Abstract
Objective: Surgical approaches utilized for minimally invasive surgery total hip arthroplasty (MIS-THA) can be classified broadly into two groups: the muscle-sparing approach and the muscle-dissection approach. Although the muscle-sparing approach is attractive because accelerated recovery has been reported, more precise evaluation must be conducted in terms of complications, safety, and accurate implant positioning. We previously used the direct lateral approach with muscle dissection (group D), but then we started using the muscle-sparing anterolateral approach (group A) in 2005. The objective of this study was to compare results in groups A and D.
Methods: MIS-THA has been performed on a total of 254 hips at our institute since 2006; 117 hips belonged to group D and 137 hips to group A. Anteversion of the femur was measured preoperatively using three-dimensional computed tomography templating software, and implant positioning was planned to be between 40° and 50°, defined by the amount of femoral anteversion and acetabular cup anteversion. We evaluated the accuracy of implant positioning as well as complications, such as fractures, dislocations, and others.
Results: The mean values of acetabular cup lateral inclination, acetabular cup anteversion, and femoral stem anteversion were 41.3°, 5.7°, and 27.1° for group D and 42°, 12.5°, and 29.3° for group A, respectively. After correction of data using the method reported by Matsubara, et al., total anteversion was 45.8° for group D and 55.4° for group A; both groups were implanted within the safe zone and no dislocation occurred. One case of intraoperative fracture in each group was experienced, but these could be handled with wire fixation.
Conclusion: We believe that the muscle-sparing approach is not problematic in terms of accuracy of implant positioning and safety. It should be considered as one of the alternative approaches for MIS-THA.
