OBJECTIVES

To compare the biomechanical failure properties of the fibular intramedullary nail with locking plate and lag screw fixation in the management of unstable elderly distal fibular fractures.

METHODS

Twelve fresh-frozen cadaveric lower limbs (6 matched-pairs) were studied. A simulated OTA/AO 44-B fracture was created, then randomly allocated within each pair to intramedullary nail or locking plate fixation supplemented with an interfragmentary lag screw. The limbs were secured with the foot rigidly held in 20 degrees of supination, loaded to 700N and subjected to progressive external rotation until failure.

RESULTS

The mean specimen age was 86.5 years (61-97). Mean torque to failure was greater in the intramedullary nail group, but did not reach statistical significance (23.5 N·m vs. 21.6 N·m; P = 0.463). The nail failed at a significantly greater angle of rotation compared with plate fixation (66.5 degrees vs. 53.3 degrees; P = 0.046). There was no significant difference between the groups with respect to construct stiffness (P = 0.673) or energy absorbed (P = 0.075). The locking plate specimens failed through plate and screw construct pull off at the implant-bone interface. In contrast, the intramedullary nail specimens failed at the lateral ligament complex, whereas the fracture-implant construct remained intact.

CONCLUSION

Intramedullary nailing and locking plate fixation have similar biomechanical characteristics when tested to failure. The benefits of the minimally invasive surgery offered by the intramedullary nail make it an attractive implant in the management of these patients.