Knee > Kneecap Tendon Rupture

What is a Kneecap Tendon?

Your kneecap (patella) attaches to your shinbone (tibia) via the patellar tendon. The patellar tendon holds your kneecap in place on the bottom as your thigh muscles pull on the kneecap from the top when you straighten your knee.

Your kneecap (patella) attaches to your shinbone (tibia) via the patellar tendon. The patellar tendon holds your kneecap in place on the bottom as your thigh muscles pull on the kneecap from the top when you straighten your knee. The kneecap tendon usually tears close to its end, where it attaches to the kneecap. When the tendon ruptures, it splits into two pieces and the kneecap is left with nothing holding it in place on the bottom. Most people cannot actively straighten their knee when the kneecap tendon ruptures. If you suspect you have suffered a ruptured tendon, you should seek treatment as soon as possible. Surgery within two weeks of the tendon rupture is the only available treatment that can help you to return to activities.

Force to a flexed knee is the most common cause of kneecap tendon ruptures. In general, it takes pressure about 17 times greater than your body weight to rupture the kneecap tendon. In comparison, the most strenuous daily activity, climbing stairs, puts about 3.2 times the force of your body weight on the kneecap tendon. Healthy knees are at the highest risk of suffering a ruptured kneecap tendon during activities that involve high speeds, direct contact, or twisting ­ such as skiing, football, and basketball. Landing a jump, heavy weightlifting, and losing your balance can also rupture your kneecap tendon. People between the ages of 30 and 40 suffer the majority of kneecap tendon tears. But at any age, a history of repeated knee injuries, previous knee surgery, or joint disease could put you at greater risk of a kneecap tendon rupture. This means that a force less than 17 times your body weight could rupture your kneecap tendon if you have suffered multiple microtears, or minor injuries over the years, and especially if you have a disease like rheumatoid arthritis that weakens the fiber material (collagen) in your tendons.

Non-operative treatments are generally ineffective. Ruptured kneecap tendons almost always require surgery to sew the split tendon back together. Surgery is most effective when performed within two weeks after the injury. If you wait more than two weeks to seek treatment, your ruptured tendon may begin to heal in an abnormal position, which makes repairing the tendon more difficult and decreases your chance of returning to activities at full strength. Kneecap tendon repair cannot be done arthroscopically.

There are usually three parts to an orthopedic evaluation: medical history, physical examination, and tests your physician may order.

Your doctor will likely ask you when your kneecap tendon rupture occurred, how it has been feeling since the pain began, and if your knee has been previously injured. Physicians also typically ask about other conditions, such as diabetes and allergies, and medications currently being taken. The doctor may also ask about your physical and athletic goals - information that will help him decide what treatment might be best for you in achieving those goals.

A physician usually can make an early assessment of an injury by feeling around the area. Because the kneecap is easily visible, physicians can quickly test for pain and tenderness. Physicians generally move your kneecap up and down. A ruptured kneecap tendon usually causes your kneecap to move abnormally up towards your thigh. Physicians can sometimes feel a hole where your kneecap tendon has split in two, helping them make a clear diagnosis.

TESTS

Should your physician require a closer look, these tests may be conducted.

   X-rays can clearly show when your kneecap is too high in your thigh, signaling that the attachment to the shinbone has been ruptured.

   MRI (magnetic resonance imaging) may be obtained if the diagnosis is in question. It can show the rupture to the tendon, and may indicate damage to other knee structures.

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