Cartilage Transfer Surgery of the Knee

Cartilage is an important tissue in your body.  There are several different types of cartilage the body makes, and one of them is the soft cushion in your joints.  The cartilage surface of a joint allows for smooth motion.  Unfortunately, injuries and arthritis can cause damage to the cartilage of the joint, causing movement to become painful and limited.  In the knee joint, people with cartilage damage may have knee pain and stiffness.

There are a number of options for patients who have cartilage damage in the knee joint.  One of those options in people who have smaller, more isolated areas of cartilage damage is called a cartilage transfer surgery.

A cartilage transfer procedure is a surgery that uses healthy cartilage from a normal area of the knee, and moves it to a damaged area of the knee. The two types of cartilage transfer procedures are called:

• Mosaicplasty
  • A mosaicplasty moves round 'plugs' of cartilage and underlying bone to damaged areas. The plugs are each a few millimeters in diameter, and when multiple plugs are moved into a damaged area the result is a mosaic appearance--the multiple small plugs of cartilage look like mosaic tiles.
• OATS
  • OATS stands for 'osteochondral autograft transfer system,' and the technique is very similar to mosaicplasty. In the OATS procedure the plugs are usually larger, and therefore only one or two plugs are needed to fill the area of cartilage damage. Because of this it does not take on the mosaic appearance, but the principle is the same.

The cartilage plugs are taken from areas of the knee that are non-weight-bearing areas. The hope is that the body will not miss this cartilage and it can be used where it is needed. Over time the holes left from where the plugs are taken will fill with bone and scar tissue.

The cartilage transfer procedure usually begins with an arthroscopic inspection of the knee. If there is an area of cartilage damage that is suitable to cartilage transfer, then the arthroscope is removed and an incision is made.

The first step is to prepare the area of damaged cartilage. A coring tool is used to make a perfectly round hole in the bone in the area of damage. This hole is sized to fit the plug.

The next step is to 'harvest' the plug of normal cartilage. The plug is taken with the underlying bone to fit into the hole that was prepared in the area of damage. The plug is just slightly larger than the hole so it will fit snugly into position.

The final step is to implant the harvested plugs into the hole that was created in the damaged area. Over time, the hope is that the implanted bone and cartilage will incorporate into its new environment.