Dislocation of primary total hip arthroplasty and the risk of redislocation.

6554 primary total hip arthroplasties were reviewed. Risk factors for dislocation were analysed to assess which were important in terms of predicting recurrent instability. The patients risk of having a second dislocation was independently associated with the surgical approach adopted (p = 0.03) and the time to first dislocation from the primary hip replacement (p = 0.002). Early dislocators whose surgery was performed through an anterolateral approach had less recurrence than late dislocators through a posterior or transtrochanteric approach. None of the other risk factors including head size (p = 0.59), modularity (p = 0.54), mechanism of dislocation (p = 0.23), leg length discrepancy (p = 0.69) and acetabular inclination (p = 0.31) were influential. The use of an abduction brace was not useful in preventing a further dislocation with 69.2% of those braced re-dislocating compared to 68.5% who were not braced (p = 0.96).