There are approximately 23,000 ankle injuries daily in the US, making up 10-15% of sport related injuries. A lateral ankle sprain is the most common and this happens when the ankle rolls inward, called inversion, while the ankle is in plantarflexion (up on the toes with the heel off the ground). This typically involves an injury to the anterior talofibular ligament (ATFL) which runs from the bottom of the fibula, which is the large bone protruding on the outside of the ankle, forward to the talus, the first bone on the top of the foot. Involvement of the ATFL alone is considered a grade 1 sprain. A grade 2 sprain also involves an injury to the calcaneofibular ligament (CFL) which runs from the bottom of the fibula down to the side of the heel. A grade 3 sprain is an injury/rupture of the ATFL, CFL, and the posterior talofibular ligament (PTFL), which runs from the bottom of the fibula around the back of the ankle to the talus.
One of the most common impairments associated with an ankle sprain is joint laxity, which means the ligaments responsible for keeping the joint stable have become loose, making the joint vulnerable to future ankle sprains. Impairments also include pain and decreased strength, specifically of the muscles responsible for ankle eversion, called the peroneals. Eversion is the opposite motion of inversion as it turns your ankle outward. When these muscles are weak they are less able to resist inversion, which is the most common position for an ankle sprain. Another common deficit is decreased joint mobility, particularly in dorsiflexion range of motion (ability to lift your toes up) and mobility between of the small bones of the foot. With decreased ROM, the foot becomes more rigid and is therefore less able to adapt to different surfaces and terrain.
An ankle sprain may also disrupt the sensory nerve fibers in the supporting structures of the ankle (ligaments, tendons, and muscles) which can cause decreased proprioception, also called joint position sense. This is one’s ability to perceive the joint’s position based on internal cues instead of visually seeing the position of the joint. More specifically, proprioception is the ability to detect motion in the foot and make postural adjustments of the whole body in response to these motions. It also involves our ability to perceive the position of the foot before it contacts the ground, as inversion ankle sprains may occur because the foot is already in an improper position as it contacts the ground and receives the additional force of your body weight. With decreased proprioception you are at further risk of future ankle sprains because you are less able to perceive foot positioning and make adjustments accordingly.
Chronic Ankle Instability
Up to 33% of individuals with an ankle sprain will resprain within 3 years, which may lead to chronic ankle instability (CAI). CAI is characterized by repeated ankle sprains with a history of giving way and feeling of instability at the ankle joint. Individuals with CAI report a significant decrease in function, due to both a mechanical and functional instability. The mechanical deficits include joint laxity with decreased mobility while the functional deficits refer to the altered proprioception and secondary neuromuscular and dynamic postural control limitations.
There is a 30% prevalence of CAI after the first ankle sprain often because first time acute ankle sprains are generally mismanaged or the athlete is allowed to return to sport too quickly. Management should include manual therapy based on ROM deficits and to improve joint mobility, neuromuscular re-education to improve proprioception, and sport specific training (jump/landing training). Prolonged immobilization only encourages decreased joint mobility, proprioception/balance, strength and ROM.
Balance training for CAI
Balance training is crucial after an ankle sprain to restore ankle strength and proprioception in order to prevent CAI. As stated above, with decreased proprioception you get decreased postural stability because the body is no longer able to detect and adjust to ankle movements. Poor balance is then demonstrated by an increased postural swaying in response to ankle movement, particularly while standing on just the affected foot.
Balance training is focused on the awareness of body position by maintaining the center of gravity over the base of support (the foot). This functional training should include standing on a wobble board and adjusting to an unstable surface and progress to more dynamic single leg weight bearing activities, like a single leg squat for example.
Be cautious!
With an ankle sprain it is always important to rule out the possibility of a fracture. Red flags include tenderness at the bones of the foot and ankle and an inability to bear weight through the injured foot. If a fracture is suspected you should seek care from either your primary care provider or visit the emergency room. If a fracture is not suspected physical therapy can be beneficial.
For more information on ankle sprains, contact Total Performance Physical Therapy to schedule an appointment.
