The patellar tendon connects the kneecap (the patella) to the shin bone. This is part of the ‘extensor mechanism’ of the knee, and together with the kneecap quadriceps tendon and the quadriceps muscle, these structures allow your knee to straighten out, and provide strength for a kicking motion. The patellar tendon, like other tendons, is made of tough string-like bands. These bands are surrounded by a vascular tissue lining that provides nutrition to the tendon.
Patellar tendonitis is the condition that occurs when the tendon becomes inflamed and irritated. This condition is most often seen in athletes who do repetitive jumping, the reason patellar tendonitis is often called “jumper’s knee.” Patellar tendonitis is most often seen in participants of sports including basketball and volleyball, although can also be seen in runners and other types of athletes.
Patellar tendinitis is a common overuse injury. It occurs when you place repeated stress on your patellar tendon. The stress results in tiny tears in the tendon, which your body attempts to repair. But as the tears in the tendon become more numerous, they cause pain from inflammation and a weakening of the tendon structure. When this tendon damage persists over more than a few weeks, it is called tendinopathy.
A combination of factors may contribute to the development of patellar tendinitis, including intense and frequent physical activity, especially repeated jumping, tight leg muscles (quadriceps and hamstrings), and muscular imbalance with some muscles of the leg stronger than others, a condition which creates an uneven pull on the patellar tendon.
Patellar tendonitis and usually cause pain directly over the patellar tendon. The tendon is usually tender and swollen. Movement of the knee may cause a crunching sensation directly over the swollen tendon.
The other common symptom of patellar tendonitis is pain with activities, especially jumping or kneeling.
The pain in your knee may:
Initially be present only as you begin physical activity or just after an intense workout
Progress to the point that it interferes with your sports performance
- Eventually interfere with daily tasks such as climbing stairs or getting up from a chair