Objectives

Surgical marking during tendon surgery is often used for technical and teaching purposes. This study investigates the effect of a gentian violet ink marker pen, a common surgical marker, on the viability of the tissue and cells of tendon.

Introduction. The aim of this study was to investigate whether methylene blue dye, commonly used in sterile surgical marker pens, would have an effect on human chondrocyte viability, when cultured on a collagen membrane in-vitro. Methods. Bilayered collagen membranes were seeded in duplicate with 12 million human chondrocytes per ml and cultured for 24 hours under standard conditions. Group A consisted of a membrane marked with methylene blue ink on its smooth side, group B marked on its porous side, and group C acting as an unmarked control. At the end of the culture period the membranes were qualitatively analysed for cell survival by live/dead fluorescent staining under confocal microscopy. Results. The control membranes of group C showed normal ‘live’ staining of cells. A marked reduction in chondrocyte viability was seen in groups A and B, with a significant reduction in viability seen opposite to the ink mark on the smooth side in A, and practically no cell viability in the same position on the porous side in group B. Conclusions. Methylene blue dye in surgical marker pen ink has been shown to be cytotoxic to chondrocytes cultured on bilayered collagen membranes. Sterile surgical marker pens are commonly used in cartilage repair surgery to aid in the placement of periosteal patches or collagen membranes in autologous chondrocyte transplantation. Surgeons need to be aware of the potential harmful effects of methylene blue dye when using surgical marker pens in cell based regenerative therapies