CTSK and osteoarthritis: As we continue to move towards the application of biologic therapies for human disc degeneration, it may be efficacious to consider inclusion of selective, specific approaches to inhibit cathepsin K. Yasuca et al. reported in 2005 that some cathepsin K inhibitors are now in clinical trials for osteoporosis therapy, and noted that cathepsin K is a preferable drug target for non-inflammatory osteoarthritis with positive pre-clinical data [3].