with a high complication rate and poor functional outcome. A multidisciplinary algorithm is proposed for treatment of these complex injuries., Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

An automated algorithm for detection of the acetabular rim was developed. Accuracy of the algorithm was validated in a sawbone study and compared against manually conducted digitization attempts, which were established as the ground truth. The latter proved to be reliable and reproducible, demonstrated by almost perfect intra- and interobserver reliability. Validation of the automated algorithm showed no significant difference compared to the manually acquired data in terms of detected version and inclination. Automated detection of the acetabular rim contour and the spatial orientation of the acetabular opening plane can be accurately achieved with this algorithm., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Although the ischial spine sign (ISS) has been advocated to detect acetabular retroversion, it is unknown whether the sign is valid on anteroposterior (AP) pelvic radiographs with tilted or rotated pelves. We therefore evaluated reliability of the ISS as a tool for diagnosing acetabular retroversion in the presence of considerable pelvic tilt and/or malrotation. We obtained radiographs of 20 cadaver pelves in 19 different malorientations resulting in 380 pelvis images (760 hips) for evaluation. In addition, 129 clinical radiographs of patients' hips that had varying pelvis orientations were reviewed. We found an overall sensitivity of 81% (90%), specificity of 70% (71%), positive predictive value of 77% (80.7%), and negative predictive value of 75% (85%) in the cadaver (patient) hips. Our data suggest the ISS is a valid tool for diagnosing acetabular retroversion on plain radiographs taken using a standardized technique regardless of the degree of pelvic tilt and rotation.

Objective: Elimination of an intraarticular femoroacetabular impingement conflict. Creation of a pain-free, normal range of motion of the hip., Indications: Femoroacetabular impingement of any type (cam/pincer) and any localization (anterior/posterior)., Contraindications: Absolute: advanced hip osteoarthritis, local infections around the hip. Relative: excessive acetabular retroversion with deficiency of the posterior wall., Surgical Technique: Lateral decubitus position. Straight lateral incision centered over the greater trochanter. Entering of the Gibson interval. Digastric trochanteric osteotomy with protection of the medial circumflex femoral artery. Opening of the interval between the piriformis and the gluteus minimus muscle. Z-shaped capsulotomy. Dislocation of the femoral head. Detachment of the labrum. Trimming of the excessive acetabular rim. Refixation of the labrum. Creation of a sufficient femoral head-neck offset. Suture of the capsule. Refixation of the trochanter., Postoperative Management: During hospital stay, intensive mobilization of the hip joint using a continuous passive motion machine with a maximum flexion of 90 degrees . No active abduction and passive adduction over the body's midline. Maximum weight bearing 10-15 kg for 6 weeks. Subsequently, first clinical and radiographic follow-up. Deep venous thrombosis prophylaxis until full weight bearing., Results: Short- and mid-term results showed an improvement of the postoperative clinical score (Merle d'Aubigné Score) in 95% of all patients, depending on the individual degenerative joint alterations at the time of surgery. Good to excellent results were obtained in 91% of all cases. Cumulative 5-year survival was 91% (endpoint total hip arthroplasty or poor Merle d'Aubigné Score). Long-term results are not available yet.

The widely used procedure of evaluation of cup orientation following total hip arthroplasty using single standard anteroposterior (AP) radiograph is known inaccurate, largely due to the wide variability in individual pelvic orientation relative to X-ray plate. 2D-3D image registration methods have been introduced for an accurate determination of the post-operative cup alignment with respect to an anatomical reference extracted from the CT data. Although encouraging results have been reported, their extensive usage in clinical routine is still limited. This may be explained by their requirement of a CAD model of the prosthesis, which is often difficult to be organized from the manufacturer due to the proprietary issue, and by their requirement of either multiple radiographs or a radiograph-specific calibration, both of which are not available for most retrospective studies. To address these issues, we developed and validated an object-oriented cross-platform program called "HipMatch" where a hybrid 2D-3D registration scheme combining an iterative landmark-to-ray registration with a 2D-3D intensity-based registration was implemented to estimate a rigid transformation between a pre-operative CT volume and the post-operative X-ray radiograph for a precise estimation of cup alignment. No CAD model of the prosthesis is required. Quantitative and qualitative results evaluated on cadaveric and clinical datasets are given, which indicate the robustness and the accuracy of the program. HipMatch is written in object-oriented programming language C++ using cross-platform software Qt (TrollTech, Oslo, Norway), VTK, and Coin3D and is transportable to any platform.

Objective: Anatomic reduction and stable fixation by means of tissue- preserving surgical approaches. INDICATIONS Displaced acetabular fractures. Surgical hip dislocation approach with larger displacement of the posterior column in comparison to the anterior column, transtectal fractures, additional intraarticular fragments, marginal impaction. Stoppa approach with larger displacement of the anterior column in comparison to the posterior column. A combined approach might be necessary with difficult reduction. CONTRAINDICATIONS Fractures > 15 days (then ilioinguinal or extended iliofemoral approaches). Suprapubic catheters and abdominal problems (e.g., previous laparotomy due to visceral injuries) with Stoppa approach (then switch to classic ilioinguinal approach)., Surgical Technique: Surgical hip dislocation: lateral decubitus position. Straight lateral incision centered over the greater trochanter. Entering of the Gibson interval. Digastric trochanteric osteotomy with protection of the medial circumflex femoral artery. Opening of the interval between the piriformis and the gluteus minimus muscle. Z-shaped capsulotomy. Dislocation of the femoral head. Reduction and fixation of the posterior column with plate and screws. Fixation of the anterior column with a lag screw in direction of the superior pubic ramus. Stoppa approach: supine position. Incision according to Pfannenstiel. Longitudinal splitting of the anterior portion of the rectus sheet and the rectus abdominis muscle. Blunt dissection of the space of Retzius. Ligation of the corona mortis, if present. Blunt dissection of the quadrilateral plate and the anterior column. Reduction of the anterior column and fixation with a reconstruction plate. Fixation of the posterior column with lag screws. If necessary, the first window of the ilioinguinal approach can be used for reduction and fixation of the posterior column., Postoperative Management: During hospital stay, intensive mobilization of the hip joint using a continuous passive motion machine with a maximum flexion of 90 degrees . No active abduction and passive adduction over the body's midline, if a surgical dislocation was performed. Maximum weight bearing 10-15 kg for 8 weeks. Then, first clinical and radiographic follow-up. Deep venous thrombosis prophylaxis for 8 weeks postoperatively., Results: 17 patients with a mean follow-up of 3.2 years. Ten patients were operated via surgical hip dislocation, two patients with a Stoppa approach, and five using a combined or alternative approach. Anatomic reduction was achieved in ten of the twelve patients (83%) without primary total hip arthroplasty. Mean operation time 3.3 h for surgical hip dislocation and 4.2 h for the Stoppa approach. Complications comprised one delayed trochanteric union, one heterotopic ossification, and one loss of reduction. There were no cases of avascular necrosis. In two patients, a total hip arthroplasty was performed due to the development of secondary hip osteoarthritis.

Femoroacetabular impingement (FAI) of the hip joint is increasingly being recognized as one of the causes of hip pain and restriction of hip motion in young adults. The main subtypes are Pincer and Cam types. MRI digagnostic and relevant surgical information is presented.

The purpose of this study was to validate the accuracy, consistency, and reproducibility/reliability of a new method for correction of pelvic tilt and rotation of radiographic hip parameters for pincer type of femoroacetabular impingement on an anteroposterior pelvic radiograph. Thirty cadaver hips and 100 randomized, blinded AP pelvic radiographs were used for investigation. To detect the software accuracy, the calculated femoral head coverage and classic hip parameters determined with our software were compared to reference measurements based on CT scans or conventional radiographs in a neutral orientation as gold standard. To investigate software consistency, differences among the different parameters for each cadaver pelvis were calculated when reckoned back from a random to the neutral orientation. Intra- and interobserver comparisons were used to analyze the reliability and reproducibility of all parameters. All but two parameters showed a good-to-very good accuracy with the reference measurements. No relevant systematic errors were detected in the Bland-Altman analysis. Software consistency was good-to-very good for all parameters. A good-to-very good reliability and reproducibility was found for a substantial number of the evaluated radiographic acetabular parameters. The software appears to be an accurate, consistent, reliable, and reproducible method for analysis of acetabular pathomorphologies., ((c) 2008 Orthopaedic Research Society)

Introduction: We report the results of a titanium acetabular reinforcement ring with a hook (ARRH) in primary total hip arthroplasty (THA), which was introduced in 1987 and continues to be used routinely in our center. The favorable results of this device in arthroplasty for developmental dysplasia and difficult revisions motivated its use in primary THA. With this implant only minimal acetabular reaming is necessary, anatomic positioning is achieved by placing the hook around the teardrop and a homogenous base for cementing the polyethylene cup is provided., Materials and Methods: Between April 1987 and December 1991, 241 THAs with insertion of an ARRH were performed in 178 unselected, consecutive patients (average age 58 years; range 30-84 years) with a secondary osteoarthrosis in 41% of the cases., Results: At the time of the latest follow-up, 33 patients (39 hips) had died and 17 cases had been lost to follow-up. The median follow-up was 122 months with a minimum of 10 years. Eight hips had been revised, leaving 177 hips in 120 living patients without revision. Six cups were revised because of aseptic loosening. Two hips were revised for sepsis. The mean Merle d'Aubigné score for the remaining hips was 16 (range 7-18) at the latest follow-up. For aseptic loosening, the probability of survival of the cup was 0.97 (95% confidence interval, 0.94-0.99). However, analysis of radiographs implied loosening in seven other cups without clinical symptoms., Conclusions: The results of primary THA using an acetabular reinforcement ring parallel the excellent results of these implants often observed in difficult primary and revision arthroplasty at a minimum of 10 years. Survivorship is comparable to modern cementless implants. Medial migration that occurs with loosening of the acetabular component seems to be prevented with this implant. Radiographic loosening signs can exist without clinical symptoms.

Unlabelled: The goal of the Bernese periacetabular osteotomy is to correct the deficient acetabular coverage in hips with developmental dysplasia to prevent secondary osteoarthrosis. We determined the 20-year survivorship of symptomatic patients treated with this procedure, determined the clinical and radiographic outcomes of the surviving hips, and identified factors predicting poor outcome. We retrospectively evaluated the first 63 patients (75 hips) who underwent periacetabular osteotomy at the institution where this technique was developed. The mean age of the patients at surgery was 29 years (range, 13-56 years), and preoperatively 24% presented with advanced grades of osteoarthritis. Four patients (five hips) were lost to followup and one patient (two hips) died. The remaining 58 patients (68 hips) were followed for a minimum of 19 years (mean, 20.4 years; range, 19-23 years) and 41 hips (60%) were preserved at last followup. The overall mean Merle d'Aubigné and Postel score decreased in comparison to the 10-year value and was similar to the preoperative score. We observed no major changes in any of the radiographic parameters during the 20-year postoperative period except the osteoarthritis score. We identified six factors predicting poor outcome: age at surgery, preoperative Merle d'Aubigné and Postel score, positive anterior impingement test, limp, osteoarthrosis grade, and the postoperative extrusion index. Periacetabular osteotomy is an effective technique for treating symptomatic developmental dysplasia of the hip and can maintain the natural hip at least 19 years in selected patients., Level of Evidence: Level III, prognostic study.

Total hip arthroplasty (THA) still carries a higher failure rate in patients with avascular necrosis of the femoral head (AVN) than in a similar patient population with THA for other reasons. This is particularly true for the acetabular component. One of the major factors accounting for this is the compromised acetabular bone quality with structural defects subsequent to collapsing of the femoral head in high-grade AVN. In this study we implanted an acetabular reinforcement ring with hook (ARRH), which had been used successfully for other indications with acetabular bone stock deficiency, in 32 consecutive THA's in 29 patients with AVN. Five patients died during the observation period of causes unrelated to the surgery, one patient was lost to follow-up and one patient could not be followed up due to chronic illness, leaving 25 hips (23 patients) with a minimum follow-up of ten years (mean: 11.8; range: 10-15). The mean Merle d'Aubigne score increased significantly from 7.7 preoperatively to 16.6 postoperatively (p < 0.001). One revision was performed for aseptic stem loosening. Of the unrevised hips, one acetabular component was classified as definitively loose. The cumulative 12-year survivorship for THA with ARRH in AVN was 95.2% (confidence interval: 86.1-100%) for both components, 100% for the cup and 95.2% for the stem (86.1-100%).

The range of motion of normal hips and hips with femoroacetabular impingement relative to some specific anatomic reference landmarks is unknown. We therefore described: (1) the range of motion pattern relative to landmarks; (2) the location of the impingement zones in normal and impinging hips; and (3) the influence of surgical débridement on the range of motion. We used a previously developed and validated noninvasive 3-D CT-based method for kinematic hip analysis to compare the range of motion pattern, the location of impingement, and the effect of virtual surgical reconstruction in 28 hips with anterior femoroacetabular impingement and a control group of 33 normal hips. Hips with femoroacetabular impingement had decreased flexion, internal rotation, and abduction. Internal rotation decreased with increasing flexion and adduction. The calculated impingement zones were localized in the anterosuperior quadrant of the acetabulum and were similar in the two groups and in impingement subgroups. The average improvement of internal rotation was 5.4 degrees for pincer hips, 8.5 degrees for cam hips, and 15.7 degrees for mixed impingement. This method helps the surgeon quantify the severity of impingement and choose the appropriate treatment option; it provides a basis for future image-guided surgical reconstruction in femoroacetabular impingement with less invasive techniques.

This paper addresses the problem of estimating postoperative cup alignment from single standard X-ray radiograph with gonadal shielding. The widely used procedure of evaluation of cup orientation following total hip arthroplasty using single standard anteroposterior radiograph is known inaccurate, largely due to the wide variability in individual pelvic position relative to X-ray plate. 2D-3D image registration methods have been introduced to estimate the rigid transformation between a preoperative CT volume and postoperative radiograph(s) for an accurate estimation of the postoperative cup alignment relative to an anatomical reference extracted from the CT data. However, these methods require either multiple radiographs or a radiograph-specific calibration, both of which are not avaiable for most retrospective studies. Furthermore, these methods were only evaluated on X-ray radiograph(s) without gonadal shielding. In this paper, we propose to use a hybrid 2D-3D registration scheme combining an iterative landmark-to-ray registration with a 2D-3D intensity-based registration to estimate the rigid transfromation for a precise estimation of cup alignment. Quantitative and qualitative results evaluated on clinical and cadaveric datasets are given which indicate the validity of our approach.

A CT-based method ("HipMotion") for the noninvasive three-dimensional assessment of femoroacetabular impingement (FAI) was developed, validated, and applied in a clinical pilot study. The method allows for the anatomically based calculation of hip range of motion (ROM), the exact location of the impingement zone, and the simulation of quantified surgical maneuvers for FAI. The accuracy of HipMotion was 0.7 +/- 3.1 degrees in a plastic bone setup and -5.0 +/- 5.6 degrees in a cadaver setup. Reliability and reproducibility were excellent [intraclass correlation coefficient (ICC) > 0.87] for all measures except external rotation (ICC = 0.48). The normal ROM was determined from a cohort of 150 patients and was compared to 31 consecutive hips with FAI. Patients with FAI had a significantly decreased flexion, internal rotation, and abduction in comparison to normal hips (p < 0.001). Normal hip flexion and internal rotation are generally overestimated in a number of orthopedic textbooks. HipMotion is a useful tool for further assessment of impinging hips and for appropriate planning of the necessary amount of surgical intervention, which represents the basis for future computer-assisted treatment of FAI with less invasive surgical approaches, such as hip arthroscopy., ((c) 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Using a total of 30 cadaveric hips, the accuracy of a fluoroscopy-based computer navigation system for cup placement in total hip arthroplasty (THA) was investigated and an error analysis was carried out. The accuracy of placing the acetabular component within a predefined safe zone using computer guidance was compared to the precision that could be achieved with a freehand approach. Accurate control measurements of the implanted cup were obtained using fiducial-based matching to a pre-operative CT scan with respect to the anterior pelvic plane. A significantly higher number of cups were placed in the safe zone with the help of the navigation system. The variability of cup placement could be reduced for cup abduction but not substantially for cup version. An error analysis of inaccurate landmark reconstruction revealed that the registration of the mid-pubic point with fluoroscopy was a potential source of error. Keeping this pitfall in mind, fluoroscopy-based navigation in THA is a useful tool for registration of the pelvic coordinate system, particularly those points that cannot be reached by direct pointer digitization with the patient in the lateral decubitus position.

Unlabelled: Pelvic tilt and rotation can drastically affect the apparent cup orientation on conventional anteroposterior pelvic radiographs. It was hypothesized that nonstandardized radiographic cup version and abduction can differ significantly from the corresponding anatomic angles if not measured to the anterior pelvic plane, defined by the pubic tubercles and the anterior superior iliac spine. Differences in preoperative and postoperative pelvic orientation and their influence on radiographic measurements of the two angles were analyzed. Conventional radiographs and preoperative and postoperative computed tomography scans of 37 total hip arthroplasties were compared. Calculations were made with the preoperative planning station of a computer navigation system. Significantly smaller values of cup version were seen on nonstandardized radiographs, whereas abduction could be measured reliably when referenced to horizontal pelvic landmarks seen on radiographs. The underlying cause for this difference was the variation of pelvic tilt that ranged 27 degrees (range, -7 degrees -20 degrees). Influence of pelvic tilt on the apparent cup orientation can be seen with simple nomograms. The orientation of the anterior pelvic plane before and after surgery did not differ. We think that version measurement on nonstandardized radiographs without anatomic referencing is highly inaccurate., Level of Evidence: Diagnostic study, Level II-1 (development of diagnostic criteria on basis of consecutive patients--with universally applied reference "gold" standard). See Guidelines for Authors for a complete description of levels of evidence.

Untreated femoro-acetabular impingement is a common cause of osteoarthrosis of the hip. Surgical debridement of the adult hip with femoro-acetabular impingement recently has been advocated with the aim of relieving symptoms and slowing or halting progression of the arthrosis. At surgery, femoral sources of impingement are relieved by debriding the aspheric peripheral portion of the femoral head and the adjacent femoral neck. Acetabular sources of impingement can be relieved by debridement of the anterior rim. The most fundamental questions concerning these procedures relate to the preoperative and postoperative function, postoperative survivorship of these hips and the incidence of osteonecrosis. The current study assesses a group of 23 hips in 23 patients treated by surgical debridement for impingement. Twenty-two patients were treated by full surgical dislocation and one patient was treated by relief of impingement without dislocation. Followup ranged from a minimum of 2 years to 12 years. At most recent evaluation, seven patients had been converted to total hip arthroplasty, one had arthroscopic debridement of a recurrent labral tear, and 15 patients have had no further surgery. No hips developed osteonecrosis. Of the seven patients who had to have their procedure converted to total hip arthroplasty, three of these hips failed early and four patients' hips recovered and functioned well and subsequently deteriorated with total hip arthroplasty done between 6.4 and 9.5 years after debridement. Hips at greatest risk of failure have advanced arthrosis or a combination of impingement and instability preoperatively. The procedure effectively treats hips with impingement and without considerable secondary arthrosis or instability.