Intra-Articular Injection of the Metatarsophalangeal Joints

Indications and Clinical Considerations

The metatarsophalangeal joints are 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 metatarsophalangeal joint pain. However, rheumatoid arthritis and posttraumatic arthritis also are common causes of metatarsophalangeal pain secondary to arthritis ( Fig. 177.1 ). Less common causes of arthritis-induced metatarsophalangeal pain include the collagen vascular diseases, infection, villonodular synovitis, and Lyme disease. Acute infectious arthritis usually is accompanied by significant systemic symptoms, including fever and malaise, and should be easily 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 metatarsophalangeal joint, although metatarsophalangeal joint pain secondary to collagen vascular disease responds exceedingly well to the intra-articular injection technique described later.

The majority of patients with metatarsophalangeal joint pain secondary to osteoarthritis and posttraumatic arthritis pain experience pain localized to the dorsum of the foot. Activity, especially inversion and adduction of the metatarsophalangeal joints, makes the pain worse; rest and heat provide some relief. The pain is constant and is characterized as aching and may interfere with sleep. Some patients report a grating or popping sensation with use of the joint, and crepitus may be present on physical examination. In addition to the previously mentioned pain, patients with arthritis of the metatarsophalangeal joint often experience a gradual decrease in functional ability with decreasing metatarsophalangeal range of motion, making simple everyday tasks, such as walking and climbing stairs, quite difficult.

Plain radiographs are indicated for all patients with metatarsophalangeal 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. Computed tomography (CT), magnetic resonance imaging, and ultrasound imaging of the metatarsophalangeal joints are indicated if joint instability, occult mass, or tumor is suggested.

Clinically Relevant Anatomy

Each joint of the midtarsus has its own capsule ( Fig. 177.2 ). The articular surface of these joints is covered with hyaline cartilage, which is susceptible to arthritis. The metatarsophalangeal joint capsules are lined with a synovial membrane that attaches to the articular cartilage and allows the gliding motion of the joints. Various ligaments provide the majority of strength to the metatarsophalangeal joints. The muscles of the metatarsophalangeal joint and their attaching tendons are susceptible to trauma and to wear and tear from overuse and misuse.