A brief overview of the current treatments of osteoarthritis and promising approaches (Section 2), development of epiphyseal cartilage (Section 3) and articular cartilage (Section 4), degradation of cartilage (Section 5), function and level of expression of cathepsin K (Section 6), in vitro effects of cathepsin K inhibitors (Section 7), and pre-clinical and clinical trials on cathepsin K inhibitors (Section 8) are presented. This evidence concerns the gene CTSK and osteoarthritis.