Jumper’s Knee, which is also known as patellar tendinosis, is when there is an injury or degeneration of the patellar tendon. The patellar tendon is the tissue that joins the kneecap to the shinbone. Jumper’s Knee is caused by constant jumping and landing, in sports that have a lot of repetitive jumping, i.e. gymnastics, track, volleyball and basketball. It results from putting too much-repeated stress on the patellar tendon. This then causes tiny tears in the tendons that cause initial inflammation and a weakening of the structure, but then becomes chronically degenerated.