Healing Cartilage

Cartilage in the joints, better known as articular cartilage, can suffer wear and tear over the years, especially in competition animals. Cartilage also can be destroyed due to injury or disease. Whatever the cause, when cartilage disappears, it means bone is rubbing against bone, and that means pain, osteoarthritis, and usually the end of a horse's athletic career.

The destruction of cartilage has, until recently, been an untreatable disease and was considered an irreversible process. Research has, however, offered new hope to horses with cartilage damage. Treatments, including joint lubricants, can help slow the disease process. And now, a surgical technique used in humans has been shown to enhance tissue formation in the joints of horses.

"Both long- and short-term studies show enhancement of tissue formation with the subchondral micropick technique," reported Wayne McIlwraith, BVSc, PhD, Diplomate ACVS, of Colorado State University, at the recent AAEP Convention.

The micropick technique involves punching small holes in the subchondral bone in the cartilage near a joint surface injury. The technique was developed by J. Richard Steadman, MD, an internationally renowned human orthopedic surgeon and director of the Steadman-Hawkins Sports Medicine Foundation in Vail, Colo. There is research collaboration between Steadman and McIlwraith, who is director of Equine Sciences and Orthopedic Research at Colorado State.

The technique is presumed to allow access of mesenchymal stem cells and growth factors from cancellous bone into the defect site of the cartilage without compromising the subchondral bone plate, noted McIlwraith. The technique possibly provides improved attachment of the repair tissue.

Two studies were reported on, one a long-term study and the second a short-term study (evaluating gene expression of critical matrical components). In the short-term study, enhancement of gene expression for Type II collagen was not demonstrated in the carpal defects, reported McIlwraith.

"It is obvious that there are differences depending on location and joint. The lack of enhancement of aggrecan synthesis while augmenting Type II collagen synthesis is in agreement with earlier work done by this research group, where it seems the biggest limiting factor to long-term functional healing is a decreased aggrecan content."
In tandem with the micropick research are studies looking at the use of growth factors to further augment repair. The combination of micropick surgery and hormone treatments could prevent injured horses and human athletes who suffer from osteoarthritis from retirement, in the case of horses, or needing joint replacement in the case of humans.
McIlwraith concluded that the micropick technique is being used routinely in his clinical cases "in the horse when there is retention of subchondral bone plate but loss of articular cartilage."

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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