Dislocation and its recurrence after revision total hip arthroplasty.

Purpose: Dislocation is a leading cause of failure after revision total hip arthroplasty (THA). This study was conducted to examine the risk factors for dislocation as well as their recurrence after revision THA.
Methods: We retrospectively reviewed 178 revision THAs in 162 patients between 1998 and 2013. The mean patient age was 65.2 years at operation and the mean follow-up period was 6.7 years. Multivariate logistic regression was performed to identify risk factors for dislocation, and further comparison was made between patients with single and recurrent dislocations.
Results: Sixteen hips in 15 patients (9.0 %) dislocated at a mean of 9.1 months (range, 0-83 months) after revision THA. Multivariate analysis identified advanced age (odds ratio [OR] = 2.94/10 years) and osteonecrosis of the femoral head (OR = 7.71) as the independent risk factors for any dislocations. Risk factors for recurrent dislocations, which were observed in eight hips (50 %), were later dislocations (≥4 months) and lower BMI.
Conclusion: Dislocation is a serious problem after revision THA with multiple risk factors. Although our findings were limited to revision THAs done through posterolateral approach, recognition of these factors is helpful in patient education and surgical planning.