One of the most common injuries of the foot is an ankle sprain. Most of the time ankle sprains are thought of as a sports injury, they can be caused by daily activities such as walking off a curb, stepping on a rock, or missing a step. The ankle joint is unique in the body as it is composed of three bones built to bear and stabilize about ½ of the body’s weight while still being fairly mobile. To help understand the injury, some background anatomy is needed.
There are two bones in the lower leg and one in the foot that make up the ankle joint. The two bones in the foot run together from the knee to the ankle. The inner and larger bone is called the tibia. This bone supports ½ of the body’s weight above it. The smaller and outside bone is called the fibula. This long skinny bone serves as an attachment point for muscles and tendons. The tibia and fibula are joined just above the ankle joint by the distal tabiofibular ligament. The bone in the foot is called the talus. This bone fits into the space between the tibia and fibula. The talus pivots in this space allowing movement between the foot and leg. On the inside of the ankle joint the talus and tibia are connected by a group of ligaments called the deltoid ligament. On the outside, the talus and fibula are connected by three ligaments: anterior talofibular ligament, calcaneofibular ligament, posterior talofibular ligament. The last thing to talk about is the two broad ligaments that wrap around the entire joint. These are called the flexor retinaculum and extensor retinaculum and help stabilize and keep all of the parts of the ankle joint together.
Now that some of the anatomy is clear it’s time to read about the different types of ankle sprain, how they are caused, and graded. The term “sprain” is used when a ligament is damaged or ruptured. The three basic types of ankle sprains are inversion, eversion, and syndesmosis or high-ankle sprains. The most common is an inversion sprain. This occurs when the foot is pointed toward the floor and the foot rolls inward placing the body weight over the outside of the foot and ankle. An inversion sprain usually happens by stepping or landing on uneven ground or making a cutting motion. These sprains damage the ligaments on the outside of the ankle with the anterior talofibular ligament most commonly damaged. Eversion ankle sprains require a large amount of force to occur. The most common way they occur is when an athlete has a foot planted and there is a blow from the side of the planted leg. The syndesmosis or high-ankle sprain is a stretch of the distal talofibular ligament. This occurs when the talus bone twists between the tibia and fibula, forcing the two leg bones unnaturally apart. This injury is most common when the foot is planted and the body twists over the planted foot.
During the diagnosis of a joint sprain, doctors may use the following scale. This helps them categorize the degree of damage to the joint and develop a treatment plan.
Grade 1: The joint has mild pain with little to no swelling. Minor tears and stretching of the ligament have occurred. There is only minimal loss of function and stiffness of the joint. Expected recovery is a few days.
Grade 2: The joint has moderate to severe pain with swelling. A partial tear of ligaments and moderate loss of function has occurred to the joint. Joint is also experiencing stiffness. Full recovery is within 2-3 months.
Grade 3: Initially there is severe joint pain but afterwards little or no pain. The joint becomes very stiff with large amounts of swelling. Ligaments are completely ruptured and joint has complete loss of function. Full recovery can take up to 4 months.