Metatarsophalangeal joint injection is a useful procedure in the treatment of joint inflammation secondary to rheumatoid arthritis.
After obtaining informed consent, the patient is positioned for optimal access to the dorsal surface of the foot. The metatarsophalangeal joints are palpated for swelling and point tenderness. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. Light traction is applied to the toe of the joint to be injected. A ½- to 1-in. (1.5- to 2.5-cm), 25-gauge needle is inserted perpendicular to the skin, directly into the joint space. Aspiration is attempted until the needle has entered the synovial space. If there is an effusion of the joint, the aspiration is completed. After negative aspiration or the aspirated fluid is noninflammatory (clear and viscous), the joint is injected with a 0.5-mL mixture of 5 mg of triamcinolone acetate (or equivalent) and local anesthetic (see Fig. 67-58B).
FIGURE 67-58. Foot injections. A: Approach for plantar fasciitis or calcaneal bursitis injection. B: Approach for aspiration and injection of metatarsophalangeal joint.
These joints are often limited to 0.5 mL of solution. The first metatarsophalangeal joint may be approached from the medial side with the needle advanced tangentially under the extensor tendon.
Corticosteroids should not be injected if there is any suspicion that the joint is infected. If the fluid appears infected, then it should be sent for culture and sensitivity and the patient treated appropriately for the infection.