THE RELATIONSHIP OF ACETABULAR AND FEMORAL VERSION IN PATIENTS UNDERGOING PERIACETABULAR OSTEOTOMY

Abstract

Background: Hip dysplasia is a complex, three dimensional diagnosis. Little is known about version (acetabular, femoral and the relationship between the two) in dysplastic patients. We sought to 1) compare femoral and acetabular version between hips that underwent a primary periacetabular osteotomy (PAO) versus nondysplastic hips (CEA >25degrees); 2) estimate the correlation between femoral and acetabular version in dysplastic hips; 3) estimate the correlation of femoral and acetabular version with preoperative range of motion in dysplastic hips; 4) estimate the association of femoral and acetabular version with patient-reported outcome measures 11-23 months postoperatively in patients that underwent PAO. We hypothesized an association between acetabular and femoral version, and an association between version and patient reported outcomes. Methods: We retrospectively reviewed our institution’s hip registry to identify all PAO patients from March 2010 and June 2016. We included patients who had pre-operative computed tomography (CT) imaging and a minimum of 1 year follow-up. We created a comparison group of non-dysplastic patients (CEA > 25degrees). We calculated the association between acetabular version, femoral version and hip range of motion (ROM), as well as between femoral version, acetabular version, age, sex, and preoperative and 1 year postoperative modified Harris Hip Score (mHHS), Hip Outcome Score (HOS), and International Hip Outcome Tool 33 (iHOT33) score. Results: 75 PAO patients met inclusion criteria (93% female, mean age 24) and 1332 non-dysplastic patients (45% female, mean age 25). Pre-operative CT measurements (95% CI) demonstrated mean CEA for our PAO patients was 24, and for the non-dysplastic group 37. We found a very weak correlation between acetabular version and femoral version. Dysplastic patients had significantly greater acetabular and femoral version than nondysplastic patients (8 vs 1 at 1 o’clock; 15 vs 10 at 2 o’clock; 21 vs 16 at 3 o’clock, FV 21 vs 14, all p<0.001). We found only a weak correlation of hip ROM to acetabular version, but there was a moderate correlation of hip ROM and femoral version. We found no evidence of an association between mHHS, HOS-activities of daily living (ADL), HOS-sport specific (SS), or iHOT-33 scores and pre-operative femoral version, acetabular version, age, or sex. Conclusions/Significance: Our current investigation confirmed a statistically higher acetabular and femoral version in dysplastic hips than nondysplastic hips. However, while acetabular version measurements correlated strongly, there was only a very weak correlation between acetabular version and femoral version. Pre-operative ROM was correlated only moderately with femoral version, but not correlated with acetabular version. Additionally there was no association with acetabular or femoral version and patient reported outcomes after PAO, suggesting that femoral version does not need to be addressed at the time of PAO surgery.