Corticosteroid Injections – Doctors sometimes inject corticosteroids directly into the knee joint for quick relief of pain and inflammation. Their benefits may last anywhere from a few days to more than six months. While the injections bring targeted relief to the joint and lack many of the side effects of oral corticosteroid medications, they are not without risks. Repeated knee injections may actually contribute to cartilage breakdown. For that reason your doctor will likely put a limit on the number of injections you can receive.