Patellar tendinitis is an injury that affects the tendon connecting your kneecap (patella) to your shinbone. The patellar tendon plays a pivotal role in the way you use your leg muscles. It helps your muscles extend your knee so that you can kick a ball, run uphill and jump up in the air.
Patellar tendinitis is most common in athletes whose sports involve frequent jumping — such as basketball and volleyball. For this reason, patellar tendinitis is commonly known as jumper’s knee. However, even people who don’t participate in jumping sports can experience patellar tendinitis.