Carmelo Anthony has missed four of the past six games and is questionable to play Sunday, and one orthopedic surgeon who has not examined Anthony speculated that the New York Knicks' forward has either a partially torn meniscus or an arthritic knee.

Anthony had his knee drained in New York after the Knicks' loss to the Denver Nuggets on Wednesday. Having fluid in the back of the knee is rarely found in a patient "with a 100 percent normal knee," according to the surgeon.

“It means there is something going on with the knee,” the doctor added. “The question is, where did the fluid come from? What is the source of the fluid? Something inside the knee produces that fluid, so what is going to stop the fluid from coming back.”

The Knicks initially described Anthony's injury as just soreness.