reyes4.jpgAccording to Mike Francesa of WFAN, Jose Reyes has been diagnosed with tendonitis behind the right kneecap.  He cannot do any further damage, has rejoined the team and is day-to-day.Seif_knee anatomy01.jpgFrom about.com:What is tendonitis?Sometimes the tendons become inflamed for a variety of reasons, and the action of pulling the muscle becomes irritating. If the normal smooth gliding motion of your tendon is impaired, the tendon will become inflamed and movement will become painful. This is called  tendonitis, and literally means inflammation of the tendon.What causes tendonitis?The most common cause of tendonitis is overuse. Commonly, individuals begin an exercise program, or increase their level of exercise, and begin to experience symptoms of tendonitis. The tendon is unaccustomed to the new level of demand, and this overuse will cause an inflammation and tendonitis.Another common cause of symptoms of tendonitis is due to age-related changes of the tendon. As people age, the tendons loose their elasticity and ability to glide as smoothly as they used to. With increasing age, individuals are more prone to developing symptoms of tendonitis. The cause of these age-related changes is not entirely understood, but may be due to changes in the blood vessels that supply nutrition to the tendons.Sometimes, there is an anatomical cause for tendonitis. If the tendon does not have a smooth path to glide along, it will be more likely to become irritated and inflamed. In these unusual situations, surgical treatment may be necessary to realign the tendon.UPDATE: According to MLB.com's Anthony DiComo, this diagnosis was originally made Saturday at AT&T Park by 'a doctor.'  Below is an excerpt from his article published 05/17/09 7:38 PM ET: {But on the bench Reyes will remain, at least for one more game. For the fourth straight day, Reyes insisted that his calf had improved, but for the fourth straight day, the Mets were unwilling to take a chance. Reyes saw a doctor Saturday at AT&T Park and received a new diagnosis: a mild case of tendinitis in the leg.Rest was the prescription, along with his now-usual routine of ice, heat and massage."I have to be worried about it, no doubt," Reyes said, rattling off a few contradictions. "It's getting better, but I mean it's slow. I don't think it's going to be that long before I get on the field."Originally feeling the injury prior to Wednesday's game, Reyes tried to run since then but was met with pain. He has been taking regular fielding and batting practice and could conceivably pinch-hit in a close game, as he did Saturday, but running -- a Reyes forte -- remains an issue."It's affecting my running," Reyes said. "I'm not able to run the way I want to. That's dangerous. If I play like that, maybe I can make it worse.""We just have to be careful with it," manager Jerry Manuel said, expressing surprise at how long the calf has taken to heal, but insisting that Reyes is not considering a trip to the disabled list. "It's still a little tender."Manuel's only relief is that the Mets are doing just fine without Reyes. In three games against the Giants, the Mets have scored 24 runs, rapped out 42 hits and -- here's the kicker -- stolen 13 bases. That latter statistic is a franchise record over a three-game span.Yet Reyes is missing the party."It's too boring for me to be on the bench," he said, hardly joking. "There's nothing to do there."}