Morphological effects of arthroscopic partial synovectomy in horses.

This research investigates the effects of a surgical technique, arthroscopic partial synovectomy, and its impact on the synovium and articular cartilage of a horse’s middle carpal joint. The study found no observable joint degeneration but noted that 30 days after the procedure, normal synovium had not reformed in the area.

Study Design and Implementation

• Researchers studied both gross (observable to the naked eye) and microscopic changes in the synovium and the articular cartilage in the middle carpal joints of 15 horses. The synovium is a soft tissue that lines the spaces of diarthrodial joints, bursae, and tendon sheaths, and the articular cartilage is a smooth, slippery, white tissue that covers the ends of bones where they come together to form joints.
• In the study, a 7mm diameter motorized synovial resector was inserted into each middle carpal joint in all the horses. Subsequently, arthroscopic partial synovectomy and lavage (a cleaning procedure where the joint is washed out), or just arthroscopic lavage alone, was performed.

Studying the After-Effects

• The effects of these interventions were then investigated across different intervals: immediately (in three horses), 16 days later (in another three horses), and 30 days post-intervention (in the remaining six horses).
• No gross evidence of degenerative changes to the joints was found on either day 16 or 30. Degenerative joint disease typically exhibits symptoms such as pain, swelling, and decreased motion.

Findings and Conclusion

• On the 30-day check, it was observed that the resected areas lacked villi, or the small, hair-like extensions found in the synovium and other structures. There was also the deposition of fibrin (a protein involved in blood clotting) on the synovial surface, along with differing amounts of newly formed fibrovascular tissue (composite tissue made up of fibrous tissue and blood vessels).
• Most notably, 30 days after this surgical intervention, the equine middle carpal joints had not formed normal synovium, suggesting a sustained change to the joint’s internal structures post-arthroscopic synovectomy.