Addressing Posterior Malleolar Ankle Fractures
Posterior malleolar ankle fractures can be a challenge to reduce and fixate. Accordingly, these authors provide compelling case examples and emphasize the use of computed tomography and a posterior approach to facilitate optimal outcomes.
The on-call foot and ankle surgeon is likely to see a variety of fractures at the local emergency room. Due to different mechanisms of ankle injury/fracture variability, our management varies from immobilization to complex reconstruction. Posterior malleolar fractures have always provided a more difficult reduction than their medial and lateral counterparts because of the location. Over the years, many surgeons have shied away from the open approach and have opted for indirect fixation due to concern for neurovascular compromise and difficult dissection.
In addition to reviewing current trends, such as indirect visualization, which we believe are often inappropriate, we will take a closer look at the posterior approach as well as effective imaging to assist the surgeon.
There is no true consensus in the foot and ankle literature on whether to fixate posterior malleolar fractures. Numerous papers have quoted displacement of 20 to 30 percent of the joint surface as justifying fixation with these percentages being based on the lateral radiograph. We believe there are many morphologies of posterior malleolar fractures that can have a tremendous impact on joint kinematics.
Due to a large variety of fracture patterns, we advocate the use of computed tomography (CT). This imaging modality not only allows the surgeon to clearly see how many fragments are present but helps determine where the major fragment is located. The major fracture fragment will allow the surgeon to decide between a posterior medial or posterior lateral approach.
Pertinent Pearls On Technique
We favor using radiographs after obtaining reduction and putting the patient in a splint (no need to keep the ankle dislocated for imaging). If there is a suspicion of a posterior malleolar fracture, order a CT scan to evaluate the size and location of the main fracture fragments. This will help determine the surgical approach. In most circumstances, we favor immediate operative management. Surgery may be delayed if the patient needs further medical evaluation.
Regardless of fracture fragment positioning, as long as a posterior malleolar fracture is present, we ensure that the patient is in a prone position. This allows for proper visualization of the fracture.
Medial approach. With the main fracture fragment medially located, as determined with radiographs and CT, place the incision just posterior to the medial malleolus. Although the medial aspect of the ankle contains many vital structures, there are “safe zones” that allow clear visualization into the ankle joint. Carry dissection down to the posterior tibial tendon. This creates an anatomic plane that allows one to retract the posterior tibial tendon anteriorly and ensures that one can retract the neurovascular bundle posteriorly. With these structures protected, the surgeon can carry the incision directly to the distal tibia. You can clearly visualize the fracture fragment at this point.
Lateral approach. When the main fracture fragment is laterally based, center the incision at the interval between the peroneal tendons and Achilles tendon. Within the superficial dissection, one must locate and carefully retract the sural nerve. Visualize the flexor hallucis muscle belly and elevate it from the interosseous membrane. This will allow the surgeon to visualize the posterior malleolar fracture.
What You Should Know About Reduction And Fixation
Surgeons can most often achieve reduction utilizing a simplified technique by dorsiflexing the ankle. Many times, this will push the fragment out to length. With regard to fixation, the surgeon can utilize a variety of options.