WHAT IS PATELLAR TENDONITIS / JUMPER’S KNEE? Patella tendonitis, or more commonly known as Jumper’s knee, is a condition that causes sharp pain at the front of the knee just below the knee cap. As the name suggests, this condition is commonly seen in the athletic population, especially in sports that involve lots of running and jumping. It is a condition that is aggravated with an increase in load and insufficient rest between activities. It is therefore a common problem in athletes with a strict training regimen or with high impact sports. Learn more about Jumper's Knee.