Paper 47: Clinical Outcomes in Patients with Femoral Acetabular Impingement Syndrome and Acetabular Retroversion: A 3D Analysis

OBJECTIVES: To use computed tomography (CT)-based three-dimensional (3D) bone models to (1) quantify acetabular version in patients with femoroacetabular impingement syndrome (FAIS) and (2) explore the relationship between the magnitude of acetabular version and clinical outcomes following hip arthroscopy. METHODS: Preoperative CT scans were acquired in 105 consecutive patients prior to hip arthroscopy for FAIS, of which 84 (80.0%) completed minimum two-year patient reported outcomes. 3D models of the pelvis and femur were generated by semi-automated segmentation, and aligned to a standard coordinate system. Acetabular version was quantified at the 12, 2, and 3 o’clock position. (Figure I) Acetabular version classifications were based on the version at the 3 o’clock position, and were defined as follows: acetabular retroversion (AR [<15°]), normal acetabular version (NV [15°-25°]), and acetabular anteversion (AA [>25°]). Patient demographic characteristics and clinical outcomes including the Hip Outcome Score – Activities of Daily Living (HOS-ADL), Hip Outcome Score – Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), international Hip Outcome Tool (iHOT-12), and Visual Analog Scale (VAS) for pain and satisfaction were analyzed. RESULTS: Mean age and body mass index (BMI) of patients was 33.9±12.6 years and 26.0±5.4 kg/m(2), respectively, while 70.2% were female. The average acetabular version at 12, 2, and 3 o’clock for the study cohort was 9.3° ± 9.3°, 12.3° ± 7.4°, and 20.9° ± 5.7°, respectively (Figure II). After stratification based on the magnitude of acetabular anteversion at the 3 o’clock position, the number of patients and the average torsion within each group were as follows: AR (n=12; 11.3°±2.7°), NT (n=56; 20.7°±2.9°), AA (n=16; 28.5°±2.7°) (Figure III). At minimum two-year follow-up, significant between group differences in mHHS, iHOT-12, VAS for pain and satisfaction (P < 0.05) were appreciated (Table I). Post hoc analysis with Bonferroni correction (P < 0.0167) found lower scores on mHHS, iHOT-12, VAS for pain and satisfaction in patients with AR compared to NV (Table I). Lower VAS for satisfaction scores were reported in patients with AR when compared to AA (P = 0.006), but not mHHS (0.023), iHOT-12 (0.032), or VAS for pain (0.072) (Table I). CONCLUSIONS: Patients with AR reported inferior outcomes when compared to patients with NV and AA following hip arthroscopy for FAIS.