Galaxy striker Adam Cristman has become the latest sports figure to retire because of concussion-related issues, the club announced today.

Cristman, 27, made 13 MLS appearances over two seasons for the Galaxy, scoring one goal.

“The concussions I have suffered this year have forced me to retire,” Cristman said in a statement released by the club. “While this is not the way I wanted to leave the game, I am excited for what the future holds as I transition into the next phase of my life.”

Cristman missed the first two months of the season because of a concussion suffered in a preseason game against New York.

He made his season debut as a second half substitute in the 1-1 home draw with FC Dallas April 28 and then started the following game at Seattle before suffering a second concussion in training.

The University of Virginia product also scored the Galaxy’s opening goal in their unsuccessful CONCACAF Champions League campaign against Motagua, added a goal against Seattle in the U.S. Open Cup, two more in the MLS Reserve League and one more against Real Madrid in an exhibition game.

The Washington D.C. native has also played for D.C. United, Kansas City Wizards and the New England Revolution since starting his MLS career in 2007.

In a second move Tuesday that even took some club officials by surprise, injured defender Omar Gonzalez, who played 45 minutes in a scrimmage Monday, was activated off the disabled list making him eligible to play in Wednesday’s game against the Philadelphia Union.

The move does not, however, mean the MLS 2011 Defender of the Year is likely to make an equally surprising return to first team action in the game, a club official observed.