The 2 most common types of injections to the knee are steroids and visco-supplementation. Steroids, such as cortisone shots, are placed directly in the knee to reduce swelling. They often result in pain releif, as the swelling is reduced and the knee can function more normally again. Viscosuplementation includes the hyalgan, synvisc, neovisc, etc. They contain lab-produced hyaluraonic acid, the natural lubricant in the joint. Studies haven't concluded which came first, but arthritic joints have lower levels of synovial fliud (which is primarily hyaluronic acid). These shots replace what the body is missing, and can help increase joint space, reduce friction, and reduce pain. There are different brand names, and probably different concentration levels, etc. But part of the option depends on what country you're in. Pharmaceutical companies may market the same product under different names in different countries.
Hope this helps.
