Section 5. Bone, Joint, and Muscle Disorders

Chapter 72. Foot Problems

Topics: Introduction | Foot Pain | Ankle Sprain | Tarsal Tunnel Syndrome | Plantar Fasciitis | Achilles Tendon Bursitis | Ingrown Toenail | Onychomycosis | Onychia | Corns and Calluses | Onychauxis and Onychogryphosis | Hallux Valgus and Bunion | Hammer Toe | Sesamoiditis

Ankle Sprain

An ankle sprain is an injury to the ligaments (the tough elastic tissue that connects bones to one another) in the ankle.

See the figure Spraining an Ankle.

Any of the ligaments in the ankle can be injured. Sprains usually occur when the ankle rolls outward, causing the sole of the foot to face the other foot (invert). This kind of injury usually occurs when a person steps on uneven ground, especially when stepping on a rock or off the edge of a curb. Loose ligaments in the ankle, weak or nerve-damaged leg muscles, certain types of shoes such as spiked heels, and certain walking patterns (such as an in-toed pattern) tend to cause the ankle to roll outward, increasing the risk of a sprain. People with specific foot types, such as a high arch, may also be more prone to ankle sprains.

Symptoms

The severity of the sprain depends on the degree of stretching or tearing of the ligaments. In a mild sprain, the ligaments may stretch, but they do not actually tear. The ankle usually does not hurt or swell very much, but a mild sprain increases the risk of a repeat injury. In a moderate sprain, a ligament tears partially. Obvious swelling and bruising are common, and walking is usually painful and difficult. In a severe sprain, a ligament tears completely, causing swelling and sometimes bleeding under the skin. As a result, the ankle is unstable and unable to bear weight.

Diagnosis and Treatment

Physical examination of the ankle can give clues as to the extent of ligament damage. X-rays are often taken to determine whether a bone is broken, but they cannot assess the ligaments. Stress x-rays (taken with the ankle in different positions) may indicate the extent of ligament damage, as can magnetic resonance imaging (MRI). Arthroscopy, in which a fiber-optic scope is used to view inside the joint, is used only if surgery to repair a torn ligament is being considered.

Treatment depends on how severe the sprain is. Usually, mild sprains are treated by wrapping the ankle and foot with an elastic bandage or tape, applying ice packs to the area, elevating the ankle, and, as the sprain heals, gradually increasing the amount of walking and exercise. Treatment consists of rest, ice, compression, elevation (RICE). For moderate sprains, a walking cast or a removable cast boot can be applied and left in place for up to 3 weeks. It immobilizes the lower leg but allows a person to walk on the injured ankle.

A severe ankle sprain requires immediate medical attention; if left untreated, it may result in long-term instability of the ankle, pain, and osteoarthritis of the ankle. Surgery may be needed. However, physical therapy is usually tried first. Whether to perform surgery is controversial; some surgeons believe that surgically reconstructing badly damaged and torn ligaments is no better than treatment without surgery. Physical therapy to restore movement, strengthen muscles, and improve balance and response time is very important before a person resumes strenuous activity.

For people who sprain their ankles easily, subsequent injuries may be prevented by wearing soft or rigid ankle supports (depending on the type and degree of injury). High-top shoes and the use of padding or inserts (orthotics) in the shoe can help to stabilize the foot and ankle.

Complications

Sometimes a moderate or severe sprain causes problems even after the ligament has healed. A small nodule (meniscoid body) can develop in one of the ankle's ligaments and cause constant friction in the joint, leading to chronic inflammation and eventually permanent damage. Relief from the pain and inflammation is usually possible by having the doctor inject the ankle with a mixture of corticosteroids (usually two different formulations to provide short- and longer-lasting effects) along with a local anesthetic (such as lidocaine). Surgery is rarely needed.

A nerve that travels over one of the ankle's ligaments may also be damaged in a sprain. The resulting pain (neuralgia) and tingling are often relieved, sometimes permanently, by an injection of a mixture of a local anesthetic and a corticosteroid.

People who have a sprained ankle may walk in a way that overuses the tendons on the outside of the ankle, resulting in inflammation. This condition, called peroneal tenosynovitis, can cause chronic swelling and tenderness of the outer ankle. Treatment consists of wearing ankle supports that limit movement of the ankle joint. Cortisone injections into the sheath of the tendon may also be effective but must not be overused.

Occasionally, the shock of a severe sprain causes blood vessels in the ankle to go into prolonged spasm, thereby reducing blood flow. As a result, areas of bone and other tissues may be damaged because they are deprived of blood and may begin to waste away. This condition, called reflex sympathetic dystrophy (see Section 6, Chapter 78) or Sudeck's atrophy, is a rare complication of an ankle sprain. It can cause the foot to swell painfully. Pain, often severe, can move from one location to another in the ankle and foot. Despite the pain, a person usually should continue to walk. Physical therapy and analgesics taken by mouth may help. A local anesthetic injected into or around the nerve (a nerve block) supplying the ankle, corticosteroids, and psychologic counseling can help people cope with the chronic, intense pain.

Sinus tarsi syndrome is persistent pain in the area between the heel bone (calcaneus) and the ankle bone (talus) after a sprain. It may be related to partial tearing of ligaments deep in the foot. Injections of corticosteroids and local anesthetics often help.