The interphalangeal joints are hinge-type joints between the phalanges that allow flexion and extension of the fingers (Fig. 80.1). The primary function of the interphalangeal joints of the fingers is to aid in the gripping and pinching functions of the hand. The articular cartilage of the interphalangeal joints of the fingers is susceptible to damage, which, if left untreated, will result in arthritis with its associated pain and functional disability. Osteoarthritis is the most common cause of arthritis in the interphalangeal joints. Less common causes of arthritis-induced pain of the interphalangeal joints of the fingers include the collagen vascular diseases, infection, posttraumatic arthritis, villonodular synovitis, and Lyme disease (Fig. 80.2). Acute infectious arthritis of the interphalangeal joints of the fingers joint is best treated with early diagnosis, with culture and sensitivity of the synovial fluid and prompt initiation of antibiotic therapy. The collagen vascular diseases generally manifest as a polyarthropathy rather than a monoarthropathy limited
to the interphalangeal joints of the fingers, although pain of the interphalangeal joints of the fingers secondary to the collagen vascular diseases responds exceedingly well to ultrasound-guided intra-articular injection.

Patients with pain of the interphalangeal joints of the fingers secondary to arthritis, gout, synovitis, and collagen vascular disease-related joint pain complain of pain that is localized to the head of the metacarpals. Activity, including grasping and pinching motions, makes the pain worse, with rest and heat providing some relief. The pain is constant and characterized as aching in nature. Sleep disturbance is common with awakening when patients roll over onto the affected hand. Some patients complain of a grating, catching, or popping sensation with range of motion of the joints, and crepitus may be appreciated on physical examination. Swelling of the joints commonly occurs with enlargement of the distal interphalangeal joints (called Heberden nodes) and enlargement of the proximal interphalangeal joints (called Bouchard nodes) (Figs. 80.3 and 80.4).

Plain radiographs are indicated in all patients who present with pain of the interphalangeal joints of the fingers (see Fig. 80.4). Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody
testing. Magnetic resonance imaging or ultrasound of the interphalangeal joints of the fingers joint is indicated if fracture, effusion, tendinopathy, crystal arthropathy, joint mice, synovitis, bursitis, or ligamentous injury is suspected (Figs. 80.5 and 80.6).