VARIABILITY OF FEMORAL AND ACETABULAR VERSION AMONG PATIENTS WITH SYMPTOMATIC HIP DISEASE AND CLINICAL IMPLICATIONS

Acetabular and femoral version are recognized as contributing factors to the development of hip pain in patients with femoroacetabular impingement (FAI) and hip dysplasia. This study aims to assess (1) the prevalence of version abnormalities among adults presenting with hip pain, and (2) the influence of version on presentation This is a prospective, cross-sectional study of 257 patients (282 symptomatic hips) who presented at a tertiary referral center for hip preservation surgery between 2018-2021 (mean age 33.2±9.1years, 66.3% females, mean BMI 27.2±14.3kg/m2). Of these, 71% underwent hip arthroscopy, 26% peri-acetabular osteotomy, 2% surgical hip dislocation, and 1% femoral derotation osteotomy. Patients underwent CT scans to measure the acetabular version (AV) and femoral version (FV), which was classified as “normal” between 10°-25°. KcKibbin index was calculated. Patient-reported measures were recorded using iHOT. Variability was defined as 2xSD. Mean AV was 18.2°±5.8° and mean FV 14.4°±10.6°. Although 74% of hips fell within “normal” range of AV, only 44% had ”normal” FV. Variability in version was double for femoral compared to acetabular (21.2° vs 11.6°;p<0.001). Patients with high FV presented younger (29.0±6.9y) compared to patients with “normal” (32.8±9.0y; p=0.027) or low FV (35.4±9.5y; p<0.001). Patients with combined low version presented much older in comparison to others (p=0.012). Mean preoperative iHOT was not different among version abnormality groups (p=0.945). Previously defined values of “normal” version may need to be revisited as significantly different variability exists between acetabulum and femur and thus boundaries of normality can not be the same. This is of interest, as addressing femoral rotation is receiving progressively more interest in hip assessment and pre-op planning for preservation and arthroplasty surgery. While patients with combined low version (impingement-pattern) present at an older age, patients with combined high version (instability-pattern) present younger, indicating that instability is more difficult to cope with than impingement.