A patient, aged 20 years, presented with ankle pain four months after an open reduction and internal fixation of a left bimalleolar ankle fracture with distal tibiofibular syndesmotic screw fixation.
The patient reported she was walking down stairs earlier in the day and tripped on ice. She felt a “popping sensation” in the left ankle. The patient was able to put weight on the ankle after the injury but stated the ankle didn’t feel right.
An anteroposterior (AP) mortise x-ray was taken.
This case has been brought to you in partnership with the Journal of Orthopedics for Physician Assistants.
Submit your diagnosis to see full explanation.
Syndesmotic injuries are commonly seen with fibular fractures proximal to the level of the ankle mortise. Syndesmotic screw fixation is performed to reduce tibiofibular diastasis and prevent talar displacement. Tricortical fixation with a single screw may be appropriate with mildly displaced syndesmosis injuries.
In theory, tricortical fixation offers less rigidity to the repair and may provide improved ankle motion post-operatively. This reduces the risk of fatigue on the screw and may prevent the need for removal when weight bearing is initiated post-operatively.
Quadricortical fixation with a single or with double screws is often used when significant fracture displacement is present for a more rigid repair. Quadricortical fixation constrains the ankle and requires removal of the screw — typically at 3 months post-operatively. The number of screws used and cortices included is variable and ultimately determined by the discretion of the surgeon.
Normal physiological motion occurs between the tibia and the fibula during weight-bearing activities. Weight bearing motion at the syndesmosis after rigid screw fixation is known to cause stress on the screw.
Studies have shown that up to 30% of tricortical syndesmotic screws will break with full weight bearing. For this reason, syndesmotic screws are commonly removed at 3 months post-operatively and prior to initiating full weight bearing activities. Patients who break the syndesmotic screw may feel a sudden pop and mild-to-no pain after.
Retained broken syndesmotic screws have not been shown to cause damage and may be left in place in asymptomatic patients. Broken screws, however, may be a source of ankle pain and should be taken out in symptomatic patients after the syndesmosis has healed.
Dagan Cloutier, MPAS, PA-C, practices in a multispeciality orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants (JOPA).