Histological evaluation of osteoarthritis: (a) there were no degenerative changes of the cartilage in the knees from control rabbits that were treated with saline or Torin 1. The saline-treated rabbits had loss of cartilage surface, Safranin O staining, and had lesions extending into the radial zone at eight weeks after collagenase injection. In contrast, Torin 1-treated rabbits had abrogated loss of Safranin O staining and chondrocyte disappearance in the transitional zone at eight weeks after collagenase injection, and the cartilage surface was preserved. b) The Mankin scores showed that saline-treated rabbits had a significantly higher score than Torin 1-treated rabbits at eight weeks after induction of OA with collagenase injection. In saline-treated rabbits, the score of the collagenase-induced group was significantly higher than the control group. ***p < 0.001 (Magnification, ×100).