FP15.2 Is the alpha angle a surgical decision-making threshold? A radiographic–arthroscopic correlation study demonstrating superior predictive value over anterior offset ratio in femoroacetabular impingement

Abstract

Abstract ICLB15 - The Preservation Scorecard: Fundamentals of Tracking Outcomes and Standardizing Recovery, Session Room 12 (BMCC Level 3), October 9, 2026, 14:00 - 16:00 Background Cam morphology plays a central role in the pathomechanics of femoroacetabular impingement (FAI) and the development of chondral damage. However, defining a clinically meaningful radiographic threshold that predicts intra-articular cartilage injury remains a major challenge in hip preservation surgery. Purpose To determine whether the alpha angle can serve as a clinically relevant threshold for predicting chondral lesion severity, and to compare its predictive performance with the anterior offset ratio (AOR). Methods A cross-sectional study including 115 consecutive patients undergoing hip arthroscopy for symptomatic FAI after failed conservative treatment. Preoperative radiographs (Dunn 45° view) were used to measure alpha angle and AOR. Chondral lesions were graded intraoperatively using the Beck classification. Correlation analysis and comparative predictive assessment between parameters were performed. Results The mean alpha angle was 68.2° (SD 9.7°), and the mean AOR was 0.14 (SD 0.02). A strong positive association was identified between increasing alpha angle and higher-grade chondral lesions, whereas AOR demonstrated a weaker inverse relationship. Importantly, alpha angles exceeding 66° were consistently associated with advanced cartilage damage. Compared to AOR, the alpha angle showed superior discriminatory capacity in identifying clinically relevant chondral injury. Conclusion The alpha angle is not only associated with chondral damage but may represent a clinically actionable threshold in FAI. Values above 66° identify patients at higher risk of advanced cartilage injury and may support earlier surgical intervention. In contrast, AOR appears to have limited predictive utility. Take-Home Message: The alpha angle should be considered a key decision-making parameter in hip preservation surgery, with potential to refine patient selection and optimize timing of intervention. Keywords Femoroacetabular impingement; Alpha angle; Chondral damage; Hip arthroscopy; Surgical indication