Ankle Sprain Classification

Topic Overview

An inversion injury, the most common cause of ankle sprains, occurs when the ankle rolls outward and the foot turns inward. It results in stretching and tearing of the ligaments on the outside of the ankle. In an eversion injury, the ankle rolls inward and the foot turns outward, damaging the ligaments at the inside of the ankle. If the foot is forced up, or the leg twists forcefully while the foot is planted, the ligaments that join the leg bones together above the ankle may be injured. This is called a high ankle sprain. It can happen either alone or along with an inversion or eversion sprain. See a picture of types of ankle sprains.

In an ankle sprain, damage to the ligament varies from simply stretched or slightly torn to completely torn. Your doctor will grade your sprain accordingly:

• Grade I is stretching or slight tearing of the ligament with mild tenderness, swelling, and stiffness. The ankle feels stable, and it is usually possible to walk with minimal pain.
• Grade II is a larger but incomplete tear with moderate pain, swelling, and bruising. Although the ankle sometimes feels stable, the damaged areas are tender to the touch, and walking is painful. See a picture of a grade II ankle sprain.
• Grade III is a complete tear of the affected ligament or ligaments with severe swelling and bruising. The ankle is unstable and may feel "wobbly." Walking is usually not possible because the ankle gives out and there is intense pain, although initial pain may quickly subside.