[Symptomatic os trigonum with irritation of the flexor hallucis longus tendon - arthroscopic management via a dorsal approach].

Therapy-resistant pain in the region of the medial mallelous in the presence of an os trigonum is suggestive for irritation of the flexor hallucis longus tendon. Two patients were treated by arthroscopy in the prone position via a dorsal approach; the os trigonum was removed and the tendon released. Under the conditions of blunt dissection, dorsal arthroscopy of the os trigonum is a safe and expedient operation in our toolbox. After two weeks of partial load-bearing with 2 crutches, pain-free full load-bearing is already possible and after 3 weeks the patients can return to work.