Impact of the biopsy forceps size on histological analysis and performances of the histological scoring systems

To improve the reliability of the quantitative scorings of the synovial biopsies, we evaluate whether diameter of arthroscopic forceps influences histological quality of synovial tissue and/or histological scores and we compare the intra- and inter-observer performances of the main histological scoring systems. Synovial biopsies were retrieved in the same part of the joint using 1, 2 and 4 mm diameters grasping forceps. After standard staining and immunohistochemistry with anti-CD68 antibody, slides were scored blindly by 2 independent experienced operators for tissue quality and with Krenn score, de Bois-Tak score and CD68 semi-quantitative score. Four samples did not pass quality control. No difference other than a higher number of vessels in the 4 mm versus 2 mm forceps (p = 0.01) was found among the 3 groups. CD68 score was significantly higher in the 2 versus 4 mm forceps (p = 0.009). So we concluded that only vessels quantification and CD68 semi-quantitative score seemed affected by the forceps size. The intra-reader agreement was variable across observers and features: 0.78 (0.66–0.87) for the Krenn scoring system, 0.89 (0.78–0.97) for the de Bois-Tak score and 0.93 (0.81–1.00) for the CD68 score. Interobserver reliabilities of Krenn score, de Bois-Tak score and CD68 scores were satisfactory: 0.95 (0.92–0.99) for Krenn, 0.98 (0.96–0.99) for de Bois-Tak and 0.80 (0.71–0.89) for CD68.