Most lateral ankle sprains involve the ATFL, with the CFL more likely to be involved in more substantial injuries. Many sprains recover well, but a subset of patients develop persistent pain, recurrent sprains or episodes of giving way. Those chronic symptoms may reflect ligament insufficiency, sensorimotor deficits, joint pathology or another missed diagnosis.
Understanding which of these is present is the difference between a rehabilitation plan that works and months of treating the wrong thing.
How often sprains become chronic
Chronic instability
Up to 40%
estimated proportion of people with a first-time lateral ankle sprain who develop chronic ankle instability
PMID 31162943
Ligaments in chronic cases
ATFL in all
of 179 surgical patients; the CFL was injured in a minority
PMID 42282263
The 40% figure is an estimate from a narrative model, and the surgical series describes patients selected for arthroscopy, not everyone with a sprain.
The lateral ligament complex
Three ligaments stabilize the outside of the ankle:
- Anterior talofibular ligament (ATFL): runs from the front of the fibula to the talus. It resists the talus sliding forward and rolling inward, especially when the foot is pointed down, which is the position of most sprains.
- Calcaneofibular ligament (CFL): runs from the tip of the fibula down to the calcaneus, spanning both the ankle and subtalar joints. It contributes to lateral stability across different ankle positions.
- Posterior talofibular ligament (PTFL): runs from the back of the fibula to the talus and is less commonly injured in a typical inversion sprain.
The ATFL is the ligament most commonly injured during a lateral ankle sprain, while the CFL becomes increasingly important when the injury is more substantial or instability persists.
What surgery shows about chronic cases
In a 2026 series, 179 patients underwent arthroscopy for chronic lateral ankle instability. All had ATFL injuries. The most common pattern, in 73.2%, was an isolated injury to the upper band of the ATFL, which the authors linked to milder microinstability. The remaining 26.8% also had injuries to the lower ATFL band, with or without the CFL; the CFL itself was involved in 5.6% (Vermorel, 2026).
More than half of these patients, 54.7%, also had problems inside the joint, most often soft-tissue impingement in 43.6% and osteochondral lesions in 15.1%. Agreement between the preoperative diagnosis and what arthroscopy found was poor. These patients had already been selected for surgery, but the pattern is a useful reminder: a chronically symptomatic ankle often has more than one problem.
Why some sprains become chronic
An updated model of chronic ankle instability describes how the initial ligament injury can lead to a set of interrelated pathomechanical, sensory-perceptual and motor-behavioral impairments (Hertel, 2019). In plain terms, chronic symptoms are rarely explained by the ligament alone. Contributors include:
- Residual ligament laxity: the ligament heals elongated or insufficient.
- Incomplete rehabilitation: pain settles before strength, balance and reaction time return.
- Balance and proprioceptive deficits: the ankle's sense of position and the speed of protective responses are reduced.
- Strength deficits: particularly in the peroneal muscles, which resist inversion, and the calf.
- Restricted dorsiflexion: stiffness changes how the ankle loads during walking, running and landing.
- Joint pathology: soft-tissue impingement, osteochondral lesions or synovitis.
- Fear and altered movement: avoiding certain movements changes control and confidence.
- Premature return to sport: high-demand activity before the ankle is ready.
Chronicity should not be reduced to scar tissue. Several of these factors are treatable, and identifying which apply is the starting point.
Recurrent sprains and giving way
A meaningful proportion of patients continue to experience recurrent sprains, giving way or persistent symptoms after an initial lateral ankle sprain. The updated model characterizes chronic ankle instability as a propensity for recurrent sprains, frequent episodes or perceptions of giving way, and persistent symptoms such as pain, swelling, limited motion, weakness and reduced function, more than 12 months after the first sprain (Hertel, 2019).
Research definitions of chronic ankle instability emphasize recurrent sprains, episodes of giving way and validated measures of instability rather than simply a history of one prior ankle sprain. The International Ankle Consortium published standardized selection criteria so that studies enroll comparable patients (Gribble, 2014).
Mechanical and functional instability
Chronic ankle instability is broader than ligament laxity. Some patients have true mechanical instability, while others experience recurrent giving way because of deficits in neuromuscular control, balance or confidence. Many have both.
An International Ankle Consortium consensus on assessing acute sprains states that chronic instability develops from the interaction of mechanical and sensorimotor impairments and recommends evaluating both early (Delahunt, 2018). Laxity on testing is interpreted alongside the giving-way history and functional control.
Other problems that look like a chronic sprain
Osteochondral lesion of the talus. Persistent deep ankle pain after a sprain should not automatically be attributed to the ligament. Osteochondral lesions of the talus can coexist with or follow ankle trauma and may require MRI or orthopedic evaluation. Clues include deep joint pain, swelling after activity, catching or locking, and a recovery that stalls despite good rehabilitation.
Syndesmotic injury. A high ankle sprain injures the ligaments joining the tibia and fibula above the ankle joint. Pain sits higher, between the shin bones, and is provoked by external rotation of the foot, push-off and cutting. Syndesmotic injuries are harder to diagnose and usually take longer to recover than lateral sprains. Weight-bearing radiographs, sometimes stress views and advanced imaging help determine stability, and unstable injuries may need surgery (Alpert, 2026). They should not be treated like a routine inversion sprain.
Peroneal tendon problems. Peroneal tendinopathy, split tears or tendon instability cause pain behind the outside ankle bone and can mimic chronic lateral ankle pain. They are covered on our peroneal tendinopathy page.
Sinus tarsi pain. Pain in the small depression in front of the outside ankle bone can follow an inversion injury or accompany instability.
Anterior impingement. Painful compression at the front of the ankle during dorsiflexion is a different problem, discussed in anterior ankle impingement vs chronic ankle instability.
How the ankle is assessed
- Pain location: ligament, joint line, syndesmosis, tendon or sinus tarsi
- Laxity with anterior drawer for the ATFL and talar tilt for the CFL
- Dorsiflexion range and where it is limited
- Peroneal and calf strength
- Single-leg balance, hop and landing control
- Syndesmotic provocation and bone tenderness
- Swelling, catching and locking that point to the joint
Rehabilitation is the foundation
A clinical guideline prefers supervised exercise-based programs over passive modalities, recommends considering ankle braces to prevent recurrent sprains and reserves surgery for cases that do not respond to thorough exercise-based treatment (Vuurberg, 2018). An overview of 46 systematic reviews found strong evidence for bracing and moderate evidence for neuromuscular training in preventing recurrence (Doherty, 2017). A 2026 network meta-analysis of 48 randomized trials in 1,630 people with chronic ankle instability found that all seven exercise approaches studied improved dynamic postural control, although the certainty of evidence for ranking them was very low (Chen, 2026).
Progressive rehabilitation may include:
- Restoring dorsiflexion where it is restricted
- Calf and peroneal strengthening
- Single-leg balance and proprioceptive training, progressing to unstable surfaces and eyes closed
- Hopping and landing mechanics
- Change of direction, running and sport-specific drills
- Graded return to the activities that previously caused giving way
An unstable ankle has to be retrained for the movements that expose the instability. Balance and strengthening are only the beginning; cutting, landing and reactive control matter when the patient's activity requires them.
What recovery usually looks like
Recovery after a lateral sprain is not linear. Pain and swelling often settle first, while balance, strength and confidence take longer. A common trap is returning to sport when the ankle stops hurting rather than when it can handle hopping, landing and cutting without giving way. Progress is best judged by function: single-leg balance, hop tests and the specific demands of a person's activity, not by pain alone.
Bracing
A brace can reduce risk during high-demand activity, but it does not replace rehabilitation of strength and sensorimotor control. It also does not repair or tighten the ligament.
Manual therapy
Manual treatment may help restore motion when mechanical restriction is present, but it does not reconstruct an insufficient ligament. A systematic review of interventions for dorsiflexion after ankle sprain found only small effects of mobilization with movement in people with recurrent sprains, and concluded that clinicians need to identify what is actually limiting dorsiflexion (Terada, 2013).
Where shockwave fits
We did not find controlled human trials showing that shockwave can heal a chronically insufficient ATFL or CFL or restores mechanical stability. Shockwave should not be used as a substitute for stability rehabilitation or surgical evaluation when clinically significant ligament insufficiency is present. The broader evidence is reviewed in shockwave therapy for chronic ankle pain.
When surgery is considered
A surgical opinion is reasonable when an ankle remains mechanically unstable and keeps giving way despite a thorough rehabilitation program, or when an osteochondral lesion, significant syndesmotic injury, loose body or other structural problem is identified.
How Novo approaches post-sprain ankle problems
We localize the pain, test laxity and functional control, screen for osteochondral, syndesmotic and tendon problems, and build rehabilitation around the deficits we find. See how we approach chronic ankle pain, sprain and impingement.
References
- Hertel J, Corbett RO. An updated model of chronic ankle instability. Journal of Athletic Training. 2019;54(6):572-588. PMID 31162943. (link)
- Vermorel PH, Vega J, Dalmau-Pastor M, Pantalone A, Zaourak J, Guelfi M. Arthroscopic findings and accuracy of preoperative diagnosis in patients with chronic lateral ankle instability. Journal of Experimental Orthopaedics. 2026;13(2):e70739. PMID 42282263. (link)
- Gribble PA, Delahunt E, Bleakley C, et al. Selection criteria for patients with chronic ankle instability in controlled research: a position statement of the International Ankle Consortium. British Journal of Sports Medicine. 2014;48(13):1014-1018. PMID 24255768. (link)
- Delahunt E, Bleakley CM, Bossard DS, et al. Clinical assessment of acute lateral ankle sprain injuries (ROAST): 2019 consensus statement and recommendations of the International Ankle Consortium. British Journal of Sports Medicine. 2018;52(20):1304-1310. PMID 29886432. (link)
- Alpert M, Duchman K, Johnson A, Jelsing E. Evaluation and management of syndesmotic injuries: a review of the literature. Current Sports Medicine Reports. 2026;25(6):174-178. PMID 42241598. (link)
- Vuurberg G, Hoorntje A, Wink LM, et al. Diagnosis, treatment and prevention of ankle sprains: update of an evidence-based clinical guideline. British Journal of Sports Medicine. 2018;52(15):956. PMID 29514819. (link)
- Doherty C, Bleakley C, Delahunt E, Holden S. Treatment and prevention of acute and recurrent ankle sprain: an overview of systematic reviews with meta-analysis. British Journal of Sports Medicine. 2017;51(2):113-125. PMID 28053200. (link)
- Chen P, Zuo H, Gong Y, Yin L, Wang L. Effects of exercise therapy on dynamic posture control and self-report function in individuals with chronic ankle instability: a systematic review with pairwise and network meta-analysis. EFORT Open Reviews. 2026;11(6):470-479. PMID 42227253. (link)
- Terada M, Pietrosimone BG, Gribble PA. Therapeutic interventions for increasing ankle dorsiflexion after ankle sprain: a systematic review. Journal of Athletic Training. 2013;48(5):696-709. PMID 23914912. (link)
