Os Trigonum

An Os Trigonum is a small extra bone that sometimes develops at the back of the ankle, near the talus bone. It forms during childhood if the separate bone piece doesn't fully fuse with the main bone during growth. While many people with an Os Trigonum experience no issues, it can cause pain, swelling, and limited ankle movement, especially after activities involving pointing the toes or jumping. This condition is often diagnosed with imaging tests like X-rays, and treatment may include rest, physiotherapy, or, in some cases, surgery to remove the extra bone.