Chronic ankle instability (CAI) is a condition in which the ankle repeatedly rolls, twists, or gives way — often during ordinary activities like walking on uneven ground — because the ligaments on the outside of the ankle never fully regained their strength after an earlier sprain. Instead of one injury and a clean recovery, the ankle enters a cycle of repeated sprains that leaves it progressively weaker and less stable.
A single ankle sprain is common and usually heals within a few weeks. But when healing is incomplete — because the injury wasn't rehabbed fully, or because a second sprain happens before the first has recovered — the ligaments that hold the ankle joint together can end up permanently stretched. Once that happens, the ankle becomes easier to roll again, and each additional sprain further loosens the joint.
What causes chronic ankle instability?
CAI almost always starts with an acute lateral ankle sprain, most often from rolling the ankle outward. The ligaments on the outside of the ankle work something like rubber bands: a single stretch will spring back, but repeated overstretching gradually causes them to lose their elasticity and strength. Contributing factors include:
- An ankle sprain that wasn't given time to fully heal before returning to activity
- Skipping physical therapy or ankle-strengthening exercises after a sprain
- Repeated sprains to the same ankle over months or years
- Weak peroneal (outer lower-leg) muscles that normally help stabilize the joint
- Reduced proprioception — the ankle's sense of its own position — following ligament injury
- Naturally loose ligaments or a high-arched foot that shifts more weight to the outside of the foot
Each time the ankle rolls, the ligament stretches a little further and loses a little more of its supportive strength, making the next sprain more likely — the hallmark cycle of chronic instability.
What are the symptoms of chronic ankle instability?
People with CAI often describe a persistent feeling that the ankle can't be trusted. Common symptoms include:
- Repeated ankle sprains, sometimes from minor missteps
- A feeling of the ankle "giving way," rolling, or being unstable, especially on uneven surfaces
- Ongoing swelling, tenderness, or pain along the outside of the ankle
- Persistent stiffness or a reduced range of motion
- Weakness or a lack of confidence when walking, running, or changing direction
How is chronic ankle instability diagnosed?
Our podiatrists start with a physical exam and a detailed history of prior sprains, checking the ankle's range of motion, stability, and areas of tenderness. Stress tests can help assess how much the ligaments have loosened. Imaging — X-rays to rule out fracture or arthritis, and sometimes MRI to evaluate the ligaments and cartilage in more detail — is often used to confirm the diagnosis and check for related damage, such as cartilage injury within the joint.
How is chronic ankle instability treated?
Most people with CAI improve substantially with a structured, nonsurgical rehabilitation program, especially when it's started before the cycle of repeated sprains has caused significant joint damage.
Nonsurgical treatment
- Physical therapy focused on ankle strengthening, balance, and proprioception (the joint's position sense)
- Bracing or taping during activity to provide extra external support while the ankle rebuilds strength
- Supportive footwear and, when needed, custom orthotics to improve alignment and reduce lateral strain
- Activity modification to avoid surfaces or movements that repeatedly trigger rolling
- Anti-inflammatory measures, such as ice and NSAIDs, for acute flare-ups
Surgery
When conservative treatment doesn't restore adequate stability — or when the ankle continues to sprain despite consistent rehab — surgical ligament reconstruction may be recommended to tighten and repair the stretched ligaments. Our physicians reserve surgery for cases that don't respond to a full course of nonsurgical care.
Why chronic ankle instability shouldn't be ignored
Left untreated, the repeated injury cycle of CAI can lead to lasting damage inside the joint, including cartilage wear and early degenerative changes that may progress toward osteoarthritis. Addressing the instability early — rather than simply icing each new sprain and moving on — gives the ankle its best chance of staying strong and functional long-term.
If your ankle has rolled more than once, still feels unstable months after an injury, or gives way during normal daily activity, it's worth having it evaluated. You can request an appointment at either of our Northern Utah offices.
Medically reviewed by the physicians at Wasatch Foot & Ankle Institute. Our board-certified, fellowship-trained podiatrists provide foot and ankle care in Farmington and South Ogden, Utah. This article is for general education and is not a substitute for an in-person evaluation.