Syndesmosis injuries explained
June 11, 2021
The syndesmosis injury (or high ankle sprain) has become more and more prevalent in recent times, particularly through AFL and AFLW competitions The reasons behind that remain unclear, however some possible reasons include rule changes within the game that result in more body-to-lower-limb-contact, reduction in sliding causing leg fractures, or simply that we are looking more closely for them now, and therefore increasing diagnosis rate. Let’s look in more detail about what the syndesmosis is, and how it differs from the “classic” rolled ankle.
The syndesmosis is the ligament that holds the tibia and fibula bones in place and prevents widening between the two. It is located just above the ankle (hence high ankle sprain type injury) and is a particularly strong ligament, however has a relatively poor bloody supply. The tibia and fibular bones form the “true” ankle joint between the tibia and fibula bones and the talus bone in the foot and allows a transfer of force between the foot and the lower limb.
Injury to the syndesmosis differs from the typical ankle sprain in a couple of ways. Firstly the mechanism – the classic ankle sprain occurs when the ankle moves laterally (outwards) in relation to the foot. The sole of the foot is inverted, or points towards the midline of the body at the same time and stretches or even tears the ligaments that sit on the outside or lateral aspect of the ankle. These are the anterior-inferior talocrural ligament, the calcaneofibular ligament and the posterior talocrural ligament. In comparison to the syndesmosis, these ligaments are thin and far less rigorous and strong and therefore more prone to injury.
A syndesmosis injury is more likely to occur when the foot is everted, or the sole of the foot points outwards. This stretches the ligament on the inside of the ankle, the deltoid ligament, and with sufficient force, can also injure the syndesmosis. The other common way the syndesmosis is injured is when the foot is planted and a force (in football terms, usually a player) collided with the outside of the lower leg and forces the ankle to evert. In either sense, and injury to the syndesmosis is possible and should not be ruled out.
To diagnose a syndesmosis injury, your physio should put the ligament on stress or stretch to see if it reproduces pain in the front of your ankle. Other ways to assess for damage to the syndesmosis is a lunge with the injured leg forward, or simply the inability to weight bear on the injured leg. If these tests are not conclusive your physiotherapist from Instinct Health may refer you for a weightbearing x-ray or MRI scan to assess the extent of the damage. A weightbearing x-ray is required in this instance because as discussed earlier, the role of this ligament is to hold the tibia and fibula bones together. If there has been injury to the syndesmosis, the bones are likely to widen or separate, and this separation can be seen on x-ray. An MRI scan can also be useful as these will show the ligament itself and therefore the extent of the damage.
For recovery, a syndesmosis injury takes significantly longer for a return to sport or activity timeline than a classic lateral ankle sprain. They can often take 6-8 weeks, or even more, and in some circumstances require surgery to knit the separated bones back together and repair the torn ligament. This then leads to a period of non-weightbearing after surgery and time spent in a moonboot. The focus of rehab while in the boot is making sure strength is maintained as much as possible in the rest of the lower limb.
Once the boot is removed, in either a post-surgery or non-surgery rehabilitation pathway, your physio will guide you through increasing range of movement again in the ankle and then improving the strength of the calf, peroneal and tibialis posterior muscles. Once adequate time has passed for the ligament to heal, and there has been a sufficient improvement in strength, you can gradually return to running. Initially in straight lines, then gentle change of directions, progressing to return to sport or play as the ankle improves.
The most important thing in any ankle injury is to rule out a syndesmosis injury. They are more severe, take longer to heal and can need surgical intervention if severe enough. Our physiotherapists here at Instinct Health will be well equipped to thoroughly assess and diagnose your injury, regardless of what level of sport or activity you participate in.
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