The authors performed an in vitro study to investigate the effects of non-steroidal anti-inflammatory drugs (NSAID’s) on human tendon cell proliferation and matrix gylcosaminogylcan synthesis; processes involved in tendon healing. Fresh finger flexor tendons and patella tendons were obtained from patients during orthopedic and plastic surgery procedures. Small pieces of tendon tissue were incubated in cell culture media containing radioactive thymidine for measurement of cell proliferation and radioactive sulfate for measurement of matrix glycosaminoglycan synthesis. Four different NSAID’s were tested. The drugs were added separately to the cell culture medium containing the tendon fragments. Diclofenac and aceclofenac were found to have no significant effect on tendon cell proliferation or glycosaminoglycan synthesis. Indomethacin and naproxen, however, inhibited cell proliferation in patella tendons and inhibited glycosaminoglycan synthesis in both finger flexor and patella tendons.
The authors discussed other studies with conflicting results and hypothesized that the differences could be attributed to factors such as drug dose, species variation, and the use of different NSAID’s. The authors concluded that some NSAID’s may be harmful to tendon healing after injury or surgery. However, they appropriately cautioned against extrapolating their data to the in vivo situation. While the use of NSAID’s has been proposed to limit adhesions following flexor tendon surgery, it remains unclear if their anti-inflammatory effect will negatively impact tendon healing in the clinical setting.