Snapshot A 62-year-old woman presents to her physician for painless swelling of her ankle. She reports a history of diabetic neuropathy and regularly sees a podiatrist. Physical exam reveals a non-tender, swollen, and erythematous ankle joint with decreased range of motion. Laboratory studies show a normal leukocyte count and normal inflammatory markers. Introduction Clinical definition arthropathy due to underlying neuropathy or trauma, leading to a destruction of joints and bone Epidemiology demographics adults location foot and ankle (most common) shoulder elbows risk factors diabetic neuropathy for foot and ankle disease syringomyelia for shoulder disease syphilis for knee disease trauma leprosy Etiology Pathogenesis autonomic neuropathy can result in hyperemia, which leads to increased osteoclastic resorption of the bone peripheral neuropathy can result in loss of sensation and proprioception, which leads to unintentional repetitive trauma and injury subsequent new bone formation and healing results in deformation of joints Associated conditions diabetes mellitus tertiary syphilis tabes dorsalis chronic alcohol misuse disorder syringomyelia myelomeningocele spinal cord tumors subacute combined degeneration (vitamin B12 deficiency) Presentation Symptoms non-painful swelling of a joint Physical exam acutely, may present as non-tender, erythematous, edematous, and warm joint chronically, may present as joint or foot deformity with joint effusion and bony prominences most common deformity is a collapse of the tarsometatarsal joint, with valgus angulation may find other signs of chronic neuropathy, including foot ulcers decreased or absent vibration sensation loss of deep tendon reflexes Imaging Radiography indication for all patients findings can be normal in early Charcot joint acute bony consolidation with fractures, joint effusion, or bone destruction chronic bony deformity, new bone formation, and sclerosis resorption of bone Magnetic resonance imaging (MRI) with gadolinium indication if radiograph is unclear and if osteomyelitis is suspected finding osseous edema Bone scintigraphy (typically, technetium-99m-labeled methylene diphosphonate followed by indium-labeled leukocyte scintigraphy) indication to further distinguish neuropathic arthropathy from osteomyelitis findings negative (cold) for neuropathic arthropathy positive (hot) for osteomyelitis Studies Labs typically, normal white blood cell count and markers of inflammation (erythrocyte sedimentation rate and C-reactive protein) Making the diagnosis based on clinical presentation and imaging Differential Cellulitis distinguishing factor no bony deformities or changes on imaging Osteomyelitis distinguishing factor increased inflammatory markers MRI and bone scintigraphy findings of osteomyelitis Treatment Conservative immobilization and rest indication for all patients, especially in the acute phase accommodative footwear indication for all patients, especially in the chronic phase Operative surgical repair indications only recommended for severe deformities not usually performed Complications Spontaneous fractures Osteomyelitis