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Treatment of a Patellar Tendon Tear

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Updated August 07, 2012

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The Patellar Tendon:

The patellar tendon is the structure that connects the kneecap (patella) to the shin bone (tibia). Technically, a ligament is structure that connects bone to bone, and therefore some people refer to this structure as the patellar ligament. However, this structure is really connecting the quadriceps muscle to the shin bone, and a tendon connects muscle to bone, and therefore patellar tendon is the more common description.

The patellar tendon is an important part of the extensor mechanism of the lower extremity. The extensor mechanism includes the quadricps muscle, quadriceps tendon, patella (kneecap), and patellar tendon. These structures allow the knee to straighten, and can do so with significant strength.

Tearing the Tendon:

The typical individual who sustains a torn patellar tendon is a young, male athlete. As more middle-aged people are remaining physically active, this injury is becoming more common in an older population.

Typically the injury involves an awkward landing from a jumping position where the quadriceps muscle is contracting, but the knee is being forcefully straightened. This is a so-called eccentric contraction and places a tremendous stress on the tendon.

Cause of a Torn Patellar Tendon:

It has been found that in nearly all patients who sustain a patellar tendon rupture there is abnormal tendon tissue consistent with a chronic tendinosis. The patellar tendon is usually injured in the watershed region of the tendon, where blood flow to the tissue is poor, and the tendon is weakest.

Tendon tears can also occur in non-athletic settings. Usually there is a reason for the patellar tendon to be weakened in these individuals, such as a systemic disease that weakens tendons or recent surgery on the knee the caused tendon weakening. Treatment is usually similar in athletes and non-athletes alike.

Making the Diagnosis:

Making the diagnosis of a torn patellar tendon is usually obvious on clinical examination. People who tear the tendon will be unable to extend their knee against gravity, and unable to perform a straight leg raise test. The examiner can usually feel the gap in the tendon, just below the kneecap.

An x-ray will be obtained, as a patellar fracture can cause similar symptoms, and should be excluded as a possible diagnosis. On the x-ray, the patella is usually up higher when compared to the opposite knee, as the quadriceps pulls up on the kneecap, and nothing is holding it down. While often not needed, an MRI may be used to confirm the diagnosis and inspect the knee for any other damage that may have occurred.

Treatment of a Patellar Tendon Tear:

A torn patellar tendon does not heal well on its own, and left untreated will lead to weakness of the quadriceps muscle and difficulty with routine activities, including walking. Surgery to repair the torn tendon is relatively straightforward in concept, but can be difficult to perform.

The torn ends of the tendon need to be sewn together. The difficulty lies in the fact that it is important to restore proper tension to the tendon, not making it too tight or too loose. Also, it can be difficult to get a good repair, especially if the tendon has torn directly off the bone. In these situations, the sutures used to repair the tendon may have to be attached through the bone.

Recovery & Prognosis:

Recovering from a torn patellar tendon is difficult and takes time. One of the most important prognostic factors for recovery is the time to surgery, and surgery delayed beyond a few weeks can limit recovery ability. It is known that early mobility after surgery, protected strengthening, and preventing excessive stress on the repair will speed overall recovery. Even with these steps, there is a minimum of 3 months until return of normal daily activities, and 4-6 months until sports should be resumed.

While most people heal completely from a patellar tendon surgery, there can be long-term weakness even with a successful repair.

Sources:

Matava MJ. "Patellar Tendon Ruptures" J Am Acad Orthop Surg November 1996 vol. 4 no. 6 287-296

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