Osteoarthritis of the knee is a common problem that is increasing in prevalence as the population ages. In a knee with osteoarthritis, there is variable damage to the articular cartilage and underlying bone that can cause varying degrees of pain. When pain is bothersome, osteoarthritis is treated to improve functional abilities. One of the most recognized and used treatments is intra-articular cortisone injection. Cortisone is a powerful anti-inflammatory drug that is used to reduce pain. Unfortunately, cortisone can have significant side effects, even when injected locally. The frequency and intensity of these side effects depend largely on the total dose injected. The main side effects include increased blood sugar levels, increased blood pressure and a temporary decrease in the secretion of the stress hormone, cortisol. In the long term, a decrease in articular cartilage thickness in the injected join and overall bone density reduction is also reported. Despite many years of routine use, the smallest effective dose of cortisone injected into the knee joint is unknown. The main objective of the study is to determine the impact on pain and function of different doses of cortisone injected into the knee. The cortisone chosen for this study is triamcinolone acetonide (TA).