The most common injury in sports and physical activity is the ankle sprain. In the U.S., there is one ankle sprain for every 10,000 persons per day. Ankle sprains made up 25% of all musculoskeletal injuries. Ligaments prevent abnormal movement and promote joint stability. There are ligaments surrounding the ankle to prevent it from rolling in or out. There are not, however, any ligaments to limit plantarflexion (bending the foot and toes away from you) as they are normal and necessary movements.
Sprains are classified into three categories: Grade I (mild), Grade II (moderate), and Grade III (severe).
- A Grade I, or mild sprain, is only a minor stretching or tearing of a few fibers of the ligament. There is no loss of function with this grade of injury. There is, however, slight swelling and localized tenderness.
- A Grade II, or moderate sprain, involves more extensive tearing of the ligament fibers. This will result in more profuse swilling, some pain with movement or activity, significantly localized tenderness and some discoloration.
- A Grade III, or severe sprain, is usually very painful. There is significant loss of motion, significant swelling, extensive bruising and diffuse tenderness. The most common type of ankle sprain is the stretching of the ligaments on the outside of the ankle. This type of sprain comprises of 85% of all ankle sprains.
These are three ligaments; the anterior talofibular, posterior talofibular, and then calcaneofibular, that prevent the ankle from rolling in (inversion). A major reason for the high rate of lateral ankle sprains is due to the bony instability of the joint when the ankle is in the plantarflexed position. When the ankle is plantarflexed, there is far less contact between the bones within the joint. Consequently, the ankle must rely heavily on the ligaments for stability, thus placing the ligaments at risk for injury. When the ankle is dorsiflexed, there is more bony contact and the ankle is almost “locked” into position, allowing very little movement within the joint. The joint now has better stability and does not require as much ligamentous support.
To test this, plantarflex your ankle and try to roll it to the inside and outside. Now dorsiflex your ankle and try the same thing. Note how much further you can roll the ankle when it is plantarflexed. This is because there are no bones blocking the motions. Your ankle has much better mobility in the plantarflexed position, but much less stability as a result. Think about how you step off the curb. Normally the toes touch the ground first, followed by the heel. When you land toe first the ankle is in plantarflexed position and is more likely to roll in. Another type of ankle sprain is the stretching of the ligament on the inside of the ankle.
This ligament known as the deltoid ligament prevents the ankle from rolling out (eversion). Medial ankle sprains are not very common because this is a very thick, strong ligament. The last type of ankle sprain is known as a high ankle sprain. It is the stretching of the membrane that connects the tibia (the shinbone) and the fibula (smaller bone) called the syndesmosis where the talus is forcefully driven into the membrane. This occurs from a high impact injury regardless of the ankle rolling in or out. It needs to be stressed that full motion must be obtained before returning to aggressive activity or symptoms may persist and complications may develop.
Another important fact is that when the lateral ligaments of the ankle are torn, they do not heal “as good as new”. In fact, the ligaments DO NOT heal back together. Therefore, the ankle does not have the same restraints in rolling that it had prior to injury. All ligaments have small receptors located within them, called proprioreceptors, that give constant feedback to the brain regarding the position of the ankle at all times. When a ligament is stretched or torn, these proprioreceptors are damaged and the constant feedback to the brain is impaired.
Consequently, the brain is less aware of the position of the ankle during activity and cannot give proper signals to the muscles surrounding the ankle to control the foot. This contributes to an increased susceptibility of recurrent ankle sprains.
There are still several things that you can do to prevent future sprains:
- Always try to step heel-first, especially when walking on uneven terrain and off steps.
- Practice standing on one foot and balancing. Then try to balance with your eyes close. This will help retrain proprioreceptors and improve communication when between the ankle and the brain.
- When playing sports, or participating in activities with uncontrolled variables, wearing a protective brace may be helpful. An example of such a brace is the Aircast.
With an acute sprain, initial treatment should always include ice, elevation, compression, gentle ankle pumps and weight-bearing tolerance. It should be noted that an ankle fracture can occur in conjunction with a sprain. If you suffer an ankle sprain and do not notice significant improvement in range of motion, swelling, and pain with in the first few days after the injury, or if you experience severe pain with weight bearing, you should seek the assistance of an orthopedic surgeon. Aggressive physical therapy will always help to decrease symptoms, strengthen, restore range of motion, return to activity more quickly thank normal and ensure optimal healing.