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Arthroscopy Of The Knee

What's Wrong With Your Knee?

Last modified: 
16/03/2012 - 16:45

Contributing Author: Guy Slowik FRCS

Arthroscopy is able to deal effectively with a number of problems in the knee joint, including:

You will most likely have an MRI (magnetic resonance imaging) scan, which clearly will show the problem affecting your knee.

MRI

Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to create detailed images of the body's soft tissue structures, such as ligaments, tendons, and cartilage, which do not appear on an x-ray image of the same part of the body. A computer converts signals from the MRI scan into frontal, lateral, and cross-sectional images.

In an MRI of the knee, many separate images are produced, each one representing a 'slice' of the knee (like very thin slices of bread but a lot thinner). Each slice is a cross section image of a different section of the knee. The clarity of the images allows the radiologist and orthopedic surgeon to easily see any problems in the knee.

For more information about MRI, go to MRI.

Meniscal Injury

These are the most common knee injuries. The menisci are two pads of fibrocartilage on either side of the knee that act as cushions or shock absorbers. They also help distribute the weight load inside the knee.

  • The meniscus on the inner side of the knee is called the medial meniscus (medial means 'inner').
  • The meniscus on the outer side of the knee is called the lateral meniscus (lateral means 'outer').

Most tears of the meniscus result from a sudden twisting movement of the knee, as often occurs in sports injuries. As the knee bends and twists, the meniscus may be pinched between the bones. This is often accompanied by a "popping" sensation. The knee is likely to swell a few hours after the injury.

The tear may occur along the inner edge of the meniscus, or, less commonly, along the outer edge. There may be just a small torn "flap" of the meniscus, or a longer so-called "bucket-handle" tear, which is a tear along the length of the meniscus. Such a tear may cause the knee joint to "lock," meaning that the leg cannot be straightened.

The menisci may be also become damaged and torn as part of normal wear and tear within the knee joint as we age.

All types of meniscal tears can be treated by arthroscopy. Because the inner part of the meniscus has no blood supply, a tear along the inner part will not heal. Treatment, therefore, involves trimming away the torn piece of the meniscus. This is done with miniature motorized instruments inserted through a tiny incision on the side of the knee.

Meniscal injuries along the outer edge of the knee may be repaired rather than removed because the blood supply to this part of the meniscus is better, giving an improved chance of healing.

Ligament Injury

Ligaments are strong bands of tissue that fasten the bone ends together and stabilize the joint.

There are two ligaments inside the knee that can be reconstructed with the assistance of the arthroscope:

  • The "anterior cruciate ligament" (ACL).
  • The "posterior cruciate ligament" (PCL), which is less frequently injured.

The cruciate ligaments restrict both the forward and backward motion of the knee and its rotation. They may be torn by sudden twisting motions of the knee beyond its normal range.

Not all cruciate ligament injuries need to be reconstructed; it depends on your age, level of activity, type of activity, and what you expect from your knee. A frank discussion with your doctor will help both of you determine whether surgery would be beneficial.

  • If you enjoy active sports, it would be appropriate to have surgery.
  • If you have a sedentary-type job and are not active in your leisure time, you may not require surgery.

Unfortunately, a simple repair by suturing the torn ligament together again is not effective. A successful repair involves completely replacing the torn ligament. There are a number of ways to accomplish this, depending on the preference of the surgeon.

  1. Ligament reconstruction is most commonly performed utilizing the patella tendon graft. The orthopedic surgeon takes the central strip of the patella tendon and roots this through the knee through tunnels drilled in the tibia and femur. This creates a new ligament to replace the torn one.
  2. More and more surgeons are now using the hamstring tendons from the back of the knee. The surgeon folds over these tendons four times into a strong, thick band and passes it through the knee. The advantage of this technique is that the patella tendon is left intact. There does not appear to be any damage caused to the hamstring muscles. Results using this technique are extremely good.

    Both of these methods require an extra skin incision (about 2 inches in length) to harvest the tendons to be used.

  3. Some surgeons prefer to use a donor ligament from a recently deceased person. Most commonly, the Achilles tendon is used. The advantage of this method is that the patella tendon and hamstrings are left intact. The disadvantage is the exceptionally small risk of disease transmission.

For more information about ACL Tears, go to ACL Tears.

Loose Bodies Within The Knee

A traumatic incident to the knee can cause a fragment of cartilage, or a fragment of bone attached to cartilage, to come loose and float around the joint. This condition may result from "osteochondritis dissecans" (OCD).

Depending on the size of the fragment and whether it is still attached, the orthopedic surgeon may decide to reattach it or remove it entirely. The surgeon can perform either using the arthroscope.

A number of arthritic conditions may also cause loose bodies inside the knee.

Chondromalacia Of The Patella

This is a condition in which the cartilage surface lining the kneecap softens, sometimes to the point where the articular surface cracks, giving it an irregular surface. This may lead to discomfort felt in the front of the knee, particularly when going up and down steps.

If the problem does not respond to medication or physical therapy, some surgeons elect to smooth the rough areas of the kneecap using arthroscopic surgery.

Osteoarthritis

As we get older, our joints, including the knee, may suffer from wear and tear that can cause pain and discomfort. If medication can't control the discomfort, your surgeon may use arthroscopy to shave and smooth the roughened surfaces of the bone and trim any damage to the meniscus.

Clearing out the debris often helps reduce the pain of arthritis for a period of time. This is a significantly less traumatic procedure than a total knee replacement, which may ultimately be required if the pain and discomfort from osteoarthritis becomes severe.

For more information about osteoarthritis, go to Osteoarthritis.

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Arthroscopy Of The Knee

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From Andrew Maynard - Chair of the University of Michigan Department of Environmental Health Sciences, with help from David Faulkner - 2013 Master of Public Health graduate.