Influence of repeated arthrocentesis and exercise on synovial fluid concentrations of nitric oxide, prostaglandin E2 and glycosaminoglycans in healthy equine joints.

This research examines how regular arthrocentesis (joint fluid removal) and exercise affect concentrations of nitric oxide, prostaglandin E2, and glycosaminoglycans in the synovial fluid of healthy horse joints, which could alter the interpretation of these substances as potential markers of equine joint disease.

Study Objectives and Methods

• The primary aim of this research was to explore how repeated arthrocentesis (removal of synovial fluid) and physical activity impacted nitric oxide (NO), prostaglandin E2 (PGE2), and glycosaminoglycan (GAG) concentrations in synovial fluid (SF) from normal equine (horse) joints. These compounds are being studied for their potential as biomarkers for joint disease in horses, especially osteoarthritis (OA).
• Synovial fluid was obtained from the left metacarpophalangeal (MCP), radiocarpal, and tarsocrural joints of 16 horses. Half of the horses were regularly exercised, and arthrocentesis was conducted again on specified days after the exercise commencement in both the exercised and control group of horses.
• NO was determined only in synovial fluid from the MCP joint while PGE2 and GAG quantities were measured in all collected synovial samples.

Study Results

• Regular arthrocentesis resulted in increased NO concentration in the MCP joint, elevated PGE2 levels in the radiocarpal and tarsocrural joints, and the release of GAGs into SF of MCP and radiocarpal joints on specified days.
• Physical activity led to a rise in PGE2 levels in all joints examined, but had no noticeable effect on the other parameters measured.

Study Conclusions

• The study concluded that frequent arthrocentesis could potentially confound the interpretations of synovial NO, PGE2, and GAG levels as markers of joint disease, likely due to the procedure itself influencing the concentrations of these compounds in the SF.
• The confounding effect of regular arthrocentesis could be prevented if a week or more is allowed to elapse between arthrocentesis procedures.
• Moderate exercise was observed to cause a transient increase in PGE2 levels in SF, indicating that physical activity levels may also need to be considered when interpreting these potential joint disease markers.