Mastering The Treatment Of High Ankle Sprains
High ankle sprains can be particularly challenging to treat given the desire to return the athlete to the sport as quickly as possible. Accordingly, these authors review the biomechanics of ankle syndesmosis, the pros and cons of imaging modalities, and keys to treatment and rehabilitation that will help ensure a safe and reasonably expeditious return to play for athletes.
While lateral ankle sprains are viewed as the most common athletic injury occurring in sports, high ankle sprains have been responsible for more lost time from game play and training activities.1 Since high ankle sprains are commonly mistaken for lateral ankle sprains, they are less commonly reported.
Misdiagnosing a high ankle sprain can result in lingering pain and recovery as the treatment course for syndesmosis injuries is often protracted, requiring longer periods of offloading and rehabilitation in comparison to lateral ankle sprains.1 For recreational and elite athletes, high ankle sprain is the most common contributor to persistent ankle pain and disability.2
A high ankle sprain refers to injury of the distal tibiofibular syndesmosis. This complex is comprised of the anterior inferior tibiofibular ligament, interosseous ligament, posterior inferior tibiofibular ligament and deep transverse tibiofibular ligament. The syndesmotic complex serves as a ligamentous restraint to the fibula, resisting normal physiologic external rotation and lateral translation of the talus during the stance phase of gait. This restraint also allows an increased intermalleolar distance (an average of 1.25 mm) to accommodate the wider shape of the anterior talar dome with dorsiflexion of the ankle.3
Key Insights On The Biomechanics Of The Syndesmosis Injury
The ankle syndesmosis injury comprises a strong complex of ligaments that require significant force to cause disruption. Syndesmosis injuries often involve forceful external rotation of the foot relative to the leg and commonly occur in collision sports, such as football, hockey and court sports such as basketball.1,4
Lauge-Hansen previously described this mechanism as a pronation-external rotation injury in which the talus and foot externally rotate relative to the tibia while the foot is in a fixed, pronated position.5
While the foot is pronated, the deltoid ligament complex becomes taut. As the foot externally rotates on the ankle, the deltoid ligament is the first ligament to rupture. With the talus now unrestrained, the force of talar external rotation translates to the fibula and the anterior inferior tibiofibular ligament is the first syndesmotic ligament structure to fail. The anterior inferior tibiofibular ligament contributes 35 percent of the stiffness of the syndesmotic complex.6
Once this primary restraint ceases, the talus continues to migrate laterally and in external rotation against the fibula, causing tearing of the interosseous membrane. With rupture of both the anterior inferior tibiofibular ligament and interosseous ligament, the syndesmosis loses approximately 58 percent of its stability.6
The ankle is comprised of bony and ligamentous restraints, which are designed to stabilize the talus within the mortise of the ankle. Ankle injuries, such as isolated lateral malleolar ankle fractures and syndesmosis injuries, are considered stable provided the deltoid ligament is intact.7-9 Though the deltoid ligament complex is made up of superficial and deep fibers, it is the deep fibers that restrain the talus, maintaining stability and the physiologic motion within the ankle joint mortise.