(LOW ANKLE SPRAIN)
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related talks: achilles tendonitis; high ankle sprain; torn achilles tendon; broken ankle
What is a Common Ankle Sprain?
A common ankle sprain (aka "low ankle sprain") is a very common injury (90% of ankle injuries) that occurs after rolling your ankle, and causing one or two ligaments on the outside of your ankle to be torn. The injured ligaments are the ATFL (anterior talo-fibular ligament) and/or the CFL (calcaneo-fibular ligament). The ATFL is the most commonly injured ligament and occurs when the foot is flexed downward (plantarflexed) and forcefully internally rotated. A great example (and very common occurrence) of an injury in this foot position is a woman falling while wearing high-heels. In contrast the CFL is injuried when the foot is flexed upward (dorsiflexed) and forcefully internally rotated. Both ligaments are important for overall stability and balance. Long-term instability can prevent people from participating in athletic activities, and may lead to ankle arthritis in the future.
How is a Common Ankle Sprain diagnosed?
People report a specific incident where they rolled their ankle and then developed pain and swelling along the outside of their ankle (lateral malleolus). Additionally people will complain of feeling unstable or uneasy with internal rotation of their ankle. The swelling can be severe, and in many cases people cannot initially bear weight on the ankle. All ankle sprains don’t require an x-ray, however, an ankle fracture is caused by a similar twisting injury and x-rays are sometimes needed to differentiate between two. Doctors try to avoid taking unnecessary x-rays to minimize radiation exposure. When examining the ankle, certain findings, such as tenderness along the outside ankle bone, or the inability to take more than 4 steps on the injured leg, suggest a more significant injury that should be x-ray’d. But this is not a hard-and-fast rule, and doctors will get an x-ray if they have clinical concern. A ligament injury will not show up on x-ray, so the main use of an x-ray is to rule out fractures. If the ankle pain persists for weeks after the initial injury, an MRI is often ordered to evaluate the structural integrity of these ligaments.
Overall ankle stability can be assessed by testing the ankle for excessive anterior laxity (tested with the anterior drawer test) and/or excessive inversion (twisting, called the talar tilt test). These findings suggest a CFL or ATFL injury.
Other injuries can also occur with an ankle sprain. Injury to the cartilage (called an osteochondral defect) may occur if the ankle bones bang together causing a piece of cartilage to chip off. An ankle fracture can also occur in combo with an ankle sprain. Sometimes there are tiny fractures in the foot (like those of the 5th metatarsal base, the talus' lateral process, the os trigonum, or the calncaneus' anterior process). Doctors should be looking for all of these injuries when someone comes in having twisted their ankle.
How is a Common Ankle Sprain treated?
Treatment depends on how painful or unstable the ankle is. All types of ligament injury can be effectively treated without surgery (type 1 which is a partial tear, type 2 is complete tear of the ATFL, and a type 3 is a complete tear of the ATFL and CFL).
The first step in treatment is the classic RICE treatment (Rest, Ice, Compression, Elevation). This technique reduces swelling and inflammation. Patients are also given a walking boot to support their ankle while it heals. The brace prevents excessive twisting motion. Once the pain and swelling improves, the focus is restoring strength and stability to the ankle. This is the rehabilitation phase of recovery.
Chronic ankle instability is a concern in patients that continue to experience pain and feelings of instability (weakness, the ankle gives out or sustains recurrent sprains) despite a long rehabilitation period. Surgery has been shown to effectively treat this condition by reducing pain and increasing stability. Chronic instability can occur with all levels of injury (type 1-3) and is not always correlated with a structural deficit (as seen on an MRI). The indication for surgery is really based on the patient’s reported symptoms and their future expectations. The most common surgery is a “modified Brostrom” which is were a surgeon repairs the torn ligament and tightens the ankle joint capsule to increase the stability. Many studies indicate that about 90% of patients report the surgery to be successful. Another surgery used is “tightrope” repair of the ankle (using wire to recreate the torn ligament).
What is the long term outcome?
Ankle sprains are common injuries and most people recovery well from the injury. Athletes typically miss about 3 weeks of practice and games. Overall 15% develop severe sprains that do not improve with the initial RICE and Rehab protocol. In mild sprains, the basic RICE treatment with rehab exercises allow most athletes to return to sport after about 1-2 weeks (compared to high ankle sprains which require several weeks of rest). If pain persists and surgery is required, most patients do very well with the most commonly performed modified Brostrom. Oftentimes, if patients continue to complain of symptoms there is a chance other injuries like an osteochondral defect occurred during the initial incident and were not identified. Finally, there is an increased risk of reinjury in athletes that return to play. About 10% will develop a recurrent sprain, and it is therefore important to complete a full rehab program before going back to sport (despite the common inclination to downplay the significance of a sprain).
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