Yankees closer Mariano Rivera declared Friday that his career was not over, and according to medical experts and peers who have come back from a similar knee injury, there is no reason to believe he will not be able to return.

Rivera, who tore the anterior cruciate ligament in his right knee Thursday night, faces a recovery process that could last up to eight months. It is a relatively rare injury among baseball players, much less pitchers. Nevertheless, there does not appear to be much, including his age, that would prevent the 42-year-old Rivera from pitching again.

“With this injury, if the surgery goes the way it should go, it’s completely up to the player whether he plays again,” Stan Conte, director of medical services for the Los Angeles Dodgers, said. “The surgery has been around for a long time, and it is highly successful in athletes.”

Younger athletes normally heal better than older ones, but doctors said there was not much difference between the knees of a 22-year-old and those of a 42-year-old, particular one in good physical shape. Rivera has other factors in his favor. He does not have a history of knee problems, and as a pitcher, he does not put too much stress on the knee and is not forced to constantly pivot. The fact he hurt his right knee rather than his left, which is the leg he lands on and turns during his pitching motion, is also seen as a positive.