The effects of intra-articular methylprednisolone and exercise on the mechanical properties of articular cartilage in the horse.

This research studied the impact of steroid injections, specifically methylprednisolone acetate (MPA), together with physical activity on the mechanical characteristics of the cartilage in joints using horses as a model. The results have suggested that repetitive intra-articular administration of MPA, combined with exercise, can affect the mechanical integrity of the cartilage in joints, potentially leading to early degeneration.

Research Methodology

• The research involved eight, 2-year-old female horses. Each horse received either MPA or a placebo (diluent) in their contra-lateral middle carpal joints at two-week intervals for a total of four treatments per horse.
• They underwent a standard treadmill exercise regimen until they were euthanized at the 70th day of the experiment.
• The cartilage in the horses’ third, radial, and intermediate carpal bones was tested with an automated indentation apparatus to assess the “creep” (deformation rate under constant stress) and recovery properties of the cartilage.

Data Analysis and Results

• Using established biphasic creep indentation methodology, the experiment determined the aggregate modulus (a measure of substance’s resistance to compression), Poisson’s ratio (a measure of how much a material expands or contracts against its original shape under load), permeability, shear modulus (measure of material’s structural rigidity), thickness, as well as the creep and recovery equilibrium times and the percentage of recovery for each site.
• Data was analysed with ANOVA (Analysis of Variance) methods and multiple comparisons of the means. They considered a result statistically significant if the observed p-value was less than 0.05 (P < 0.05).
• The result of this study showed significant differences in the intrinsic material properties and thickness of the cartilage between the MPA and placebo-treated joints. Specifically, the diluent treated cartilage showed a 97% increase in compressive stiffness modulus, was 121% more permeable, exhibited an 88% rise in shear modulus, and was 24% thicker than the MPA treated cartilage.

Conclusion

• The findings imply that the regular use of MPA injections in combination with exercise changes the mechanical integrity of the articular cartilage in horses. This change could potentially speed up the degeneration of the cartilage.
• Though this research study used horses as a model, the results might have implications for the management of human connective tissue diseases like arthritis, and the study provides valuable data to consider when treating similar conditions in humans.