Overuse injuries from repetitive ankle plantar flexion stresses can be attributed to Os trigonum syndrome. The Os trigonum can be the result of fracture of a bony tubercle in the back of the ankle or it can occur when there is an unfused ossicle in childhood. This condition may also be known as posterior ankle impingement. Ballet dancers and soccer players have an inherent risk of this condition secondary to the amount of time in a forced plantar flexed position. This occurs with push off procedures and while dancing on pointe (dancing performed on the tip of the toes with the ankles in maximal plantar flexion) and demi-pointe (dancing performed on the balls of the feel with the ankle in maximal plantar flexion).
This condition is typically asymptomatic until an overuse injury or trauma occurs. Symptoms can include stiffness, chronic pain and swelling behind the ankle. Because pain and stiffness can occur with activities involving plantar flexion, compensations can occur leading to faulty positions which additionally may lead to other ankle conditions such as ankle sprains, tendonitis or tenosynovitis (inflammation of the fluid-filled sheath that surrounds a tendon). Initial conservative management of Os trigonum syndrome includes rest, ice, anti-inflammatory medication and, of course, avoidance of aggravating activities. One study demonstrated 84 per cent of patients received relief from an ultrasound-guided corticosteroid injection.
If a three to six month course of conservative treatment fails, surgical intervention may be appropriate. Resection of the Os trigonum can be performed via three methods; posterior endoscopy, arthroscopy, or an open procedure. Most studies report outcomes that posterior endoscopy and arthroscopy can allow for faster return to sport but these techniques tend to be more complex and demanding. The author of this review article argues that a careful open approach may produce long term results that are equal to that of arthroscopic and endoscopy techniques while possibly being safer. Overall, surgical outcomes show that all three techniques provide improved function and high rate of return to sport.