Madsen was using the watercraft Monday and was hurt after he had to bail off the machine and dive into the water, a team spokesman said. Team orthopedic surgeon Dr. David Fischer and Dr. Brad Nelson performed the surgery to repair his right shoulder.

"This was an unfortunate accident that I have put behind me. My focus now is to concentrate on my rehabilitation with the goal of returning to the basketball court as quickly as possible," Madsen said in a statement issued by the team.

The veteran forward averaged just 1.1 points and 1.6 rebounds in 56 games last season, but the team was going to lean heavily on Madsen this season while developing a core of young players after trading All-Star forward Kevin Garnett to Boston.

"It is an unfortunate situation," vice president of basketball operations Kevin McHale said. "Mark is one of the most determined and hardest working players in our league, and we expect him to make a full recovery. I look forward to him returning to the court and filling his role as one of the team's veteran leaders."