Tendons are like ropes which connect muscles to bone. The patellar tendon connects the kneecap (the patella) to the shinbone (the tibia). Patellar tendonitis is the condition that arises when the tendon and the tissues that surround it become irritated and painful from overuse, especially from jumping activities. This usually occurs in teenage athletes who participate in sports that have a lot of repetitive jumping, including volleyball and basketball. However, patellar tendonitis can also be seen in sports such as running and soccer.