Functional outcomes are preserved in adult acetabular dysplasia with radiographic evidence of lumbosacral spine anomalies: an investigation in hip-spine syndrome.

PURPOSE: Acetabular dysplasia (AD) is a debilitating condition which results in impaired hip function, leading to hip-spine syndrome with anomalies identifiable on plain radiographs. However, no study to date has investigated the association between radiographic spine anomalies and functional outcomes in AD. We hypothesize that AD patients with radiographic evidence of lumbar spine anomalies are associated with decreased function in comparison to those without such radiographic findings. PATIENTS AND METHODS: One hundred thirty-five hips underwent a full four-view hip radiograph series, and two observers analyzed hip and spine variables using standard radiographs and obtained Castellvi grade, assessment of spondylolisthesis, and L4-S1 interpedicular distance. A comprehensive hip questionnaire was administered which included Harris Hip Score (HHS) and Hip Disability and Osteoarthritis Outcome Score (HOOS) to assess patient function. Correlations between HHS and HOOS and radiographic spinal measurements were calculated, and p-values were corrected for multiple comparison using the Holm's method. RESULTS: Out of 135 patients, 119 were female (88.1%) and 16 were male (11.9%). Average age of presentation was 34.2 years, and average BMI was 26. There was no statistically significant correlation between Castellvi grade, presence of spondylolisthesis, or L4-S1 interpedicular distance and the patient-reported outcome measures HHS or HOOS. Conversely, a significant correlation was observed between Femoro-Epiphyseal Acetabular Roof (FEAR) index and HOOS of the contralateral hip (correlation coefficient = 0.38, adjusted p = 0.03) and Tönnis angle of AD severity and HHS of the contralateral hip (correlation coefficient = - 0.33, adjusted p = 0.04). CONCLUSION: Severity of spinal anomalies measured by Castellvi grade and spondylolisthesis in patients with AD was not associated with decreased patient function in the ipsilateral diseased hip. To our knowledge, this is the first study to date to report the relationship between radiographically identifiable lumbosacral abnormalities and hip function in AD.

The association of BMI and physical activity on acetabular dysplasia in children.

BACKGROUND: Acetabular dysplasia is an important pre-disposing factor for osteoarthritis of the hip. However, it is not completely known how acetabular dysplasia develops during childhood. OBJECTIVE: To study the prevalence of acetabular dysplasia and its association with body mass index (BMI) and physical activity in 9 year old children. DESIGN: The population for this cross-sectional study was drawn from the ongoing prospective cohort study: Generation R. 9,778 mothers with a delivery date from March 2002 until January 2006 were enrolled. In a random subgroup of these children Dual-energy X-ray absorptiometry (DXA) scanning was performed at age 9. EXPOSURES: BMI, standardized for the Dutch population and categorized in four groups based on extended international Obesity Task Force cut-offs: underweight, normal, overweight and obesity. Physical activity was based on time spent on playing outdoors, playing sports and walking/cycling to school. MAIN OUTCOMES AND MEASURES: The degree of acetabular dysplasia was determined with the centre-edge angle (CEA) and acetabular depth-width ratio (ADR) in DXA images of the hip. RESULTS: 1,188 DXA images of children's hips were available for analysis. The median age of the children was 9.86 years. Prevalence of dysplasia and mild dysplasia was respectively 6.3%; 25.6% with CEA and 4.8%; 25.0% with ADR. BMI was negatively associated with mild dysplasia (OR 0.80 CI 0.71-0.90). Obese children showed less mild dysplasia compared to normal children (OR 0.48 CI 0.24-0.97) in unadjusted analysis. Physical activity represented by walking to school showed a statistically significant negative association with mild dysplasia (OR 0.87 CI 0.76-0.99). After adjustment for age, ethnicity, sex, first born, breech presentation, birthweight, gestational age and Caesarean section, the patterns of association with dysplasia remained for both BMI and physical activity. CONCLUSIONS: In this study, being overweight and light physical activity were negatively associated with the development of (mild) acetabular dysplasia at the age of 9 years.

Part-time Abduction Bracing in Infants With Residual Acetabular Dysplasia: Does Compliance Monitoring Support a Dose-dependent Relationship?

INTRODUCTION: Residual acetabular dysplasia is often seen after successful Pavlik treatment or during follow-up for infants with risk factors for developmental dysplasia of the hip. A previous study supported the effectiveness of part-time abduction bracing for treating this residual dysplasia. However, the relationship between time in the brace and acetabular improvement was not established given the lack of compliance data. The purpose of this prospective study was to validate the effect of part-time bracing on acetabular dysplasia and determine if a dose-dependent relationship exists. METHODS: Eligibility criteria included infants ~6 months of age with an AP pelvic radiograph demonstrating acetabular dysplasia, defined as an acetabular index (AI) ≥30 degrees. After obtaining informed consent, a rigid abduction orthosis was prescribed with a thermal compliance sensor. Patients were instructed to wear the brace for nights/naps and follow-up at 1 year of age for repeat radiograph. AIs were measured by the senior author who was blinded to the compliance data. Hours of wear were compared with changes in AI over the study period using descriptive statistics and a generalized estimating equation model. RESULTS: Our series consisted of 26 infants (36 hips) with a mean age at enrollment of 5.9 months (range, 4.9 to 7.9); 84.6% were female individuals. At a mean follow-up of 6 months (range, 5.1 to 8.2), average wear time/day was 11.5 hours (range, 1.3 to 21.7), and total time in brace averaged 1698 hours (range, 218 to 3244 hours). The mean improvement in AI over the study period was 4.8 degrees (95% confidence interval, 3.9-5.5 degrees). The authors found a significant correlation between average hours of brace wear per day and improvement in AI (r=0.36, P<0.05), a relationship that remained significant in our multivariate model after adjusting for confounders. CONCLUSIONS: Part-time abduction bracing is effective for treating residual dysplasia, with the degree of improvement in AI correlating with hours of brace wear per day. Given this dose-dependent relationship, the optimal hours of wear may depend on the severity of residual dysplasia and the tolerance of the child and family to bracing.

Pseudo-Protrusio Acetabular Deformity in Osteogenesis Imperfecta Patients.

BACKGROUND: Osteogenesis imperfecta (OI) can develop a protrusio acetabuli deformity. However, the authors observed a pseudo-protrusio-type acetabular deformity (PPAD) on 3-dimensional computed tomography (3D-CT). Hence, we systematically reviewed 3D-CT and pelvis radiographs of OI patients and report the incidence and patterns of acetabular deformity in OI patients and the associated radiographic signs. METHODS: The study included 590 hips of 295 OI patients, who were older than 5 years, and did not have a pelvic fracture. The incidence of a deformed acetabulum (center-edge angle >40 degrees) and its correlation with disease severity were investigated. In 40 hips for which 3D-CT was available, 3-dimensional morphology of the acetabular deformity was analyzed to delineate PPAD. On plain radiographs, PPAD-related signs were determined, focusing on the contour of ilioischial line, iliopectineal line, acetabular line, and their relationship. These radiographic signs were also evaluated in the remaining hips with deformed acetabula that did not have 3D-CT. RESULTS: One hundred twenty-three hips of 590 hips (21%) showed deformed acetabula. The incidence of deformed acetabula was significantly associated with disease severity (P<0.001). Three-dimensional analysis showed that 10 hips had protrusio acetabuli, whereas 17 had PPAD, which showed that the hemipelvis was crumpled, the acetabular roof was rotated upwardly and medially, and the hip center migrated superiorly, uncovering the anterior femoral head. Among the PPAD-related signs, superomedial bulging of the iliopectineal line was the most predictive radiographic sign (73% sensitivity and 100% specificity). This sign was also observed in almost one third of deformed acetabula of those investigated only with plain radiographs. CONCLUSIONS: This study showed that acetabular deformity is common in OI patients and is associated with disease severity. A substantial number of hips showed PPAD, which may not cause femoroacetabular impingement but result in anterior uncovering of the hip joint. Superomedial bulging of the iliopectineal line suggests this pattern of acetabular deformity. LEVEL OF EVIDENCE: Lever IV-prognostic studies.

Incidence rate and risk factors for radiographic hip osteoarthritis in Japanese men and women: a 10-year follow-up of the ROAD study.

OBJECTIVE: To investigate the incidence and progression rate of radiographic hip osteoarthritis (OA) and its risk factors in Japanese men and women using a large-scale population of a nationwide cohort study, Research on Osteoarthritis/osteoporosis Against Disability (ROAD). METHODS: From the baseline survey of the ROAD study, 2,975 participants (1,043 men and 1,932 women) aged 23-94 years (mean, 70.2 years) living in urban, mountainous, and coastal communities were followed up with hip radiography at 3, 7, and 10 years (mean follow-up, 7.1 years). Radiographs were scored using the Kellgren/Lawrence (K/L) grading system, and radiographic hip OA was defined as K/L ≥ 2. The incidence and progression rate of hip OA were examined. Acetabular dysplasia was defined as a central-edge angle <20°. Cox's proportional hazard model was used to assess risk factors for incident and progressive radiographic hip OA. RESULTS: The incidence rate of radiographic hip OA was 5.6/1,000 person-years and 8.4/1,000 person-years in men and women, respectively. The progression rate of hip OA was 2.2/1,000 person-years and 6.0/1,000 person-years in men and women, respectively. The significant risk factors for incident hip OA were age, obesity, and acetabular dysplasia at baseline (hazard risk [HR] 1.05, 95% confidence interval [CI] 1.03-1.08; 1.78, 1.10-2.75; 2.06, 1.30-3.17, respectively). The significant risk factors for progressive hip OA were baseline hip pain and acetabular dysplasia (HR 5.68, 95%CI 1.07-22.61; 14.78, 3.66-56.06, respectively). CONCLUSION: Continued longitudinal surveys of the ROAD study will contribute to knowledge about and potential prevention of incident and progressive hip OA.

Acetabular defect classification and management : Revision arthroplasty of the acetabular cup based on 3-point fixation.

BACKGROUND: The purpose of this study was to provide a practicable and contemporary classification system that is reliable and pragmatic with respect to perioperative evaluation, planning, scientific comparison and analysis. MATERIAL AND METHODS: This was a retrospective study of 160 patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup. The assessment of the acetabular defect was based on intraoperative description of the bony configuration of the acetabulum as well as on standardized preoperative planning images (pelvic overview and axial view of the hip joint). Preoperative computed tomography (CT) was carried out in individual cases. RESULTS: Acetabular bone defects were classified into 4 types based on whether or not a 3-point fixation of the acetabular cup within the boundaries of the acetabular cavity was possible. Minor segmental defects or cup loosening without bone loss can be treated with standard hemispherical acetabular components. Bone loss can be filled with bone grafts and/or treated by the appropriate acetabular component in order to ensure stable anchorage. When conventional revision cups are no longer suitable a custom made partial pelvic replacement can be used. CONCLUSION: The proposed classification mainly relies on intraoperative findings which were confirmed by preoperative imaging in 154 cases out of 160 (96.25%); however, meticulous preoperative planning based on X­ray radiographs must be carried out. In addition, a CT scan must be performed whenever type III or type IV defects are anticipated. Compared to the existing classification systems, we can state that our classification system is practicable and pragmatic and simplifies the assessment of bone defects.

Acetabular Protrusio in Patients With Osteogenesis Imperfecta: Risk Factors and Progression.

BACKGROUND: Osteogenesis imperfecta (OI) is a genetic disorder commonly associated with osteopenia, osteoporosis, bone fractures, bone deformities, and other clinical features. A frequent radiologic finding with OI is acetabular protrusio (AP). We hypothesized that AP develops in patients with OI over time. In addition, we hypothesized that AP also develops in patients with OI without radiographic evidence of AP on initial examination. METHODS: Medical records and radiographs of 55 patients (109 hips) diagnosed with OI evaluated at our institution were retrospectively reviewed. Previously established radiographic criteria using the center-edge (CE) angle of Wiberg, position of the acetabulum relative to the iliopectineal line, crossing of the acetabulum across the ilioischial (Kohler) line, and position of the teardrop figure relative to the ilioischial (Kohler) line were utilized to assess AP severity. In addition, pharmacological treatments and patient factors including body mass index (BMI) were recorded. Radiographs of patients with OI that were taken ≥2 years apart were analyzed utilizing AP radiographic criteria to assess for changes. The changes in AP-related measurements were standardized by distance or degree per year. In addition, patient factors were evaluated for associations with AP development. RESULTS: In this series of 109 hips (55 patients), incidence of AP in earliest radiographs was 45% (49/109). Patients with OI type I and III demonstrated the highest incidence of AP (65%). Among the hips that did not meet the criteria for AP in their early radiographs, 24 (40%) were positive for AP by their latest radiograph. In the hips that initially presented with AP, 42% showed increased CE angles on later radiographs. Twenty-six hips (24%) showed either no observable changes or reduced CE angles. Risk factors that were significantly associated with greater odds of developing AP included (1) an age under 12; (2) a BMI>25; (3) presence of AP of the contralateral hip; and (4) female sex. Bisphosphonates, vitamin D, physical therapy, and other drugs related to treatment of OI reduced the risk of developing AP but did not achieve statistical significance. CONCLUSIONS: AP is a common finding in OI patients (54%). Among hips of OI patients that met criteria for AP in early radiographs, 42% (20/48) demonstrated greater CE angles in their latest radiographs. Similar changes were observed in OI patients who did not initially meet criteria for diagnosis for AP. However, CE angle measurements between the 2 groups did not significantly differ (P=0.71). In terms of Kohler line crossing, patients that met criteria for AP in early radiographs had significantly greater change per year than those that did not have AP criteria (P<0.05). The findings suggest AP may develop over time in patients with OI and may be influenced by patient factors such as age, sex, and BMI. In addition, unilateral AP may have a significant impact on the development of AP of the contralateral hip. LEVEL OF EVIDENCE: Level IV-retrospective case series.

A Possible New Radiographic Predictor of Progression of Osteoarthritis in Developmental Dysplasia of the Hip: The Center Gap.

BACKGROUND: Patients with comparable severities of developmental dysplasia of the hip (DDH) may variably progress to osteoarthritis (OA) over time. Although joint congruency may be associated with OA progression in patients with DDH, it has only been assessed subjectively. We assessed the gap between the rotational centers of the acetabulum and femoral head (center gap) as a possible predictive measure of OA progression in patients with DDH. QUESTIONS/PURPOSES: In patients with bilateral DDH, we asked: (1) What is the probability of OA progression (Tönnis grade) or symptom development (pain) in the asymptomatic contralateral hip of patients with DDH undergoing unilateral joint-preserving surgery? (2) Is the center gap measurement associated with OA progression or symptom development in these hips? (3) Is the center gap measurement correlated with previous radiographic parameters? METHODS: A total of 297 patients (319 hips) underwent unilateral eccentric rotational acetabular osteotomy at our institution between July 1989 and December 1999. We performed no other joint-preserving surgery to treat patients with DDH during this timeframe. The inclusion criteria for the study were patients younger than 55 years of age, the contralateral hip classified as Tönnis Grade 0, no previous surgical interventions, and asymptomatic at the time of eccentric rotational acetabular osteotomy (155 patients, 155 hips). The exclusion criteria were a contralateral hip without dysplasia (four patients, four hips), loss to followup before 10 years (42 patients, 42 hips [27%]), or missing medical records or radiographs (21 patients, 21 hips [14%]). The remaining 88 patients (88 hips; 11 males and 77 females) with a mean age of 39 years (range, 17-53 years) and mean followup of 20 years (range, 10-27 years) were analyzed. From the institutional database, radiographic parameters including the center gap in the AP view were assessed using radiographs at the time of eccentric rotational acetabular osteotomy, and the Tönnis grade was recorded 1 year postoperatively and annually thereafter retrospectively. We defined migration of the rotational center of the femoral head based on the rotational center of the acetabulum in the horizontal plane as center gap X (mm) and in the vertical plane as center gap Y (mm) and defined the absolute value between the centers as center gap distance (mm). Using κ statistics, intra- and interobserver reliabilities were determined to be 0.896 and 0.857 for center gap X, 0.912 and 0.874 for center gap Y, and 0.912 and 0.901 for the center gap distance, respectively. When patients reported any contralateral ipsilateral hip pain during clinic visits, the hip was considered symptomatic. Kaplan-Meier survivorship analyses were performed with OA progression or symptom development in the nonoperative hip as the endpoint. Multivariate analyses were performed to assess risk factors for each outcome using the Cox proportional hazards model. Correlation analyses between the center gap and other parameters including lateral center-edge angle, femoral head extrusion index, acetabular depth-to-width index, femoral head lateralization, minimum width of the joint space, head sphericity, and joint congruency were performed using Pearson's correlation coefficient. RESULTS: At 20 years postoperatively, the probability of OA progression in the nonoperative hip was 13% (95% confidence interval [CI], 7.1-22.1) and the probability of symptom development was 34% (95% CI, 24.7-46.1). The center gap X measurements in the groups with OA progression (lateral 2.0 ± 2.1 [SD] mm) or symptom development (lateral 0.9 ± 2.4 mm) took a more lateral direction than those in the group without OA progression (medial 0.4 ± 2.1 mm) or symptom development (medial 0.5 ± 2.0 mm) (OA progression, p < 0.001; symptom development, p = 0.005). The center gap Y measurements in the groups with OA progression (distal 2.7 ± 7.1 mm) or symptom development (distal 2.1 ± 6.0 mm) took a more distal direction than those in the group without OA progression (proximal 1.6 ± 6.2 mm) or symptom development (proximal 2.5 ± 6.1 mm) (OA progression, p = 0.027; symptom development, p = 0.001). Independent risk factors for OA progression were the femoral head extrusion index (hazard ratio [HR], 1.11; 95% CI, 1.01-1.22; p = 0.028) and the center gap X (HR, 1.52; 95% CI, 1.07-2.16; p = 0.019), whereas no independent risk factors for symptom development were found. The center gap in the horizontal plane had no correlations with any other radiographic parameter studied. CONCLUSIONS: The center gap in the horizontal plane had a modest association with OA progression in this group of patients with DDH. Future studies are needed to determine the normal value of the center gap for patients without DDH and to assess the center gap in lateral radiographic views. LEVEL OF EVIDENCE: Level IV, prognostic study.

Use of iliac crest allograft for Dega pelvic osteotomy in patients with cerebral palsy.

BACKGROUND: Dega pelvic osteotomy is commonly performed procedure in patients with cerebral palsy (CP) undergoing hip reconstructive surgery for hip displacement. However, there has been no study investigating the outcomes after Dega pelvic osteotomy using allograft in patients with CP. This study investigated the outcomes of Dega pelvic osteotomy using iliac crest allograft in CP with hip displacement and the factors affecting allograft incorporation. METHODS: This study included 110 patients (150 hips; mean age 8y7mo; 68 males, 42 females) who underwent hip reconstructive surgeries including Dega pelvic osteotomy using iliac crest allograft. To evaluate the time of allograft incorporation, Goldberg score was evaluated according to the follow-up period on all postoperative hip radiographs. The acetabular index, migration percentage, and neck-shaft angle were also measured on the preoperative and postoperative follow-up radiographs. RESULTS: The mean estimated time for allograft incorporation (Goldberg score ≥ 6) was 1.1 years postoperatively. All hips showed radiographic union at the final follow-up and there was no case of graft-related complications. Patients with Gross Motor Function Classification System (GMFCS) level V had 6.9 times higher risk of radiographic delayed union than those with GMFCS level III and IV. Acetabular index did not increase during the follow-up period (p = 0.316). CONCLUSIONS: Dega pelvic osteotomy using iliac crest allograft was effective in correcting acetabular dysplasia, without graft-related complications in patients with CP. Furthermore, the correction of acetabular dysplasia remained stable during the follow-up period.

Hemi-pelvic slope is correlated with the acetabular depth in adults-a radiological study.

OBJECTIVE: The purpose of this study was to determine if there is an anatomic relationship between pelvic geometry and acetabular depth. MATERIALS AND METHODS: One hundred and fifty-one anteroposterior pelvic radiographs (157 hip joints) were selected and analyzed in a retrospective fashion. Six parameters, including iliac offset, ischial offset, acetabular offset, pelvic height, center-edge (CE) angle of Wiberg, and acetabular index (AI) angle of Tönnis were measured for each of the hip joints. Based on the defined variables, three formulas (formulas 1, 2, and 3) were calculated to represent the hemi-pelvis slope. RESULTS: There was a strong relationship between the hemi-pelvis slope and probability of acetabular dysplasia. Wider upper pelvis was associated with deeper acetabulum and wider lower pelvis was associated with dysplastic acetabulum. CONCLUSIONS: Pelvic anatomic dimensions and the relationship between them are strongly correlated with hip dysplasia indices. Dysplastic hips tend to be found in pelvises with lower slope (low width of the upper pelvis at the level of iliac crest and high width of the lower part at the level of ischium).

Evaluation of articular cartilage following rotational acetabular osteotomy for hip dysplasia using T2 mapping MRI.

BACKGROUND: Rotational acetabular osteotomy (RAO) is one of the surgical treatments for acetabular dysplasia, and satisfactory results have been reported. We evaluated the postoperative changes of articular cartilage and whether the pre-operative condition of the articular cartilage influences the clinical results using T2 mapping MRI. METHODS: We reviewed 31 hips with early stage osteoarthritis in 31 patients (mean age, 39.6 years), including three men and 28 women who underwent RAO for hip dysplasia. Clinical evaluations including Japanese Orthopedic Association (JOA) score and Japanese Orthopedic Association Hip Disease Evaluation Questionnaire (JHEQ), and radiographical evaluations on X-ray were performed. Longitudinal qualitative assessment of articular cartilage was also performed using 3.0-T MRI with T2 mapping technique preoperatively, 6 months, and at 1 and 2 years postoperatively. RESULTS: There was no case with progression of osteoarthritis. The mean JOA score improved from 70.1 to 93.4 points, the mean postoperative JHEQ score was 68.8 points, and radiographical data also improved postoperatively. We found that the T2 values of the cartilage at both femoral head and acetabulum increased at 6 months on coronal and sagittal views. However, they significantly decreased 1 and 2 years postoperatively. The T2 values of the center to anterolateral region of acetabulum negatively correlated with postoperative JHEQ score, particularly in pain score. CONCLUSIONS: This study suggests that biomechanical and anatomical changes could apparently cause decreased T2 values 1-2 years postoperatively compared with those preoperatively. Furthermore, preoperative T2 values of the acetabulum can be prognostic factors for the clinical results of RAO.

Long-term results of a modified Spitzy shelf operation for developmental dysplasia of the hip in adults and adolescents.

The purpose of the current study was to retrospectively evaluate the long-term outcome of our shelf operation for acetabular dysplasia in adults and adolescents. We evaluated the outcome of shelf operation performed in 35 hips of 32 patients with acetabular dysplasia between 1978 and 1996. The mean age at the time of surgery was 30.6 years, and the mean follow-up period was 25.9 years. The pre-operative stage of osteoarthritis was Tönnis grade 0 in 12 hips and grade 1 in 23 hips. Clinical evaluation using the JOA hip score showed more than 85 of 100 points over 25 years. Radiologically, acetabular index was significantly improved after operation. Osteoarthritis deteriorated to grade 3 in 8 of 35 hips (23%) at an average 17.1 years, and accordingly 3 of those 8 hips were converted to THA. The shelf height was significantly higher in those which advanced to grade 3 than in those which did not. There were no significant differences in mean sharp angle, CE angle, AHI, and roundness index. Mean survival was 74% with grade 3 as the endpoint and 72% with THA conversion as the endpoint. Shelf operation provides satisfactory long-term outcome in adults and adolescents with acetabular dysplasia. Higher location of the shelf is a risk factor for advancement of osteoarthritis, whereas sphericity of the femoral head does not affect the long-term results. Further studies are needed to clarify the risk factors about OA progression among the patients with acetabular dysplasia, like as the assessment of three-dimensional morphology of hip joints.

A long term follow-up study of the development of hip disease in Mucopolysaccharidosis type VI.

Hip problems in Mucopolysaccharidosis type VI (MPS VI) lead to severe disability. Lack of data on the course of hip disease in MPS VI make decisions regarding necessity, timing and type of surgical intervention difficult. We therefore studied the development of hip pathology in MPS VI patients over time. Data were collected as part of a prospective follow-up study. Standardized supine AP pelvis and frog leg lateral radiographs of both hips were performed yearly or every 2years. Image assessment was performed quantitatively (angle measurements) and qualitatively (hip morphology). Clinical burden of hip disease was evaluated by physical examination, six minute walking test (6MWT) and a questionnaire assessing pain, wheelchair-dependency and walking distance. A total of 157 pelvic radiographs of 14 ERT treated MPS VI patients were evaluated. Age at first image ranged from 2.0 to 21.1years. Median follow up duration was 6.8years. In all patients, even in the youngest, the acetabulum and os ilium were dysplastic. Coverage of the femoral head by the acetabulum improved over time, but remained insufficient. While the femoral head appeared normal in the radiographs at young age, the ossification pattern became abnormal in all patients over time. In all patients the distance covered in the 6MWT was reduced (median Z scores -3.3). Twelve patients had a waddling gait. Four patients were partially wheelchair-dependent and ten patients had limitations in their maximum walking distance. In conclusion, clinically significant hip abnormalities develop in all MPS VI patients from very early in life, starting with deformities of the os ilium and acetabulum. Femoral head abnormalities occur later, most likely due to altered mechanical forces in combination with epiphyseal abnormalities due to glycosaminoglycan storage. The final shape and angle of the femoral head differs significantly between individual MPS VI patients and is difficult to predict.

Functional status and amount of hip displacement independently affect acetabular dysplasia in cerebral palsy.

AIM: Acetabular dysplasia is the one of main causes of hip displacement in patients with cerebral palsy (CP). Although several studies have shown a relationship between hip displacement and acetabular dysplasia, relatively few have evaluated the association between quantitative acetabular dysplasia and related factors, such as Gross Motor Function Classification System (GMFCS) level. METHOD: We performed a morphometric analysis of the acetabulum in patients with CP using multiplanar reformation of computed tomography data. The three directional acetabular indices (anterosuperior, superolateral, and posterosuperior) were used to evaluate acetabular dysplasia. Consequently, linear mixed-effects models were used to adjust for related factors such as age, sex, GMFCS level, and migration percentage. RESULTS: A total of 176 patients (mean age 9y 5mo, range 2y 4mo-19y 6mo; 104 males, 72 females) with CP and 55 typically developing individuals (mean age 13y 6mo, range 2y 5mo-19y 10mo; 37 males, 18 females) in a comparison group were enrolled in this study. Statistical modelling showed that all three directional acetabular indices independently increased with GMFCS level (p<0.001) and migration percentage (p<0.001). INTERPRETATION: Acetabular dysplasia was independently affected by both the amount of hip displacement and the GMFCS level. Thus, physicians should consider not only the migration percentage but also three-dimensional evaluation in patients at high GMFCS levels.

Acetabular Wall Indices Help to Distinguish Acetabular Coverage in Asymptomatic Adults With Varying Morphologies.

BACKGROUND: The anterior wall index (AWI) and posterior wall index (PWI) have been proposed to quantify anterior and posterior acetabular coverage using AP pelvic radiographs. However, these indices have only been reported in symptomatic patients with apparent pathomorphologies (dysplasia, overcoverage, and retroversion) undergoing osteochondroplasty or reorientation osteotomy. QUESTIONS: (1) What are the ranges for AWI and PWI from measurements obtained on AP pelvic radiographs of asymptomatic senior athletes with well-functioning hips? (2) Is there a difference between the AWI and PWI in asymptomatic athletes with acetabular morphology consistent with acetabular dysplasia, overcoverage, and retroversion when compared with asymptomatic hips that do not meet the radiographic definitions for those morphologies (controls)? METHODS: Five hundred five athletes (998 asymptomatic native hips) were independently evaluated by two readers on AP pelvic radiographs for AWI and the PWI after excluding hips with prior surgery, inadequate radiographs, or poor function (modified Harris hip score < 80). Hips with a lateral center-edge angle (LCEA) ≥ 20° and ≤ 38° and without acetabular retroversion, based on a positive crossover sign, were used as controls. Hips were categorized as developmental dysplasia of the hip (DDH; undercoverage) if the LCEA was < 20°. Finally, overcoverage was defined as an LCEA > 38°. The mean age of the athletes was 67 years (range, 50-91 years) and 55% were men. Linear generalized estimating equation regression was used to compare each individual diagnosis (DDH, retroversion, overcoverage) with the controls for both AWI and PWI adjusting for age and sex. RESULTS: The mean AWI in the study population was 0.36 (range, -0.02 to 0.91). The mean PWI was 1.13 (range, 0.12-1.74). The mean AWI and PWI in controls (n = 740) was 0.35 (range, -0.02 to 0.91) and 1.13 (range, 0.64-1.70), respectively. There were 25 (3%) with DDH in whom the mean AWI was 0.26 (range, 0.05-0.5) and the mean PWI was 1.03 (range, 0.71-1.3). There were 112 (11%) retroverted hips in whom the mean AWI was 0.42 (range, 0.1-0.89) and PWI was 1.02 (range, 0.61-1.5). There were 121 (12%) overcovered hips in whom the mean AWI was 0.43 (range, -0.18 to 0.85) and PWI was 1.22 (0.12-1.74). The AWI in the control hips was no different than that of DDH hips (ß -0.06; 95% confidence interval [CI], -0.12 to 0.002; p = 0.059) but was found to be lower than retroverted hips (ß 0.08; 95% CI, 0.04-0.11; p < 0.001) and overcovered hips (ß 0.05; 95% CI, 0.03-0.08; p < 0.001). The PWI in control hips was greater than that of DDH hips (ß -0.08; 95% CI, -0.14 to -0.02; p = 0.013) and retroverted hips (ß -0.07; 95% CI, -0.11 to -0.04; p < 0.001) but was less than overcovered hips (ß 0.07; 95% CI, 0.04-0.10; p < 0.001). CONCLUSIONS: The measurements of AWI and PWI in well-functioning, asymptomatic hips may be useful in assessing anterior and posterior acetabular coverage because it was able to distinguish between different types of known pathologic morphology. Despite evidence of these morphologic variances, these senior athletes continued to function at a high level. Thus, the identification of morphologic variance was not consistent with signs of pathology, which further supports that early screening of morphology may not predict the development of symptomatic pathology. Future work should focus on comparing these indices for morphologic variance in both symptomatic and asymptomatic hips to determine whether these measurements can be used in identifying problematic hips and as reference ranges for surgical correction. LEVEL OF EVIDENCE: Level III, diagnostic study.

Survivorship of the Bernese Periacetabular Osteotomy: What Factors are Associated with Long-term Failure?

BACKGROUND: The Bernese periacetabular osteotomy (PAO) continues to be a commonly performed nonarthroplasty option to treat symptomatic developmental hip dysplasia, but there are few long-term followup studies evaluating results after PAO. QUESTIONS/PURPOSES: (1) What is the long-term survivorship of the hip after PAO? (2) What were the validated outcomes scores among patients who had PAO more than 14 years ago? (3) What factors are associated with long-term failure? METHODS: One hundred fifty-eight dysplastic hips (133 patients) underwent PAO between May 1991 and September 1998 by a single surgeon. Of those, 37 hips (34 patients [26%]) were lost to followup; an additional seven patients (5% [eight hips]) had not been seen in the last 5 years. The 121 hips (in 99 patients) were retrospectively evaluated at a mean of 18 years (range, 14-22 years). Survivorship was assessed using Kaplan-Meier analysis with total hip arthroplasty (THA) as the endpoint. Hips were evaluated for activity, pain, and general health using the UCLA Activity Score, modified Harris hip score, WOMAC, and Hip disability and Osteoarthritis Outcome Score (HOOS). Failure was defined as a WOMAC pain subscale score ≥ 10 or having undergone THA. Hips were divided into three groups: asymptomatic (did not meet any failure criteria at any point in time), symptomatic (met WOMAC pain failure criteria at previous or most recent followup), and replaced (having undergone THA). A multinomial logistic regression model using a general estimating equations approach was used to assess factors associated with failure. RESULTS: Kaplan-Meier analysis with THA as the endpoint revealed a survival rate (95% confidence interval [CI]) of 74% (66%-83%) at 18 years. Twenty-six hips (21%) underwent THA at an average of 9 ± 5 years from the surgery. Sixty-four hips (53%) remained asymptomatic and did not meet any failure criteria at most recent followup. Thirty-one hips (26%) were symptomatic and considered failed based on a WOMAC pain score of ≥ 10 with a mean ± SD of 11 ± 4 out of 20 at most recent followup. Although some failed initially by pain, their most recent WOMAC score may have been < 10. Of the 16 symptomatic hips that failed early by pain (reported a WOMAC pain subscale score ≥ 10 in the prior study), two were lost to followup, two underwent THA at 16 and 17 years, four still failed because of pain at most recent followup, and the remaining eight had WOMAC pain scores < 10 at most recent followup. Asymptomatic hips reported better UCLA Activity Scores (asymptomatic: mean ± SD, 7 ± 2; symptomatic: 6 ± 2, p = 0.001), modified Harris hip scores (pain, function, and activity sections; asymptomatic: 80 ± 11; symptomatic: 50 ± 15, p < 0.001), WOMAC (asymptomatic: 2 ± 2, symptomatic: 11 ± 4, p < 0.001), and HOOS (asymptomatic: 87 ± 11, symptomatic: 52 ± 20, p < 0.001) compared with symptomatic hips at long-term followup. Age older than 25 years at the time of PAO (symptomatic: odds ratio [OR], 3.6; 95% CI, 1.3-9.8; p = 0.01; replaced: OR, 8.9; 95% CI, 2.6-30.9; p < 0.001) and a preoperative joint space width ≤ 2 mm (replaced: OR, 0.3; 95% CI, 0.12-0.71; p = 0.007) or ≥ 5 mm (replaced: OR, 0.121; 95% CI, 0.03-0.56; p = 0.007) were associated with long-term failure while controlling for poor or fair preoperative joint congruency. CONCLUSIONS: This study demonstrates the durability of the Bernese PAO at long-term followup. In a subset of patients, there was progression to failure over time. Factors of progression to THA or more severe symptoms include age older than 25 years, poor or fair preoperative hip congruency, and a preoperative joint space width that is less than 2 mm or more than 5 mm. Future studies should focus on evaluating the two failure groups that we have identified in our study: those that failed early and went on to THA and those that are symptomatic at long-term followup. LEVEL OF EVIDENCE: Level III, therapeutic study.

Three Patterns of Acetabular Deficiency Are Common in Young Adult Patients With Acetabular Dysplasia.

BACKGROUND: Detailed recognition of the three-dimensional (3-D) deformity in acetabular dysplasia is important to help guide correction at the time of reorientation during periacetabular osteotomy (PAO). Common plain radiographic parameters of acetabular dysplasia are limited in their ability to characterize acetabular deficiency precisely. The 3-D characterization of such deficiencies with low-dose CT may allow for more precise characterization. QUESTIONS/PURPOSES: The purposes of this study were (1) to determine the variability in 3-D acetabular deficiency in acetabular dysplasia; (2) to define subtypes of acetabular dysplasia based on 3-D morphology; (3) to determine the correlation of plain radiographic parameters with 3-D morphology; and (4) to determine the association of acetabular dysplasia subtype with patient clinical characteristics including sex, range of motion, and femoral version. METHODS: Using our hip preservation database, we identified 153 hips (148 patients) that underwent PAO from October 2013 to July 2015. Among those, we noted 103 hips in 100 patients with acetabular dysplasia (lateral center-edge angle < 20°) and who had a Tönnis grade of 0 or 1. Eighty-six patients (86%) underwent preoperative low-dose pelvic CT scans at our institution as part of the preoperative planning for PAO. It is currently our standard to obtain preoperative low-dose pelvic CT scans (0.75-1.25 mSv, equivalent to three to five AP pelvis radiographs) on all patients before undergoing PAO unless a prior CT scan was performed at an outside institution. Hips with a history of a neuromuscular disorder, prior trauma, prior surgery, radiographic evidence of joint degeneration, ischemic necrosis, or Perthes-like deformities were excluded. Fifty hips in 50 patients met inclusion criteria and had CT scans available for review. These low-dose CT scans of 50 patients with symptomatic acetabular dysplasia undergoing evaluation for surgical planning of PAO were then retrospectively studied. CT scans were analyzed quantitatively for acetabular coverage, relative to established normative data for acetabular coverage, as well as measurement of femoral version. The cohort included 45 females and five males with a mean age of 26 years (range, 13-49 years). RESULTS: Lateral acetabular deficiency was present in all patients, whereas anterior deficiency and posterior deficiency were variable. Three patterns of acetabular deficiency were common: anterosuperior deficiency (15 of 50 [30%]), global deficiency (18 of 50 [36%]), and posterosuperior deficiency (17 of 50 [34%]). The presence of a crossover sign or posterior wall sign was poorly predictive of the dysplasia subtype. With the numbers available, males appeared more likely to have a posterosuperior deficiency pattern (four of five [80%]) compared with females (13 of 45 [29%], p = 0.040). Hip internal rotation in flexion was significantly greater in anterosuperior deficiency (23° versus 18°, p = 0.05), whereas external rotation in flexion was significantly greater in posterosuperior deficiency (43° versus 34°, p = 0.018). Acetabular deficiency pattern did not correlate with femoral version, which was variable across all subtypes. CONCLUSIONS: Three patterns of acetabular deficiency commonly occur among young adult patients with mild, moderate, and severe acetabular dysplasia. These patterns include anterosuperior, global, and posterosuperior deficiency and are variably observed independent of femoral version. Recognition of these distinct morphologic subtypes is important for diagnostic and surgical treatment considerations in patients with acetabular dysplasia to optimize acetabular correction and avoid femoroacetabular impingement.

One-third of Hips After Periacetabular Osteotomy Survive 30 Years With Good Clinical Results, No Progression of Arthritis, or Conversion to THA.

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.

Reconstruction of the Shallow Acetabulum With a Combination of Autologous Bulk and Impaction Bone Grafting Fixed by Cement.

BACKGROUND: Acetabular bone deficiency, especially proximal and lateral deficiency, is a difficult technical problem during primary total hip arthroplasty (THA) in developmental dysplasia of the hip (DDH). We report a new reconstruction method using a medial-reduced cemented socket and additional bulk bone in conjunction with impaction morselized bone grafting (additional bulk bone grafting method). QUESTIONS/PURPOSES: In a population of patients with acetabular dysplasia undergoing THA using a medial-reduced cemented socket and additional bulk bone with impacted morselized bone grafting, we evaluated (1) the radiographic appearance of bone graft; (2) the proportion of cups that developed loosening and subsequent revision; and (3) clinical results (outcome scores and complications). METHODS: Forty percent of 330 THAs for DDH performed at one center between 1999 and 2009 were defined as shallow dysplastic hips. The additional bulk bone grafting method was performed on 102 THAs with shallow acetabulum (31% for DDH) at one center between 1999 and 2009. We used this approach and technique for shallow acetabuli when a cup protruded from the lateral acetabular edge in preoperative templating. The other 132 dysplastic hips without bone grafting had THA performed at the same periods and served as a control. Acetabuli were defined as shallow when the depth was less than or equal to one-fifth of the pelvic height (cranial-caudal length on radiograph). The additional bulk bone grafting technique was as follows: the resected femoral head was sectioned at 1 to 2 cm thickness, and a suitable size of the bulk bone graft was placed on the lateral iliac cortex and fixed by poly-L-lactate absorbable screws. Autologous impaction morselized bone grafting, with or without hydroxyapatite granules, was performed along with the implantation of a medial-reduced cemented socket. We defined an "incorporated" graft as remodeling and trabeculation including rounding off of the protruding edge of a graft beyond the socket. Radiographic criteria used for determining loosening were migration or a continuous radiolucent zone between the prosthesis/bone cement and host bone. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) and the Merle d'Aubigne and Postel score; complications were tallied from chart review. The followup was 10 ± 3 years (range, 6-15 years). RESULTS: One acetabular component (1%) with severe shallow and steep acetabuli showed definite radiographic evidence of loosening and was revised. Clinically, the mean JOA score for the hips treated with additional bulk bone grafting THA in this study improved from 39 ± 10 points preoperatively to 95 ± 5 points postoperatively (p < 0.05, paired t-test). The mean Merle d'Aubigne and Postel score for the hips improved from 7 ± 2 points to 17 ± 1 points (p < 0.05, paired t-test). Complications included a Trendelenburg sign in one hip, dislocation in one, and transient partial sciatic nerve palsy in one. Within 3 years 6 months postoperatively, 101 of 102 additional bulk bone grafting cases showed successful bone remodeling and bone graft reorientation without collapse on radiographs. Partial resorption of the additional bone graft on the lateral side was observed in two hips (2%) with socket abduction angles of < 35°. CONCLUSIONS: Achieving stable acetabular fixation is often challenging in the dysplastic hip, especially shallow acetabulum, and a variety of techniques have been described. Early results of combining bulk graft with impaction of morselized graft are promising. Although each surgical technique was well established, further investigation for clinical results of a combination of these techniques might be necessary to confirm longer term outcomes. LEVEL OF EVIDENCE: Level IV, therapeutic study.

What Are the Results of Surgical Treatment of Hip Dysplasia With Concomitant Cam Deformity?

BACKGROUND: Periacetabular osteotomy (PAO) is a reliable procedure to correct the deficient acetabular coverage in hips with developmental dysplasia. It is unclear how the presence of additional femoral cam-type deformity might influence the clinical and radiographic treatment results of PAO. QUESTIONS/PURPOSES: (1) Are there differences in clinical scores (WOMAC, EQ-5D) and examination findings (impingement sign) or radiographic measures of acetabular orientation and head sphericity after PAO for isolated acetabular dysplasia when compared with the combined pathology of dysplasia and additional femoral cam deformity? (2) Are these clinical and radiographic findings after combined surgical therapy for additional cam deformity influenced by different pathology-adjusted surgical techniques? METHODS: From July 2005 to December 2010, 86 patients (106 hips) underwent PAO for hip dysplasia. Surgical and outcome data were prospectively collected and retrospectively reviewed in a comparative observational study. Indications for surgery were a lateral center-edge angle less than 25° and hip pain for at least 6 months. The contraindications for surgery were advanced radiographic osteoarthritis (Kellgren-Lawrence Grade 3), incongruency of joint space, and patient age > 50 years. Depending on preoperative hip ROM, impingement test, and presence of a radiographically visible cam deformity, treatment allocation was performed: Group I: isolated PAO in patients without symptomatic asphericity, Group IIa: PAO with subsequent osteochondroplasty through arthrotomy for patients with symptomatic cam deformity and no labrochondral pathology, and Group IIb: arthroscopically assisted osteochondroplasty and additional labrochondral repair with subsequent PAO when patients had labrochondral lesions in addition to a symptomatic cam deformity. Clinical outcome (impingement test, EQ-5D, WOMAC) as well as radiographic parameters (lateral center-edge angle, crossover sign, alpha angle, osteoarthritis grade) were obtained after a mean followup of 63 ± 18 months (range, 31-102 months) and compared with the baseline data. Eleven patients (13%) were lost to followup. With the numbers available, our study had 80% power to detect a difference between Groups I and II of 10 points on the WOMAC scores. RESULTS: There was no difference in the increase of WOMAC scores in patients with PAO alone (Group I; preoperative score 74 ± 17 versus postoperative 91 ± 15, p = 0.033) when compared with PAO and concurrent osteochondroplasty (Groups II A and B preoperative 73 ± 19 versus postoperative 90 ± 13 p < 0.001). The mean postoperative alpha angles in Group II (38° ± 6°) improved when compared with preoperative values (56° ± 15°; p < 0.001) and were even lower than native offset alpha angles in Group I (47° ± 11°). Clinical scores as well as postoperative radiographic parameters were not different between patients with conventional osteochondroplasty alone (Group IIA) and patients with arthroscopically assisted cam resection and intraarticular labrochondral repair (Group IIB). CONCLUSIONS: With the numbers available, we detected no differences in outcome scores and radiographic results between patients who had been treated with PAO alone and patients who underwent combined PAO and offset correction for cam deformity. Although arthroscopically assisted treatment of advanced labrochondral lesions together with osteochondroplasty is possible during PAO and the results were not different in this small study when compared with patients with PAO and osteochondroplasty alone, the type and extent of damage that would indicate additional cartilage surgery over cam resection alone remain unclear. LEVEL OF EVIDENCE: Level III, therapeutic study.