PHOENIX - Patriots running back Laurence Maroney had offseason shoulder surgery that revealed fairly significant damage, according to a league source, though the long-term impact is unclear. Maroney felt shoulder pain down the stretch and in the playoffs that limited his ability to absorb contact. He underwent exploratory surgery that revealed more damage than anticipated, and corrective surgery was performed. The exact nature of his injury is unclear, though it was enough to land Maroney in a sling. Team spokesman Stacey James could not confirm last night if Maroney is taking part in the teams offseason conditioning program. The surgery is just the latest physical setback for the running back, who also suffered torn rib cartilage and a minor knee sprain during the season. With veteran Corey Dillon cut at the start of free agency, Maroney will enter the season as the lead back.