Abstract

Implant malposition and poor fixation are potential risks of compromising long-term results after total hip arthroplasty performed with a minimally invasive technique. Between September 2000 and February 2002, 120 cemented primary total hip arthroplasties were performed at the authors' institutions in patients with primary osteoarthritis of the hip and with BMI lower than 35. In 60 of these cases selected at random, a posterolateral incision no longer than 10 cm was used. The other 60 THA's were performed through a standard posterolateral approach. The inclination and anteversion of the cup and the position of the femoral stem were assessed on radiographs and statistically evaluated. In the miniinvasive group, the average inclination angle of the cup was 42.3 degrees (range: 36 to 52 degrees) and the anteversion angle 13.6 degrees (range: 6 to 29 degrees). The coronal alignment of the femoral component was within 3 degrees of neutral in 54 cases (90.0%). Following conventional implantation in the other group, the average cup inclination angle was 42.4 degrees (range: 35 to 50 degrees) and the anteversion angle 13.6 degrees (range: 8 to 24 degrees. A total of 53 stems (88.3 %) were implanted optimally. Statistical analysis found no significant difference between the two groups regarding components position. These findings suggest that using a smaller posterolateral incision as was done in this study does not introduce a potential risk of compromising long-term results.