Jayson undergoes surgery on thumb First the leg, now the thumb.

The Nets’ Jayson Williams, still recuperating from the surgery to repair his fractured right leg, yesterday underwent surgery at Beth Israel North Hospital to repair ligament damage to his left thumb. Noted hand surgeon Dr. Charles Melone performed the one-hour operation which was termed a success by the team.

The surgery consisted of reconstructing the ulnar collateral ligament of the thumb by grafting a tendon from his left forearm. Williams will wear a thumb cast for four weeks and will then have a month of rehabilitation.