Biochemical analysis of the articular cartilage and subchondral and trabecular bone of the metacarpophalangeal joint of horses with early osteoarthritis.

This study examines the biochemical differences in the joint tissues of horses suffering from early onset osteoarthritis as compared to healthy horse joints. The researchers found significant alterations in joint tissues which may be influenced by variations in how physical forces are applied and distributed across the joint.

Methods

• The study involved right metacarpophalangeal joints from 59 mature warmblood horses.
• Joint tissue samples were collected from two distinct and differently loaded sites within each joint.
• The biochemical composition of the samples was evaluated. Parameters analyzed included cross-link, amino acid, DNA, and ash contents; denatured collagen and glycosaminoglycan (GAG) concentrations; bone mineral density; and mineral composition.
• The obtained data were then compared with values from previous studies on nonosteoarthritic equine joints.

Results

• The cartilage from osteoarthritic joints showed lower levels of GAG concentration as compared to nonosteoarthritic joints.
• In osteoarthritic joints, there was loss of site differences related to cellularity and lysylpyridinoline (LP) cross-link content.
• In the subchondral bone in osteoarthritic joints, LP cross-link content was generally reduced and there was disappearance of site differences found in healthy joints.
• Trabecular bone from osteoarthritic joints had higher hydroxyproline content as compared to nonosteoarthritic trabecular bone.
• In all three layers of tissue (cartilage, subchondral bone, trabecular bone) and at both sites, the linear increase of the pentosidine cross-link content with age was diminished or non-existent in the horses with osteoarthritic joints.

Conclusions

• The study found distinct biochemical changes in the cartilage, and subchondral and trabecular bones of equine metacarpophalangeal joints with early osteoarthritis.
• Discrepancies in the biochemical response of different tissues and between different sites within the joint may be due to variations in biomechanical loading, force transmission, and force dissipation.

By providing a deeper understanding of the biochemical alterations in early osteoarthritic joints, the study could contribute to the development of improved strategies for diagnosis, treatment, and prevention of equine osteoarthritis.