The os trigonum is an accessory (extra) bone located at the back of the ankle, near the heel bone (calcaneus). It's present in a small percentage of the population.
More Details About Os Trigonum
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Prevalence: The os trigonum is found in approximately 2.5% to 14% of people.
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Appearance: Typically, it's round, oval, or triangular in shape and its size can vary.
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Development: It arises from a secondary ossification center of the talus (ankle bone). Usually, this ossification center fuses with the talus by adolescence. When it doesn't fuse, it remains as the os trigonum.
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Significance: In many individuals, the os trigonum causes no problems. However, it can become symptomatic due to injury, overuse, or repetitive plantarflexion (pointing the toes), leading to a condition called os trigonum syndrome. This syndrome involves pain and inflammation in the back of the ankle.
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Symptoms of Os Trigonum Syndrome: Common symptoms include:
- Pain in the back of the ankle, especially with plantarflexion.
- Tenderness to the touch.
- Swelling.
- Limited range of motion.
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Diagnosis: Os trigonum is typically diagnosed via X-rays. MRI or CT scans may be used for further evaluation of associated soft tissue injuries.
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Treatment: Treatment for symptomatic os trigonum (os trigonum syndrome) usually begins with conservative measures:
- Rest
- Ice
- Compression
- Elevation (RICE)
- Anti-inflammatory medication
- Immobilization (cast or boot)
- Physical therapy
If conservative treatment fails, surgical removal of the os trigonum may be considered.
