Ankle sprains constitute the majority of ankle injuries and account for 3%-5% of all UK emergency department attendances. They involve at least one of the ankle ligaments, with injuries ranging from a small tear to a complete rupture of one or more ligaments.
Classification and Grading
Ankle sprains are classified into lateral, medial and high ankle sprains.
Lateral ankle sprains (most common, 85%, in particular ATFL) usually result from inversion stress of a plantarflexed foot. Pain, swelling and tenderness are typically located anterior and inferior to the lateral malleolus.
Isolated medial ankle sprains are uncommon, as the deltoid ligament complex is the strongest of the ankle ligaments. These occur in combination with lateral ligament injures. An avulsion fracture of the medial malleolus may also occur. Pain and bruising are usually located inferior to the medial malleolus.
A high ankle sprain (syndesmotic sprain) involves the anterior, posterior and transverse tibiofibular ligaments and the interosseous membrane. These structures are important to ankle stability and their injury may lead to chronic complications. The region of pain and tenderness is different and is located in the groove between the distal fibula and tibia, superior to the lateral malleolus.
According to severity of injury, sprains are graded from I to III.
Grade I injuries are self-limiting, with only stretching of the ligament. Grade II and III injuries are either a partial tear or complete rupture of the ligament complex, and are typified by inability to bear weight on the leg, and by substantial amounts of swelling.
Assessment is primarily clinical, but exclusion of a bony injury is important by obtaining standard plain radiographs.
Some systematic reviews have highlighted a lack of quality evidence to aid clinical decision making, i whether to mobilise or immobilise the joint, and, if immobilisation is chosen, which types of supports provide the best choice.
However, a multicentre RCT by Lamb et al. (584 patients with acute sprains in 8 UK centres) reported that short period of immobilisation in a below-knee cast or Aircast splint resulted in faster recovery than if the patient is only given tubular compression bandage in the early stage after sprain, and promoted faster recovery of function at 3 months.
In acute phase, elevation, icepacking and compression are helpful. After an initial period of rest and protected weightbearing , gradual rehabilitation starts as soon as pain and swelling improves. Emphasis is generally focussed on improving proprioception and dorsiflexion, as an inadequate recovery has been shown to lead to recurrent sprains.
Several therapeutic interventions are tried to improve dorsiflexion including stretching, manual therapy, electrotherapy, hyperbaric oxygen therapy, ultrasound and exercises, however a combination of interventions has been found most effective.
A systematic review by Gribble et al. concluded that a static-stretching intervention as part of a standardized home exercise program had the strongest effects on improvement of ankle dorsiflexion after acute sprains.
Tightness in the gastrocnemius-soleus complex is not likely to be caused directly by acute ankle sprain but may develop as an adaptive response to immobilization and result from an abnormal gait pattern. The stretching intervention is believed to increase the flexibility before pain perception and allows the viscoelastic properties of musculo-tendinous junction to overcome the stretch reflex or increase the stretch tolerance.
Ankle dorsiflexion is typically restricted by pain, spasm and swelling. Cryotherapy and electrotherapy often are incorporated to minimise pain, spasm and neural inhibition, and thereby allowing for earlier and more aggressive interventions that aim to restore normal function.
Hyperbaric oxygen therapy is purported to cause vasoconstriction, facilitate reabsorption of extravascular fluid into the circulation, and accelerate debridement by increasing oxygen delivery to macrophages, thus assisting in controlling the amount of swelling.
Borromeo et al. reported small to moderate effect sizes for increases in ankle dorsiflexion after 1 dose of hyperbaric oxygen. Therefore, although associated with mostly favourable results, the improvement in ankle dorsiflexion after 1 dose of cryotherapy, electrotherapy, and hyperbaric oxygen may not be clinically relevant.
Green et al. reported a small associated effect size for acute increase in ankle dorsiflexion after a RICE protocol in the control group, whereas Peer et al. reported negative effects for immediate improvement in ankle dorsiflexion after a RICE protocol in patients with acute ankle sprain.
Sandoval et al. noted strong effect sizes after negative-polarity high-voltage pulsed stimulation (HVPS) with a standardised intervention program or the standardized intervention program alone.
Selection of therapeutic interventions for improving ankle dorsiflexion after ankle sprains depends on multiple limiting factors to dorsiflexion. Hence it is important for a clinician to consider an approach to improve the dorsiflexion that may necessitate recognising the key factors that limit ankle dorsiflexion.
A systematic review has reported that most recovery occurs within the first 6 months after the sprain, and re-injury rates stabilise thereafter.
For surgical management of acute and chronic instability, read 'Ankle Instability' section.
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