Less than a year after acquiring him from the Washington Bullets, the Philadelphia 76ers announced yesterday that center Jeff Ruland, 28, has retired from pro basketball because of a chronic knee injury.

"We have concluded that Jeff can no longer pass physical requirements to play professional basketball," 76ers General Manager John Nash said in a statement.

Ruland, who is 6 feet 11 and 240 pounds, could not be reached for comment. He played in five games this season after reinjuring the knee in preseason and then undergoing arthroscopic surgery. Nash said that, after meeting with club officials, Ruland concluded he had no alternative but to quit playing.

"Jeff's dedication to try and rehabilitate his knee has been an inspiration to everyone in the organization," Nash said. "Despite unanimous medical evidence to the contrary, his determination never wavered. Unfortunately, the passage of time has not improved Jeff's medical prognosis, as he is unable to pass the club's physical examination."

On June 16, 1986, Ruland was dealt to the 76ers with Cliff Robinson in exchange for Moses Malone, Terry Catledge and first-round draft choices in 1986 {used to pick Anthony Jones} and 1988.

"It's tragic when a player that age has to retire because of injury," Bullets General Manager Bob Ferry said. "When he was with us, it wasn't a recurring injury. It was a different thing every year."

As for the Bullets getting the better of the deal, Ferry said: "For every trade you make that you look good on -- well, I hope there are not quite as many that you look bad on."