An Ankle sprain is actually an injury to the ligaments of the ankle joint, which are elastic, band-like structures that hold the bones of the ankle joint together and prevent excess turning and twisting of the joint. In normal movement, the ligaments can stretch slightly and then retract back to their normal shape and size. A sprain results when the ligaments of the ankle have been stretched beyond their limits. In severe sprains, the ligaments may be partially or completely torn.
The ankle joint is fairly unstable and largely depends on the ligaments for its stability. The ankle sprain is of two types-
The most common type is the inversion ankle sprain (85%), in which the ankle rolls over on the outside. In the sprained ankle the most common damage is done to the talo-fibula ligament (if the ankle sprain is worse, the calcaneo-fibula ligament can also be damaged) - sometimes the tendons also get damaged.
Mechanism of Ankle sprain
The ligament is injured when the plantar flexed foot is suddenly forced into inversion, which may cause rupture, sprain of lateral ligament.
The injury is common in sports activity. It is quite common when a person slips off or walk on uneven surfaces. The foot is forced into inversion and plantar flexion which results in external rotation of tibia. The site of injury is generally the centre and distal attachments of anterior and middle band of the ligament.
When sudden inversion force occurs with the ankle in mid position of dorsi and plantar flexion, the injury involves the calcaneo-fibular ligament(CFL). Whereas when the excessive inversion-adduction movement is associated with forced plantar flexion, the injury commonly involves anterior talo-fibular ligament(ATFL). This can be identified by the site of pain and tenderness. Pain and tenderness over talus indicates injury to talo-fibular ligament while the same over calcaneus indicates the involvement of calcaneo-fibular ligament. This identification is necessary for prompt treatment.
Sprained ankle is often classified as
First degree ankle sprain- Some stretching or mild tearing of the ligament.- Little or no functional loss - the joint can still function and bear some weight (...but hurts!!!).- Mild pain-Some swelling- Some joint stiffness- Return to activity/functional phase in 1-2 weeks with proper ankle sprain treatment.
Second degree ankle sprain:- Some more severe tearing of the ligaments-Moderate instability of the joint- Moderate to severe pain - weight-bearing is very painful- Swelling and stiffness- Return to activity/functional phase in 2-3 weeks with proper treatment.