Patella Tendon Tear

Article by Dr. Darren R Keiser MD

The patellar tendon works with the muscles in the front of your thigh – the quadriceps – to straighten your leg. Although anyone can injure the patellar tendon, tears are more common among middle-aged people who play running or jumping sports. A complete tear of the patellar tendon is a disabling injury. It usually requires surgery to regain full knee function.

Description

Partial tears. Many tears do not completely disrupt the soft tissue. This is similar to a rope stretched so far that some of the fibers are torn, but the rope is still in one piece.

Complete tears. A complete tear will disrupt the soft tissue into two pieces.

The patellar tendon often tears where it attaches to the kneecap, and can break a piece of the bone as it tears. When the patellar tendon is completely torn, the tendon is separated from the kneecap. Without this attachment, you cannot straighten your knee.

When a tear is caused by a medical condition — like tendonitis — the tendon usually tears in the middle.

Cause

Injury
A very strong force is required to tear the patellar tendon.

Falls. Direct impact to the front of the knee from a fall or other blow is a common cause of tears. Cuts are often associated with this type of injury.

Jumping. The patellar tendon usually tears when the knee is bent and the foot planted, like when landing from a jump or jumping up.

Tendon Weakness
A weakened patellar tendon is more likely to tear. Several things can lead to tendon weakness.

Patellar tendonitis. Inflammation of the patellar tendon, called patellar tendonitis, weakens the tendon. It may also cause small tears.

Patellar tendonitis is most common in people who participate in activities that require running or jumping. While it is more common in runners, it is sometimes referred to as “jumper’s knee.”

Corticosteroid injections to treat patellar tendonitis are typically avoided in or around the infrapatellar tendon. Injections around this articular tendon have been linked to increased tendon weakness and increased likelihood of tendon rupture.

Chronic disease. Weakened tendons can also be caused by diseases that disrupt blood supply. Chronic diseases which may weaken the tendon include:

Steroid use. Using medications like corticosteroids and anabolic steroids has been linked to increased muscle and tendon weakness.

Surgery
Previous surgery around the tendon, such as a total knee replacement or anterior cruciate ligament reconstruction, might put you at greater risk for a tear.

**Call the office of Dr. Darren Keiser to set up an appointment

Article URL: http://orthoinfo.aaos.org/topic.cfm?topic=A00512&webid=2FDDE053