Tuesday, October 20, 2009

Os Trigonum Syndrome

The os trigonum usually joins with the talus by the end of the first year, forming the trigonal process, but It may remain a separate ossicle in up to 15% of patients. Its anterior surface is connected to the lateral talar tubercle by a fibrocartilagenous synchondrosis. Its inferior surface may articulate with the calcaneus.

The os trigonum syndrome, also known as talar compression syndrome, posterior ankle impingement syndrome, and posterior tibial talar impingement syndrome, is a broad term that refers to symptoms produced by pathology of the lateral tubercle of the posterior talar process. Symptoms include chronic pain with stiffness, tenderness, and edema in the posterior ankle, which are exacerbated by activities that result in extreme plantar flexion.

Different processes can lead to os trigonum syndrome:
  • Disruption of the cartilaginous synchondrosis between the os trigonum and the lateral talar tubercle: MRI will show fluid between the os trigonum and the lateral talar process.
  • Trigonal process fracture.
  • Flexor hallucis longus (FHL) tenosynovitis: The tendon for the FHL is located medial to the os trigonum between the medial and lateral tubercles of the talus. Heavy use of the FHL can result in tenosynovitis by rubbing against the os trigonum.
  • Posterior tibiotalar impingement by bone block: A bony protuberance from the calcaneus may articulate with the inferior surface of the os trigonum.
  • Intraarticular loose bodies: Just like other joints, synovial osteochondromatosis can affect the posterior subtalar joint or posterior ankle joint capsule.


Karasick D, Schweitzer ME. The os trigonum syndrome: imaging features. AJR Am J Roentgenol. 1996 Jan;166(1):125-9.

1 comment:

  1. Hi all,

    My name is Daniel, and similar to some individuals on this post, I have been diagnosed with Os Trigonum Syndrome a couple months ago. I am a male teenager who rarely is ‘pointing my feet downward.’ Instead, I was a camp counselor and was constantly walking/putting pressure on my feet. After weeks of this agonizing pain, I finally went to see a podiatrist who took x-rays and pointed to the os trigonum bone present in both of my feet/ankles. Since then, I have been receiving steroid injections in my feet, physical therapy/electrical stimulation, heel-pushers/orthotics, and consulting opinions of various medical professionals.
    NOTHING IS WORKING! This is two + months post-diagnosis and I’m scheduled to see an orthopedic surgeon very soon. Surgery is what I want and need to get my pain away. What do y’all think?
    Bye-bye bones!


Note: Only a member of this blog may post a comment.