A Prospective Randomized Pilot Study to Compare Open Versus Percutaneous Syndesmosis Repair of Unstable Ankle Fractures

High ankle fractures involve fracture of the fibula above the level of the syndesmosis (space between the tibia and fibula bones) that result from indirect mechanisms (e.g. pronation-external rotation (twisting) injuries. The method of injury is assumed to disrupt one or more of the syndesmotic ligaments, leading to instability of the ankle mortise . High ankle fractures comprise a significant proportion of ankle injuries (16 to 45 % of all ankle fractures patterns) . It is generally agreed that operative intervention of ankle injuries is indicated in cases of instability . However, recent advances in the understanding of the biomechanics of the ankle have given rise to particular areas of clinical uncertainty, including the treatment of unstable syndesmotic injuries and reliability of strictly radiographic assessment of ankle fractures .

The goal of operative treatment is to anatomically reduce the ankle mortise to permit syndesmosis ligament healing and restoration of the normal tibiofibular joint dynamics. Even 1 mm of displacement or lateral shift of the talus will affect ankle joint loading and lead to dysfunction and potentially degenerative joint changes. Accurate reduction of the syndesmosis and maintenance of this reduced position until the ligaments heal is crucial to ensure good outcome and to avoid long term arthritic changes in the tibiofibular joint .

If the ankle joint is unstable (too much sideways movement), the syndesmosis space between the two bones in the ankle (tibia and fibula) needs to be stabilized. One method to treat unstable syndesmosis injuries is making an incision to expose the ankle to provide direct visualization of fracture for anatomic reduction (alignment) and insertion of one or two syndesmosis screws to maintain the relationship of the fibula to the tibia. This is referred to as open reduction and internal fixation (ORIF).

Another method of repair is by closed reduction of the ankle joint and the use of one or two percutaneous syndesmosis screws only. That is, syndesmosis stabilization can be done percutaneously using intraoperative fluoroscopy to visualize the repair . Literature and standard practice support both of these methods.

The syndesmosis joint complex is composed of the anterior inferior tibiofibular ligament (AiTFL), the posterior inferior tibiofibular ligament (PiTFL) and the interosseous membrane (IOM). This complex is believed to permit ankle mortise stability and flexibility due to the elasticity of the ligaments, which allows the intermalleolar distance to change and facilitates tibial and fibular rotation. It also maintains the axis of balanced loading of the foot through the fibula. Adequate stability and anatomic restoration of the syndesmosis joint complex is vital to restoring normal tibiotalar contact forces in order to lessen the risk of posttraumatic arthritis.