Die Rundosteotomietechnik für die intertrochantäre Varisierung -Eine experimentelle und computergestützte Analyse

Purpose: In conventional intertrochanteric varus osteotomy, shortening of the leg and insufficiency of the abductor muscles occur frequently. To avoid these disadvantages, a curved osteotomy is presented. Method: 189 intertrochanteric barrel vault and wedge osteotomies were compared. By means of digitised preoperative radiographs the varus osteotomies were planned with a computer program optimising postoperative leg length, bone contact area at the osteotomy site, femoral offset, and abductor muscle length. Results: The average leg shortening was 3.9 mm (range: 0-5 mm) for barrel vault osteotomy and 13.6 mm (range: 8-22.2 mm) for the wedge technique. After correction the mean contact area at the osteotomy sites was 1731.6 mm 2 (range: 1087.8-2341.8 mm 2 ) in the barrel vault technique compared with 783.7 mm 2 (range: 563.7-1249.6 mm 2 ) in the wedge procedure (p<0.001, t-test). Adequate femoral offset was achieved in both types of osteotomy. In all curved osteotomies the length of the abductor muscles remained nearly constant in contrast to the wedge procedure. Additional comparative experimental barrel vault osteotomies in 22 human autopsy femora with a high-speed dissecting tool and round jigs revealed a precise application of the preoperative planning. Conclusion: The intertrochanteric curved osteotomy provides minimum leg shortening and increased bone contact area. It can prevent an insufficiency of the abductor muscles, because shortening is minimized.