Review Question - QID 3692

The strongest portion of the femoral neck is the posterior inferior neck in the region of the femoral calcar. The optimal biomechanical configuration includes an inverted triangle pattern with the single screw in the inferior aspect of the femoral neck adjacent to the calcar.

Booth et al performed a cadaveric study comparing central versus calcar (cortical-adjacent) fixation. The results demonstrated significant improved stability, load, stiffness, and displacement in all tested parameters for the group with calcar-adjacent screw fixation.

Lindequist and Törnkvist performed a Level 4 study of 72 femoral neck fractures. They found that all 5 of their nonunions had screws placed greater than 3mm from the femoral calcar. Additionally, 16 of 18 fractures healed in the group of displaced fractures where both the fixating screws were placed within 3 mm from the femoral neck cortex.

Gurusamy et al performed a Level 4 study of 395 patients undergoing femoral neck fixation. They found a reduced spread of the screws on the lateral view was associated with an increased risk of nonunion of the fracture.

Illustration A depicts the optimal configuration of an inverted triangle with the single screw being inferior and all of the screws being cortical adjacent.