Aspiration of the radiohumeral joint

Aspiration of the radiohumeral joint is performed to differentiate traumatic hemarthrosis from inflammatory arthritis and the rare case of septic arthritis. The patient is supine with the elbow flexed to 90 degrees. A triangle is made with points at the lateral epicondyle, radial head, and olecranon process. Ethyl chloride or a comparable agent is applied to the skin for anesthesia. A 1 inch (2.5 cm), 21 or 22 gauge needle is inserted in the center of the triangle, perpendicular to the skin and parallel to the radial head, 3/4 to 1 inch (2 to 2.5 cm) deep. 0.5 mL of lidocaine is injected subcutaneously, and 0.5 mL is injected at 3/4 inches (2 cm) or adjacent to the bone.