Is operative revision associated with favourable clinical outcomes in arthrofibrosis following total hip arthroplasty (THA)? A retrospective, single-centre data analysis of forty two cases.

Purpose: There is a paucity of clinical studies examining outcomes following surgical revision in cases of histologically confirmed arthrofibrosis after total hip arthroplasty (THA). Consequently, the aim of this study is to present the clinical outcomes and to identify risk factors for poor clinical and functional outcome following surgical intervention for histologically confirmed arthrofibrosis following THA.

Methods: This study included 51 patients (51 hips) with histologically confirmed arthrofibrosis of the hip based on the synovial-like interface membrane (SLIM) criteria. These were selected from 7983 revision THA cases performed during the study period After exclusion criteria were applied, 42 cases (59.5% women) with an average age of 63.6 years were included. The mean duration of follow up was 70 months (range 30-122 months). Of these, 73.8% underwent index surgery after primary THA implantation. The primary indication for revision surgery was predominantly the clinical suspicion of arthrofibrosis (n = 35). The Harris Hip Score (HHS) and the EQ-5D-3 L scores were calculated for all cases at the time of follow-up. For the risk analysis of a poor clinical outcome, two groups were divided according to the Harris Hip Score. The group with a poor clinical outcome was defined as a HHS < 55.

Results: Open arthrolysis was performed in all cases with a modular component being replaced in 73.8% of cases (n = 31) and only two cases requiring additional revision of the femoral and acetabular components due to aseptic loosening.The mean pre op Harris Hip Score (HHS) was 53.2 before revision surgery. This increased to 65.7 post op (p < 0.001). Only 34.1% of patients achieved the minimum clinical significance difference (MCID) of 18 HHS points after surgical revision. The EQ-5D Visual Analogue Scale (VAS) score and the Time Trade-Off (TTO) score averaged 0.226 (SD 0.245) and 0.221 (SD 0.37). Complications occurred in seven cases (16.7%,), with dislocation in 2 cases and persistent AF symptoms in 3 cases. Six cases required further revision surgery (14.3%). In three cases, a further open arthrolysis was performed due to persistent symptoms. Increased BMI (30.1 vs. 26.7 BMI, p < 0.05) or higher body weight (88.4 kg vs. 78.7 kg, p = 0.086), smoking and a lower preoperative HHS (p = 0.022) were identified as risk factors for a poor clinical outcome, defined as HHS < 55.

Conclusion: Results of this study suggest that mid-term clinical results following surgical intervention for arthrofibrosis following THA show a moderate to poor postoperative outcome with an acceptable complication rate. Risk factors for a poor outcome such as increased weight, BMI or smoking should be considered and critically assessed preoperatively.