The following is from UFC.com:
Griffin KO’ed by Staph Infection; Out of UFC 70
Light heavyweight contender Forrest Griffin has been sidelined by a severe staph infection in his knee and today was forced to withdraw from his UFC 70 bout with Lyoto Machida. A replacement is currently being sought to face Machida on the April 21st card, which will be held at the M.E.N. Arena in Manchester, England.