Q&A Medicine>>>>>Rheumatology
Question 4#

A 46-year-old obese woman with a history of type 2 diabetes mellitus presents with severe left-sided foot pain for the last 6 weeks. The patient has had much difficulty ambulating and has to use a wheelchair now due to the pain. Physical examination demonstrates a severely deformed left foot and x-rays confirm extra-articular bone fragments, varying sizes of osteophytes, and several effusions in the small joints of the left foot.

Which of the following is the underlying mechanism of this patient’s disease?

a. Avascular necrosis
b. Nerve damage
c. Uric acid deposition
d. Autoimmune destruction

Correct Answer is B

Comment:

Nerve damage. This patient is presenting with Charcot joint (neurogenic arthropathy) secondary to diabetic neuropathy. Charcot joint first develops from an inability to detect pain, proprioception, and temperature, which is likely the end result of years of peripheral nerve damage from diabetes. Over time, patients get secondary joint disease and deformation by traumatizing weight-bearing joints. X-ray is diagnostic and reveals osteophytes, loose bone fragments, and cartilage loss. Treatment includes managing the underlying diabetes and offering special shoes for mechanical support and to reduce further trauma. (A) Avascular necrosis (AVN) causes bone destruction from poor vascular supply (not neuropathically mediated). AVN can occur with corticosteroid use, trauma, and autoimmune disease. (C) Uric acid deposition causes gout. It usually affects the big toes and ankles and is severely painful. (D) Charcot joint is not the result of an autoimmune process such as rheumatoid arthritis.