Trimalleolar Ankle Fracture: Screws Only for Posterior Malleolus

Figure 6.1

AP radiograph shows a trimalleolar ankle fracture

Figure 6.2

Lateral radiograph shows a dislocated tibiotalar joint with a sizeable posterior malleolus fracture fragment

Treatment Considerations/Planning/Tests Needed

Ankle fractures are a common orthopedic injury, but more recent data suggest that reduction and fixation of the posterior malleolus is more critical than previously thought [1–4]. Previous literature supported that a posterior malleolar fragment of less than 25% of the articular surface would spontaneously reduce with the reduction and fixation of the lateral malleolus, provided the posterior-inferior tibiofibular ligament is intact [1–6]. Odak et al. recommended that the posterior malleolus be fixed if it was associated with a fracture dislocation and intraoperative evaluation demonstrated the tibiotalar joint was not congruent or residual talar subluxation was present [3].

The decision to open reduce and fixate the posterior malleolus may be made in the operating room; thus, the surgeon should plan accordingly and have all possible equipment and implants available. It may be beneficial to obtain a computed tomography (CT) scan prior to surgical intervention to assess for impaction, determine fragment size, and assess incarcerated fragments that could inhibit reduction.

A contraindication to acute surgical fixation may be extensive soft tissue injury including hemorrhagic fracture blisters and compromised skin. A tenuous soft tissue envelope may require provisional external fixation to allow for evaluation and care of the soft tissues, as well as provide stability prior to definitive surgical intervention.

Timing of Surgery

The risk and benefits of the procedure were discussed with the patient, including nonoperative treatment. The patient elected to have surgical intervention and this was scheduled for the day following the injury given that her soft tissues were amenable to surgical intervention. In the event that she had excessive edema or fracture blisters, she would have remained in her splint with early follow-up to reassess the soft tissue envelope. If her ankle was unstable and difficult to keep reduced in the splint, provisional external fixation would be utilized until the soft tissues were amenable to surgical intervention. Typically, this occurs with some resolution of the edema and return of skin wrinkles around the foot and ankle.

Intraoperative Tips and Tricks for Reduction/Fixation

Position

Supine with a large bump or bean bag under the ipsilateral buttock to allow posterior access to the ankle if needed.

Approach

Standard direct lateral approach over the fibula. Dissect soft tissues down until you are directly on the bone. Care should be taken to protect the superficial peroneal (nerve located approx. 7 cm proximal to the tip of the fibula) if it is encountered during your dissection.

Fracture Reduction

The fibula is typically reduced with a pointed reduction clamp (Weber) and fixed with a lag screw when possible. We prefer a 2.7 mm lag screw (inserted A-P) when available, as the smaller profile is less likely to interfere with plate fixation. We then neutralize the construct with a lateral plate on the fibula, usually with a minimum of three screws proximal to the fracture, and three distal, when possible. In comminuted fractures or osteoporotic bone, an anatomic precontoured locking fibular plate can be helpful. This will vary depending on the fracture type as well as the degree of comminution.

After the lateral malleolus has been stabilized, reduction of the posterior malleolus is assessed using fluoroscopy. If the posterior malleolus is anatomically reduced with reduction of the fibula, it can be stabilized with percutaneous lag screws placed anterior to posterior. If the reduction of the posterior malleolus is not acceptable, a percutaneous reduction with a pointed reduction or periarticular clamp should be attempted. This can be facilitated by dorsiflexing the ankle and levering the talus against the anterior joint surface; thus, applying a tensile reduction force on the posterior malleolar fragment. If a percutaneous reduction is not successful, then an open approach is required.

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