Chronic Ankle Instability

Persistent instability and recurrent giving way more than 12 months after an initial ankle sprain. Not a benign sequel: it raises the risk of ankle osteoarthritis and long-term disability.

Two overlapping mechanisms

Mechanical: structural ATFL and CFL laxity.
Functional: impaired proprioception and neuromuscular control, peroneal weakness.

Most patients have both.

How it develops

Inadequate rehabilitation after an acute sprain is the principal pathway. Up to 40% of acute sprains progress.
Repeated sprains cause cumulative ligament damage.
Damaged mechanoreceptors reduce feedback, and arthrogenic muscle inhibition suppresses the peroneals.
Secondary changes: osteochondral lesion of the talus, synovitis, impingement.

Risk factors

previous sprain with poor rehab (strongest), no brace or tape on return, early return to sport, generalised hypermobility, cavovarus alignment, higher BMI.

Presentation

Recurrent giving way (“my ankle rolls”), even without a formal sprain
Avoidance of uneven ground, sport limitation
Persistent lateral pain, recurrent swelling after activity
Positive anterior drawer (ATFL) and inversion stress (CFL)
Measure with the Cumberland Ankle Instability Tool (CAIT), single-leg balance and Y-balance.
Look for associated lesions: peroneal tendinopathy and osteochondral lesion of the talus are common. Persistent pain, locking or catching warrants imaging.

Management

Structured rehabilitation: balance and neuromuscular training is the mainstay of conservative treatment. Add peroneal and calf strengthening.
Bracing or taping in sport. Semi-rigid braces reduce inversion angle and reinjury, and can be used long term.
Orthoses if malaligned. Manual therapy for range and symptoms.
Surgery: modified Broström repair (with or without suture-tape augmentation) is the standard surgical option for mechanical instability. Consider it after a genuine 3 to 6 month rehab trial has failed, or with confirmed mechanical instability and functional limitation. Non-anatomic tenodesis is inferior.

Message for patients

the acute sprain must be rehabilitated, not just rested.

References

Chin J Traumatol 2025, doi:10.1016/j.cjtee.2024.07.011
Risk factors for CAI after first lateral ankle sprain, J Sport Health Sci 2023, doi:10.1016/j.jshs.2023.03.005
Foot Ankle Clin 2022, doi:10.1016/j.fcl.2021.11.025

Medical disclaimer: this article is general information, not personal medical advice. Always consult a qualified doctor about your own situation.