The use of one compared with two distal screws in the treatment of femoral shaft fractures with interlocking intramedullary nailing. A clinical and biomechanical analysis.

The torsional and compressive biomechanical characteristics of a system for intramedullary fixation with a slotted locking nail and either one or two distal locking screws were evaluated in sixteen femora obtained from eight cadavera. No significant difference was found in the torsional rigidity or axial load to failure when one as opposed to two distal screws had been used. We also managed twenty-seven patients who had a fracture of the femoral shaft with interlocking fixation, using only a single distal screw for distal fixation. The average duration of follow-up was nine months (range, three to twenty-five months). The average time to radiographic healing was three months (range, two to six and one-half months). There were no non-unions or failures of the implant. Clinically unimportant migration of the distal screw occurred in five patients. We concluded that one distal screw provides adequate distal fixation of fractures of the femoral shaft treated with interlocking intramedullary nailing.