Background: The effect of an intact fibula on rotational stability after a distal tibial fracture has, to the best of our knowledge, not been clearly defined. We designed a cadaver study to clarify our clinical impression that fixation of the fibula with a plate increases rotational stability of distal tibial fractures fixed with a Russell-Taylor intramedullary nail.

Methods: Seven matched pairs of embalmed human cadaveric legs and sixteen fresh-frozen human cadaveric legs, including one matched pair, were tested. To simulate fractures, 5-mm transverse segmental defects were created at the same level in the tibia and fibula, 7 cm proximal to the ankle joint in each bone. The tibia was stabilized with a 9-mm Russell-Taylor intramedullary nail that was statically locked with two proximal and two distal screws. Each specimen was tested without fibular fixation as well as with fibular fixation with a six-hole semitubular plate. A biaxial mechanical testing machine was used in torque control mode with an initial axial load of 53 to 71 N applied to the tibial condyle. Angular displacement was measured in 0.56-N-m torque increments to a maximal torque of 4.52 N-m (40 in-lb).

Results: Initially, significantly less displacement (p = 0.05) was produced in the specimens with fibular plate fixation than in those without fibular plate fixation. The difference in angular displacement between the specimens treated with and without plate fixation was established at the first torque data point measured but did not increase as the torque was increased. No significant difference in the rotational stiffness was found between the specimens treated with and without plate fixation after measurement of the second torque data point (between 1.68 and 4.48 N-m).

Conclusions: Fibular plate fixation increased the initial rotational stability after distal tibial fracture compared with that provided by tibial intramedullary nailing alone. However, there was no difference in rotational structural stiffness between the specimens treated with and without plate fixation as applied torque was increased.

Clinical Relevance: In patients with ipsilateral distal tibial and fibular fractures who are treated with Russell-Taylor intramedullary nailing of the tibia, rotational stability of the tibial fracture can be increased by plate-and-screw fixation of the fibula, which may reduce the risk of valgus malunion.