Joint Injections and Cartilage Health: More Fuel for the Fire

The potential impact of intra-articular medications on the health of cartilage in joints has been debated for decades. Adding fuel to the fire is the recent finding that two common joint medications not only support cartilage cells, they also might help to protect cartilage from being damaged by some other substances sometimes used within the joint.

The researchers found that both triamcinolone and hyaluronic acid supported cartilage cells and protected cartilage from the toxic effects of lipopolysaccharide (LPS; an endotoxin, which is a pro-inflammatory agent), amikacin, and/or the local anaesthetic mepivicaine.

"Each of these drugs is commonly administered intra-articularly in horses, yet the effect of triamcinolone in combination with other medications has not been studied," reported Alicia L. Bertone, DVM, PhD, Dipl. ACVS, Endowed Chair of Equine Clinical Medicine and Surgery at The Ohio State University's Comparative Orthopedic Research Laboratory.

In this study, researchers examined cartilage cultures from explanted samples. They treated the cultures with various combinations of LPS, triamcinolone, hyaluronic acid, amikacin, and mepivicaine.

"Microscopic analysis revealed that LPS, amikacin, and mepivicaine each had a deleterious impact on the structure of articular cartilage," explained Bertone. "Specifically, LPS, amikacin, and mepivicaine each resulted in a significant increase in empty lacunae--regions of articular cartilage that normally house the cartilage cells (chondrocytes)--and abnormal chondrocyte nuclei."

In contrast, triamcinolone and hyaluronic acid each decreased the occurrence of these events, especially when it was administered in combination with when a deleterious drug, such as LPS, amikacin, or mepivicaine.

Additional studies in live horses are required to confirm these findings as the current studies were performed on cultured cells in conditions that were relatively harsh (i.e., the cartilage was exposed to the amikacin, mepivicaine, and LPS for prolonged time).

In real life, these drugs might be resorbed quickly from the joint environment which means that the chondrocytes would not be exposed to these drugs for very long.

Bertone added, "These data suggest we should be careful about prolonged exposure, such as with continuous infusion, and that HA and triamcinolone may be protective. Further in vivo work is warranted to investigate this as other steroids may also be protective."

The study, "Effects of triamcinolone acetonide, sodium hyaluronate, amikacin sulphate, and mepivicaine hydrochloride, alone and in combination, on morphology and matrix composition of lipopolysaccharide-challenged and unchallenged equine cartilage explants" was published in volume 69 of the American Journal of Veterinary Research.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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