LOS ANGELES — Celtics starting center Kendrick Perkins had to be helped off the court after his right knee appeared to buckle in a collision with Andrew Bynum under the Lakers basket midway through the first quarter. League officials reported during the game that Perkins had sustained a sprained right knee.

The center had X-rays on the leg and his return for Game 6 was ruled out by the team during halftime. Perkins will be re-evaluated on Wednesday. His status for possible Game 7 on Thursday is uncertain.

Perkins and Bynum collided going for the rebound with 5:30 left in the first and Perkins landed awkwardly and remained on the floor several minutes while pointing at his right knee. He was helped off the court by Brian Scalabrine and Shelden Williams and could not put any weight on the leg as he made his way back to the dressing room.