Injuries to the outside of the ankle associated with rolling of the foot are known as ankle sprains. The ankle ligaments provide stability to the ankle by helping to hold the ankle bone within the ankle joint. The ankle ligaments usually involved in an ankle sprain are also known as the lateral collateral ligaments of the ankle. The lateral collateral ligaments of the ankle are comprised of the anterior talofibular ligament, the calcaneofibular ligament and the posterior talofibular ligament.
Function of the Ankle Ligaments
By their orientation, the lateral collateral ligaments provide stability to the ankle throughout the gait cycle as the foot bends up and down. Therefore total lateral stability of the ankle is provided by these three ligaments. The most anterior (front) and most frequently injured of these ligaments is the anterior talofibular ligament. This ligament is intracapsular, or blended and contiguous with the lining of the anterior lateral aspect of the ankle capsule (joint). It can be seen as a fibrous thickening of the lining of the joint and courses from the front of the fibula to the front of the lateral surface of the talus. The main function of the anterior talofibular ligament is the prevention of axial or rotational instability of the ankle. During gait as the heel is coming down, the foot is held in a dorsiflexed (up) position. Essentially the foot is pivoting on the edge of the heel only. Any irregularity in the ground, or laterally directed force, will cause the foot to twist in or out depending on the orientation of the force. Similarly, when we push off, the foot is in a plantar flexed (down) position. As the foot is plantar flexed, the postion of the foot increases the long axis of the leg and increases the torque on the ankle region. Any ground irregularity or laterally directed force will cause the foot to twist in or out depending of the orientation of the force.
Classification of Injury
Rolling in of the foot (inversion), with the sole of the foot towards the opposite leg, is defined as a lateral ankle sprain. There are several classifications of this injury. A simple definition of injury breaks the injury down in terms of physiologic injury: sprain, strain or rupture which define the extent of stretching and pulling on the fibers of the ligaments. A second classification of injury of the lateral collateral ligaments of the ankle is known as Grades 1, 2, or 3. This classification describes the functional loss of the ankle and the resultant grade or level of injury. The end result of injury of one or more of the lateral collateral ligaments of the ankle is ankle instability. This instability can show up initially as a result of the severity of the injury or later as a result of chronic ankle instability. During the moment of injury, due to the instability caused by the injury, movement and twisting of the Talus (ankle bone) in the ankle joint resulting in bone to bone compaction and twisting of other ligaments, tendons and nerves may occur. Injuries beyond the level of the ligaments themselves can occur and will occur depending of the level of injury. MRI, CT scans, bone scans and electro diagnostic testing may be recommended to evaluate for these secondary injuries. Chronic Ankle instability occurs much later than then original injury. Once the lateral collateral ankle ligaments are injured, they no longer provide the ability to stop ankle twisting and to hold the Talus within the ankle joint. As you walk or run with an unstable ankle, the talus can twist within the joint and partially come out of the joint. This movement is unnatural and abnormal and redirects force to the outside of the joint. With an increase in joint load to the outside, the foot will roll to the inside producing further tearing of the ligament and further injury.
Conservative treatment for ankle sprain depends on the necessity to stabilize the foot to restore the anatomical position of the ankle ligaments. The often noted RICE formula (rest, ice, compression elevation) is the standard initial treatment. Any treatment provided is to allow the ligaments to heal in the correct position and at the correct length. Depending on which ligaments are injured and to what degree the ligaments are injured, your Weil Podiatric physician can provide you with the best ankle brace to stabilize your ankle. Supplemental treatment for secondary injuries incurred at the time of injury will be diagnoses and treated at the same time as the treatment for the ankle ligaments.
Surgical treatment of the ankle ligaments or associated injury conditions are performed when instability develops later or the injury is severe enough initially that stabilization must be done to allow for proper healing. For more information see one of the Doctors of the New Mexico Foot & Ankle Institute.