Injections into the knee joint are performed without the need for x ray guidance. These injections can be used to help to diagnose the knee as the source of pain (diagnostic knee joint injection) or can be used to help relieve knee pain (therapeutic knee joint injection). Diagnostic knee injections involve the injection of a long acting local anaesthetic. Therapeutic injections usually involve the injection of a viscosupplementation agent (“shock absorbing” hyaluronic acid) that aims to help relieve some of the pain of arthritis. These injections can be very successful in certain individuals. Steroids can also be used to do this, but we only perform steroid injections into arthritic joints in rare cases, as such steroid injections can increase the risk of infection of any subsequent joint replacement.