- An Os trigonum is a congenital accessory bone behind the talus that is classically asymptomatic
- Symptoms may occur following forced or repetitive plantar flexion causing stretching or tearing of the connecting soft tissue, or even fracture.
- DDx include Achilles pathology or talus fracture
- Patients typically complain of pain pain in the back of the ankle, worse on push off and plantarflexion.
- Examination may reveal localised tenderness or swelling.
- Diagnosis may be confirmed with plain radiographs.
Treatment is normally conservative
- Prescribe PRICE
- Short term NSAIDs
- Steroid injections are appropriate if skilled with a confirmed diagnosis.
- Physiotherapy for stretching exercises.
- Diagnostic uncertainty
- Failure of conservative measures after a minimum of 3months
- Referral for formal physiotherapy
- Referral for steroid injection or arthroscopic or open excision.