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Background: Radiographs play a central role in the evaluation of the extent of arthritic change and the quantification of morphological parameters characteristic of femoroacetabular impingement (FAI) and/or dysplasia. Reporting of these parameters is widespread in the literature, occasionally as an instrument for data pooling in collaborative research endeavors. Yet, the metrological properties of commonly used radiographic descriptors of acetabular and femoral architecture relevant to the field of hip preservation have not been reviewed systematically. The purpose of the present review was twofold: (1) to identify the current body of data available on the reliability of commonly used radiographic descriptors of the pre-arthritic hip and (2) to collate best practices and methodological pearls and pitfalls from the existing investigations that have explored the reliability of these radiographic measures., Methods: Article screening methodology involved an extensive search of 2 databases (PubMed Central, Embase). Metrological reliability data and best practices and frequencies with which these practices have been reported in existing investigations were extracted from the methods of the included studies. The radiographic parameters that were chosen as a focus for the present review were based on a discussion among a number of experienced hip-preservation surgeons., Results: Forty-three articles met all inclusion criteria and were included in this review. Eleven recurring components of study design were isolated from the included investigations as being critical for minimizing bias in the assessment of the reliability of these radiographic morphological parameters. Sixteen (37.2%) of the included studies reported the use of at least 1 quality-control measure for ensuring radiographic integrity. The radiographic parameters with the most reliability data included the lateral center-edge angle (22 studies), the Tönnis angle (14 studies), and the alpha angle (18 studies). Categorical markers of acetabular retroversion and the extent of osteoarthritis have been less-frequently studied with respect to their reliability, with the exception of the crossover sign, which was evaluated in 11 of the included studies., Conclusions: The radiographic parameter with the most metrological evidence in support of its reliability was the lateral center-edge angle (with 22 [100%] of 22 studies reporting acceptable reliability), whereas the Tönnis grade of osteoarthritis consistently demonstrated subpar interrater and intrarater reliability. Side-arm investigations for testing reliability may be needed by individual studies to prove the validity of data-pooling practices as collaborative endeavors continue to become more widespread.

Background: Salter innominate osteotomy has been identified as an effective additional surgery for the dysplastic hip. However, because in this procedure, the distal segment of the pelvis is displaced laterally and anteriorly, it may predispose the patient to acetabular retroversion. The degree to which this may be the case, however, remains incompletely characterized., Questions/purposes: We asked, in a group of pediatric patients with acetabular dysplasia who underwent Salter osteotomy, whether the operated hip developed (1) acetabular retroversion compared with contralateral unaffected hips; (2) radiographic evidence of osteoarthritis; or (3) worse functional scores. (4) In addition, we asked whether femoral head deformity resulting from aseptic necrosis was a risk factor for acetabular retroversion., Methods: Between 1971 and 2001, we performed 213 Salter innominate osteotomies for unilateral pediatric dysplasia, of which 99 hips (47%) in 99 patients were available for review at a mean of 16 years after surgery (range, 12-25 years). Average patient age at surgery was 4 years (range, 2-9 years) and the average age at the most recent followup was 21 years (range, 18-29 years). Acetabular retroversion was diagnosed based on the presence of a positive crossover sign and prominence of the ischial spine sign at the final visit. The center-edge angle, acetabular angle of Sharp, and acetabular index were measured at preoperative and final visits. Contralateral unaffected hips were used as controls, and statistical comparison was made in each patient. Clinical findings, including Harris hip score (HHS) and the anterior impingement sign, were recorded at the final visit., Results: Patients were no more likely to have a positive crossover sign in the surgically treated hips (20 of 99 hips [20%]) than in the contralateral control hips (17 of 99 hips [17%]; p = 0584). In addition, the percentage of positive prominence of the ischial spine sign was not different between treated hips (22 of 99 hips [22%]) and contralateral hips (18 of 99 hips [18%]; p = 0.256). Hips that had a positive crossover or prominence of the ischial spine sign in the operated hips were likely also to have a positive crossover sign or prominence of the ischial spine sign in the unaffected hips (16 of 20 hips [80%] crossover sign, 17 of 22 hips [77%] prominence of the ischial spine sign). At the final visit, five hips (5%) showed osteoarthritic change; one of the five hips (20%) showed positive crossover and prominence of the ischial spine signs, and the remaining four hips showed negative crossover and prominence of the ischial spine signs. There was no significant difference in HHS between the crossover-positive and crossover-negative patient groups nor in the prominence of the ischial spine-positive and prominence of the ischial spine-negative patient groups (crossover sign, p = 0.68; prominence of the ischial spine sign, p = 0.54). Hips with femoral head deformity (25 of 99 hips [25%]) were more likely to have acetabular retroversion compared with hips without femoral-head deformity (crossover sign, p = 0.029, prominence of the ischial spine sign, p = 0.013)., Conclusions: Our results suggest that Salter innominate osteotomy does not consistently cause acetabular retroversion in adulthood. We propose that retroversion of the acetabulum is a result of intrinsic development of the pelvis in each patient. A longer-term followup study is needed to determine whether retroverted acetabulum after Slater innominate osteotomy is a true risk factor for early osteoarthritis. Femoral head deformity is a risk factor for subsequent acetabular retroversion., Level of Evidence: Level III, therapeutic study.

Background: Developmental dysplasia of the hip (DDH) and acetabular retroversion represent distinct acetabular pathomorphologies. Both are associated with alterations in pelvic morphology. In cases where direct radiographic assessment of the acetabulum is difficult or impossible or in mixed cases of DDH and retroversion, additional indirect pelvimetric parameters would help identify the major underlying structural abnormality., Questions/purposes: We asked: How does DDH and retroversion differ with respect to rotation and coronal obliquity as measured by the pelvic width index, anterior inferior iliac spine (AIIS) sign, ilioischial angle, and obturator index? And what is the predictive value of each variable in detecting acetabular retroversion?, Methods: We reviewed AP pelvis radiographs for 51 dysplastic and 51 retroverted hips. Dysplasia was diagnosed based on a lateral center-edge angle of less than 20° and an acetabular index of greater than 14°. Retroversion was diagnosed based on a lateral center-edge angle of greater than 25° and concomitant presence of the crossover/ischial spine/posterior wall signs. We calculated sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve for each variable used to diagnose acetabular retroversion., Results: We found a lower pelvic width index, higher prevalence of the AIIS sign, higher ilioischial angle, and lower obturator index in acetabular retroversion. The entire innominate bone is internally rotated in DDH and externally rotated in retroversion. The areas under the ROC curve were 0.969 (pelvic width index), 0.776 (AIIS sign), 0.971 (ilioischial angle), and 0.925 (obturator index)., Conclusions: Pelvic morphology is associated with acetabular pathomorphology. Our measurements, except the AIIS sign, are indirect indicators of acetabular retroversion. The data suggest they can be used when the acetabular rim is not clearly visible and retroversion is not obvious., Level of Evidence: Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.