Addressing Posterior Malleolar Ankle Fractures

Author(s): 
Nicholas Todd, DPM, AACFAS, Meagan Jennings, DPM, FACFAS, Shannon Rush, DPM, FACFAS, Ryan Wood, DPM, and Richard Jensen, DPM, FACFAS

   Our fixation method relies on AO principles. After reducing the fracture, place temporary fixation utilizing K-wires. One can achieve permanent fixation with an under-contoured, one-third tubular plate in an antiglide fashion. The reason for utilizing an antiglide, under-contoured plate is that it will push the posterior malleolar fracture into the body of the tibia at the fracture apex. In past reductions, we have noted that bulkier plates, although pre-contoured, do not provide the reduction and have been “bulkier” than a simple one-third tubular plate.

   The one caveat to posterior reduction is that the surgeon must be aware that an under-contoured plate can cause the fragment to displace distally if one does not temporarily fixate it.

   Most posterior malleolar fractures have concomitant injuries such as lateral or medial malleolar fractures. We have found that fixating these fractures with the patient in the prone position enables the surgeon to achieve excellent reduction. With regard to distal fibular fractures, posterior plating (the anti-glide technique) has been far superior biomechanically to lateral plating in our experience. After fixating the posterior malleolus, surgeons can turn their attention to the fibula through the posterior lateral incision. With regard to the medial malleolus, one can easily use the posteromedial incision to fixate the malleolus utilizing screws or plating techniques.

Key Insights On Effective Postoperative Care

With a majority of ankle fractures, the treating physician can allow protective weightbearing once the skin has healed. Unlike medial and lateral malleolar fractures, posterior malleolar fractures can be displaced with direct axial compression. That is why our postoperative protocol includes six weeks of non-weightbearing. Once we feel the skin has healed, we begin open kinetic chain range of motion.

   We have also started to employ postoperative CT scans to ensure that the articular surface of the tibia has healed. Once the patient has achieved radiographic healing, he or she can begin weightbearing and continue physical therapy for approximately three months.

Case Study One: When A Patient Presents With A Dislocated Trimalleolar Ankle Fracture

A 29-year-old female presented to the emergency room with a dislocated trimalleolar ankle fracture. There was a visible tenting in the anterior skin of her ankle. The treating physician performed an immediate reduction of the fracture and the lateral radiograph revealed what appeared to be a small posterior malleolar fracture. A CT scan exposed a large posterior fragment with bony fragments interlocking on the lateral aspect.

   The patient went to the OR that night. With the patient in the prone position, surgeons reduced the posterior malleolar fracture from a posterior lateral approach. Surgeons fixated the lateral malleolus fracture with an anti-glide plate and fixated the medial side with standard screw fixation. The ankle was stressed and there was noted syndesmotic instability. The surgeon made a small stab incision over the lateral malleolus and the use of a lateral plate allowed for syndesmosis reduction with two screws.

   Postoperative care involved immobilization for four weeks followed by two more weeks in a non-weightbearing protective boot. This allowed the patient to begin range of motion. At six weeks, a follow-up CT scan showed that the posterior malleolus was healed and helped ensure the patient could bear weight without disastrous consequences. The patient returned to physical activities at six months.

Case Study Two: When The CT Reveals A Large Posterior Medial Fragment And Associated Distal Fibular Comminution

A female in her 30s suffered a slip in a rural area. She presented to an outpatient clinic where she learned that she suffered an ankle fracture and would need operative treatment. The patient presented at our clinic 36 hours later with the ankle still dislocated. In the clinic setting, surgeons reduced the fracture and splinted her. Her X-rays showed a dislocated trimalleolar fracture. A CT determined the best operative approach. The CT revealed a large posterior medial fragment with associated distal fibular comminution. Physicians delayed surgery for five days in order to allow for the swelling to diminish.

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