Biomechanical determination of the optimal number of fixation screws for the sliding hip screw plate.

Laboratory measurement of the tensile forces on the plate fixation screws of the sliding hip nail demonstrated that most of the force is borne by the proximal three screws in an intertrochanteric fracture model. Testing of an intact femur, which simulate a healed femur, demonstrated a proximal shift of the screw forces. Four screws appear adequate for fixation if screw torque is controlled.