✅ Medically reviewed by Dr. Tom Biernacki, DPM — Board-certified podiatrist specializing in foot & ankle surgery. View credentials.
What Is Chronic Ankle Instability?
Chronic ankle instability (CAI) is the condition that develops when a lateral ankle sprain fails to heal properly, leaving the ankle prone to repeated sprains, a persistent feeling of “giving way,” and ongoing pain or swelling. For specialized treatment, see our ankle sprain treatment Michigan. Approximately 40% of patients who sustain an acute ankle sprain develop chronic instability—the ankle ligaments heal with elongation or scar tissue rather than at their original length and tension, leaving the joint mechanically lax. Over time, repeated sprains cause cumulative cartilage damage, and untreated instability is a leading cause of post-traumatic ankle arthritis.
CAI should be distinguished from functional instability (the feeling of giving way without true mechanical laxity) and from acute ligament tears. True chronic mechanical instability involves demonstrable laxity on clinical examination and stress X-rays. The anterior talofibular ligament (ATFL) is the most commonly injured ligament, followed by the calcaneofibular ligament (CFL). Both are on the lateral (outside) ankle and are stretched or torn during inversion (rolling the ankle inward) sprains.
Symptoms and Diagnosis
Patients with CAI describe their ankle feeling unstable, uncertain, or “loose”—they hesitate on uneven terrain, avoid activities that require lateral movement, and may have ongoing aching even on flat ground. Episodes of giving way may be frequent or occur only with specific activities. Recurrent sprains are the hallmark. Associated symptoms include persistent lateral ankle swelling, peroneal tendon pain (the tendons that run along the outside of the ankle and stabilize against inversion), and occasionally popping or clicking from peroneal tendon subluxation.
Examination demonstrates anterior drawer sign (excessive forward translation of the talus under the tibia) and talar tilt test (excessive inversion of the ankle with stress). Stress radiographs under fluoroscopy can quantify the degree of laxity. MRI evaluates the ligament integrity, identifies associated pathology (osteochondral lesions, peroneal tendon tears, loose bodies), and guides surgical planning. Up to 50% of patients with CAI have associated osteochondral lesions of the talus—a finding that significantly affects prognosis and treatment planning.
Conservative Treatment
For most patients with CAI, comprehensive physical therapy and ankle bracing provide adequate stability for daily activities and recreational sports. Physical therapy for CAI focuses on proprioceptive retraining (restoring the ankle’s ability to sense position and respond to perturbation), peroneal muscle strengthening (to provide dynamic stability against inversion forces), and functional movement retraining. Studies show that proprioceptive training reduces the rate of re-sprain by 50–60% in CAI patients. The program typically spans 6–12 weeks with progressive functional loading.
Ankle bracing—with a lace-up or semi-rigid brace—provides external stability during activity and is appropriate for athletes or highly active patients. Custom ankle-foot orthoses are indicated for severe instability or associated subtalar joint laxity. Anti-inflammatory medications and cortisone injection address reactive synovitis. High-level athletes who require maximal performance may proceed to surgical reconstruction sooner rather than accept the performance limitations of bracing.
Surgical Reconstruction: The Broström Procedure
For patients who fail conservative treatment—persistent instability despite 3–6 months of PT and bracing, or high-level athletes with recurrent sprains—lateral ankle ligament reconstruction is indicated. The gold standard procedure is the modified Broström-Gould repair: the stretched ATFL and CFL are surgically tightened (imbricated) and reinforced with a flap of the inferior extensor retinaculum (a tissue band that provides additional reinforcement). This anatomic repair restores the ligaments to their normal position and tension without sacrificing other tendons (unlike older non-anatomic procedures).
The Broström procedure is performed arthroscopically (all-arthroscopic Broström) or as an open procedure depending on surgeon preference and ligament quality. Outcomes are excellent—85–95% of patients return to full activity including sports. Recovery involves a short period of immobilization (2 weeks), followed by progressive weight-bearing in a boot, then physical therapy from 6–12 weeks. Return to sport typically occurs at 3–6 months. Complications are uncommon; the most important is sural nerve irritation from the lateral approach. In patients with generalized ligamentous laxity or failed primary repair, allograft or autograft augmentation may be required.
Frequently Asked Questions
How many ankle sprains is too many—when should I consider surgery?
There is no fixed number of sprains that automatically indicates surgery. The decision depends on: whether the instability limits your function and activities, whether you have completed a structured physical therapy program (not just rested), whether ankle bracing provides adequate control for your activity level, and whether associated pathology (osteochondral lesion, peroneal tendon tear) is identified that requires surgical treatment anyway. Generally, patients who have completed 3–6 months of dedicated PT and bracing, continue to have significant instability or recurrent sprains, and whose function or sport participation is impaired are appropriate surgical candidates. Early surgical intervention may be appropriate for competitive athletes with clear mechanical laxity to prevent cumulative joint damage.
Can ankle instability cause arthritis?
Yes. Untreated chronic ankle instability is one of the leading causes of post-traumatic ankle arthritis. Each time the ankle gives way, the talus undergoes abnormal translation and impingement against the tibial plafond—damaging the articular cartilage. Over years, this repeated microtrauma produces osteochondral lesions and ultimately cartilage loss and ankle arthritis. Studies show significantly higher rates of ankle arthritis in patients with long-standing untreated instability compared to those who receive appropriate treatment. This is one of the important reasons not to dismiss recurrent ankle sprains as a minor inconvenience—treating the instability protects the joint long-term.
Does ankle bracing weaken the ankle over time?
This is a common concern but the evidence does not support it—there is no good evidence that wearing an ankle brace for activity causes the surrounding muscles to weaken when bracing is combined with appropriate rehabilitation. The key is that bracing should be paired with physical therapy to strengthen the peroneal muscles and improve proprioception, not used as a substitute for rehabilitation. Using a brace during activities that risk re-sprain while performing progressive strengthening exercises is both safe and effective. If anything, bracing reduces re-injury risk, which prevents the further damage that occurs with each additional sprain.
Medical References & Sources
- American Orthopaedic Foot & Ankle Society — Chronic Ankle Instability
- PubMed Research — Broström Repair Outcomes
- PubMed Research — Ankle Instability Rehabilitation
Dr. Tom Biernacki, DPM is a board-certified podiatric surgeon at Balance Foot & Ankle in Howell and Bloomfield Hills, Michigan. He evaluates and treats chronic ankle instability with physical therapy, bracing, and the modified Broström-Gould lateral ligament reconstruction.
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Medically Reviewed by: Dr. Tom Biernacki, DPM — Board-Certified Podiatrist, Balance Foot & Ankle Specialists
Chronic Ankle Instability? Get Back on Solid Ground
Recurring ankle sprains and instability can lead to long-term joint damage. Our specialists offer both conservative stabilization programs and surgical repair when needed.
Clinical References
- Hintermann B et al. Medial ankle instability: an exploratory, prospective study of fifty-two cases. Am J Sports Med. 2004;32(1):183-190.
- Gould N et al. Early and late repair of lateral ligament of the ankle. Foot Ankle. 1980;1(2):84-89.
- Hertel J. Functional anatomy, pathomechanics, and pathophysiology of lateral ankle instability. J Athl Train. 2002;37(4):364-375.
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.