Effect of intra-articular gentamicin sulfate on normal equine synovial membrane.

The research explores the impact of administering gentamicin sulfate intra-articularly into healthy horse joints, focusing on changes in the synovial fluid and synovial membrane. It found that the gentamicin-injected joints had higher levels of red and white blood cells, inflammation, and loss of synovial lining cells, though these effects dissipated within a week.

Research Overview

• The study set out to investigate the effect of intra-articular gentamicin sulfate administration on the normal synovial membrane in equine radiocarpal joints.
• Gentamicin sulfate, an antibiotic frequently used in treatment procedures with horses, was injected intra-articularly, that is, directly into the joints, in experimentally controlled conditions.
• The study provides an understanding of how the gentamicin sulfate impacts synovial fluids and membranes in the joints, crucial for orthopedic treatments.

Methods and Procedures

• The researchers administered gentamicin sulfate (3 ml; 50 mg/ml) into 30 normal equine radiocarpal joints after performing arthrocentesis (a procedure to remove synovial fluid).
• Comparatively, they performed only arthrocentesis on 10 normal radiocarpal joints, working as a control group.
• The assessment of the synovial fluid and synovial membrane was carried out at daily intervals over ten days under both gross and microscopic examinations.

Results and Findings

• The joints injected with gentamicin demonstrated a greater amount of turbidity, higher red blood cell (RBC) and white blood cell (WBC) count, and a higher refractive index in synovial fluid compared to joints without gentamicin injection.
• The most significant increases were observed on the 1st and 2nd days following the gentamicin injection, with mean total WBC, large mononuclear cell, small mononuclear cell, and polymorphonuclear cell counts of 23,860, 11,853, 857, and 11,150 cells/microliter, respectively.
• Arthrocentesis alone resulted in smaller increases in these cell counts in comparison to the gentamicin-injected joints.
• Microscopic examination revealed changes such as edema (swelling), leukocytic infiltration (infiltration of white blood cells indicating an immune response), and loss of synovial lining cells in the synovial membrane of gentamicin-injected joints. These are indicative of inflammation within the joint.
• The inflammatory changes observed resolved within 7 days post the gentamicin injection, indicating that the drug’s effects are relatively short-term.