What Is an Ankle Sprain?
An ankle sprain is an injury of the ligaments that stabilize the ankle joint, caused by a forced movement beyond physiologic range. It is the most frequent musculoskeletal injury in emergency departments and the most common in sport, accounting for about 25% of all sports injuries.
The most common mechanism is forced inversion of the foot (twisting inward), which injures the lateral ligaments — especially the anterior talofibular ligament (ATFL). Eversion sprains (twisting outward) are less frequent but are often more severe, involving the medial ligamentous complex (deltoid ligament) and the tibiofibular syndesmosis.
Mechanism
Forced inversion of the foot — stepping on an uneven surface, landing from a jump, change of direction in sport
At-Risk Population
Athletes in sports with jumps and changes of direction (basketball, soccer, volleyball), patients with prior sprain
Main Complication
Chronic ankle instability in 30-40% of cases — the biggest risk factor is a prior, inadequately treated sprain
Impact
Days to months away from sport, with long-term risk of ankle osteoarthritis if chronic instability develops
Pathophysiology
Ankle ligaments are dense connective-tissue structures composed mainly of type I collagen fibers, organized in parallel bundles that resist tension forces. When the ankle is forced beyond its physiologic range, these fibers undergo stretching, partial rupture, or complete rupture, depending on the intensity of the applied force.
The anterior talofibular ligament (ATFL) is the most frequently injured because it is the weakest of the three lateral ligaments and is the first to be tensioned during inversion. If the force continues, the calcaneofibular ligament (CFL) is injured next. Rupture of the posterior talofibular ligament (PTFL) is rare and indicates a high-energy sprain.
Beyond the ligament injury, a sprain damages the articular mechanoreceptors (Ruffini corpuscles, Pacini corpuscles, and ligament receptors) that are fundamental for proprioception. The proprioceptive loss is the main factor in chronic functional ankle instability and explains why neuromuscular rehabilitation is so important.
Symptoms
Symptoms vary by sprain grade. The main symptom is acute ankle pain immediately after the twisting mechanism, accompanied by progressive edema. In more severe grades, the patient reports having heard or felt a "pop" at the moment of injury.
- 01
Acute lateral ankle pain after twisting
- 02
Progressive edema (maximum in 24-48 hours)
- 03
Ecchymosis (bruising) on the lateral or medial ankle
- 04
Difficulty or inability to bear weight on the foot
- 05
Pop sensation at the moment of injury
- 06
Instability or sensation of ankle "giving way"
- 07
Joint stiffness from edema
- 08
Tenderness on palpation of the injured ligaments
Diagnosis
The diagnosis of ankle sprain is clinical, based on the mechanism of injury, physical examination, and application of the Ottawa Rules to decide the need for radiograph. Magnetic resonance imaging is reserved for cases with atypical evolution or suspicion of associated injuries (osteochondral lesion, tendon rupture).
🏥Ottawa Rules for the Ankle
- 1.Radiograph indicated if malleolar-zone pain AND: tenderness on palpation of the posterior edge of the distal 6 cm of the lateral malleolus
- 2.Tenderness on palpation of the posterior edge of the distal 6 cm of the medial malleolus
- 3.Inability to take 4 steps immediately after the injury and at assessment
- 4.Foot radiograph indicated if: pain at the base of the fifth metatarsal or at the navicular
- 5.Sensitivity: >98% to rule out fracture — safe for avoiding unnecessary radiographs
TESTS ON PHYSICAL EXAMINATION
| TEST | WHAT IT ASSESSES | INTERPRETATION |
|---|---|---|
| Anterior drawer | Integrity of the ATFL | Anterior translation of the talus indicates ATFL rupture |
| Talar tilt (forced inversion) | ATFL and CFL | Excessive medial opening indicates combined injury |
| Squeeze test | Tibiofibular syndesmosis | Syndesmotic pain when compressing fibula against tibia |
| External rotation test | Tibiofibular syndesmosis | Pain with external rotation of the foot — syndesmotic injury |
| Bony palpation | Associated fractures | Point tenderness at malleolus, base of the 5th metatarsal, navicular |
Differential Diagnosis
Although ankle sprain is the most common injury after a twisting mechanism, several other conditions can present similarly. Correctly identifying the underlying injury is essential to avoid inadequate treatment and long-term complications.
DIAGNÓSTICO DIFERENCIAL
Differential Diagnosis
Ankle Fracture (Ottawa Rules)
- Inability to bear weight for 4 steps
- Bony pain at the distal fibula or medial malleolus
- Positive Ottawa Rules
- Positive Ottawa = mandatory radiograph
Testes Diagnósticos
- Radiograph per Ottawa Rules
5th Metatarsal Fracture
- Pain at the base of the 5th metatarsal
- Inversion + plantarflexion mechanism
- Tender palpation of the base of the 5th metatarsal
Testes Diagnósticos
- Foot radiograph
Peroneal Tendon Rupture
- Persistent lateral instability
- Pain posterior to the lateral malleolus
- May worsen with resisted inversion
Testes Diagnósticos
- Ultrasonography
- MRI
Sinus Tarsi Syndrome
- Lateral ankle pain after sprain
- Persistent and subtle
- Tender palpation of the sinus tarsi
Testes Diagnósticos
- Diagnostic infiltration
- MRI
Superficial Peroneal Nerve Neuropathy
- Numbness on the dorsum of the foot
- Burning pain
- After severe sprain or compression
Testes Diagnósticos
- EMG/NCS
- Diagnostic block
Fractures associated with ankle twisting
The Ottawa Rules were developed precisely to distinguish ligamentous sprain from fracture, avoiding unnecessary radiographs. Two anatomic sites require special attention: the base of the 5th metatarsal (avulsion by the peroneus brevis) and the navicular, which are frequently overlooked on initial examination. Inability to take four steps with weight bearing, both immediately after trauma and at medical evaluation, is the most sensitive functional criterion for indicating imaging.
Jones fracture (in the diaphysis of the 5th metatarsal, 1.5-2 cm from the base) deserves special attention because it has a high non-union rate and may require surgical treatment — unlike avulsion fracture of the base of the 5th metatarsal, which generally resolves with conservative treatment. Careful clinical examination with selective palpation distinguishes the two.
Peroneal tendon injuries: persistent lateral instability
Peroneal tendon rupture — peroneus longus and peroneus brevis — can occur alongside a lateral ankle sprain and is frequently underdiagnosed. A patient with persistent lateral instability after a properly treated sprain should be evaluated for this possibility. The pain is located posterior to the lateral malleolus, distinguishing it from the more anterior ligamentous pain.
Ultrasonography and MRI are the studies of choice for assessing the peroneal tendons. Longitudinal rupture of the peroneus brevis is the most common injury and may require surgical repair in athletes with persistent functional instability. Early identification prevents progression to chronic instability refractory to conservative treatment.
Sinus tarsi syndrome and peroneal neuropathy: causes of residual pain
Sinus tarsi syndrome is an under-recognized cause of persistent lateral pain after sprain, resulting from damage to the ligamentous and nervous structures of the sinus tarsi — the anatomic space between the talus and calcaneus. The pain is subtle, persistent, and worse on uneven terrain, with tenderness on direct palpation of the sinus tarsi (lateral point below the fibular malleolus). Diagnostic infiltration with local anesthetic confirms the diagnosis.
Superficial peroneal nerve neuropathy can arise after a severe sprain from nerve traction or compression during acute edema. The patient reports numbness and burning on the dorsum of the foot, in the distribution of this nerve. Electroneuromyography and diagnostic block aid confirmation. The acupuncturist physician may consider needling along the nerve's path as a complementary approach for residual neuropathic pain.
Treatment
The treatment of most ankle sprains is conservative, even in grades II and III. The PRICE protocol (Protection, Relative rest, Ice, Compression, Elevation) has evolved into the concept of PEACE & LOVE, which emphasizes early mobilization and neuromuscular rehabilitation as pillars of treatment.
Acute Phase — PEACE (0-3 days)
Protection (avoid excessive load, do not immobilize completely), Elevation, Avoid anti-inflammatories in the first days, Compression, Education (avoid excessive passive treatments).
Subacute Phase — LOVE (3-14 days)
Load (progressive loading as tolerated), Optimism (positive expectations), Vascularization (cardiovascular exercise without pain), Exercise (mobility, strengthening, proprioception).
Rehabilitation (2-6 weeks)
Strengthening of the peroneals and ankle stabilizers. Intensive proprioceptive training (balance board). Progressive return to running and sports activities.
Return to Sport (6-12 weeks)
Functional jump and balance tests. Gradual return to sport with protection (functional brace or taping). Recurrence prevention program.
Acupuncture as Treatment
Acupuncture can be used as a complementary treatment in ankle sprain, both in the acute phase for control of pain and edema and in the rehabilitation phase. The mechanisms involve pain modulation through release of endogenous opioids, improvement of local microcirculation, and a possible effect on resolution of inflammatory edema.
Studies suggest acupuncture can accelerate edema resolution and allow earlier mobilization by reducing pain. In the rehabilitation phase, electroacupuncture can facilitate neuromuscular activation of the peroneals, contributing to proprioceptive recovery. Acupuncture does not replace, but complements, proprioceptive training.
Prognosis
The prognosis for grade I and II sprains is generally favorable with adequate rehabilitation. Grade I sprains resolve in 1-2 weeks; grade II in 4-6 weeks; grade III in 8-12 weeks. The most important prognostic factor is the quality of proprioceptive rehabilitation, not the grade of the initial injury.
The main problem is the high rate of recurrence and chronic instability. About 30-40% of patients with lateral sprain develop chronic ankle instability, defined by repeated episodes of giving way and recurrent sprains. Proprioceptive rehabilitation reduces this rate by half.
Myths and Facts
Myth vs. Fact
A mild sprain needs no treatment — just wait for the pain to pass.
Even grade I sprains require proprioceptive rehabilitation to prevent chronic instability. Rest alone does not restore lost proprioception.
The ankle must be immobilized with a cast or boot after a sprain.
Prolonged rigid immobilization is harmful. Early mobilization with functional protection (semi-rigid brace) outperforms a cast.
Anti-inflammatories should be taken immediately after a sprain.
Recent evidence suggests that NSAIDs in the first 48-72 h can delay ligament healing. Initial inflammation is a necessary part of the repair process.
If you can walk, it cannot be serious.
Some patients can walk even with complete ligament rupture (grade III). Weight-bearing ability is not a reliable indicator of injury severity.
When to Seek Medical Help
Frequently Asked Questions
Ankle Sprain: Common Questions
No. The Ottawa Rules indicate radiograph only when there is bony tenderness on palpation of the malleoli or foot AND inability to take 4 weight-bearing steps. When the rules are negative, fracture risk is less than 2% and the radiograph can be safely omitted, avoiding unnecessary tests.
It depends on the grade: grade I sprains heal in 1-2 weeks; grade II in 4-6 weeks; grade III in 8-12 weeks. However, full functional recovery — including proprioception — can take longer than pain resolution. Keep the rehabilitation program going even after symptoms improve.
Return to sport should be based on functional criteria, not just on time. The criteria are: absence of pain on weight bearing, complete range of motion, symmetric peroneal strength, and approval on functional jump and balance tests. Use of a functional brace on return reduces the risk of re-sprain.
Chronic instability is defined as repeated episodes of the ankle giving way for more than 12 months after the initial sprain, affecting 30-40% of patients. The main cause is untreated proprioceptive deficit. Adequate proprioceptive rehabilitation from the first sprain is the best prevention.
No. Current evidence shows that rigid immobilization (cast) is inferior to early mobilization with functional protection (semi-rigid brace or taping). Complete rest and casts delay recovery and raise the risk of joint stiffness and muscle atrophy. The PEACE & LOVE concept has replaced the old PRICE.
Recent evidence recommends avoiding NSAIDs in the first 48-72 hours, since initial inflammation is a necessary part of ligament healing. For severe pain, acetaminophen is a safer option in this phase. From day 3, NSAIDs can be used if needed, but only for a limited time.
Yes, as a complementary treatment. In the acute phase, distal points can reduce pain and edema without direct needling in the inflamed area. In rehabilitation, electroacupuncture can facilitate neuromuscular activation of the peroneals and support proprioceptive recovery. Medical acupuncture does not replace proprioceptive exercises but can enhance them.
The main strategies are: a proprioceptive training program (balance board, single-leg stance) for at least 6 weeks after the sprain; a functional brace or taping during sport for 6-12 months; strengthening of the peroneals and ankle-stabilizing muscles; and adequate sports footwear.
The vast majority of sprains (even grade III) resolve with conservative treatment. Surgery is indicated in rare cases of chronic instability refractory to a rehabilitation program of at least 3-6 months, or in associated injuries (tendon rupture, severe osteochondral lesion). The most common procedure is anatomic ATFL reconstruction (Broström-Gould technique).
In most cases, yes. Acute edema resolves in 2-4 weeks with adequate treatment. However, some periarticular thickening may persist for months, especially in grade II and III sprains. Persistent edema after 6-8 weeks warrants reassessment to rule out an associated injury (tendon, osteochondral) or sinus tarsi syndrome.