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.