Unclear diagnosis

A 25yo presented at the musculo outpatients clinic with intermittent knee pain. He is the ruckman in his footy team and jumps off on his left knee and has had to stop playing due to the pain. He only gets pain with SLSquats and very mild pain when coming up from a full squat. McConnel's fx test was positive which hinted at PFJ problems which we ruled out by further ax. when we tried McConnel taping the pain also became much worse. Apart from tight ITB and hip flexors, all other knee ax came up normal. the only pain he has is on the tibial tuberosity, no pain in the tendon, patellar or reffering pain. The pt says there was no traumatic event where he could have landed on his knee and bruised the tibial tuberosity and the pain started a few weeks ago and is gradually getting worse. By process of elimination, my supervisor and i came up with the diagnosis of Osgood schlatter's disease as his symptoms mirror that condition and the pain was relieved by infrapatellar taping to unload the tibial tuberosity which is commonly used to rx OSD. So we are treating him by taping, regular icing over the tibial tuberosity and stretches. However, im still sceptical as to how a 25 yo with no PMH of OSD could get this condition as he is definitly out of the age bracket! does anyone else have any ideas on what could be the problem?