HOUSTON -- Houston Rockets All-Star guard Steve Francis underwent surgery Thursday to repair a shoulder injury and won't be able to play basketball for the next 16 to 18 weeks.

"We expect Steve to return to the court near the start of training camp,'' Rockets trainer Keith Jones said.

Francis' right shoulder is temporarily immobilized after the operation by team physicians Walter Lowe and Bruce Moseley.

The arthroscopic surgery repaired a problem with the lining of Francis' shoulder, known as the labrum. The labrum provides attachments for shoulder ligaments and tendons and contributes to shoulder stability. In athletes, overhead arm activities, particularly throwing, stress the shoulder excessively and cause labrum injury.

Francis missed the last three games of the season because of what was called shoulder strain. The problem first was disclosed in early March.

"This surgery repaired a lesion in the labrum instead of simply cleaning up the shoulders lining, as the damage was more extensive than anticipated,'' Jones said.

Doctors initially believed, based on a magnetic resonance imaging test Francis underwent with the completion of the season, he only would require about four to six weeks of rehabilitation.

Francis has averaged 19.7 points over his three years with the Rockets. His scoring average is the fourth best in franchise history.

Despite being sidelined for 25 games this past season by a number of other ailments, most notably migraine headaches that kept him out of seven games, the 6-foot-3 Francis averaged 21.6 points, a career high.

The Rockets, however, finished out of the playoffs for a third straight year, staggering to 28-54 record, their worst finish in nearly two decades.

Francis represented the Rockets May 19 at the lottery to determine the NBA draft order. Houston won and has the top pick in the June 26 draft.