The 49ers signed Kenny Rowe, an outside linebacker from Oregon who participated in 49ers training camp a year ago.The 49ers waived safety Mark LeGree, who did not see any action on defense in the exhibition opener Friday night against the Minnesota Vikings. The 49ers roster stands at 89 players, one less than the maximum.Rowe joins the 49ers at a time when the team has a shortage of outside linebackers. Aldon Smith is expected to miss some time with a right hip bruise. Rookie Cam Johnson, who underwent arthroscopic surgery to clean up a knee condition, has not returned to 100-percent health. He did not suit up for Friday's game.Also, rookie Darius Fleming is not active and is not expected to play this season after undergoing surgery to repair a torn knee ligament.Rowe (6-foot-3, 235 pounds) originally signed with the 49ers as undrafted rookie last year. Rowe appeared in 52 games (26 starts) in his Oregon career. He recorded 109 tackles, 23.5 sacks, 10 forced fumbles and two fumble recoveries. He earned second-team All-Pac 10 honors as a senior.LeGree spent two weeks last season on the 49ers' practice squad.