Management of hyperextension of the metacarpophalangeal joint in association with trapeziometacarpal joint osteoarthritis.

This study investigates the management of metacarpophalangeal joint (MCP) hyperextension in patients undergoing trapeziectomy for thumb base osteoarthritis. A total of 297 thumbs with painful trapeziometacarpal osteoarthritis were assessed on pain and thumb key and tip pinch preoperatively and at 1 year. Before surgery 101 had no MCP hyperextension, 168 had hyperextension ≤ 30° and 28 had hyperextension ≥ 35°. Of these 157 hyperextension deformities ≤ 30° and eight ≥ 35° were not treated. The others were treated by temporary insertion of a Kirschner wire (n = 9), MCP fusion (n = 6), sesamoid bone tethering to the MC head (n = 5) and palmar capsulodesis using a bone anchor (n = 11). Untreated MCP hyperextension deformities < 30° did not influence the outcome of trapeziectomy. MCP hyperextension deformities ≥ 35° can be improved by capsulodesis or MCP fusion but this may not improve the clinical outcome.