34th Annual Scientific Meeting proceedings

Objectives:

Arthroscopic and histologic evaluation are good indicators of synovitis. Unlike for inflammatory synovitis, the involvement of cytokines in septic synovitis has not been well documented. Aims are providing broader identification of inflammatory factors involved in septic versus non-septic synovitis and better describe the correlation between synovitis, arthroscopic and histopathologic evaluations of synovial membrane.

Methods:

Three populations were defined, horses undergoing therapeutic arthroscopy (group1), horses with confirmed septic synovitis that underwent arthroscopic lavage (group2), and horses presenting with periarticular injuries without synovial involvement (group3). Synoviocentesis was performed and samples were processed for cytokines quantification using the MILLIPLEX® Panel. Groups 1 and 2 underwent synovial biopsy at the time of arthroscopy. Arthroscopic and histological scores were assigned to each synovial exploration and sample according to a previously established scoring system.

Results:

Macroscopic and histological scores of group2 were significantly higher than group1. Arthroscopic and histological evaluations only significantly correlated for group1. Cellularity significantly correlate to arthroscopic scores for groups 1 and 2 but do not correlate with histological scores. The principal component analysis shows that the highest discrimination between group2 and others is due to the high concentration in IL6 and IL1β, in addition, group2 presented significantly higher concentrations of IFNγ, and IL10. A significantly higher concentration of TNFα was also found in group2 compared to group1.

Conclusions:

Although synovial cellularity provides valuable information about the condition of the joint, histological evaluation in synovial sepsis should be considered as an additional modality for accurate diagnosis. Dosage of IL6, IL1β and TNFα could serve as synovial biomarkers of septic involvement.