Synovial regeneration in the equine carpus after arthroscopic mechanical or carbon dioxide laser synovectomy.

This research compares the regeneration of synovial membranes in horse joints after they have been subjected to mechanical or carbon dioxide (CO2) laser synovectomy, a surgical procedure for removing inflamed synovial tissue. The findings indicate that synovial villi do not regenerate post-surgery, that new intimal tissue matures faster after laser synovectomy, and that operating a CO2 laser requires preliminary training. Further research is recommended to examine the physiological implications of the lack of villus regeneration in horses.

Methodology

• The study involved twelve horses, aged 3 to 6 years, randomly separated into three groups.
• Different treatments were assigned to each horse’s antebrachiocarpal and intercarpal joints, such that one joint was treated as a control (underwent only arthroscopic lavage), one joint underwent partial dorsal carpal synovectomy either mechanically or using a CO2 laser, and in one joint, a combination of both techniques was used.
• The horses were euthanized postoperatively at 1, 3, and 6 months for specimen collection.
• Both gross and histological evaluations of the synovial membrane took place, alongside transmission and scanning electron microscopy (TEM and SEM).

Results

• Regeneration in the synovial villi did not occur in any of the groups. A month post-operation, the intimal cell layer was still incomplete while its surface was granulating.
• At the third month, while intimal regeneration was completely observed in all groups, it was more mature in the CO2 laser synovectomy groups compared to the mechanical ones.
• Six months post-operation, all groups had completely regenerated intima. Fibrous tissue replaced the subintima, which segregated the original subintimal vascular bed from the newly regenerated synovial surface.
• Operating a CO2 laser required preliminary training and the air environment altered the intraoperative evaluation of the synovectomy site.

Conclusions

• Post synovectomy, villous regeneration does not occur in horses. Healing of all synovial membranes post-surgery was observed with a fibrous subintima and less populated intima.
• The CO2 laser, despite requiring preliminary training to operate effectively, was found to perform more superficial synovectomy than achieved with mechanical synovectomy using a motorized arthroscopic synovial resector.
• While both mechanical and CO2 laser synovectomy can be performed on horses, further evaluation is needed to understand the physiological implications of the lack of villus regeneration in this species.
• Lastly, the researchers advise against the use of combined resection techniques due to the increased risk of full-thickness capsular defects.