Chronic Ankle Instability: Causes, Diagnosis & Treatment from a Podiatrist

Chronic Ankle Instability: Causes, Diagnosis & Treatment from a Podiatrist

You sprained your ankle months ago. The acute pain and swelling resolved, but the ankle never felt quite right. You roll it on uneven ground, on steps, walking down a ramp — situations that never bothered you before. The ankle gives way unpredictably, sometimes accompanied by a sharp pain, other times just a sensation of the joint shifting. This is chronic ankle instability, and it’s one of the most undertreated conditions in sports medicine — largely because the ankle “looks fine” on routine X-rays and patients are told their sprain has healed when it functionally hasn’t.

What Is Chronic Ankle Instability?

Chronic ankle instability (CAI) is defined as the persistence of instability, giving-way episodes, and reduced function for more than 12 months after an acute lateral ankle sprain. It develops when the mechanical and neuromuscular deficits from an acute sprain are not fully rehabilitated. The anterior talofibular ligament (ATFL) — the most commonly injured ligament in a lateral ankle sprain — when incompletely healed or mechanically elongated, allows excessive anterior translation and internal rotation of the talus within the mortise. The calcaneofibular ligament (CFL) is frequently injured concurrently and contributes to subtalar instability.

Up to 40% of acute lateral ankle sprains progress to CAI — a substantial percentage that reflects under-rehabilitation of the neuromuscular deficits (proprioception loss, peroneal muscle weakness) that are equally important as the structural ligament damage. Patients who return to sport too quickly without formal rehabilitation are at highest risk.

Chronic Ankle Instability Symptoms

• Recurrent giving-way — the ankle rolls or “gives” unexpectedly during normal activities, not just sport
• Persistent sense of looseness — subjective feeling that the ankle is not firmly seated, even without actual giving-way episodes
• Recurrent sprains — repeated lateral ankle injuries with decreasing force required to produce them
• Anterolateral ankle pain — chronic pain at the ATFL footprint, which may represent synovitis, impingement, or incomplete ligament healing
• Reduced confidence on uneven ground — patients adapt by avoiding certain surfaces, activities, or sports, a form of functional limitation that extends far beyond the ankle itself

How We Diagnose Chronic Ankle Instability

The diagnosis of CAI is primarily clinical. We use two manual tests: the anterior drawer test (anterior translation of the talus under the tibia, testing ATFL integrity) and the talar tilt test (inversion stress testing CFL integrity). Both tests are compared side-to-side — asymmetric laxity confirms mechanical instability. Weight-bearing X-rays are obtained to rule out osteochondral lesions, os subfibulare, or arthritic changes. MRI is ordered for suspected osteochondral defect of the talus (OCD), chronic peroneal tendon tears, or pre-operative planning when surgery is being considered.

Chronic Ankle Instability Treatment

Neuromuscular rehabilitation is the cornerstone of conservative treatment and achieves full resolution in 70-85% of patients when performed correctly and completely. The rehabilitation program addresses four components: peroneal muscle strengthening (the primary dynamic stabilizers of the lateral ankle), proprioception and balance training (single-leg stance progressions, balance board, perturbation training), ankle joint range of motion restoration, and sport-specific functional progressions. A formal physical therapy program supervised by a therapist experienced in ankle rehabilitation typically spans 6-12 weeks.

Ankle bracing provides functional support during rehabilitation and sport participation. Lace-up braces or semi-rigid stirrup braces (AirCast) reduce the risk of recurrent sprains during rehabilitation. Chronic reliance on bracing without addressing the neuromuscular deficits is a management failure — the goal is to rehabilitate the ankle to the point where bracing is no longer required for daily activities, even if sport-specific bracing continues.

Brostrom-Gould lateral ankle ligament reconstruction is the gold standard surgical procedure for CAI that fails conservative management. The ATFL and CFL are anatomically repaired with augmentation using the inferior extensor retinaculum (the Gould modification), which also addresses subtalar instability. Outcomes are excellent — over 90% of patients achieve full return to sport with restored stability. Recovery takes 4-6 months to full activity. Arthroscopic evaluation at the time of surgery allows concurrent treatment of any osteochondral defects or synovitis.

The Most Common Mistake We See

The most common mistake is treating CAI with just an ankle brace and never completing formal neuromuscular rehabilitation. Patients brace for sport, avoid the activities that cause giving-way, and gradually develop progressive ankle arthritis from repeated micro-instability episodes that the brace doesn’t fully prevent. The only way to restore true dynamic stability is to strengthen the peroneal muscles and retrain proprioception — a brace alone cannot achieve this.

Frequently Asked Questions

Can chronic ankle instability heal on its own?
Mild cases with predominantly neuromuscular deficits may improve with an independently performed home exercise program. However, established mechanical instability (demonstrable laxity on examination) typically requires formal rehabilitation and sometimes surgery to restore reliable stability. Instability that persists untreated leads to progressive cartilage damage.

How long does ankle instability rehabilitation take?
A structured 6-12 week supervised rehabilitation program resolves the majority of chronic ankle instability cases. Return to full sport typically takes 12-16 weeks from the start of formal rehabilitation for patients who complete the program consistently.

What is the Brostrom procedure?
The Brostrom-Gould procedure is the gold standard surgical repair for chronic lateral ankle instability. It anatomically restores the ATFL and CFL using the patient’s own tissue (no graft required), with excellent long-term results and preservation of normal ankle kinematics. Over 90% of patients return to pre-injury sport level.

The Bottom Line

Chronic ankle instability is highly treatable — with formal neuromuscular rehabilitation for most patients, and the Brostrom-Gould procedure for the minority who fail conservative management. The key is not accepting recurrent sprains and giving-way as a permanent consequence of an old ankle injury. With the right treatment, the vast majority of patients achieve full stability and return to all activities including competitive sport.

Sources

• Vuurberg G et al. Diagnosis, treatment and prevention of ankle sprains. Br J Sports Med. 2018.
• Gribble PA et al. 2016 Consensus statement on ankle instability. J Athl Train. 2016.
• Krips R et al. Long-term outcome of the modified Evans procedure. JBJS. 2022.