Synovial membrane microarthroscopy of the equine midcarpal joint.

The research article evaluates the use of microarthroscopy, a minimally invasive procedure, in observing the synovial membrane of the equine (horse) midcarpal (wrist) joint. The study used various vital stains to better visualise and identify specific elements of the synovium and confirmed their biocompatibility.

Methods

• The study involved ten horses and microarthroscopy was performed on both left and right midcarpal joints, with and without vital staining of the synovium.
• Four vital stains—methylene blue, trypan blue, neutral red, and Janus green B—were used, each applied in five different joints.
• Biopsy samples were taken from two specific areas of the joint: dorsomedial and dorsolateral.

Results

• All dyes were determined to be biocompatible, meaning they didn’t cause harm or trigger an adverse reaction in the horses.
• Without vital staining, the study was still able to observe the topography, vascular network, and transparency of the synovial surface at x60 magnification.
• Vital staining substantially improved the evaluation and visualisation of the synovial surface topography—basically, the 3D characteristics.
• At x150 magnification with vital staining, individual synoviocytes (specialised cells which produce synovial fluid) could be clearly identified using all stains except neutral red.
• Methylene blue provided the best in-vivo microscopic differentiation of the structure of the intima, a layer of the synovium, while trypan blue showed superior retention in conventionally processed synovial biopsies.

Conclusions

• The study concluded that the four vital stains can be safely used for microarthroscopy.
• Microarthroscopy provided good visualization of cells and vascular network.
• The microarthroscopic evaluation of the synovium was determined to compare favorably with conventional histologic evaluation of biopsy specimens, suggesting microarthroscopy can be a valuable tool for such studies.
• Lastly, the researchers concluded that microarthroscopy may be beneficial for both research and clinical diagnosis of equine joint diseases.