A sprained ankle is a very common injury. Approximately 25,000 people experience it everyday. A sprained ankle can happen to athletes and non-athletes, children and adults. It can happen when you take part in sports and physical fitness activities. It can also happen when you simply step on an uneven surface, or step down at an angle.
The ligaments of the ankle hold the ankle bones and joint in position. They protect the ankle joint from abnormal movements-especially twisting, turning, and rolling of the foot.
A ligament is an elastic structure. Ligaments usually stretch within their limits, and then go back to their normal positions. When a ligament is forced to stretch beyond its normal range, a sprain occurs. A severe sprain causes actual tearing of the elastic fibers.
How It Happens
Ankle sprains happen when the foot twists, rolls or turns beyond its normal motions. A great force is transmitted upon landing. You can sprain your ankle if the foot is planted unevenly on a surface, beyond the normal force of stepping. This causes the ligaments to stretch beyond their normal range in an abnormal position.
Mechanism of Injury
If there is a severe in-turning or out-turning of the foot relative to the ankle, the forces cause the ligaments to stretch beyond their normal length. If the force is too strong, the ligaments can tear. You may lose your balance when your foot is placed unevenly on the ground. You may fall and be unable to stand on that foot. When excessive force is applied to the ankle’s soft tissue structures, you may even hear a “pop”. Pain and swelling result.
The amount of force determines the grade of the sprain. A mild sprain is a Grade 1. A moderate sprain is a Grade 2. A severe strain is a Grade 3.
- Grade 1 sprain: Slight stretching and some damage to the fibers (fibrils) of the ligament.
- Grade 2 sprain: Partial tearing of the ligament. If the ankle joint is examined and moved in certain ways, abnormal looseness (laxity) of the ankle joint occurs.
- Grade 3 sprain: Complete tear of the ligament. If the examiner pulls or pushes on the ankle joint in certain movements, gross instability occurs.