Intra-Articular Injection of the Metacarpophalangeal Joints

Indications and Clinical Considerations

The metacarpophalangeal joint is susceptible to developing arthritis from a variety of conditions that all have the ability to damage the joint cartilage. Osteoarthritis of the joint is the most common form of arthritis that results in metacarpophalangeal joint pain. However, rheumatoid arthritis, posttraumatic arthritis, and psoriatic arthritis also are common causes of metacarpophalangeal pain secondary to arthritis ( Figs. 91.1 and 91.2 ). Less common causes of arthritis-induced metacarpophalangeal pain include the collagen vascular diseases, infection, and Lyme disease. Acute infectious arthritis usually is accompanied by significant systemic symptoms, including fever and malaise, and should easily be recognized by the astute clinician and treated appropriately with culture and antibiotics rather than injection therapy. The collagen vascular diseases generally manifest as a polyarthropathy rather than a monoarthropathy limited to the metacarpophalangeal joint, although metacarpophalangeal pain secondary to collagen vascular disease responds exceedingly well to the intra-articular injection technique described later.

FIG. 91.1, Rheumatoid arthritis: abnormalities of synovial joints. Sequential radiographic changes in metacarpophalangeal joints. A, The earliest abnormalities consist of soft tissue swelling (solid arrows), periarticular osteoporosis, loss of a portion of the subchondral bone plate on the metacarpal head (open arrow) , and minimal joint space narrowing. B, With progression, increases in soft-tissue swelling (arrows) and osteoporosis are associated with marginal erosions of the metacarpal heads (open arrow). C, The later stages of rheumatoid arthritis are characterized by complete obliteration of the articular space and large central and marginal osseous erosions (open arrows).

FIG. 91.2, Classic ulnar drift deformity of poorly managed rheumatoid arthritis causing deformity of the metacarpophalangeal joints.

The majority of patients with metacarpophalangeal pain secondary to osteoarthritis and posttraumatic arthritis pain report pain localized to the bases of the proximal phalanges and the heads of the metacarpal bones. Activity, especially with gripping motions, exacerbates the pain; rest and heat provide some relief. The pain is constant and is characterized as aching. The pain may interfere with sleep. Some patients report a grating or “popping” sensation with use of the joint; crepitus may be present on physical examination. Swelling of the joints is common.

In addition to the previously mentioned pain, patients with arthritis of the metacarpophalangeal joint often experience a gradual decrease in functional ability with decreasing grip strength, making everyday tasks, such as turning a doorknob or opening a jar, quite difficult. With continued disuse, muscle wasting may occur and an adhesive capsulitis with subsequent ankylosis may develop.

Plain radiographs are indicated for all patients with metacarpophalangeal joint pain. On the basis of the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging and/or ultrasound of the metacarpophalangeal joints is indicated if joint instability or abnormality is suspected ( Figs. 91.3 and 91.4 ). Color Doppler imaging will aid in identifying active synovitis of the metacarpophalangeal joint ( Fig. 91.5 ).

FIG. 91.3, Longitudinal ultrasound image demonstrating osteoarthritis of the metacarpophalangeal joint. Note the joint mouse.

FIG. 91.4, Hand involvement in rheumatoid arthritis. A, Metacarpophalangeal joint synovitis on longitudinal dorsal view. B, Tenosynovitis of the finger flexor tendons on transverse volar view. C and D, Bone erosion at the lateral aspect of the second metacarpal head, depicted on longitudinal (C) and transverse (D) views.

FIG. 91.5, Color Doppler image of advanced rheumatoid arthritis of the second metacarpophalangeal joint. Note the significant erosions of the articular surfaces and active synovitis.

Clinically Relevant Anatomy

The metacarpophalangeal joint is a synovial, ellipsoid joint that serves as the articulation between the base of the proximal phalanges and the head of its respective metacarpal ( Figs. 91.6 and 91.7 ). The joint’s primary role is to optimize the gripping function of the hand. The joint allows flexion, extension, abduction, and adduction. It is lined with synovium, and the resultant synovial space allows intra-articular injection. The joint is covered by a capsule that surrounds the entire joint and is susceptible to trauma if the joint is subluxed. Ligaments help strengthen the joints; the palmar ligaments are particularly strong.