Chronic Ankle Instability

Ankle sprains are one of the most common injuries, particularly in athletics- occurring in at least 20% of athletes. Acute ankle sprains are typically treated conservatively with RICE (rest, ice, compression, and elevation) with a quick return to activity- usually within a few weeks. However, for many, there are lingering deficits that may go unnoticed at first and can lead to chronic ankle instability. Up to 33% of patients continue to report difficulties 1 year after an ankle sprain. Commonly reported difficulties to include pain, weakness in the foot, and ankle muscles, poor balance, poor neuromuscular control (How our brain and muscles coordinate movements), and poor proprioception (how our brain knows where our body is in space). 

Chronic ankle instability can be functional, mechanical, or a combination of the two. Functional instability is typically based on reported symptoms and results from the deficits listed above. Mechanical instability is a direct result of increased laxity (i.e. looseness) of the supporting ligaments of the ankle, which can occur after injury. Chronic ankle instability can lead to recurrent ankle sprains and may result in further injury to ankle joint and surrounding bones, muscles, and ligaments.

Ankle Anatomy:

• Bones: The ankle joint is formed by the tibia, fibula, and talus. These 3 bones articulate (move) in a complex manner that allows your foot and ankle to adapt to the changing demands as you walk. The talus sits right on top of the calcaneus (Heel bone), and right behind the navicular; Though the calcaneus and navicular are not inherently part of the ankle joint, but they are closely connected. The ankle can move dorsiflexion (up), plantarflexion (down), inversion (Foot comes in), and eversion (foot goes out). 

• Ligaments: There are many ligaments that attach these bones together
  • The inner part of your ankle is supported by the strong deltoid ligament complex that attaches the tibia to the navicular, the calcaneus, and the talus. It keeps the ankle stable during eversion of the foot and prevents subluxation of the ankle joint.
  • The outer part of your ankle is supported by 3 small ligaments that are attached to the fibula and the talus, and calcaneus: anterior talofibular ligament, calcaneofibular ligament, & posterior talofibular ligament. These function to stabilize the ankle and guide its motion. They are resistant to inversion and internal rotation of the ankle. However, these are thin ligaments and are frequently injured with ankle injuries with the anterior talofibular ligament being the most commonly injured ligament. 
• Muscles