Cactus thorn arthritis: case report and review of the literature.

Synovitis secondary to penetrating plant thorn injuries is an infrequently reported event. Despite its wide geographic distribution, thorns from the prickly pear cactus (Optunia ficusindica) are a rare source of this type of inflammatory arthritis. We hereby present an unusual case of an individual who developed an acute monoarthritis of the knee shortly after sustaining a penetrating cactus thorn injury. The clinical and pathophysiologic features of cactus thorn arthritis are reviewed and the unusual features present in this individual are highlighted. Treatment options, with an emphasis on rapid diagnosis and therapeutic interventions, are discussed. Increased physician awareness and recognition of this unusual but not rare entity are essential as a means of improving clinical outcome.