De Quervain's disease.

This is a tenosynovitis of the abductor pollicis longus and extensor pollicis brevis tendons contained within the osseofibrous tunnel of the distal radius. Multiple tendons for the abductor pollicis longus and a separate, severely narrowed sheath for the extensor pollicis brevis make nonsurgical treatment difficult at times. While avoiding damage to nerve branches, surgical treatment is aimed at release of both tendon sheaths.