Thorn synovitis of the knee joint with Nocardia pyarthrosis.

Pyarthrosis of the knee with Nocardia asteroides occurred concomitantly with thorn synovitis in an 11-year-old boy who was otherwise healthy. A review of the orthopedic and infectious disease literatures did not disclose a similar report. Contrary to common teaching, effusions from joints violated by thorns should not be presumed sterile. Culture for bacterial and fungal infections is recommended when treating cases of thorn synovitis.