Ankle sprains are among the most common joint injuries seen by orthopaedists. Ankle sprains are injuries to one or more ligaments surrounding the ankle joints, of which there are two groups: the weaker outside lateral collateral ligaments and the thick inside deltoid ligament. Ligament injury can range from being stretched, to partially torn to severed. Types of ankle sprains include inversion, eversion, distraction and direct blunt trauma.
Inversion
Ankle sprains are most frequently caused by excessive internal rotation of the foot, termed "inversion", which forces the ankle to "roll out" laterally. When this occurs, the relatively weaker and thinner lateral collateral ligaments are injured--the anterior talofibular in mild sprains, but also the calcaneofibular ligament in more serious sprains. Many circumstances increase the risk of inversion sprains, such as: playing sports--especially gymnastics and basketball, wearing unstable or unsupportive footwear, walking on uneven ground or around any potholes, and simply being clumsy. In addition, people who have high arches and are supinate when they walk--meaning they put more pressure on the outsides of their feet--are more susceptible to inversion sprains. Inversion sprains account for 80 to 90 percent of all ankle sprains.
Eversion
A less common type of ankle sprain is caused by excessive external rotation of the foot, termed "eversion", which forces the ankle to "roll in" medially and collapse. When this occurs, the deltoid ligament, which spreads out to cover the tibia and the inner surfaces of the talus, navicular, and calcaneus, is injured. The degree of ligament damage is usually less with eversion sprains. Again, participating in athletics--especially track and field, gymnastics and weightlifting--and walking on uneven ground increase the likelihood of eversion injuries. In addition, people who have flat arches andare pronate when the walk, meaning they put more pressure on the insides of their feet, are more susceptible to eversion sprains.
Distraction
Ankle sprains are sometimes caused by excessive distraction, which occurs when the foot and the lower leg are pulled apart, creating excessive space in the ankle joints. When this occurs, ligaments on both sides of the ankle are stretched and injured, although more damage frequently occurs in the weaker lateral group. Examples include getting a foot caught in a stirrup and being dragged by a horse, or getting a foot wedged into a crevice while climbing or hiking.
Direct Blunt Trauma
Finally, sprains can occur when the ligaments of either side of the ankle are injured with direct blunt trauma, which occurs in motor vehicle accidents, sporting events or household mishaps. Direct blunt trauma rarely tears or severs ligaments, but it frequently causes inflammation, bruising and joint dysfunction.
References
- Foot Health Facts
- "Sports Medicine of the Lower Extremity"; Steven I. Subotnick, et al; 1999
- MedlinePlus: Ankle Injuries
