Evaluation of Total Hip Prosthesis Planning Using a Method with CT Images at 115% in Approximately 52 Cases

Abstract

Introduction : The planning of a total hip prosthesis (THP) is an important step conditioning the success of the intervention itself. Since Müller’s description, every school, every surgeon, or every hospital tries to adapt the basic principles to their own method and work context. This study aims to evaluate a THP planning method using scanning at 115% magnification. Methodology : Fifty-two first-line PTHs were planned by CT scan at 115% magnification, in 52 patients admitted consecutively to the hospital center of Carcassonne, and were evaluated in order to measure the reproducibility of the method. The size of the implants, the length inequality of the limbs, and the femoral offset calculated pre- and post-operatively were compared. Results: The planning of the femoral stem was consistent with the final implant in 69.2% of cases, while that of the cotyloid cup was consistent in 82.7% of cases. Generally speaking, we had about 70% compliance. 94.4% (49) of our patients had postoperative limb length equalization to within 5 mm. The average improvement in terms of length inequality was 1.4 mm. The postoperative femoral mean offset was compatible with normal life. Discussion : This method, which is closer to 3D planning methods, seems reproducible for implant size. It seems more precise for the size of the acetabulum without being less precise than other methods regarding the size of the femoral stem and the correction of inequalities in limb length.