Chronic Ankle Instability: Causes, Diagnosis & Treatment

Understanding Chronic Ankle Instability

Chronic ankle instability (CAI) is characterized by persistent subjective instability — the feeling that the ankle will “give way” — along with recurrent ankle sprains occurring on uneven ground or during sports activities. CAI affects up to 40% of patients following an initial ankle sprain and is one of the most common sports-related conditions seen in podiatric practice.

The condition arises from inadequate healing of the lateral ankle ligaments — most commonly the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) — after one or more inversion sprains. Incompletely healed ligaments remain lax, allowing excessive inversion movement and leading to repeated injury cycles that perpetuate and worsen instability over time.

Risk Factors and Symptoms

Risk factors include inadequate rehabilitation of the initial sprain, high-arched or supinating foot structure, peroneal muscle weakness, and impaired proprioception. The hallmark symptom is a subjective feeling of ankle weakness or “giving way,” particularly on uneven terrain during cutting movements or when landing from jumps. Many patients report repeated sprains over months to years, along with chronic soreness and swelling after activity on the outer ankle.

Untreated CAI leads to osteochondral lesions of the talus (cartilage damage from repeated traumatic loading), peroneal tendon pathology, and early ankle arthritis as long-term consequences — making prompt treatment important beyond just symptom relief.

Diagnosing Chronic Ankle Instability

The anterior drawer test assesses ATFL laxity by translating the talus anteriorly; a positive test with significant laxity compared to the opposite ankle indicates instability. The talar tilt test evaluates CFL integrity. MRI is indicated to evaluate associated pathology including osteochondral lesions and peroneal tendon tears. Diagnostic ankle arthroscopy may reveal intra-articular pathology not visible on MRI.

Conservative Treatment: Physical Therapy and Bracing

The foundation of CAI treatment is a structured physical therapy program. Peroneal muscle strengthening is critical — strong peroneals act as dynamic stabilizers that compensate for ligament laxity. Proprioceptive retraining using balance boards and perturbation training restores the ankle’s ability to rapidly correct during destabilizing movements. Lace-up ankle braces provide external mechanical support during sports and significantly reduce re-sprain rates. Custom orthotics with lateral posting address supinated foot mechanics that increase inversion stress on the lateral ligaments.

Surgical Treatment: The Broström Procedure

When 4–6 months of dedicated conservative treatment fails, surgical ligament reconstruction is indicated. The modified Broström procedure is the gold standard for CAI surgery — it tightens and re-anchors the stretched ATFL (and sometimes CFL) to the fibula using suture anchors, restoring appropriate mechanical stability to the lateral ligament complex. The procedure has excellent long-term outcomes with high patient satisfaction. Most patients return to sports and full activity within 4–6 months. Minimally invasive arthroscopic-assisted versions are increasingly available and may offer faster recovery.

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Dr. Tom Biernacki, DPM

Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.