Case of the Month

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Michelle Jacobs, RPA-C

Michelle Jacobs works in the Department of Internal Medicine, Einstein-Weiler Hospital of the Montefiore Medical Center, Bronx, New York. She has indicated no relationships to disclose relating to the content of this article.

CASE

A 28-year-old male with a history of mild psoriasis (fewer than two flares a year) and tobacco abuse (1 pack of cigarettes per day for 12 years) presented to the orthopedist for evaluation of pain in the left wrist. He reported that he had experienced episodic pain in this wrist since the age of 18 years. He denied any traumatic events. He said that the pain usually recurred a day or two after he had used the affected arm during strenuous activity. He described the pain as “prickly” and “numblike” and said that it stayed localized. Although the pain was unrelieved by heat or ice packs, OTC NSAIDs and wearing an arm brace provided temporary relief.

The patient worked as a real estate manager during the day. He was right-hand dominant. He said that the pain did not significantly interfere with his work but that it did make caring for his three young children difficult. A hand radiograph ordered by the patient’s primary care provider showed no abnormalities. At the consultation, the patient told the orthopedist that the pain was recurring more frequently.

On physical examination, there were no obvious signs of trauma or abnormality. No erythema, swelling, or crepitus was noted, but deep palpation elicited mild tenderness over the dorsal aspect of the hand. All fingers had full range of motion without pain. Rota-tion of the hand at the wrist elicited a “prickly” pain. The fingertips were sensitive to both light and heavy touch. Capillary refill was normal. The patient was sent for MRI of the hand (see Figure 1).

WHAT IS YOUR DIAGNOSIS?

Carpal tunnel syndrome
Avascular necrosis of the lunate
Tendinitis
Occult scaphoid fracture

DISCUSSION

On the MRI, the lunate is whitened out, signifying decreased metabolic activity secondary to decreased blood flow. This clinical entity is known as avascular necrosis of the lunate, lunatomalacia, or Kienböck’s disease. The exact etiology is unknown, although repetitive strain or injury is implicated. Most cases of Kienböck’s disease are unilateral and involve the dominant hand. Anatomic or biomechanical features of the lunate may predispose it to injury. A vulnerable blood supply and the fixed position of the lunate in the wrist may also subject this bone to increased stress.

Clinically, progressive pain, swelling, and disability can occur. Radiographic findings are classic but do not seem to correlate with clinical findings. Initially, plain films can show a linear compression fracture and, subsequently, an increased density of the lunate as well as an altered shape and slightly diminished size. Eventually, collapse and fragmentation occur. Other complications include scapholunate dissociation and secondary degenerative joint disease of the radiocarpal and midcarpal compartments of the wrist.

Treatment ranges from pain management and watchful waiting to surgery. Bracing seems to stabilize the lunate and decrease pain. In addition, it allows revascularization of the lunate and may prevent disease progression. Surgery can include changing the length of the ulna or radius or even complete lunar replacement. Patients who opt for conservative treatment may be saving themselves from undergoing unnecessary surgery, but they also may be risking the development of severe osteonecrosis and bone collapse. Surgical repair is then more difficult and less likely to be successful.

This patient opted for the more conservative approach at first. However, as his pain began to worsen, he decided to undergo radial shortening. This process involves mechanically shortening the radius by 3 to 4 mm, thereby allowing the lunate bone more room to revascularize. Poor postoperative progression with the radial healing was noted a few weeks after the surgery, and it was attributed to the patient’s tobacco use. A bone stimulator, worn for 12 hours daily, alternating with an arm brace, was recommended. The bone stimulator uses a magnetic field to stimulate blood circulation (thought to be thwarted by tobacco use), which in turn enhances bone regeneration. Amazingly, after a couple of weeks, not only had the radial fragments began to reconnect, but the lunate bone came to life. Six months postoperatively, the lunate was almost completely revascularized and the radius showed adequate healing.

The evaluation of wrist pain can be tricky, especially when there is no recent history of trauma, as was the case with our patient. As always, the history is important and can help the PA to reach the correct diagnosis. The patient should be questioned about daily activities, occupation, and history of trauma, no matter how remote. Plain films may be inconclusive, even in cases of fractures. MRI, although costly, is often solicited to r ule out underlying pathology or occult fracture. JAAPA

Erich Fogg, PA-C, MMSc, department editor