Spontaneous Extensor Pollicis Longus Rupture Associated With an Extensor Digitorum Brevis Manus

A 64-year-old left-handed man with no history of rheumatoid arthritis or distal radius fracture presented with spontaneous loss of thumb interphalangeal joint extension. Intraoperatively, the patient was found to have a variant extensor indicis proprius with extensor digitorum brevis manus. Prior extensor digitorum communis ruptures have been reported in the literature secondary to the distal extensor digitorum brevis manus muscle belly, but there are no prior reports of extensor pollicis longus rupture. This case demonstrates a unique etiology of extensor pollicis longus rupture and highlights the alteration in the surgical plan required secondary to the absence of an extensor indicis proprius tendon.