Review of methods to quantify lag screw placement in hip fracture fixation.

This review considers methods used to quantify lag screw placement within the femoral head following proximal femoral fracture. Implants used for fixation of femoral neck fractures can lead to unwanted outcomes in some patients. Cutting out of the screw within the femoral head has been shown to be the commonest cause of failure and is related to lag screw placement within the femur. Until now, there have been two methods published which quantify lag screw position within the femoral head. These are the concepts of 'Tip Apex Distance' and Parker's ratio method of lag screw placement. We shall discuss each one in turn and their implications in terms of fracture fixation failure.