A sprain is a common injury involving the stretching or tearing of ligaments, the tough bands of connective tissue that stabilize joints. While most ankle injuries occur on the outer side, a sprain can certainly affect the inside, or medial side, of the ankle. This medial injury is far less frequent than a lateral ankle sprain because the anatomical structures on the inner ankle are significantly more robust, requiring a much greater force to cause damage.
The Anatomy of Medial Ankle Sprains
The medial ankle is stabilized by a strong, fan-shaped collection of ligaments known as the Deltoid ligament complex. This complex consists of multiple deep and superficial layers that connect the tibia to several bones in the foot. Its broad attachment points and layered structure make it exceptionally strong, providing powerful resistance against forces that would cause the ankle to roll outward.
The inherent strength of the Deltoid ligament is why medial sprains account for only about 5% to 15% of all ankle sprains. The ligaments on the outer side of the ankle are comparatively thinner and more susceptible to injury during the common mechanism of an ankle rolling inward. An injury to the Deltoid ligament complex can range from a minor stretch to a partial or complete tear, often classified in grades one through three. Because of the high force required to damage this structure, a medial ankle sprain is frequently associated with more serious injuries, such as a fracture of the outer ankle bone.
How Eversion Injuries Occur
A medial ankle sprain is caused by a specific biomechanical event called an eversion injury. This occurs when the foot is forcibly rolled outward, or away from the body’s midline, placing excessive tension on the Deltoid ligament. The mechanism often involves the foot moving outward (eversion) combined with external rotation.
This outward rolling motion happens in various scenarios, particularly during dynamic activities. Common causes include landing awkwardly from a jump, stepping into a hole or off a curb with the foot turning out, or sustaining a direct blow to the outer side of the ankle while the foot is planted. Since the Deltoid ligament is so strong, the required force is substantial, leading to a higher risk of associated bone fractures. Sometimes, the stress is so high that the ligament pulls off a small piece of bone in an avulsion fracture.
Recognizing Symptoms and Initial Steps
The symptoms of an acute medial ankle sprain center on the inner side of the joint. Individuals typically experience immediate, sharp pain directly over the bony prominence on the inside of the ankle, called the medial malleolus. Swelling and bruising quickly develop in the same localized area, which can spread toward the heel and the sole of the foot.
Difficulty bearing weight is a common sign, and in severe cases, the individual may be completely unable to walk. Initial self-management should involve the RICE protocol: Rest, Ice, Compression, and Elevation. Resting the ankle means avoiding painful activities; an ankle brace or crutches may be necessary. Applying a cold pack for 10 to 20 minutes every few hours controls swelling and pain, while wrapping the ankle provides compression. Elevating the foot above heart level helps reduce fluid accumulation.
If the pain is severe, if weight-bearing is impossible, or if the injury is accompanied by a popping or tearing sensation, professional medical attention should be sought immediately.
Medical Treatment and Recovery
A medical professional will first work to differentiate a ligament sprain from a fracture. Imaging, such as X-rays, is usually ordered to check for a broken bone. Sometimes a stress view X-ray or an MRI is used to assess the extent of the ligament damage. Sprains are graded based on severity, which dictates the treatment plan, ranging from simple immobilization to potential surgery.
Nonsurgical treatment for most isolated medial sprains involves a period of immobilization using a walking boot or a cast, followed by structured physical therapy. Rehabilitation focuses on restoring the ankle’s full range of motion, strengthening supporting muscles, and re-training balance and joint awareness (proprioception). Recovery from a Deltoid ligament sprain can take longer than a typical lateral sprain, with moderate to severe injuries potentially requiring months of dedicated rehabilitation.