Miami Dolphins running back Knowshon Moreno underwent arthroscopic surgery on his left knee, which will keep him out of practices for four to five weeks.

It would appear the surgery could be a set back for Moreno who would have had the opportunity to battle in training camp with fellow running backs Lamar Miller and Daniel Thomas for the lead carrying duties.

Moreno, who had 1,038 rushing yards and 10 rushing touchdowns last year, signed with the Dolphins for one year after receiving little interest from any other teams. The bum knee could be the reason why.

Photo: Mile High Sports