Ankle Anatomy
Many times the term "High Ankle Sprain" is used in sports without adequate explanation of the specific injury, as well as without differentiation from a common ankle sprain. There are three bones that make up the ankle joint. Those bones are called the fibula which sits laterally, the tibia which sits superior and medially (inside) and the talus which sits inferiorly. There are several supportive ligaments of the ankle that help keep it stable while performing sports activities. The primary stabilizing ligaments over the outside (lateral) of the ankle are called the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL) and posterior talofibular ligament (PTFL) which, can be seen in the photos below. These ligaments are most frequently injured with a common ankle sprain. Additionally, the primary stabilizing ligament of the medial ankle is called the deltoid ligament.
Lateral View of Ankle
Posterior View of Ankle
When an ankle injury occurs to these lateral and medial stabilizing ligaments this is referred to as a common ankle sprain. However, there are another set of ligaments that hold the two lower leg bones together (tibia and fibula) that when injured constitute a high ankle sprain. Those ligaments include the anterior inferior tibiofibular ligament, posterior inferior tibiofibular ligament, transverse tibiofibular ligament and the interosseous membrane (ligament).
Ligaments Associated with High Ankle Sprain
Ligaments Associated with High Ankle Sprain
Mechanism of Injury
The typical mechanism of injury for a high ankle sprain is when the foot is planted and a force causes the ankle to be pushed inward as the foot is rotated outward. This process causes the talus bone to act as a lever to pry open the connection between the tibia and fibula and disrupt the associated ligaments. A high ankle sprain can be seen more often in rugby and football as well as with booted sports such as hockey and skiing.
Examination
In general, a full examination of the ankle and lower leg should be performed. However, there are a few key findings that can help differentiate a high ankle sprain from a common ankle sprain. The classic physical examination finding in patients with an acute high ankle sprain is tenderness in the front of the ankle between the tibia and fibula. This area would correspond to the interosseous membrane and anterior tibiofibular ligament in the picture above. In general, the greater the distance of pain extends up the leg, the more severe the injury. High ankle sprains have a high association with ankle fractures, therefore the bony landmarks should be assessed for a fracture as well.
There are two well-known exam techniques to help confirm the diagnosis. One test is called the squeeze test, which consists of squeezing the lower leg from the sides trying to reproduce the pain. Additionally, and external rotation test is performed by stabilizing the lower leg and externally rotating the foot, again trying to reproduce the pain. These tests usually will not be positive with a common ankle sprain and therefore if positive should raise suspicion about a high ankle sprain.
Evaluation
Plain x-rays can be helpful in determining the presence of an injury to the syndesmosis, which is considered a high ankle sprain. A plain x-ray may show widening of the ankle joint and the distance between the tibia and fibula, which is called diastasis. The ankle diastasis can occur with or without a fracture. The photo below shows an increased in the medial clear space which is consistent with an unstable syndesmosis injury. Compare the medial clear space to the normal ankle x-ray photo at the top of the post. In addition to x-ray, MRI can be helpful to make the diagnosis if the presence of a syndesmosis injury is in question.
Unstable Syndesmosis Injury
Treatment
Syndesmosis sprains without diastasis are generally managed with a conservative course of treatment. The process usually involves some form of immobilization, most commonly in a boot. Additionally, some degree of restricted weight-bearing is instituted based on pain and severity of the injury. Although return to play is highly variable, high ankle sprain treated non-operatively generally have an estimated return of about 6 weeks. On the other hand, surgical intervention for high ankle injuries is quite controversial. Options for surgical stabilization include a screw fixation or a suture fixation device called a tightrope. In regards to surgical stabilization, the treatment protocols are highly variable so it would be difficult to speculate on a return to play.
Return to Play
Return to play after a high ankle sprain can be difficult for cutting and pivoting sports. Athletes should consider a functional ankle stabilization brace once cleared back to sports participation.
Reference: Management of Syndesmosis Injuries in the Elite Athlete. Mak, MF et al. Foot and Ankle Clinics, 2013-06-01, Volume 18, Issue 2, Pages 195-214.