Is acetabular osteoplasty always required in mixed impingement?

Abstract

Mixed femoroacetabular impingement (FAI) is typically managed with both femoral and acetabular rim osteoplasties, but it has not been reported if the rim osteoplasty is always required. We hypothesized that mixed FAI managed by femoral or combined femoral and acetabular osteoplasties will both attain satisfactory clinical results, provided intraoperative impingement-free functional motion is attained. We retrospectively reviewed 30 hips (23 patients, mean age at surgery 24.3 years, mean follow-up time 1.6 years) with mixed FAI who underwent surgical dislocation of the hip and had femoral osteochondroplasty with rim trim (RT, n = 21) or no rim trim (NRT, n = 9). Physical examination results and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) scores were evaluated. Mean (± SD) WOMAC pain scores improved from 6.56 (± 2.96) to 2.33 (± 3.64) in the NRT group (p = .002) and from 6.86 (± 4.15) to 3.86 (± 3.95) in the RT group (p = .014). Function improved in both groups, but the difference was significant only for the NRT group (p < .001). Over 50 % of patients in both groups had resolution of impingement sign. Internal rotation increased from 8.6° (± 11.8) to 20.0° (± 10.4) in the NRT group (p = .043) and from 4.0° (± 12.1) to 18.6° (± 14.0) in the RT group (p < .001). Both groups had increased flexion post-operatively to normal range, but the change was only significant for the RT group (p = .02). Both groups had insignificant decreases in external rotation. Satisfactory clinical outcomes were seen in hips with mixed impingement, regardless of whether RT was performed, provided impingement-free functional motion was attained and no severe cartilage damage was seen.