Chronic Ankle Sprains (Medial Ankle Instability): Overview

Chronic Ankle Sprains (Medial Ankle Instability): Overview

The ankle is made up of many ligaments that help stabilize the joint. An ankle sprain is a very common injury that most often affects the ligament at the outer side of the ankle. Less commonly, an ankle sprain can affect the group of ligaments on the inner side of the ankle, known as the deltoid ligament complex.

The deltoid ligament complex is made up of a top layer and bottom layer of several different ligaments that all function together to stabilize the inner side of the ankle. The deltoid ligament can be injured in a variety of ways, but injury is more likely to occur with a forceful motion when the foot is pointed and turned out. These injuries overstretch the ligament more than normal and can tear the ligament's fibers.

Medial ankle sprains commonly occur with sports like gymnastics, soccer, and American football, with direct contact being the most common source of injury. Ankle strengthening and balance exercises can help prevent ankle sprains, while wearing an ankle brace can help prevent an ankle sprain from occurring again if one has already occurred in the past.

Medial ankle sprains usually do not occur on their own and often happen alongside another injury, like injury to another ankle ligament or a fracture to the fibula, the small bone on the outer side of the lower leg. Approximately 50% of all medial ankle sprains occur with a high ankle sprain, which results from injury to the connecting ligaments between the tibia and fibula bones above the ankle.

When the deltoid ligament is sprained or torn, it cannot properly stabilize the ankle joint and can lead to chronic or long-term instability. Symptoms of medial ankle instability include pain, swelling, and bruising at the inner side of the ankle. It may also be difficult to bear weight through the affected foot with standing and walking.

To diagnose a medial ankle sprain, a healthcare provider will examine the foot and ankle to assess for pain, range of motion, and instability. Testing the strength of the muscles around the inner side of the ankle to see if they can still function will also help rule out a tendon injury. If no other injury has occurred with a medial ankle sprain, x-rays will typically look normal, so stress x-rays will likely be performed.

These types of x-rays are taken with the ankle rotated outward to examine the gap along the inner side of the ankle joint. More space than normal on the inner side of the ankle means that the ligament is damaged and unable to properly stabilize that side of the ankle joint. Other imaging methods that may be used to diagnose medial ankle instability include an MRI, CT scan, or ultrasound.

If significant injury is suspected, a healthcare provider may need to directly examine the ligament through arthroscopic visualization. This technique involves making a small incision in the ankle to insert an arthroscope, a surgical instrument with a tiny camera, to view inside the ankle and determine the extent of injury to the deltoid ligament. A health care provider will use the results from any imaging method performed, along with a patient's symptoms, to determine which type of treatment is best.