CEMENT AUGMENTATION OF INTERTROCHANTERIC FRACTURE FIXATION - A CADAVER COMPARISON OF 2 TECHNIQUES

We evaluated 2 techniques of cement augmentation to enhance fixation o f intertrochanteric hip fractures. 4 fixation groups with 6 cadaver fe murs in each group were compared: stainless steel lag screw and side p late with and without cement augmentation and a titanium alloy expanda ble dome plunger and side plate with and without cement augmentation. Gauges were used to establish the mechanical behavior of intact and th en fractured femurs to simple uniaxial loads. Subsequent loading to fa ilure allowed determination of maximum fixation strengths and modes of failure. Cement augmentation of each device increased its load to fai lure. There was no significant difference between the cemented lag scr ew and the uncemented dome plunger groups with average loads to failur e of 4.0 x 10(3) N. The greatest average load to failure was in the ce mented dome plunger group (5.6 x 10(3) N) with the lowest in the uncem ented sliding hip screw group (3.6 x 10(3) N). Device cut-out as a cau se of failure occurred mostly in the uncemented lag screw group. Slidi ng was enhanced by those methods that increased the fixation surface a rea within the femoral head, unless cement encroached in the region of the barrel-screw junction. Strain analysis showed that the dome plung er unloaded the bone at the calcar, regardless of cement augmentation, while the sliding hip screw allowed for compressive stresses in this area. Proper cement augmentation increases load to failure and minimiz es nail cut-out for both devices studied. However, the dome plunger, a device with a large fixation area in the femoral head, was equally ef fective and eliminated potential cement encroachment. failure of inter trochanteric fracture fixation in osteoporotic bone may be minimized b y an appropriate choice of device or cement augmentation.