Randon Hall, MD
The Basics of a Common Ankle Sprain
Injury: Ankle Sprain
Let's set the story straight on the 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. When an ankle injury occurs to these lateral or medial stabilizing ligaments this is referred to as a common ankle sprain. To be clear: An ankle sprain is the same thing as ligament damage to the ankle!
Lateral View of Ankle
Posterior View of Ankle
Mechanism of Injury
The typical mechanism of injury for a common ankle sprain is when the foot turns inwards, which is also called inversion. This process causes the outer ankle ligaments to become stretched and torn causing an ankle sprain. If the foot turns outward during the injury this will cause an injury to the deltoid ligament, which is located on the inner aspect of the ankle. The lateral ankle ligaments are injured much more frequently than the inner ankle ligaments.
In general, a full examination of the ankle and lower leg should be performed. However, there are a few key findings that can help determine an ankle sprain. One finding that is not very reliable, is the degree of swelling or bruising that is present with the injury. A fracture can be present with minimal swelling, as well as a sprain can be present with dramatic swelling and bruising. The classic physical examination finding in patients with an acute sprain is tenderness over the lateral or medial ankle ligaments. Ankle sprains can be associated with a syndesmosis injury (high ankle sprain) or a fracture, therefore the ankle should be assessed for these injuries as well.
There are exam techniques to help confirm the diagnosis as well as evaluate instability of the ankle. One test is called the talar tilt test, which consists of turning the foot inwards to stretch the lateral ligaments and reproduce pain or instability. Additionally, an anterior drawer test is performed by stabilizing the lower leg with one hand and grasping the heel in your palm with the other. The examiner will pull the foot forward from the heel and again trying to reproduce the pain and instability. Further evaluation for a high ankle sprain can be found in my post, Understanding the Diagnosis of a High Ankle Sprain.
If an athlete has inability to walk, bone pain over the medial or lateral ankle, pain over the fifth metatarsal bone or pain over the navicular bone, (Ottawa Criteria), x-rays should be highly considered. Plain x-rays can be helpful in determining the absence of a fracture or injury to the syndesmosis. An x-ray will not show the actual ligaments. If the physical exam is consistent with an ankle sprain and imaging confirms that no fracture or high ankle sprain is present, then no further imaging is typically ordered.
Normal Ankle X-ray
Most ankle sprains are generally managed with a conservative course of treatment. At first, the process usually involves some form of supportive bracing or immobilization. A good rule-of-thumb is to use the least restrictive bracing as possible. Minor ankle sprains many only require a simple ace wrap or tape, where as more severe injuries may require brief immobilization in a walking boot. It is usually recommended that the athlete start working on range of motion and physical therapy exercises as soon as possible. The key to optimal return to sports is regaining the strength, balance and agility that was present before the injury. Although return to play is highly variable depending on the severity of the injury, ankle sprains treated non-operatively generally have an estimated return of about 2 - 4 weeks.
Return TO PLAY
Return to play after an ankle sprain can be difficult for cutting and pivoting sports. Athletes should consider a functional ankle stabilization brace once cleared back to sports participation.