5. Tom Rees
Former England international Tom Rees was been forced to retire at the age of 27 because of a serious knee injury in March 2012..
Rees, who was capped 15 times, ruptured his anterior cruciate ligament last summer and has been advised to stop playing immediately.
The at the time Wasps captain made his club debut in 2003 and made 113 appearances.
He endured three shoulder operations between April 2009 and December 2010 before his most recent setback in August last year, restricting him to 18 first-team appearances in his last three campaigns.