Reliability of A Novel Arthroscopic Femoral Head and Neck Subchondral Bone Health Classification: Subchondral Porosity and Resilience Score (SPRS)

Abstract The field of hip arthroscopy has rapidly advanced, becoming a primary treatment for hip disorders like femoroacetabular impingement (FAI) and labral tears. While effective for addressing mechanical impingement, managing subchondral injuries remains challenging. The condition of subchondral bone, critical for joint stability and load distribution, is often overlooked, with no established classification system for assessing its health. This study aims to assess the interobserver and intraobserver reliability of a novel subchondral porosity and resilience score (SPRS) classification for evaluating subchondral femoral head and neck bone health. A prospective study was conducted on adult patients undergoing hip arthroscopy for FAI at a tertiary orthopedic center. A novel scale was developed to quantify SPRS observations of trabecular volume, porosity, and deformity and was employed to assess subchondral bone health after the removal of articular cartilage. Grading was performed by three fellowship-trained orthopedic surgeons based on arthroscopic images and intraoperative videos. Interobserver and intraobserver reliability were assessed using the intraclass correlation coefficient (ICC) and Fleiss’ kappa statistics. A total of 58 patients were evaluated. The overall interobserver agreement was high, with a percent agreement of 90.8% and an ICC of 0.92. Fleiss’ kappa value was 0.85, indicating substantial agreement among raters. Each individual SPRS grade showed substantial to perfect agreement, particularly Grade 4, which achieved a kappa value of 1.00. Kendall’s coefficient of concordance was 0.94, demonstrating high concordance among raters. The SPRS classification demonstrates strong interobserver and intraobserver reliability, suggesting its potential utility for assessing subchondral bone health during hip arthroscopy. A standardized grading system could enhance clinical decision-making and inform future research on the relationship between bone quality and patient outcomes.