What is it?

Os Trigonum Syndrome is a painful condition located on the back of the ankle that arises from an extra bone that sometimes develops from the back of the ankle bone (talus). The condition may also be referred to as posterior ankle impingement. The extra bone uncommonly develops during adolescence when a part or piece of the talus (ankle bone) does not fuse with the rest of the bone. This syndrome is most often caused by overuse with repetitive pointing of toes commonly seen in ballet dancers, soccer and football players.

Symptoms/Risks

Symptoms may be present on one or both ankles if this extra bone is present. Symptoms may include: aching pain, tenderness, and possibly swelling to back of ankle, most commonly to the outside portion of the ankle next the Achilles tendon and the outside ankle bone (lateral malleolus). Pain may worsen when pushing off of big toe or pointing of toes.

Sports Medicine Evaluation & Treatment

If you visit a sports medicine physician, a physical exam will be performed of your injured foot/ankle. Your doctor will likely order an X-ray and/or ultrasound to look for evidence of extra bone or injury to the tissues around the back of the ankle. An MRI or CT scan may also be suggested if the extra bone is not present on X-ray or if considering surgery for possible treatment.

Treatment of Os Trigonum Syndrome usually begins with nonsurgical treatment. Non-surgical treatment options include rest, immobilization/bracing, anti-inflammatory medications, physical therapy and corticosteroid injections.

Surgery may be determined necessary, typically after 3-6 months of non-surgical treatment. Surgery is done to remove the extra bone to prevent further pain and damage to the tissues around the back of the ankle.

Injury Prevention

Most cases of Os Trigonum Syndrome are caused by overuse or repetitive movements. Minimizing repetitive motions, including pushing off or pointing of the toe, may help minimize risk of injury. Adequate stretching and strengthening of ankle may also help.

Return to Play

Return to play is determined by the severity of your symptoms and if surgery is warranted after trial of non-surgical treatment as discussed previously. Following surgery, most athletes return to their prior activity level by 2-3 months of rehabilitation. Studies have shown quicker return to play in soccer players and longer return to play for dancers.

AMSSM Member Authors
Blair B. Rhodehouse, DO and Shane L. Larson, MD

References
Nault ML, Kocher MS, Micheli LJ. Os Trigonum Syndrome. J Am Acad Orthop Surg. 2014;22(9):543-553
Lavery KP, McHale KJ, Rossy WH, Et Al. Ankle Impingement. J Orthop Surg Research. 2016;11:97
Ribbans WJ, Ribbans HA, Cruichshank JA, Et Al. The Management of posterior ankle impingement syndrome in sport: a review. Foot Ankle Surg. 2015;21(1):1-10
Filipa A, Barton K. Physical Therapy Rehabiliation of an Adolescent Preprofessional Dancer Following Os Trigonum Excision: A Case Report. J Orthop Sports Phys Ther. 2018;48(3):194-203