Achilles tendon rupture
During pre-season, Hearn picked up a calf and achilles problem on his right leg, thus ended up missing Grimsby's following pre-season games against Hull City, Scunthorpe United and Lincoln City. Hearn appeared to be on the road to recovery, on 14 August 2012 in the 2–1 defeat at Stockport County, he came on as a 58th-minute substitute. However, on 17 August 2012, he injured his left leg in training, tests revealed an Achilles tendon rupture and he would be out for several months.