Myrtol improves the level of TGF-β1 in a PTKO mouse model, as determined using ELISA. **P<0.01 vs. control model group; ##P<0.01 vs. PTKO group. PTKO, post-traumatic knee osteoarthritis; LDM, low dose myrtol; MDM, medium dose myrtol; HDM, high dose myrtol; TGF, transforming growth factor.