Background: Chlorhexidine (CLX) has been reported as a popular and effective disinfectant of contaminated tendon grafts with no biomechanical sequelae; however, its biochemical effects on tendon collagen and fibroblasts remain unknown.
Purpose: To determine whether CLX disinfection of contaminated tendon grafts has deleterious effects on tendon collagen or a toxic effect on fibroblast function.
Study design: Controlled laboratory study.
Methods: Collagen fibrils prepared from purified bovine collagen type I were treated with various CLX concentrations (0.5%-4%) and incubation times (10-40 minutes), and the effects on fibril degradation and solubility were then examined using gel electrophoresis. Fresh bovine tendons were treated with sterile water or 2% CLX; then, fibroblast mobility and metabolic activity were evaluated using light microscopy and Alamar Blue assay, respectively.
Results: No effect on collagen fibrils was observed when they were exposed to 0%, 0.5%, or 2% CLX at any exposure time. However, 4% CLX dissolved the fibrils even after short incubation times. Fibroblasts migrated out from the control tendon explants but not from explants treated with 2% CLX, and a 5-fold reduction in metabolic activity was observed throughout the tendon in explants exposed to 2% CLX, suggesting that CLX penetrated and killed cells throughout the tissue.
Conclusion: Four-percent CLX caused collagen fibrils to dissolve in vitro, and tendon graft disinfection with 2% CLX was cytotoxic to the cells.
Clinical relevance: Because of its chemical effect on tendon collagen and cytotoxic effect on tendon fibroblasts, 4% CLX should not be used as a disinfectant. Two-percent CLX can be used to disinfect contaminated ACL grafts, but such treatment will drastically reduce the metabolic activity of the cells within the graft, making it similar to an acellular allograft tendon.