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ICD-9 Code for Os Trigonum Syndrome

02/21/2006      Howard Dananberg, DPM


Query: ICD-9 Code for Os Trigonum Syndrome

What would be the appropriate diagnostic code of os trigonum syndrome?

Howard Dananberg, DPM, Bedford, NH

Response: Os trigonum syndrome [posterior ankle impingement (PAI) syndrome; posterior tibiotalar impingement syndrome (PTTIS)] is the result of an impingement or compression of the posterior talus (with os trigonum present) and the surrounding soft tissues between the tibia and the calcaneus on plantar flexion of the foot. It is seen in patients whose activities involve excessive or recurrent plantar flexion motion (e.g. ballet dancers, soccer players, basketball players, runners, and volleyball players).

The symptoms can occur either gradually or acutely. The patient complains of pain in the posterior ankle with the area behind the Achilles tendon at that site sore to the touch. The syndrome can involve swelling and stiffness in the posterior ankle area. The differential diagnoses for os trigonum syndrome include Achilles tendinitis, calcaneal or talar fracture, retrocalcaneal bursitis, posttraumatic arthritis, ankle ligament sprain, osteochondritis dissecans, tarsal coalition, and posterior tibialis, peroneal, and flexor hallucis longus tendinitis.

There is no specific ICD-9 code for os trigonum syndrome. There are, however, a number of possible ICD-9 codes that may describe either conditions or signs/symptoms present (os trigonum syndrome can be made up of several groups clinical pathologic entities), including (but not limited to):

ICD-9 726.90 - Enthesopathy of specified site (Capsulitis NOS) ICD-9 726.70 - Enthesopathy of ankle and tarsus, unspecified ICD-9 726.71 - Achilles bursitis or tendonitis ICD-9 959.7 - Injury, knee, leg, ankle and foot ICD-9 729.5 - Pain in limb ICD-9 719.57 - Stiffness of joint, not elsewhere classified

It is important NOT to code "rule outs"  so if there is no talar fracture present, do not include that ICD-9 code in your billing; if there is no Achilles tendinitis present, do not code for it, etc.

Harry Goldsmith, DPM, Cerritos, CA