Outcomes of revision from hip resurfacing to total hip arthroplasty: a matched comparative study with primary total hip arthroplasty at seven and a half years follow-up.

BACKGROUND: Hip resurfacing arthroplasty(HRA) is an attractive alternative to total hip arthroplasty(THA) for different reasons: femoral bone stock preservation, large femoral head reducing the risk of dislocation, restoration of physiological hip biomechanics and absence of thigh pain. There is a paucity of data about evolution after revision of HRA to THA(RTH). The aim of this study was to evaluate the functional outcomes after RTH and compare them with matched patients undergoing primary THA on hip osteoarthritis. METHODS: A retrospective case-control study was conducted including patients who underwent revision from HRA to THA with a minimum follow-up of three years. Among 5268 HRAs performed by a single surgeon, 22 required revision(0.42%). After exclusions and loss to follow-up, 18 patients were included. Each patient was matched with a control undergoing primary THA according to age(± 5 years) and preoperative Oxford Hip Score(OHS, ± 2 points). Functional outcomes were assessed using the OHS, Merle d'Aubigné-Postel score(MDP), UCLA activity scale, and Joint Forgotten Score(JFS-12). Perioperative data, complications, and implant survival were also analyzed. RESULTS: The indications for revision were aseptic femoral loosening(54.5%), infection(18.1%), groin pain(13.6%), aseptic acetabular loosening(4.6%), aseptic bipolar loosening(4.6%) and periprosthetic acetabular fracture(4.6%). At a mean follow-up of 7.5 years for the RTH group and 6.1 years for the THA group, no significant differences were observed between groups in OHS (14 vs 13; p = 0.5), UCLA score (7.3 vs 6.6; p = 0.06), or JFS-12 (85 vs 92; p = 0.06). Surgical time and blood loss were significantly greater in the revision group(74 vs 33 min, p < 0.001; 374 vs 205 mL, p = 0.003). Patient satisfaction based on the PASS threshold was high in both groups(94% vs 100%, p = 0.233). Kaplan-Meier survivorship of RTH was 93% at ten years. CONCLUSION: Revision of HRA to THA provides satisfactory functional outcomes and high patient satisfaction, comparable to primary THA when matched for age and preoperative function.