OakLeaf Medical Network Healthy Viewpoints, Winter 2003
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Troy Berg, MD

Full thickness cartilage defect in the knee (femoral condyle).

Microfracture technique for cartilage defect in knee.


Cartilage Restoration.
Getting back in motion.

By Troy Berg, MD, Orthopedic Surgery
Chippewa Valley Orthopedics

Healthy cartilage is vital to a physically active lifestyle. As more people desire to remain active, increasing attention is being given to the diagnosis and treatment of cartilage disorders. The treatment of cartilage injuries is multi-faceted and usually performed by Orthopedic Sports Medicine Specialists. There continue to be significant advances in the non-surgical and surgical treatment of cartilage problems.

What is cartilage?

In this article we will focus on the cartilage in knees. There are two types. The first type is articular or hyaline cartilage. This is the same type of cartilage that is found in the joints throughout body. It is the white smooth substance that covers the ends of joint bones and allows them to glide easily. The second type of cartilage in the knee is the meniscal cartilage. When someone has “torn cartilage in the knee” it is usually this cartilage that has been damaged. Both kinds of cartilage are made from a protein called collagen, which is secreted from the cells that live in cartilage. Collagen holds cartilage together similar to the way metal rods hold concrete in reinforced concrete.

Cartilage can be damaged in many ways. Meniscal cartilage is often damaged from trauma, such as a twisting injury. Articular cartilage can be damaged from a variety of “wear and tear”.

Cartilage has very little capacity to heal itself. The cartilage cells live at the deepest layers of the cartilage and do not have a blood supply. They rely on nutrition from the fluid in the joints. If the cartilage has been damaged, the nutrition may be affected and the cells could die. If cartilage defects are left untreated, they can lead to further cartilage damage and functional disability.

How to restore cartilage.

There are three main techniques. The most common, microfracture chondroplasty, involves drilling small holes in the bone at the base of the cartilage. This causes bleeding from the bone. The blood fills the defect and forms a blood clot. Scar tissue replaces the blood clot, and ultimately the scar tissue is replaced by cartilage. For the cartilage to grow it needs two things: motion to distribute the joint fluid and provide nutrition, and the use of crutches to limit the strain applied to the cartilage while it is growing. This usually means six weeks of crutches after surgery. The cartilage that grows back is not normal hyaline cartilage, but rather fibrocartilage or scar cartilage. It is inferior to the original cartilage, but it can help restore joint cushioning, reduces pain and improves function. This technique is done arthroscopically and requires healthy surrounding cartilage to help bear some of the load for the newly formed scar cartilage.

The second technique is mosaicplasty, the transplantation of cylindrical plugs of bone and cartilage. A hollow cylindrical tool is used to take plugs of varying size and depth from one part of the knee and place them into corresponding holes made in the defect area, which is typically in an important weight-bearing area. This technique has the advantage of restoring normal hyaline cartilage, but is limited to use for small defects. This technique also requires using crutches for six weeks.

Finally, there is the Carticel technique. First, a small biopsy of healthy cartilage is harvested arthroscopically from the knee. The sample of cartilage is then sent to the Carticel laboratory where the cells are cultured and multiplied. This usually takes three weeks to grow enough cells for transplanting. For this procedure a patch of tissue is harvested from a nearby area of bone and carefully sewn over the defect. The cartilage cells are then injected underneath the patch. They will slowly grow into healthy hyaline cartilage. This means six to ten weeks of crutches after surgery. Because of the extended recovery time and cost, this technique is not for everyone, but it is an excellent option for relatively large defects or for multiple defects in the same knee.

If you suffer from cartilage related joint problems, talk to your physician about the possibilities available through a skilled Orthopedic and Sports Medicine Specialist.

For more information, call Dr. Lisa Buenger, Oak Leaf Pediatrics, Eau Claire 715.830.0732