● Ankle Condition

Chronic Ankle Instability: Why Your Ankle Keeps Giving Way

By Dr Mike Smith · 8 November 2023

What Is Chronic Ankle Instability?

Chronic ankle instability (CAI) develops when the lateral ankle ligaments, damaged during an acute ankle sprain, fail to heal adequately, leaving the ankle mechanically or functionally unstable. Patients describe a persistent feeling of the ankle "giving way," particularly on uneven ground or during sport.

Why Does It Happen?

The lateral ankle is stabilised by three ligaments: the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and posterior talofibular ligament (PTFL). Inversion sprains most commonly injure the ATFL and CFL. If these ligaments heal with laxity or are re-injured repeatedly, chronic instability results.

Symptoms

Repeated ankle sprains (two or more in one year)
Sensation of the ankle giving way, particularly on uneven ground
Persistent ankle pain or swelling
Reduced confidence and avoidance of sporting activity

Conservative Management

Many patients with chronic ankle instability can be successfully managed with physiotherapy: peroneal muscle strengthening, proprioceptive retraining, and balance exercises. Ankle bracing and taping during sport provides mechanical support. Most patients require 3–6 months of targeted rehabilitation before considering surgery.

Surgical Ligament Reconstruction

Surgery is recommended for patients who have failed adequate physiotherapy, with confirmed mechanical laxity. The most common procedure is the Brostrom repair, the ATFL and CFL are tightened and reattached to their fibular origin. This can be performed arthroscopically (keyhole) or with a small open incision, and is augmented with a local tissue flap (Gould modification) for added strength.

For patients with poor tissue quality or failed previous surgery, a ligament reconstruction using a tendon graft may be required.

Recovery

After Brostrom repair, a below-knee cast or boot is worn for 4–6 weeks. Physiotherapy follows for 3–4 months. Return to sport is typically 4–6 months post-operatively. Results are excellent, with recurrence rates below 10%.