Mechanics of the treatment of hip injuries.

When treated operatively, mechanical problems associated with intertrochanteric hip fracture include malunion and nonunion. Their frequency and severity are directly related to the mechanical effectiveness of internal fixation, which is determined by 5 independent variables: bone quality, fragment geometry, reduction, implant, and implant placement. While all 5 variables are of importance, bone quality and fragment geometry are the product of the patient and the trauma and cannot be significantly modified by the treating surgeon. Reduction, implant placement, and implant selection are the variables which the surgeon can manipulate. While all 3 are important, implant selection and implant placement are of relatively greater importance than reduction. Implant placement in the biomechanically ideal position for the individual patient is probably the single most important of the 5 variables.