Martin, a right-handed power pitcher taken with the 15th overall pick out of Stephens County High School in Georgia, suffered the injury during fielding drills. He signed earlier this month for a $1.73 million bonus.
Martin, 19, was named the 2008 Georgia State High School Player of the Year by Gatorade after going 11-1 with a 0.99 ERA as a senior. He also had 141 strikeouts in 79 innings. He was named a 2007 AFLAC All-American after his junior season, during which he went 6-1 with 81 strikeouts and a 1.41 ERA.
He was rated by Baseball America as having the second-best fastball among Draft-eligible high school pitchers. He is also rated by the publication as having the third-best secondary pitch. Dodgers assistant general manager Logan White projects Martin to compare with Diamondbacks pitcher Dan Haren.
Chris Withrow, the Dodgers' first-round pick last year, has not pitched this season because of arm and control problems.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.