WASHINGTON (AP) — Robert Griffin III underwent reconstructive knee surgery Wednesday and faces a challenging rehab if he is to return for the start of next season.The Washington Redskins quarterback had his lateral collateral ligament repaired and his ACL in his right knee reconstructed for a second time. The surgery was performed in Florida by orthopedist James Andrews, who was optimistic that Griffin would be back on the field this fall.“We expect a full recovery, and it is everybody’s hope and belief that due to Robert’s high motivation, he will be ready for the 2013 season,” Andrews said in a …