COLORADO SPRINGS, Colo. -- Caydee Denney and John Coughlin won't defend their pairs title they earned last year in San Jose at the upcoming U.S. Figure Skating Championships while he recovers from hip surgery.

U.S. Figure Skating said Tuesday that the two had withdrawn but gave no other details. Coughlin had surgery Dec. 4 to repair a torn labrum in his left hip.

The injury means the U.S. will have its fifth new pairs champion in as many years, creating instability in a discipline where longevity is a key factor in success. Denney and Coughlin's withdrawal also means none of last year's pairs who earned medals in San Jose last year will be at nationals, which begin Jan. 24 in Omaha, Neb.

Runners-up Mary Beth Marley and Rockne Brubaker have split, as have bronze medalists Amanda Evora and Mark Ladwig.