Often, people do not know they have an os trigonum if it has not caused any problems. However, some people with this extra bone develop a painful condition known as os trigonum syndrome.
Os trigonum syndrome is usually triggered by an injury, such as an ankle sprain. The syndrome is also frequently caused by repeated downward pointing of the toes, which is common among ballet dancers, soccer players and other athletes.
For the person who has an os trigonum, pointing the toes downward can result in a “nutcracker injury.” Like an almond in a nutcracker, the os trigonum is crunched between the ankle and heel bones. As the os trigonum pulls loose, the tissue connecting it to the talus
The signs and symptoms of os trigonum syndrome may include:
- Deep, aching pain in the back of the ankle, occurring mostly when pushing off on the big toe (as in walking) or when pointing the toes downward
- Tenderness in the area when touched
- Swelling in the back of the ankle
Os trigonum syndrome can mimic other conditions, such as an Achilles tendon injury, ankle sprain or talus fracture. Diagnosis of os trigonum syndrome begins with questions from the doctor about the development of symptoms. After the foot and ankle are examined, x-rays or other imaging tests are often ordered to assist in making the diagnosis.
Relief of the symptoms is often achieved through treatments that can include a combination of the following:
Rest. It is important to stay off the injured foot to let the inflammation subside.
Immobilization. A walking boot is often used to restrict ankle motion and to allow the injured tissue to heal.
Ice. Swelling is decreased by applying a bag of ice covered with a thin towel to the affected area. Do not put ice directly against the skin.
Oral medication. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may be helpful in reducing the pain and inflammation.
Injections. Sometimes cortisone is injected into the area to reduce the inflammation and pain.