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High Ankle Sprains: Mechanisms, Pathology and Recovery
High ankle sprains, also known as syndesmotic sprains, pose unique challenges in the realm of sports medicine and physiotherapy. The syndesmosis is the joint between the tibia and the fibula and it is stabilised by a number of ligaments. When these ligaments are injured, it is considered to be a high ankle sprain or a syndesmosis injury and it can lead to instability of the ankle joint.
Anatomy and Function of the Ankle Joint:The ankle joint is a hinge joint formed by the tibia, fibula, and talus bones. The joint allows for dorsiflexion (pointing the toes up) and plantarflexion (pointing the toes down). The tibia and fibula bones are connected by a syndesmosis (fibrous connective tissue), which serves to unite parallel bones and prevent their separation. The syndesmosis between the tibia and fibula strongly unites the bones, allows for little movement, and firmly locks the talus bone in place between the tibia and fibula at the ankle joint, stabilised by a number of ligaments. The main ligaments of the syndesmosis complex are the interosseous ligament are the anterior inferior tibiofibular ligament (AITFL), the posterior inferior tibiofibular ligament (PITFL), and the interosseous ligaments.
While the ATFL is the most commonly injured ligament in an ankle sprain. It is located on the front of the ankle joint and helps to prevent the fibula from moving forward relative to the tibia. The Posterior Talofibular Ligament (PTFL) is located on the back of the ankle joint and helps to prevent the fibula from moving backward relative to the tibia. The interosseous ligament & the Anterior Inferior Tibiofibular Ligament (AITFL), are located between the tibia and fibula bones and help to connect them together, all these structures could be involved in a high ankle sprain.
Mechanism of Injury:
The most common mechanism of injury for a high ankle sprain is an external rotation force applied to the foot while the ankle is dorsiflexed (pointed up). This can happen during sports activities such as football, rugby, basketball, or during a fall mechanism which is more common in high impact sports. The external rotation force causes the fibula to move forward relative to the tibia, which can stretch or tear the ligaments of the syndesmosis.
The symptoms of a high ankle sprain can include pain, swelling, bruising, and stiffness in the ankle joint. These are similar to a common ATFL sprain, but there are subtle differences and without a clear understanding of the mechanism of injury a physical examination would need to be distinguished. In some cases, especially if the ankle sprain hasn’t recovered in a normal period of time, symptoms may remain, and there may be instability of the ankle joint.
The diagnosis of a high ankle sprain is usually made based on the patient's history and physical examination. A Physiotherapist will take a detailed history and although it may be difficult to recall the exact mechanism of injury at time, as much detail as possible is important. The physiotherapist will perform a physical exam, trying to distinguish as best they can, which structure may be contributing to the injury.
It is important to rule out other pathologies with similar mechanisms of injury, including fractures, concurrent lateral ankle sprains, as well as other more uncommon pathologies. Imaging may be necessary in some cases, but as with all imaging, it should only be indicated in order to rule out major pathology such as breaks, or if the treatment pathway may be changed and the sprain is significant enough to potentially require surgery.
The treatment of a high ankle sprain depends on the severity of the injury. Mild sprains can be treated with POLICE principles. More severe sprains may require immobilisation in an Aircast or walking boot. In some cases, surgery may be necessary to repair the ligaments depending on the severity and the chance of instability, surgery is more common in the high performing multidirectional athlete due to the extreme forces they intend to put through the joint.
Surgery is only necessary for higher grade high ankle sprains. It is usually only considered for severe sprains that do not respond to conservative treatment and there are two main types of surgery for the syndesmotic injury.
Traditionally two screws would be drilled through both bones to pull them together and over time allow the interosseous ligament, PITFL and AITFL to heal. However this can cause significant restriction in range of motion in the ankle joint and over time can be problematic, often leading to them being removed at a later date.
A more modern approach is to use a suture button device, which will draw the tibia and fibula together but allow for more natural biomechanical interaction at the ankle mortise due to less rigidity compared to the more traditional screws.
The recovery time for a high ankle sprain can vary depending on the severity of the injury. A High ankle sprain will usually take longer than a normal ATFL ankle sprain, and usually responds well to early immobilisation in order to splint the tibia and fibula bones together allowing the syndesmosis and other structures time to attenuate while reducing the ground reaction forces placed on these structures.
Typically a High ankle grade not requiring surgery would take around 4-6 weeks to heal and probably around 6-12 weeks to get back to training.
With early recognition and surgical intervention of a high grade high ankle sprain a similar return to sport time frame can be expected of around 6-12 weeks.
Preventing high ankle sprains can be more difficult than preventing a more common ankle sprain due to the mechanism being more forceful.
There are a few things that can potentially be done to prevent high ankle sprains including:
Strengthening lower limb and acclimatising to ground reaction forces.
Plyometric training including single leg plyometrics.
Change of direction and lower limb skill acquisition drills.
Education on mechanism of injury and how to avoid situations that may lead to injury.
Preventative ankle braces especially if you’re prone to recurrent ankle sprains or have chronic ankle instability.
High ankle sprains involve different anatomy to the more common ankle sprain, they are disabling injuries and can cause significant long term issues if not treated well in the initial healing phases. A sound understanding of the mechanism of injury and how this differentiates high ankle sprains from other ankle pathology is extremely important in early recognition of the severity of the injury and therefore establishing early interventions for the most optimal treatment strategy.
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