Cement augmentation of intertrochanteric fracture fixation: a cadaver comparison of 2 techniques

We evaluated 2 techniques of cement augmentation to enhance fixation of intertrochanteric hip fractures. 4 fixation groups with 6 cadaver femurs in each group were compared: stainless steel lag screw and side plate with and without cement augmentation and a titanium alloy expandable dome plunger and side plate with and without cement augmentation. Gauges were used to establish the mechanical behavior of intact and then fractured femurs to simple uniaxial loads. Subsequent loading to failure allowed determination of maximum fixation strengths and modes of failure. Cement augmentation of each device increased its load to failure. There was no significant difference between the cemented lag screw and the uncemented dome plunger groups with average loads to failure of 4.0 x 10(3) N. The greatest average load to failure was in the cemented dome plunger group (5.6 x 10(3) N) with the lowest in the uncemented sliding hip screw group (3.6 x 10(3) N). Device cut-out as a cause of failure occurred mostly in the uncemented lag screw group. Sliding was enhanced by those methods that increased the fixation surface area within the femoral head, unless cement encroached in the region of the barrel-screw junction. Strain analysis showed that the dome plunger 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 minimizes nail cut-out for both devices studied. However, the dome plunger, a device with a large fixation area in the femoral head, was equally effective and eliminated potential cement encroachment. Failure of intertrochanteric fracture fixation in osteoporotic bone may be minimized by an appropriate choice of device or cement augmentation.