34th Annual Scientific Meeting proceedings

Objectives:

The objective was to analyze the biochemical, biomechanical composition and architecture of three clinically relevant areas of the equine stifle that are subjected to different in-vivo loading patterns. We hypothesize that they differ from one another and that these site-dependent characteristics correlate with the biomechanical features of the articular cartilage.

Methods:

Thirty osteochondral plugs were harvested from the lateral trochlear ridge (LTR) , the intercondylar notch (ICN) and the medial femoral condyle (MFC) for a total of ninety plugs. The samples underwent biochemical, biomechanical and structural analysis. A linear mixed model with location as a fixed factor and horse as a random factor was used, followed by pair-wise comparisons of estimated means with false discovery rate correction, to test for differences between locations. Correlations between biochemical and biomechanical parameters were tested using Spearman’s correlation coefficient.

Results:

Significant differences were present among all sites for glycosaminoglycan content, equilibrium, dynamic modulus and viscosity. Weightbearing areas (LTR and MCF) and non-weightbearing areas (ICN) differed significantly in collagen content, paralelity index and angle of collagen fibers. The strongest correlations were seen between proteoglycan content and equilibrium modulus, dynamic modulus and phase shift, and between collagen orientation angle and equilibrium modulus, dynamic modulus and phase shift.

Conclusions:

The adult equine stifle joint showed significant differences  in the biochemical composition, biomechanics and architecture of the extracellular matrix of the cartilage between three differently loaded sites. The biochemical and structural composition correlated with the mechanical characteristics. These differences need to be taken into account when considering cartilage repair strategies.