Os Styloideum and Third Metacarpal Partial Coalition Nonunion After Traumatic Fracture: A Report of Three Cases

The Os Styloideum (OS) is an accessory carpal bone located in the dorsal aspect of the wrist between the base of the second and third metacarpal bones and the trapezoid and the capitate. It is frequently partially coalited with the metacarpal bones and is usually asymptomatic. It may become symptomatic after a traumatic fracture, developing swelling, edema, and pain. We report 3 cases with a fracture of an OS partial coalition with the third metacarpal bone with signs of delayed consolidation. They all complain of persistent pain at the dorsal aspect of the hand that increased with activity. One patient rejected surgery, had a platelet-rich plasma injection, shock wave therapy, and afterward did physiotherapy rehabilitation without complete solution; the other two patients underwent surgical excision with local anesthesia and had a complete recovery after 2 months of follow-up. The OS is an infrequent entity yet must be correctly diagnosed as a possible cause of dorsal pain in the hand and wrist. If symptoms are refractory to medical treatment, surgical excision should be considered. Open excision under local anesthesia is a simple, reproducible procedure with excellent results.