Displacement of the common peroneal nerve associated with upper tibial fracture: implications for fine wire fixation.

The constant anatomic position of the common peroneal nerve is relied on when performing fine wire external fixation in the upper tibia. We report the case of a sixty-two-year-old woman with a Schatzker Type V fracture of her right tibial plateau and upper-third diaphyseal fracture associated with displacement and shortening of the upper tibia. She was treated by minimal internal fixation of the intraarticular fracture and application of a Sheffield Hybrid External Fixator. During percutaneous insertion of the reference wire in the fibular head, a distal muscle twitch alerted the surgeon, and the common peroneal nerve was duly explored and found displaced forward over the fibular head, dangerously close to the wire. It is postulated that at the time of injury, the common peroneal nerve was displaced anteriorly and that despite reduction of the tibial fractures, it had failed to return to its original position. The mechanism of this was confirmed by an anatomic study on an above-the-knee amputation specimen in which the metaphyseal-diaphyseal element of the fracture was reproduced. We recommend insertion of the reference fibular wire with the knee in flexion. Open insertion of this wire, with an incision down to bone and exposure of the fibular head, is recommended in cases in which severe trauma with shortening of the upper tibia, with possible disruption of the tibiofibular joint, puts the nerve in danger of injury.