ANATOMICAL REDUCTION IS NOT NECESSARY IN TREATING NON-POROTIC UNSTABLE INTERTROCHANTERIC FRACTURE ― A BIOMECHANICAL STUDY OF PORCINE MODEL

摘要

Intertrochanteric fracture occurred more than 200,000 cases each year in the United States, with mortality rate up to 20 percents. Evans classified the intertrochanteric fracture pattern to stable and unstable group. Most of the complications occurred in the unstable group. It is speculated that in the unstable intertrochanteric fracture, the lag screw migrates easily into the porotic femur head and than causing fixation failure. So the treatment of porotic unstable femoral intertrochanteric fracture depends on the bone quality, severity of comminution, anatomical reduction and methods of fixation. An abundant of studies had been focused on how to reinforce the porotic unstable intertrochanteric fracture including osteotomies, cement augmentation, anatomical reduction, and different implant applications. Among the many techniques, the anatomical reduction using cerclage wiring was widely used to enhance the stability of osteoporotic fractured femur. However, in the young adult, the application of cerclage wiring is controversial. The current study compares the mechanical properties of two anatomical reduction techniques of unstable intertrochanteric fracture reconstructed by a compression hip screw. Four porcine femurs of 10 months-old were used to simulate the non-porotic human bone. The specimens were stripped of all soft tissues. Each femur was prepared with four holes for dynamic hip screws following the standard surgical procedure. The anatomical reduction was achieved by a cerclage wiring and without cerclage wiring. The results reveal that in the non-porotic porcine model, there is no statistically difference in stiffness, plate strain and medial bone strain per load. No matter the unstable intertrochanteric fracture is reduced with cerclage wire or not. The non-porotic unstable intertrochanteric fracture anatomical reduction is not necessary if protective weight bearing is obeyed. However, whether the cerclage wiring is necessary or not for the osteoporotic unstable femur fracture needs further study.