PROPHYLACTIC CERCLAGE - A METHOD OF PREVENTING FEMUR FRACTURE IN UNCEMENTED TOTAL HIP-ARTHROPLASTY

The incidence of femur fracture in noncemented hip arthroplasty has been reported to be between 4.1 % and 27.8 %. To quantitate the hoop stress generated during insertion of a femoral broach in total hip arthroplasty and determine the effect of cerclage with both braided cable and wire, we harvested 14 pairs of embalmed cadaver femurs. These were reamed and broached to duplicate the surgical technique of inserting a straight non-cemented femoral component. Group one consisted of eight matched cadaver femurs which were tested using a single 2.0 mm chrome-cobalt cable placed around the calcar of one femur, with the other serving as a control. Group two consisted of five matched cadaver femurs which were tested using a single 18 gauge cerclage wire in the same manner. In group one, the femurs serving as controls were found to have a mean microstrain of (1425.00 +/- 1180.19). The eight femurs tested with a 2 mm cable were determined to have a mean microstrain of (4179 +/- 2853.89). In group two, the femurs serving as controls were found to have a mean microstrain of (962.60 +/- 956.78). The five femurs in group two tested with a cerclage wire were determined to have a mean microstrain of (1112.00 +/- 975.66). Using a paired t-test, statistical significance was achieved with a confidence level of P less-than-or-equal-to .01 in group one. Prophylactic wiring of the proximal femur with 2 mm cable increases the hoop stress resistance and, therefore, should decrease the incidence of intraoperative femur fractures in uncemented total hip arthroplasty.