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Background: Acetabular retroversion is associated with impingement and instability. An adequate interpretation of acetabular version and coverage on radiographs is essential to determine the optimal treatment strategy (periacetabular osteotomy vs hip arthroscopic surgery). The crossover sign (COS) has been associated with the presence of acetabular retroversion, and the anterior wall index (AWI) and posterior wall index (PWI) assess anteroposterior acetabular coverage. However, the radiographic appearance of the acetabulum is sensitive to anterior inferior iliac spine (AIIS) morphology and pelvic tilt (PT), which differs between the supine and standing positions. Purpose: To (1) identify differences in the acetabular appearance between the supine and standing positions among patients presenting with hip pain; (2) determine factors (acetabular version, AIIS morphology, and spinopelvic characteristics) associated with the crossover ratio (COR), AWI, and PWI; and (3) define relevant clinical thresholds to guide management. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients who presented to a hip preservation surgical unit (n = 134) were included (mean age, 35 ± 8 years; 58% female; mean body mass index, 27 ± 6). All participants underwent supine and standing anteroposterior pelvic radiography to assess the COS, COR, AWI, and PWI as well as standing lateral radiography to determine standing PT. Computed tomography was used to measure supine PT, acetabular version, and AIIS morphology. Acetabular version was measured at 3 transverse levels, corresponding to the 1-, 2-, and 3-o'clock positions. The correlation between radiographic characteristics (COR, AWI, and PWI) and acetabular version, AIIS morphology, and PT was calculated using the Spearman correlation coefficient. Receiver operating characteristic curve analysis was performed to define thresholds for the COR, AWI, and PWI to identify retroversion (version thresholds: <10°, <5°, and <0°). Results: The COS was present in 55% of hips when supine and 30% when standing, with a mean difference in the COR of 12%. The supine COR (rho = −0.661) and AWI/PWI ratio (rho = −0.618) strongly correlated with acetabular version. The COS was more prevalent among patients with type 2 AIIS morphology (71%) than among those with type 1 AIIS morphology (43%) (P =.003). COR thresholds of 23% and 28% were able to identify acetabular version <5° (sensitivity = 81%; specificity = 80%) and <0° (sensitivity = 88%; specificity = 85%), respectively. An AWI/PWI ratio >0.6 was able to reliably identify acetabular version <0° (sensitivity = 83%; specificity = 84%). In the presence of a COR >30% and an AWI/PWI ratio >0.6, the specificity to detect retroversion was significantly increased (>90%). Conclusions: The presence of the COS was very common among patients with hip pain. False-positive results (high COR/normal version) may occur because of AIIS morphology/low PT. Relevant thresholds of COR >30% and AWI/PWI ratio >0.6 can help with diagnostic accuracy. In cases in which either the COR or AWI/PWI ratio is high, axial cross-sectional imaging can further help to avoid false-positive results. [ABSTRACT FROM AUTHOR]

Background: Radiographic evaluation plays an important role in detecting and grading hip dysplasia. Acetabular sector angles (ASAs) measure the degree of femoral head coverage provided by the acetabulum on computed tomographic (CT) scans. In this study, we aimed to determine ASA values at different axial levels in a control cohort with asymptomatic, high-functioning hips without underlying hip pathology and a study group with symptomatic, dysplastic hips that underwent periacetabular osteotomy (PAO), thereby defining the ASA thresholds for hip dysplasia. Methods: This was a cross-sectional study evaluating a control group of 51 patients (102 hips) and a study group of 66 patients (72 hips). The control group was high-functioning and asymptomatic, with an Oxford Hip Score of >43, did not have osteoarthritis (Tönnis grade ≤1), underwent a pelvic CT scan, had a mean age (and standard deviation) of 52.1 ± 5.5 years, and was 52.9% female. The study group had symptomatic hip dysplasia treated with PAO, had a mean age of 29.5 ± 7.3 years, and 83.3% was female. Anterior ASA (AASA) and posterior ASA (PASA) were measured at 3 axial CT levels to determine equatorial, intermediate, and proximal ASA. The thresholds for dysplasia were determined using receiver operating characteristic (ROC) curve analysis, including the area under the curve (AUC). Results: Patients with dysplasia had significantly smaller ASAs compared with the control group; the differences were most pronounced for proximal AASAs and proximal and intermediate PASAs. The control group had a mean proximal PASA of 162° ± 17°, yielding a threshold for dysplasia of 137° (AUC, 0.908). The mean intermediate PASA for the control group was 117° ± 11°, yielding a threshold of 107° (AUC, 0.904). The threshold for anterior dysplasia was 133° for proximal AASA (AUC, 0.859) and 57° for equatorial AASA (AUC, 0.868). The threshold for posterior dysplasia was 102° for intermediate PASA (AUC, 0.933). Conclusions: Measurement of ASA is a reliable tool to identify focal acetabular deficiency with high accuracy, aiding diagnosis and management. A proximal PASA of <137° or an intermediate PASA of <107° should alert clinicians to the presence of dysplasia. [ABSTRACT FROM AUTHOR]