Ankle sprains are among the most common joint injuries seen by orthopaedists. Ankle sprains are injuries to one or more ligaments surrounding the ankle joints. Ligament injury can range from mild (merely stretched), to moderate (partially torn), to severe (completely severed). Ankle sprains usually fully resolve, but when inappropriate treatment, or significant injury, or premature return to activity has occurred, complications can arise such as prolonged pain, persistent swelling, stiffness, instability, and nerve dysfunction.
Prolonged or chronic pain is the most common complication of an ankle sprain. Even severe sprains should be healed and pain-free after 8 weeks, so if pain persists (with inflammation) there is likelihood of an undiagnosed fracture, cartilage tear, or ruptured tendon. Prolonged pain without inflammation occurs primarily with nerve injury. Chronic pain frequently disrupts normal walking, which then can affect joints of the hips, lower back and knees.
Persistent swelling of the ankle is caused by several conditions, most commonly from unhealed torn ligaments, or by bone contusion leading to compression between the ankle joints, or by damaged and impinged blood vessels. Chronic swelling is sometimes caused by synovitis, which is inflammation of the inner lining of the ankle joint capsules. Persistent swelling of the ankle joints is usually accompanied by low-grade pain, but sometimes can occur without pain.
Stiffness is another complication of ankle sprains and usually a consequence of excessive swelling or inflammation. Ankle stiffness is usually accompanied by achy pain and leads to reduced range of motion, especially dorsiflexion. Over many months, reduced range of motion and joint dysfunction can lead to osteoarthritis, which is evidenced by bone spurs and reduced joint space on x-ray.
Ankle instability occurs when a sprained ligament (usually the outside lateral ones) heals in a stretched position (gross laxity) as opposed to its normal anatomic position, causing the ankle to become hyper-mobile and move in abnormal ways. Instability creates a sense of the ankle about to "give away" and may be accompanied by persistent low-grade swelling and pain. Ankle instability usually involves consistent weakening of the joints and greatly increases the likelihood of future ankle sprains.
Nerve injuries may occur with either a significant twisting of an ankle sprain, and/or chronic swelling of the ankle leading to pressure on the cutaneous nerves surrounding the ankle. Symptoms include burning pain, shooting pain, numbness, and muscle weakness, all of which are usually exacerbated by walking. Muscle weakness often causes re-injury due to reduced coordination. Abnormal proprioception may also result, which affects balance and stability of the foot and ankle.