What is Os Trigonum Syndrome?

Before getting to know what os trigonum syndrome is, it is important to know what an os trigonum is. The os trigonum is a bone that has not properly fused with the ankle bone or the talus. Instead of getting properly fused, the os trigonum is connected to the ankle bone through cartilaginous or fibrous tissue. In most cases, this non-fusion of the bone does not lead to any problems but, some people can experience severe pain, which we refer to as os trigonum syndrome.

What Leads to Os Trigonum Syndrome?

The os trigonum or the extra bone is a congenital problem that can affect nearly 7-9 percent population. In most cases, as mentioned above, the extra bone causes no problems. But in a few, the syndrome caused by the extra bone becomes evident. Let us look at the situations that can trigger the syndrome.

  • The syndrome can be the resultant of an ankle injury, usually a sprain.
  • Also, people who are into sports like soccer and those into ballet dancing also can trigger the syndrome as their toes are pointed downwards for extended periods. When the toes remain pointed downwards for extended periods, the os trigonum can pull loose and inflame or tear the fibrous tissue that was holding it to the talus.
  • People who are into jobs where a lot of climbing up and down the stairs with heavy weights in their hands are also vulnerable to triggering the syndrome.

Symptoms of the Syndrome

The following are the symptoms of this syndrome-

  • swelling, especially in the ankle’s back
  • tenderness to touch
  • pain when trying to walk or when pointing the toes downwards


Often, non-surgical techniques are enough to alleviate the symptoms caused by the extra bone in the ankle’s back. Let us look at these non-surgical techniques.

  • Firstly, rest is important. The injured foot should not be used and should be properly rested.
  • Immobilizing the ankle using a walking boot would make sure that there is no pressure which will speed up the healing process.
  • NSAIDs and corticosteroid injections can help deal with the pain and inflammation, if any.

If the above non-surgical techniques fail to have an impact on the os trigonum syndrome, a surgery would be required to remove the extra bone, as it is not required for a normal foot functioning as such.

1 response to What is Os Trigonum Syndrome?

  1. I had surgery to remove the os trigonum bone 7 days ago. The pain is severe whenever I stand up or have my feet in the veriticAl position. How long can I expect this pain to last?