What is the main type of ligament involved in Grade I ankle sprains?

In a Grade I ankle sprain, the primary ligament involved is the anterior talofibular ligament (ATFL). This type of injury typically involves a mild stretching or microscopic tearing of the ligament, which commonly occurs during ankle inversion. The ATFL is located on the lateral aspect of the ankle and is most commonly injured due to its positioning and the mechanism of injury, especially during sports or activities that require sudden direction changes.

The anterior talofibular ligament is crucial for maintaining ankle stability, particularly in preventing excessive inversion of the foot. In Grade I sprains, the integrity of the ligament remains largely intact, but there is often pain and tenderness around the ligament and mild swelling without significant loss of function.

While the ankle joint capsule and the calcaneofibular ligament may play roles in ankle stability, they are less commonly involved in the initial injury associated with Grade I sprains. The posterior talofibular ligament is even less likely to be involved due to its position and the nature of the typical injury mechanism. Understanding this can help in both diagnosis and treatment, as management strategies may differ based on the specific ligaments affected.