Knee joint aspiration and injection.

Knee joint aspiration and injection are performed to aid in diagnosis and treatment of knee joint diseases. The knee joint is the most common and the easiest joint for the physician to aspirate. One approach involves insertion of a needle 1 cm above and 1 cm lateral to the superior lateral aspect of the patella at a 45-degree angle. Once the needle has been inserted 1 to 1 1/2 inches, aspiration aided by local compression is performed. Local corticosteroid injections can provide significant relief and often ameliorate acute exacerbations of knee osteoarthritis associated with significant effusions. Among the indications for arthrocentesis are crystal-induced arthropathy, hemarthrosis, unexplained joint effusion, and symptomatic relief of a large effusion. Contraindications include bacteremia, inaccessible joints, joint prosthesis, and overlying infection in the soft tissue. Large effusions can recur and may require repeat aspiration. Anti-inflammatory medications may prove beneficial in reducing joint inflammation and fluid accumulations.