Degenerated and healthy cartilage are equally vulnerable to blood-induced damage

Background: Joint bleeds have a direct adverse effect on joint cartilage, leading to joint deterioration and, ultimately, to disability. Objective: To examine the hypothesis that because degenerated cartilage has a limited repair capacity, it is more susceptible than healthy cartilage to blood-induced cartilage damage. Methods: Healthy, degenerated (preclinical osteoarthritic) and osteoarthritic (clinically defined) human cartilage was exposed to 10% vol/vol whole blood for 2 days, followed by a recovery period of 12 days in the absence of blood. The effect of exposure to blood on cartilage was determined by measuring proteoglycan synthesis rate, release and content, as well as protease (matrix metalloproteinase (MMP)) activity. Results: In general, exposure to blood led to a decrease in proteoglycan synthesis rate, an increase in the release of proteoglycans and in MMP activity, and therefore, ultimately, in a decrease of the proteoglycan content of the tissue. Impaired cartilage was as least as susceptible as healthy cartilage to this blood-induced damage. Conclusion: These results demonstrate that degenerated cartilage is not more susceptible than healthy cartilage to blood-induced damage. Even though these are just in vitro findings, it remains of great importance, also, in joints already affected, to prevent joints bleeds, and when they do occur, to treat them adequately.