The Result of Transmuscular versus Transosseous Repair of the Posterior Capsule on Early Dislocations in Primary Hip Arthroplasty

Purpose Dislocation is a concerning complication of the posterolateral approach for total hip arthroplasty (THA). Use of a larger size femoral head and a correct repair of the posterior structures can reduce the risk on dislocation of the hip prosthesis. In this study we investigated if there was a difference in dislocation rate between transmuscular and transosseous repair of the posterior soft tissues with use of 36 mm heads. Methods A power analysis showed that with a standardised effect size of 0.3 and p-value of 0.05, each group should include at least 174 patients. A total of 465 consecutive primary THAs with a posterolateral approach were performed in patients with primary osteoarthritis by 3 orthopaedic surgeons. There were 246 patients operated using transmuscular repair, the other 219 by using transosseous repair. All patients were given the same prostheses. Results Dislocation rate was 1.7% in all patients with at least 1 year follow-up. No significant difference was found in dislocation between both reconstruction techniques. Clinical outcome scores were comparable between the groups. Conclusions Transosseous and transmuscular repair were equally effective techniques in closing the posterior soft tissues after THA through the posterolateral approach, without difference in dislocation rate or complication rate.