Association between clinical signs and histopathologic changes in the synovium of the tarsocrural joint of horses with osteochondritis dissecans of the tibia.

This research project seeks to establish a scoring system for changes observable in the synovium in horses’ tarsocrural joints due to osteochondritis dissecans. By examining 93 horses afflicted by this condition, the researchers found an association between these changes and joint effusion, but not lameness.

Study Objective and Methods

This research was aimed at developing a reliable scoring system for checking histopathological changes caused by osteochondritis dissecans (OCD) in the tarsocrural joints (TCJs) of horses. It also purposed to establish any relationships between these changes and clinical signs like joint effusion or lameness.

• The study was performed on 93 horses with OCD and 38 control horses without the condition.
• All horses underwent several tests including lameness check, TCJ effusion, and pelvic limb flexion.
• Synovial biopsy specimens were collected from the OCD-affected horses during arthroscopy while the control horses provided similar postmortem tissue specimens.

Criteria and Scoring

The histological synovitis signs in all 172 biopsy samples were evaluated by two pathologists (A and B), making use of two criteria: synoviocyte proliferation and cellular infiltration.

• For pathologist A, the intraobserver agreement score was good to very good (WK, 0.76 to 0.81)
• For pathologist B, this score ranged from moderate to good (WK, 0.56 to 0.63).
• The interobserver agreement scores for synoviocyte proliferation and cellular infiltration ranged from fair to moderate.

Results and Conclusions

The research findings indicated a significant connection between joint effusion and both synoviocyte proliferation and cellular infiltration. However, no associations were established between histopathological changes and lameness.

• Thus the researchers concluded that their developed scoring system is useful in evaluating synovial inflammation caused by OCD in horses.
• They also found through their research that histopathological signs of synovial inflammation were correlated with effusion, but not with lameness.