The protective effect of locking screw placement on nonlocking screw extraction torque in an osteoporotic supracondylar femur fracture model.

Objective: To examine the impact of number and position of locking screws in the diaphyseal portion of an osteoporotic distal femoral fracture model with hybrid fixation.

Methods: Four groups containing 5 osteoporotic bone models were used with varying combinations of diaphyseal screw fixation: 4 nonlocking screws (control); 1 locking screw adjacent to the osteotomy and 3 nonlocking screws; 1 locking screw in the most proximal screw hole of the plate and 3 nonlocking screws; and 2 locking screws at opposite ends of the diaphyseal fixation with 2 nonlocking screws in between. Fixation in the distal articular segment was identical in all constructs.