What is an ankle sprain?
Ankle sprain results from twisting of the foot and causes pain and swelling. While painful, ankle sprain is not debilitating. People with an ankle sprain can walk on the foot, although carefully and with pain. Ankle sprain may result from taking part in sports and physical fitness activities, and by stepping on uneven surfaces, or stepping down at an angle.
Ankle sprain involves injuries to the ligaments of the ankle, which hold the ankle bones and joint in position. Ligaments are elastic in nature and they stretch to protect the ankle joint from abnormal and excessive movements (like turning, twisting, and rolling of the foot). If during a movement, the ligament is stretched beyond its normal range, it gets sprained. A severe sprain can tear the elastic fibers of the ligament.
How common is an ankle sprain?
Ankle sprains are very common. Most sprained ankles are self-treated and hence the true incidence of ankle sprain may be difficult to assess. Ankle sprains contribute to 30% of sports injuries. In the United States, more than 23,000 people experience ankle sprains daily. Ankle sprains are more common in female basketball, soccer, and volleyball players, who are 25% more likely to develop ankle strain than male athletes.
Types of ankle sprains
Ankle sprains can be divided in following 3 grades:
Grade 1 injuries involve a stretch of the ligament with tiny tears not visible to naked eyes. These sprains do not present loss of functionality or joint instability. Though swollen, the ankle can still bear full or partial weight.
Grade 2 injuries involve a stretch of the ligament with partial tear, may cause moderate loss of function and joint instability. Symptoms include discolored, bluish-black skin, moderate-to-severe swelling, and difficulty bearing weight.
Grade 3 injuries, which involve complete rupture of the ligament, present instant and severe swelling, bluish-black discoloration of the skin, an inability to bear weight, severe pain, and moderate-to-severe instability of the joint.
Location of the sprain
Ankle sprains affect the ankle joint, which is made up of three bones: the lower tibia, the lower fibula, and the talus. These bones are held together by three sets of ligaments, called lateral ligaments, syndesdmostic ligaments, and deltoid ligaments. An injury or tearing of any of these ligaments can result in ankle sprain.
Picture from Wikimedia Commons
Syndesdmostic ligaments and deltoid ligaments are stronger than lateral ligaments. As a result, injuries to lateral ligament complex contribute to more than 85% of all ankle sprains. Just 10% cases are syndesmotic injuries, whereas rest 5% cases of sprains include the deltoid ligaments.
How does an ankle sprain occur?
The ankle joint is responsible for up-and-down movement of the foot, whereas other joints around the ankle enable other movements. Together, all the joints give the ankle a total range of motion (ROM) like a ball and socket.
The lateral ankle ligament complex (made up of the anterior and posterior talofibular and calcaneofibular ligaments) is most commonly injured. Of these ligaments also, the anterior talofibular ligament (ATFL) is most likely involved in an ankle injury.
The following conditions can result in an ankle sprain:
- If the foot is bent backwards (towards the leg), the posterior talofibular ligament (PTFL) can rupture.
- If the foot is bent too much forward (towards the earth), the ATFL can rupture.
- If the foot is forced to rotate inwards, it can rupture both ATFL and PTFL.
- If foot is rotated extremely outwards, it can damage the deltoid ligament.
The syndesmotic ligament is stronger and is rarely sprained. Only a great amount of force (for example, force generated during an ankle fracture) can strain syndesmotic ligament, which would require surgical treatment.
Signs and symptoms
Symptoms of sprained ankle vary, depending upon which ligament is injured. Common symptoms may include the following:
- Sudden and intense pain
- Rapid onset of swelling
- Appearance of a bruise
- Inability or reduced ability to bear weight
- Cold sensations to the feet or sensations of tickling, burning, tingling, pricking, or numbness (les common)
- Decrease in discoloration of the skin and swelling upon treatment with ice, compression, and elevating ankle
- Symptoms worsening upon flexing the foot downward, toward the sole
- Appearance of a dimple over the area of the ATFL (less common)
Causes and Risks
An ankle sprain is a result of excessive force on the foot causing a stretching of the ligaments beyond their limits that stabilize the ankle joint. Factors contributing to spraining of ankle can be grouped as predisposing (risk) and provocative (causative) factors.
Lack of physical conditioning predisposes the ankles to sprains and other injuries. Such factors include:
- Poor muscle tone
- Short and/or contracted tendons
- Difficulty sensing the movement and spatial orientation
- Inadequate physical training
Such factors include accidents and other situations, in which ankle ligaments are stretched beyond their bending limits (the range of motion of the ankle joint). These include:
- Sports injury
- Falls, causing twisting of the ankle
- Walking or exercising on uneven surfaces
- Awkward landing on the foot
- Obesity (increasing pressure on the joints)
Recurrent ankle sprains are very common and result from damage to the healing or weakened ligaments.
Tests for Ankle Sprain
In most instance an ankle sprain is diagnosed by the clinical presentation (signs and patient’s report of symptoms) as well as the medical history as a patient reports the causative incident. The following diagnostic tests can confirm the diagnosis and exclude more serious injuries like a fracture.
- Plain x-rays may diagnose an abnormal swelling, ankle instability, or ankle or foot fracture.
- MRI scan is taken only in the cases of severe swelling, discoloration, pain, or recurrent ankle sprains; reasons of which are not diagnosed on plain radiographs.
- A CT scan may reveal the problems with soft tissues.
- Arthrographic imaging involves taking multiple X-rays of ankle joint and is done before a surgery. The images show the number of damaged ankle ligaments.
- Bone scanning detects bone abnormalities (like defects in bone and cartilage, stress fracture, and problems in the joints between bone and ligaments).
Sprained Ankle Treatment
Treatment aims at reducing pain and improving movement and strength of the ankle joint.
Treatment of acute sprain aims at controlling pain and minimizing swelling. Rest, ice, compression, and elevating the ankle (abbreviated as RICE) help immensely in achieving a faster recovery.
Physical therapy is recommended during the recovery period and aims at regaining full range of motion, strength, and improving abilities to sense movements and spatial orientation.
Splints or braces can be used for 1 to 3 weeks, or till there is swelling and pain. Ankle foot or orthoses are also recommended frequently.
The following simple self-care steps help in recovering from sprained ankle:
- Taking rest to promote tissue healing.
- Avoiding prolonged immobilization.
- Avoiding activities that increase pain or swelling.
- Exercising to regain range of motion.
- Using ice wrapped in a towel to control pain, swelling, and muscle spasm.
- Compressing with a wrap, sleeve, or an ankle support.
- Wearing high-top shoes to reduce swelling.
- Elevating the injured ankle above the level of the heart to reduce swelling.
For controlling pain due to an acute strain, non-steroidal anti-inflammatory drugs (NSAIDs) or other pain-relievers (like acetaminophen) may be used. Though NSAIDs reduce inflammation and pain; their overuse can have adverse affects and may increase swelling.
Surgery is considered rarely, in following cases :
- In case of severe damage to talofibular ligaments.
- Sprain with the deltoid ligament.
- For chronic ankle instability.
The prognosis for properly treated acute ankle sprains is excellent and more than 85% patients recover fully within the first 6 months. Recurrent sprains show excellent prognosis with early conservative treatment. However, increased wear of ankle joints (post-traumatic osteoarthritis) is common in patients with repetitive ankle injuries.