Ankle

In human anatomy, the ankle joint is formed where the foot and the leg meet. The ankle, or talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus bone in the foot. The articulation between the tibia and the talus bears more weight than between the smaller fibula and the talus.

The term ankle is used to describe structures in the region of the ankle joint proper.

Name derivation
The word ankle or ancle is common, in various forms, to Germanic languages, probably connected in origin with the Latin "angulus", or Greek "αγκυλος", meaning bent.

Evolution
It has been suggested that dexterous control of toes has been lost in favour of a more precise voluntary control of the ankle joint.

Bony Anatomy
The boney architecture of the ankle consists of three bones: the tibia, the fibula, and the talus. The articular surface of the tibia is referred to as the plafond. The medial malleolus is a boney process extending distally off the medial tibia. The distal-most aspect of the fibula is called the lateral malleolus. Together, the malleoli, along with their supporting ligaments, stabilize the talus underneath the tibia. The boney arch formed by the tibial plafond and the two malleoli is referred to as the ankle "mortise." The joint surface of all bones in the ankle are covered with articular cartilage.

Ligaments
The ankle joint is bound by the strong deltoid ligament and three lateral ligaments: the anterior talofibular ligament, the posterior talofibular ligament, and the calcaneofibular ligament.
 * The deltoid ligament supports the medial side of the joint, and is attached at the medial malleolus of the tibia and connect in four places to the sustentaculum tali of the calcaneus, calcaneonavicular ligament, the navicular tuberosity, and to the medial surface of the talus.
 * The anterior and posterior talofibular ligaments support the lateral side of the joint from the lateral malleolus of the fibula to the dorsal and ventral ends of the talus.
 * The calcaneofibular ligament is attached at the lateral malleolus and to the lateral surface of the calcaneus.

Though it does not span across the ankle joint itself, the syndesmotic ligament makes an important contribution to the stability of the ankle. This ligament spans the syndesmosis, which is the term for the articulation between the medial aspect of the distal fibula and the lateral aspect of the distal tibia. An isolated injury to this ligament is often called a high ankle sprain.

The boney architecture of the ankle joint is most stable in dorsiflexion. Thus, a sprained ankle is more likely to occur when the ankle is plantar-flexed, as ligamentous support is more important in this position. The classic ankle sprain involves the anterior talofibular ligament (ATFL), which is also the most commonly-injured ligament during inversion sprains. Another ligament that can be injured in a severe ankle sprain is the calcaneofibular ligament.



Symptoms
Symptoms of an ankle fracture can be similar to those of ankle sprains (pain), though typically they are often more severe by comparison. It is exceedingly rare for the ankle joint to dislocate in the presence of ligamentous injury alone. However, in the setting of an ankle fracture the talus can become unstable and subluxate or dislocate. Patients may complain of ecchymosis (brusing), or there may be an abnormal position, abnormal motion, or lack of motion.

Evaluation
On clinical examination, it is important to evaluate the exact location of the pain, the range of motion and the condition of the nerves and vessels. It is important to palpate the calf bone (fibula) because there may be an associated fracture proximally (Maisonneuve fracture), and to palpate the sole of the foot to look for a Jones fracture at the base of fifth metatarsal (avulsion fracture).

Evaluation of ankle injuries for fracture is done with the Ottawa ankle rules, a set of rules that were developed to minimize unnecessary X-rays. There are three x-ray views in a complete ankle series: anteroposterior, lateral, and oblique (or "mortise view"). The mortise view an anteroposterior x-ray taken with the ankle internally rotated until the lateral malleolus is on the same horizontal plane as the medial malleolus, and a line drawn through both malleoli would be parallel to the tabletop, resulting in a position where there normally is no superimposition of tibia and fibula on each other. It usually requires 10 to 20 degrees of internal rotation.

On X-rays, there can be a fracture of the medial malleolus, the lateral malleolus, or of the anterior/posterior margin of the distal tibia. The posterior margin (known as the posterior malleolus), is much more frequently injured than the anterior aspect of the distal tibia. If both the lateral and medial malleoli are broken, this is called a bimalleolar fracture (some of them are called Pott's fractures). If the posterior malleolus is also fractured, this is called a trimalleolar fracture.

There are several classification schemes for ankle fractures, including the Lauge-Hansen classification and the Danis-Weber classification. The Lauge-Hansen system classifies fractures based on the mechanism of the injury as it relates to the position of the foot and the deforming force (most common type is supination-external rotation). The Danis-Weber system classifies an ankle fracture by the level of the fracture of the distal fibula (type A = below the syndesmotic ligament, type B = at its level, type C = above the ligament). A special form of type C fracture is the Maisonneuve fracture, which involves a fracture of the fibula far above the ankle joint itself. This occurs in the setting of injury to the syndesmosis and the interosseous membrane.

Treatment
Treatment of ankle fractures is dictated by the stability of the ankle joint. Certain fracture patterns are deemed stable, and may be treated similar to ankle sprains. All other types require surgery, most often an open reduction and internal fixation (ORIF), which is usually performed with permanently implanted metal hardware that holds the bones in place while the natural healing process occurs. A cast or splint will be required to immobilize the ankle following surgery.

Kiep ankle disorder
A new study from Cornell University has investigated relatively recent findings of a new cause of ankle pain known as Kiep Ankle Disorder. It lasts up to 6 months and can not be treated with surgery. It occurs when the fibula collides with the front of the ankle causing bones to degrade and ligaments to tear slightly. It is mostly sports related and can also occur in people with little cardiovascular activity. It is most common in women between the ages of 14-25 years old.