[The impact of capsular repair on the dislocation rate after primary total hip arthroplasty: a retrospective analysis of 1972 cases].

BACKGROUND: Dislocation is the second most frequently encountered complication in primary total hip arthroplasty (THA) and occurs more commonly in the early postoperative rehabilitation phase. Sir Charnley recommended the "avoidance of resection of the capsule" and emphasised its contribution to hip joint stability in THA. Several authors, however, doubted its significance and considered resection of the capsule to be essential. Since 2002, some surgeons increasingly adopted a modified, less invasive technique of THA via Bauer approach, including the preservation and repair of the hip joint capsule with focus on maintaining its acetabular origin. Another group of surgeons applied the traditional technique including the resection of the joint capsule via an anterolateral approach. In this case-control study we investigated whether the dislocation rate can be reduced through joint capsule reconstruction and whether any negative impact on patient satisfaction, functional results or revision rate is observed.
MATERIAL AND METHODS: All cases of primary THA performed in our institution in a timeframe between 2002 and 2009 were included with the only exceptions of resurfacing arthroplasty, dual mobility and tumour hip replacements. Joint capsule repair cases were gathered in the study group (SG), capsule resection cases in the control group (CG). Additional patient-related data were taken from the anaesthesia records. The WOMAC score and a questionnaire focusing on detection of dislocations and revision surgeries was sent out for each case. Further targeted research was conducted that included requesting records and reports from external hospitals. In the case of non-responding patients, all available data (operating room documentation, electronic files, archive, X-rays) were reviewed for incidents of dislocation and revision surgery. Groupings and classifications were exclusively performed by senior surgeons. SG and CG were compared regarding epidemiologic, implant-associated and surgery-specific data. Statistical evaluations were performed using the Chi-squared test and the Mann-Whitney U test.
RESULTS: 1972 cases of primary THA were included: 992 in the SG and 980 in the CG. The follow-up rates were 92.7 % in the SG and 76.4 % in the CG, the mean follow-up times 33.5 months and 73.4 months, respectively, with a follow-up of at least 12 months in all cases. In the SG, the dislocation rate was 0.3 % (n = 3) and thus significantly lower than the 2.55 % in the CG (n = 25, p < 0.001). Both the WOMAC score (SG: 1.46 ± 1.73; CG: 1.53 ± 1.80; p > 0.05) and the revision rate (SG: 5.24 %; CG: 6.84 %; p = 0.139) showed no significant differences.
CONCLUSION: Preservation and repair of the hip joint capsule causes an 88-%-reduction of the dislocation rate in primary THA in this large series including 1972 cases, operated via the Bauer or the anterolateral approach. Several authors reported comparable results after THA using similar techniques of soft tissue and capsular repair through the posterior or posterolateral approach. Sparing and reconstructing the hip joint capsule therefore seems to reduce the dislocation rate after primary THA by one order of magnitude regardless of the surgical approach and, especially, if the acetabular origin is preserved. Capsule-related specific complications such as an increased revision rate, malfunction or pain were neither recorded in our study nor by others. Thus, careful preservation and reconstruction of the hip joint capsule may be expressly recommended in primary THA. Georg Thieme Verlag KG Stuttgart · New York.