Os Trigonum Syndrome

What is Os Trigonum Syndrome?

An os trigonum is a small accessory bone located behind the ankle that forms in some people. When an os trigonum becomes inflamed and painful is called os trigonum syndrome. Usually os trigonum syndrome is caused by an injury such as an ankle sprain or in people who perform repetitive and forceful ankle motions such as ballet dancers. Pain is felt in the back of the ankle especially when toes are pointed downward as the os trigonum is compressed.

Diagnosis

Clinical symptoms and the X-ray finding of an os trigonum strongly suggest os trigonum syndrome. Sometimes an MRI or a diagnostic injection may be recommended.

Nonsurgical Treatment

  • Rest
  • Ice
  • Oral medications-Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can help relieve the pain and inflammation.
  • Short period of immobilization in a cast or cast boot.

Surgical Treatment

In patients who have no improvement after conservative treatment, removing the os trigonum surgically can be considered. This can be performed open or as an arthroscopic procedure. Usually a period of non-weightbearing for 2 weeks after surgery is required until the skin incision heals. Physical therapy is important during the rehabilitation phase post operatively to ensure that scar tissue does not form behind the ankle joint.


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