A New Radiographic Method of Measuring Femoral Offset. The Sundsvall Method

Restoring femoral offset (FO) is an important factor for the success of total hip arthroplasty (THA). However, earlier methods of measuring FO do not take in consideration the positioning of the acetabular component. In this study we introduce and evaluate a new radiological method of measuring FO as the horizontal distance between the femoral axis and the midline of the pelvis, at the height of the lateral tip of the greater trochanter.Ten patients operated with THA underwent a plain radiographic examination of the pelvis (AP view) and a CT scanogram for the pelvis and lower limbs (scout view). The radiological FO measurement using the new method was initially compared to FO measurement on CT scanogram and subsequently to the traditional radiological method of measuring FO. We tested the interobserver reliability and the intraobserver reproducibility of the new method.We found an excellent agreement between the new radiological method and the CT measurement and between the new radiological method and the traditional radiological method. We also found an excellent interobserver reliability and an intraobserver reproducibility of the new method. We believe the new method is easier than and as reliable as previously described methods.