Roddrick Muckelroy, who has started all three games at weakside linebacker this season, sustained the injury in Texas' 52-7 victory at Rice. No timetable has been set on his return.
"This type of tendon injury takes longer to heal and requires a lot more caution during that process than a bone injury," Boyd said. "It's important to get the surgery taken care of and begin the healing process as soon as possible in order to maintain the use of the finger. The surgery was successful and we anticipate a full recovery."
Muckelroy recorded 10 tackles (nine solo), three tackles for loss (-10 yards) and a sack (-3 yards) in three games. A prep first-team 4A All-State pick that spent the 2005 season redshirting, he had a season best four tackles at Rice.
"This is an unfortunate setback for Roddrick and our defense," said Mack Brown. "He was really playing well and was developing into a key part of our defense. We'll need to have someone step up to fill his void and hopefully we'll get him back as soon as possible."
Junior Scott Derry will move into the starting role at weakside linebacker. A versatile fourth year player who missed the 2005 season with a broken ankle, Derry has worked at all three linebacker spots this season. He has played in all three games and posted 10 tackles (six solo), four TFLs (-14 yards) and a sack (-7 yards). Derry, who will be starting his first game, has played in 15 career games and recorded 31 tackles (16 solo), six TFLs (-20 yards) and two sacks (-12 yards).
"Scott has really come on strong and is doing a tremendous job for our defense," Brown said. "He's been a very unselfish and versatile player for us. With the injuries we've had at linebacker, we're really fortunate to have him."
Texas also will welcome the return of junior Drew Kelson at weakside linebacker. Kelson missed the first three games with an ankle injury. He played in all 13 games, starting three, in 2005 and posted 36 tackles (17 solo), two TFLs, a sack, one interception, four pass breakups, two forced fumbles and a fumble recovery.