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Knee News

Factors Affecting Results of Microfracture Cartilage Repair

Full-thickness cartilage defects in the knee are usually treated with microfracture repair. The two-year results of this treatment for 48 patients are reported in this article.

There are several layers of cartilage and bone in the knee. The outermost layer is called the hyaline cartilage. The next layer is the calcified cartilage. The first layer of bone next to the cartilage is the subchondral bone plate. And finally comes the cancellous bone.

Cancellous bone is spongy bone found at the ends of femur (thighbone), the upper portion of the knee joint. This spongy bone has red bone marrow, which helps with the production of red blood cells. Cancellous bone is where most of the blood vessels of the bone are located.

A full-thickness defect removes the protective cartilage and results in bone rubbing on bone. The microfracture treatment removes the calcified cartilage first. This helps improve bonding between repair tissue and the subchondral bone.

Then a special tool called an awl is used to put holes in the subchondral bone layer. The surgeon must push the awl far enough in to reach the layer of cancellous bone. The authors describe the steps of the microfracture procedure in detail.

Results were measured by increase in activities of daily living and overall function. Factors negatively affecting improvement included obesity, length of time before the operation, and poor fill in of the defect.

Positive factors for a good outcome are just the opposite: low body mass index (BMI) and short time of preoperative symptoms. Good fill in was more likely when the layer of calcified cartilage was scraped away first. The authors say a systematic approach during surgery is important for a good clinical outcome.

Kai Mithoefer, MD, et al. Chondral Resurfacing of Articular Cartilage Defects in the Knee with the Microfracture Technique. In The Journal of Bone and Joint Surgery. September 2006. Vol. 88-A. Supplement 1. Part 2. Pp. 294-304.


*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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