THE SIDELINES : Cowboys’ Walen Out for Season

Dallas Cowboys starting defensive lineman Mark Walen, a third-year veteran from UCLA, will miss the 1989 season as a result of arthroscopic surgery on his left knee, a team spokeswoman said today.

Walen was reported in good condition today at Mary Shields Hospital in Dallas. Dr. Robert Vandermeer repaired a torn interior cruciate ligament and damaged cartilage in Walen’s knee.

The 6-foot-5, 267-pound lineman injured his knee in Saturday’s 20-17 preseason victory over the Raiders. The injury was originally diagnosed as a severe sprain.