Joint injections are used to treat knee pain after non-invasive treatment options have been exhausted. Relief is often temporary, and excessive injections can be harmful. Knee pain caused by arthritis can be treated with injections. Common injections used to treat arthritic knees include: Hyaluronic acid supplements – acts as a shock absorber and lubricant; Corticosteroid – provides relief of pain and inflammation; Arthrocentesis – removal of excess fluid, easing pain and swelling.