Plain Radiographic Signs of Acetabular Retroversion Can Accurately Detect Global Retroversion With High Sensitivity and Specificity Without a Computed Tomography Scan

PURPOSE: To examine the relationship between radiographic signs of acetabular retroversion (AR) in symptomatic femoroacetabular impingement syndrome (FAIS) patients and global AR (GAR) measured on 3-dimensional imaging. METHODS: A retrospective cohort study was conducted to identify patients between 2017 and 2024, with radiographic and clinical FAIS. Standardized pelvic radiographs were analyzed for crossover sign (COS; including crossover percentage), ischial spine sign (ISS), and posterior wall sign (PWS). Alpha angle, femoral torsion, lateral center-edge angle (LCEA), and acetabular version at 1, 2, and 3 o'clock were collected from computed tomography (CT) scans. Patients with AR, defined as >/=5° of retroversion relative to normal values at the 1, 2, and 3 o'clock positions were identified. The sensitivity and specificity of each sign were calculated using CT scans to establish groups of focal and GAR. Continuous variables were compared using one-way analysis of variance and linear regression analyses. RESULTS: = .1008, P = .0003). Gender-based sensitivity and specific analyses show COS and PWS are most sensitive, and an isolated COS% greater than 30% is most specific at detecting GAR in male patients. A positive ISS was more prevalent among females, whereas a positive PWS was more prevalent among males. CONCLUSIONS: This retrospective review of patients with symptomatic FAIS and radiographic signs of FAI accurately detects GAR with high sensitivity and specificity without a CT scan. Crossover percentage was associated with the extent of AR and may be valuable as a predictive tool. This may help identify patients with more complex deformities that may benefit from CT imaging. LEVEL OF EVIDENCE: Level III, retrospective diagnostic case series.