Purpose: We wanted to evaluate the risk factors that predispose a patient to dislocation after undergoing primary total hip arthroplasty with the transtrochanteric approach.
Materials and Methods: Between July 1995 and May 2007, 593 consecutive total hip arthroplasties using the trantrochanteric approach were performed. A matched comparative study was performed for the dislocated group(18 hips) and the non-dislocated control group(18 hips). The patient-related factors and mechanical factors were retrospectively reviewed to evaluate the risk factors for dislocation.
Results: Dislocation occurred in 18 hips(3.04%). The mean age was 57.1 years in the dislocated group and 55.2 years for all of the patients (p>0.05). Statistical analyses of the BMI, inclination and anteversion of the cup, lowering of the hip center, a leg length discrepancy, the size of the femoral head and nonunion of the greater trochanter revealed no significant differences between the two groups. Nonunion of the greater trochanter was observed in 16 hips(2.84%). The risk of dislocation was 8.5 times higher in the patients with excessive alcohol intake (p<0.05). The combination of more than 3 risk factors significantly affected the incidence of dislocation after total hip arthroplasty (p<0.05).
Conclusion: After primary total hip arthroplasty with the transtrochanteric approach, in the cohort of this study, excessive alcohol intake was the main risk factor for dislocation and a combination of risk factors contributed to dislocation.

Keywords: Hip dislocation, Total hip arthroplasty, Risk factor, Transtrochanteric approach