5) Morgan Stoddart
Wales and Scarlets back Morgan Stoddart has retired with immediate effect after failing to recover from a broken leg.
The 28-year-old was six games into his Scarlets comeback after 14 months out with a double leg fracture.
But he has experienced “significant pain” since his return and has followed medical advice to stop playing.
The incident was so graphic that match broadcaster Sky Sports chose not to show a replay, so be warned.