Arthrocentesis of the Knee

Diagnostically, arthrocentesis is indicated to rule out septic arthritis in individuals presenting with a single or several inflamed joints. Arthrocentesis can also be used to differentiate between crystal arthropathies, such as gout and pseudogout, inflammatory and noninflammatory effusions, and hemarthroses. It should be emphasized that a single inflamed joint should almost always undergo at least one diagnostic aspiration. Therapeutically, arthrocentesis may be performed to drain large effusions, hemarthroses, or to inject steroids or local anesthetic. Arthrocentesis should be avoided in patients with cellulitis overlying the site of needle entry, out of concern of seeding the joint cavity with bacteria. Known . . . .