The ankle syndesmosis refers to a group of ligaments that are responsible for maintaining the relationship between your tibia and fibula at the level of your ankle. You can injure this complex, resulting in what is commonly known as a high ankle sprain, and it sometimes can have an associated fracture. These are much less common than your typical low ankle sprains and only account for about 10% of total ankle sprains. These injuries typically happen from an external rotation injury, which drives your fibula away from your tibia resulting in disruption of the ligamentous complex. This can lead to a wide range of injuries from a minor sprain to complete disruption and instability.
Anatomy:
The four ligaments that make up your syndesmosis are the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), inferior transverse ligament (ITL), and the interosseous ligament (IOL).
Physical Exam:
If the injury is very unstable, usually patients will have difficulty bearing weight. There will often be swelling and bruising around the ankle. There are several provocative tests used to assess for a syndesmotic injury. One is the squeeze test when the examiner will squeeze your tibia and fibula together about midcalf level, which is positive if pain is felt down towards the ankle. Another test used for more subtle or chronic injuries is the syndesmotic tape test. The patient is asked to do a single leg heel rise. If this is painful around the syndesmosis the tape is applied circumferentially just above the ankle, and the exam is repeated. Improvement in pain with the tape is indicative of a syndesmotic injury.
Imaging:
The imaging used to asses this injury is an xray of the ankle for which you are looking for increased space between the tibia and fibula. If those xrays are unrevealing, you can do an external rotation stress radiograph to see if widening occurs. If all xrays remain normal, CT or MRI can be used for further evaluation.
Treatment:
Nonsurgical treatment is used for injuries that include a sprain, but do not show any widening between the tibia and fibula and have no evidence of instability. These patients are typically treated with either a boot. The recovery process for this type of injury is typically much longer than that of a low ankle sprain and may even require double the amount of time to recover comparatively. On average, it can take football athletes approximately one month to return to play after a high ankle sprain.
Management:
Surgical management is recommended for the following:
- Unstable injuries - typically require more than 1 of the 4 ligaments to be torn and you can see widening between the tibia and fibula on imaging.
- More subtle injuries that do not respond to non surgical treatment
- High level athletes with more minor injuries due to their increased activity level
Surgical options include either fixation with screws, sutures buttons, or both. There are pros and cons to both fixation types, and use of one over the other is controversial. Benefits to flexible fixation is that it restores mechanics closer to normal between the tibiofibular joint than the more rigid screw fixation. Screw fixation has the risks of screw breakage, and also can requires a second surgery to remove the screws after healing has occurred. In a very unstable fracture with syndesmotic disruption, it might be more suitable to have more rigid fixation with screws. In more subtle ligamentous injuries, flexible fixation may be more appealing.
When should athletes undergo tightrope fixation for syndesmotic injuries? While there is a bit of grey area when answering this question, to put it simply:
- If you have an injury with obvious widening of the tibiofibular joint on xray
- If you have a more subtle injury that is not responsive to nonoperative management
- If you are looking to return to play faster, surgical fixation may speed up your return to play timeline in select cases.
This post is for educational purposes only. Please consult with a board certified orthopedic surgeon when seeking care regarding ankle injuries.
