EP3.37 Anatomical Location of Cam Morphology Does Not Influence Functional Outcomes or Hip Survivorship at 15-Year Follow-Up

Abstract Background Cam type morphology is an important driver of femoroacetabular impingement syndrome (FAIS), but the impact of lesion location is unclear. Therefore, this study evaluated the long term impact of cam lesion location on survivorship and functional outcomes after hip arthroscopy (HA). Methods A retrospective review was performed of a prospectively enrolled cohort of patients undergoing HA for FAIS (2007 to 2012) with mean 15 year follow up. Cam lesions were defined by preoperative alpha angle ≥60° and intraoperative findings. Lesion location was determined by the view demonstrating the greatest alpha angle: superolateral (AP), anterolateral (45° Dunn), and anterior (90° Dunn). Preoperative and 15 year patient reported outcomes (modified Harris Hip Score [mHHS] and Non Arthritic Hip Score [NAHS]), clinically meaningful thresholds (minimal clinically important difference [MCID], patient acceptable symptom state [PASS], and substantial clinical benefit [SCB]), radiographic parameters, and reoperation rates were compared. Results Sixty-one patients were included (36 superolateral, 15 anterolateral, 10 anterior). Baseline characteristics were similar, including age (36.5 ± 11.4 years), body mass index (BMI; 25.7 ± 4.0 kg/m2), sex (57.4% male), and laterality (52.5% right sided). The superolateral and anterior groups had greater preoperative alpha angles (70.1° and 68.8°, both p < 0.001) and significant postoperative reductions in alpha angle (Δ = -2.8° and -3.1°) and lateral center edge angle (Δ = -0.8° and -2.9°) (all p ≤ 0.025). All groups demonstrated improvements in mHHS (Δ = 33.7, 49.3, and 33.1) and NAHS (Δ = 37.3, 48.8, and 38.6) (all p ≤ 0.008), with the greatest mHHS improvement in the anterolateral group (p = 0.012). Rates of MCID (mHHS/NAHS: 93.4%/98.4%), PASS (75.4%/72.1%), SCB (65.6%/52.5%), and reoperation (11.5%) were similar across groups. Conclusion Anterolateral cam lesions demonstrated the greatest mHHS improvement at 15 years, while lesion location did not significantly influence long term functional outcomes, clinically meaningful thresholds, or survivorship following HA. These findings suggest that cam lesion location alone may not be a critical determinant of long term outcomes after hip arthroscopy for FAIS.