Biomechanics of the Injured Fibula Following Plate Fixation of a Concomitant Tibia Fracture To Fix or Not to Fix?

The mechanical role of supplemental fibula fixation in both bone lower leg fractures is not well defined. The benefit of fibula plate fixation in this context is controversial. The purpose of this study was to ascertain the mechanical contributions of the fibula under three conditions (intact, fractured, or plated fibula) following standard tibia locked plating.A laboratory fracture model was created with 10 cadaveric legs (5 matched pairs) with no known history of lower extremity trauma or other musculoskeletal conditions. A both bone lower leg fracture was simulated by performing distal osteotomies, 3 to 5 cm above the tibia plafond, leaving a bony defect to simulate an unstable fracture (AOTrauma OTA classification 43-A3). Coronal and sagittal gauge-pins were placed above and below the fracture sites to measure relative displacement across three planes of motion. Axial and torsional loads were applied to the leg under the following conditions: tibia intact and fibula intact (control 1), tibia fracture and fibula intact, tibia fracture and fibula fracture (control 2), and the three conditions of primary interest: tibia plated and fibula intact, tibia plated and fibula fracture (osteotomy), and tibia plated and fibula plated. The load applied for level 1 was 75 N of axial compression and 0.3 Nm of torque, and the load for level 2 was 175 N of axial compression and 1.3 Nm of torque.There were significant differences in motion across the fracture site of the injured leg when the tibia was not plated compared with an intact and plated tibia, p < 0.05. However, when the tibia was plated, there were no significant differences in fracture motion when the fibula was left either intact, osteotomized, or underwent supplemental plate fixation, p > 0.05. This was true regardless of the loads applied.The mechanical stability of supplemental fibula fixation in a both bone lower leg fracture model was not significantly improved from standalone distal tibia fixation in this laboratory model. The clinical effects of these findings are yet to be demonstrated.