The third metacarpal boss.

A swelling and ache on the dorsum of the wrist in relation to the base of the 3rd metacarpal bone may indicate a bony lesion or an enlarged styloid process. It may also be due to an old fracture of the process or an accessory ossicle (os styloideum). Approximately half the 14 patients (15 wrists) had a history of an injury, usually a hit with the fist. Recurrent occupational strain may also produce symptoms at this site. Excision of the metacarpal base with the adjacent capitate or trapezoid, and repair of the periosteum and extensor tendon, will remove the lump and usually relieve symptoms.