The researchers examined the effect of lidocaine on torn rotator cuff tendons in vitro (human tendons) and in vivo (rat tendons). They found that cell viability decreased after exposure to 0.1% lidocaine for 24?hours. At 2 and 4 weeks following surgery, the ultimate load to failure decreased more in the lidocaine group than in the control group, with significantly reduced stiffness in the lidocaine group 2 weeks after surgery. In addition, collagen organization significantly decreased in the lidocaine group by 4 weeks after surgery but returned to baseline at 8 weeks. Further, lidocaine caused cytotoxicity to tenocytes under both conditions, decreased biomechanical properties, and induced apoptosis and delay of collagen organization. Learn more...