A 62-year-old man comes to the office due to difficulty walking and mild pain in the left foot for the past several months. He now ambulates with a cane and recently began using an old ankle brace for support. The patient's medical history is significant for type 1 diabetes mellitus, hypertension, and hypercholesterolemia. Physical examination shows a significantly deformed left ankle and a mildly deformed left foot. X-ray of the left foot with weight bearing shows bone loss, large osteophytes, and several extraarticular bone fragments, as seen in the image below. Which of the following is the most likely cause of this patient's foot pain?

Question

A 62-year-old man comes to the office due to difficulty walking and mild pain in the left foot for the past several months.  He now ambulates with a cane and recently began using an old ankle brace for support.  The patient's medical history is significant for type 1 diabetes mellitus, hypertension, and hypercholesterolemia.  Physical examination shows a significantly deformed left ankle and a mildly deformed left foot.  X-ray of the left foot with weight bearing shows bone loss, large osteophytes, and several extraarticular bone fragments, as seen in the image below.  Which of the following is the most likely cause of this patient's foot pain?

Quizplus · Accepted Answer

11ec25c8_d96d_c805_bc81_6bc2aadd270f_MD0003_00 This patient has destruction and collapse of the ankle joint and arch consistent with neurogenic arthropathy (Charcot joint). Neurogenic arthropathy is due to impaired sensation and proprioception in the foot, leading to altered weight bearing, mechanical stresses, and recurrent trauma. It is most commonly seen in diabetic peripheral neuropathy, other neuropathies (eg, vitamin B₁₂ deficiency), syringomyelia, spinal cord injury, and tabes dorsalis. Neurogenic arthropathy causes difficulty in weight bearing and ambulation. Patients may also have acute inflammation (eg, redness, swelling) following minor trauma. However, pain is mild due to the underlying loss of sensation. Examination shows skeletal deformity, skin calluses, and neuropathic ulcers. skin calluses, and neuropathic ulcers Laboratory tests in neurogenic arthropathy, including blood counts, inflammatory markers (eg, C-reactive protein), and synovial fluid analysis, are typically normal. X-rays show bony destruction (eg, deformity, fragmentation), decreased bone mass, osteophyte formation, and loss of joint spaces. Management involves casting and orthotic footwear to assist weight bearing and decrease further trauma. (Choice A) Avascular necrosis is bone destruction due to poor perfusion. Common causes include corticosteroids, systemic lupus erythematosus, and sickle cell disease. It typically affects the proximal or distal femur and causes significant pain. (Choice B) Septic arthritis causes acute fever, redness, swelling, and joint pain. Osteomyelitis can present as a chronic, indolent infection, but is typically seen in association with a neuropathic ulcer with sinus tracts or exposure of the underlying bone; x-ray shows bone necrosis with surrounding sclerosis and periosteal thickening, rather than collapse of the joint. periosteal thickening (Choice C) Bone demineralization in osteoporosis typically causes pathologic fractures (eg, hip, wrist, vertebrae) rather than joint destruction. (Choice D) Gout results from precipitation of uric acid crystals in the synovium. It can affect the ankle, but causes acute, severe pain. X-rays in chronic gout reveal punched-out erosions with an overhanging rim of cortical bone ("rat bite" lesion). punched-out erosions (Choice F) Rheumatoid arthritis typically presents as a symmetric, polyarticular arthritis, and most patients have upper extremity (eg, hands, wrists) involvement. X-rays reveal periarticular osteoporosis, joint erosions, and joint space narrowing. Educational objective: Neurogenic arthropathy (Charcot joint) is due to abnormal lower extremity sensation and proprioception, leading to altered weight bearing, mechanical stresses, and recurrent trauma. It is most common in patients with diabetic neuropathy. It can cause impaired ambulation, but pain is typically mild. Examination shows deformity of the foot, and x-ray reveals bony destruction, osteophyte formation, and loss of joint spaces. References: The Charcot foot: pathophysiology, diagnosis and classification. (http://www.ncbi.nlm.nih.gov/pubmed/27587513)

A 62-Year-Old Man Comes to the Office Due to Difficulty