Restoration of femoral offset during hip replacement. A radiographic cadaver study.

Restoration of femoral offset is an important part of total hip arthroplasty. Since radiographs showing the femur at a sufficient degree of internal rotation to allow direct measurement of femoral offset are not usually available, templates of the prosthesis at 25 and 45 degrees of rotation were created. Radiographs of 20 cadaver femurs with a mean offset of 44 +/- 5 mm (r 36-56) were then obtained at different degrees of rotation. Simple guidelines to indicate the correct template for each projection of the femur were found. The system could be used to select a prosthesis with correct offset using radiographs obtained at angles of rotation between 20 degrees internally and 40 degrees externally.