Lesser Trochanter Size on Plain Anteroposterior Radiographs Correlates With Native Femoral Anteversion.

Background: Assessing femoral version in orthopedic surgery is important for preoperative planning of total hip arthroplasty, especially for recognizing excessive anteversion or retroversion. The present study addressed the following: (1) Is the position of the lesser trochanter correlated to the femoral neck axis? (2) If so, may femoral version be assessed by means of plain pelvic radiographs?

Methods: Three-dimensional computed tomography scans of 60 patients undergoing minimally invasive cement-free total hip arthroplasty were retrospectively analyzed, particularly with regard to the relation between the femoral neck axis and the lesser trochanter, the femoral version, and the size of the projected lesser trochanter in different rotational positions. Based on linear regression, a biomathematical formula was developed to assess femoral anteversion on plain radiographs depending on the visible part of the lesser trochanter.