Jumpers knee or patellar tendonitis is pain in the tendon which attaches the kneecap (patella) to the shin bone. It is usually an overuse injury due to repeated eccentric quad contractions, as occur when landing from a jump - hence the name jumper's knee!
He has since been sent down to Tampa to be examined and get an MRI. The injury will need a lot of rest and plenty of rehabilitation before he's back to normal, so it doesn't look like he'll be returning soon.
Now, based on comments made by Thunder manager Tony Franklin, it looks like his season might be over:
Franklin on Heathcott:There isn’t much (time left in season), so you can draw your own conclusions on that. All the tests and things that...— Nick Peruffo (@nickperuffo) August 14, 2013
…will be dealt with will be done in Tampa. They feel its significant enough to bring him down, shut him down for awhile and find out what...— Nick Peruffo (@nickperuffo) August 14, 2013
the problem is, and figure out a route to go. It’ll probably keep him shut down for a while.— Nick Peruffo (@nickperuffo) August 14, 2013
His season as a whole has been a little disappointing and maybe even a step backwards after hitting .261/.327/.411, however, since July 1 he's hit .307/.367/.518 with four of his eight home runs. He's still had a better season than Mason Williams (.264/.330/.353) and Tyler Austin (.254/.344/.367), who hasn't played in a month because of a bone bruise in his wrist. It's been an underwhelming year for Yankees outfield prospects.
Slade's wild style of play has gotten him in trouble before, so if he's jumping and diving a lot it might not be the best thing for his health. In 2013, Heathcott has played 90 games in center field and hasn't played a corner outfield position since last season when he only played three games in left field. Moving him to left might prevent him from overexerting himself while trying to cover center, but the problem is that center field might be what's keeping him a top prospect because he's already slipped out of MLB.com's top five of Yankees prospects.
If he is shut down for the rest of the season it could mean that Heathcott and Williams will play for Double-A Trenton at the same time in 2014. One of them is going to have to move for the other and right now it looks like Williams could be the better center fielder.