Rehabilitation Strategy After a Medial Ankle Sprain: Key Steps to Reduce Chronic Instability

A medial ankle sprain is an injury to the deltoid ligament complex, occurring when the foot is forced into eversion and external rotation.

• The deltoid ligament complex is made up of four superficial and two deep components.

• Grading of a medial ankle sprain:

• Grade I sprain: mild stretching of the ligament with microscopic tearing. The patient has mild swelling and tenderness, no joint instability, is able to bear weight and walk, and has only mild pain.

• Grade II sprain: incomplete tearing of the ligament. The patient has moderate pain, swelling, tenderness, and bruising. Joint examination shows mild to moderate instability, limited range of motion, and loss of function, with pain on weight-bearing and walking.

• Grade III sprain: complete tearing of the ligament. The patient has severe pain, swelling, tenderness, and bruising. Joint examination shows marked mechanical instability, with severe loss of function and range of motion, and an inability to bear weight or walk.

Epidemiology

• A medial ankle sprain is less common than a lateral ankle sprain, with an incidence of about 6%, but the prognosis is important.
• A deltoid ligament sprain is often accompanied by a lateral malleolus fracture and/or syndesmotic injury.
• If symptoms persist for a year after the initial ankle sprain, chronic ankle instability may develop (the ankle continues to feel “loose”).

Risk factors

• A previous history of ankle sprain.
• High-risk sports, including soccer, basketball, and long jump.
• A valgus foot type.
• Low arches (flat feet).
• Spring ligament dysfunction.
• Tibialis posterior dysfunction.
• Overuse fatigue of the peroneus longus.

Commonly associated conditions

• Syndesmotic tear or sprain.
• Lateral malleolus fracture and/or tibial fracture.
• Medial malleolus avulsion fracture.
• Bimalleolar and trimalleolar fractures.
• Severe lateral ligament injury.
• Spring ligament dysfunction.
• Tibialis posterior dysfunction.
• Flexor hallucis longus injury.
• Traction injury of the posterior tibial nerve and/or saphenous nerve.

History

• The injury mechanism includes landing with the foot in pronation and eversion, leading to forced external rotation, abduction, and eversion.
• Symptoms include medial ankle pain, swelling, and bruising.
• The patient should be asked about any previous ankle injury and episodes of ankle instability.

Physical examination

• Assess for medial malleolar tenderness and swelling.
• Check the stability and tenderness of the deltoid ligament.
• Assess weight-bearing ability and gait.
• A sense of a foreign object when walking.
• Perform the eversion stress test and the external rotation test to determine the extent of the deltoid ligament injury.
• Assess the patient’s gait and for a valgus flatfoot deformity on standing.

Differential diagnosis

• Syndesmotic tear or sprain.
• Tibialis posterior tendon tear or subluxation.
• Flexor hallucis longus tendon tear or sprain.
• Distal tibial fracture.
• Osteochondral fracture of the talar dome.
• Calcaneal fracture.
• Fracture of the lateral process of the talus.
• Medial ankle sprain with a proximal fibular fracture (Maisonneuve fracture).

Diagnostic tools

• In an acute injury, the Ottawa ankle rules are recommended to determine whether an X-ray is needed (inability to bear weight, tenderness at the posterior edge or tip of the lateral/medial malleolus, or tenderness at the base of the fifth metatarsal or the navicular).
• X-ray examination includes anteroposterior, lateral, and mortise views to rule out a fracture.
  • Anteroposterior, lateral, and inversion X-rays of the injured ankle are important to rule out a fracture (weight-bearing if possible).
  • At the level of the talar dome, a medial clear space greater than 3 mm between the lateral border of the medial malleolus and the medial border of the talus is abnormal and indicates a deltoid ligament rupture.
  • Consider an eversion talar tilt stress X-ray to assess for significant instability and whether surgical treatment is needed: compared with the contralateral ankle, a talar abduction tilt angle difference greater than 10 degrees is abnormal (perform this examination only in the absence of an associated fracture).
• Magnetic resonance imaging (MRI) has high sensitivity and specificity for examining superficial/deep injuries of the deltoid ligament.
• When MRI cannot be performed promptly, ultrasound is an alternative method with high sensitivity and specificity.

Initial treatment

• The PRICE principle: protect the injured area, rest, ice, compression, and elevation.
• Limit inversion/eversion stress by using an Aircast or a bladder-type boot while preserving sagittal-plane motion.
• Limit weight-bearing, using crutches or another assistive device, until the patient can walk normally.
• Ice or cold-water immersion for 15 to 20 minutes every 2 to 3 hours, for 48 hours or until swelling improves.
• Early compression to control and reduce swelling, usually with an elastic bandage or brace.
• Elevate the injured ankle above heart level to further reduce swelling.
• Short-term anti-inflammatory pain medication (NSAIDs) is an appropriate treatment.

Follow-up treatment

• Grade I sprain: functional recovery and possibly a splint or brace; the time from diagnosis to return to sport (3 to 6 weeks) is usually longer than for a lateral sprain (1 to 3 weeks).

• Grade II sprain: the same as grade I, but in addition may need a period of immobilization in a posterior splint or walking boot (3 to 4 weeks).

• Prolotherapy injection and PRP are treatment options that may be considered for relieving pain and improving chronic ankle instability.

• Follow-up rehabilitation is very important for restoring activity and reducing chronic instability. Exercises include:

• Achilles tendon stretching, ankle circles, and letter tracing.

• Isometric and isotonic plantarflexion, dorsiflexion, inversion, eversion, and toe curls.

• Picking up marbles.

• Heel walking, toe walking, a balance ball, and walking on different surfaces.

• Walk-jog, jog-run.

Surgery

• Referral considerations:

• A 4 mm medial clear space on the mortise view (bilateral, weight-bearing if possible).

• A grade III injury may need surgical repair to prevent long-term complications.

• Medial malleolus fracture.

• A displaced lateral malleolus fracture.

• Conservative treatment has failed and the injury has progressed to chronic ankle instability.

• Patients with neurovascular compromise.

Prognosis

• Pain decreases rapidly in the first 2 weeks after injury.
• The prognosis depends on the extent of the injury and any concurrent injuries. For most patients the prognosis is good, but up to 70% of patients may have some minor residual symptoms or a tendency to recur.
• More severe injuries may need a longer period of rehabilitation.
• Patients with recurrent instability are prone to early degeneration.
• Patients at high risk of recurrence may need a functional brace or taping.

Complications

• Usually more serious than a lateral ankle sprain.
• Stiffness from prolonged immobilization, recurrent instability, osteochondral defects, and chronic pain syndrome.

References

• Br J Sports Med. 2017;51(2):113–125
• Sports Med. 2014;44(1):123–140.
• Biomedicines.2024 Apr 26;12(5):963.