Patella Tendon Rupture

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 requires surgery to regain full knee function.

Patellar tendon tears can be either partial or complete.

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.

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  requires surgery to regain full knee function.

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:

  • Chronic renal failure
  • Hyper betalipoproteinemia
  • Rheumatoid arthritis
  • Systemic lupus erythmatosus (SLE)
  • Diabetes mellitus
  • Infection
  • Metabolic disease
  • Steroid use. Using medications like corticosteroids and anabolic steroids has been linked to increased muscle and tendon weakness.

Symptoms

When a patellar tendon tears there is often a tearing or popping sensation. Pain and swelling typically follow.

Additional symptoms include:

  • An indentation at the bottom of your kneecap where the patellar tendon tore
  • Bruising
  • Tenderness
  • Cramping
  • Your kneecap may move up into the thigh because it is no longer anchored to your shinbone
  • You are unable to straighten your knee
  • Difficulty walking due to the knee buckling or giving way

Diagnosis

Medical History

Your Wisconsin Bone & Joint doctor will discuss your medical history.

Questions you might be asked include:

  • Have you had a previous injury to the front of your knee?
  • Do you have patellar tendonitis?
  • Do you have any medical conditions that might predispose you to a quadriceps injury?
  • Have you had surgery to your knee, such as a total knee replacement or an anterior cruciate ligament reconstruction?

Knee Extension

To determine the exact cause of your symptoms, your doctor will test how well you can extend, or straighten, your knee. While this part of the examination can be painful, it is important to identify a patellar tendon tear.

Imaging Tests

To confirm the diagnosis, your doctor may order some imaging tests, such as an X-ray or magnetic resonance imaging (MRI) scan.

X-rays

The kneecap moves out of place when the patellar tendon tears. This is often very obvious on a lateral or “sideways” X-ray view of the knee. Complete tears can often be identified with these X-rays alone.

MRI

This scan creates better images of soft tissues like the patellar tendon. The MRI can show the amount of tendon torn and the location of the tear. Sometimes, an MRI is required to rule out a different injury that has similar symptoms.

Treatment

If you have been diagnosed with a patellar tendon tear, you should go to an orthopaedic surgeon for treatment.

The type of treatment you require will depend on several things:

  • The type and size of tear you have
  • Your activity level
  • Your age
  • Nonsurgical Treatment
  • Very small, partial tears respond well to nonsurgical treatment.

Immobilization

Your doctor may recommend you wear a knee immobilizer or brace. This will keep your knee straight to help it heal. You will most likely need crutches to help you avoid putting all of your weight on your leg. You can expect to be in a knee immobilizer or brace for 3 to 6 weeks, often longer for a tear requiring surgery.

Physical therapy

Specific exercises can restore strength and range of motion.

While you are wearing the brace, your doctor may recommend exercises to strengthen your quadriceps muscles. Straight-leg raises are often prescribed. As time goes on, your doctor or therapist will unlock your brace. This will allow you to move more freely with a greater range of motion. You will be prescribed more strengthening exercises as you heal.

Surgical Treatment

Most people require surgery to regain the most function in their leg. Surgical repair reattaches the torn tendon to the kneecap.

People who require surgery do better if the repair is performed early after the injury. Early repair may prevent the tendon from scarring and tightening in a shortened position.

Tendon repairs are sometimes done on an outpatient basis. Many people do stay in the hospital at least one night after this operation. Whether or not you will need to stay overnight will depend on your medical needs.

The surgery may be performed with regional (spinal) anesthetic or with a general anesthetic (breathing tube). It cannot be done under local anesthesia.

Procedure

To reattach the tendon, sutures are placed in the tendon and then threaded through drill holes in the kneecap. The sutures are tied at the top of the kneecap.Your surgeon will carefully tie the sutures to get the correct tension in the tendon. This will also make sure the position of the kneecap closely matches that of your uninjured kneecap.

Your surgeon will discuss your need for this extra protection before your operation. Sometimes, surgeons make this decision for additional protection during surgery. It is then that they see the tendon shows more damage than expected, or the tear is more extensive.

If your tendon has shortened too much, it will be hard to re-attach it to your kneecap. Your surgeon may need to add tissue to lengthen the tendon. This sometimes involves using donated tissue (allograft).

Tendons often shorten if more than a month has passed since your injury. Severe damage from the injury or underlying disease can also make the tendon too short. Your surgeon will discuss this additional procedure with you prior to surgery.

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