Charcot (Neuropathic) Arthropathy of the Shoulder

The defining feature of a Charcot shoulder is destruction out of proportion to pain: the joint is grossly swollen and disorganised, often unstable, yet relatively painless, because the underlying problem is loss of protective sensation and proprioception. The leading cause of an upper-limb neuropathic joint (elbow and shoulder) is syringomyelia, so a painless destroyed shoulder should prompt MRI of the cervical spinal cord to find a syrinx. The mechanism combines the neurotraumatic theory (unperceived repetitive microtrauma) and the neurovascular theory (autonomic dysregulation increasing bone resorption). Radiographs show resorption and fragmentation of the humeral head with bony debris - the disorganised 'bag of bones', summarised as the 6 Ds (Destruction, Density, Debris, Dislocation, Disorganisation, Distension).

• Exclude the dangerous mimics first. The grossly swollen, destroyed, fluid-filled shoulder can look like a tumour (an expansile mass) or infection (septic arthritis/osteomyelitis); image appropriately and, when there is doubt, aspirate and/or biopsy before attributing the destruction to neuropathy.
• Find and treat the underlying cause. Image the cervical cord (MRI) for a syrinx (often with a Chiari malformation); neurosurgical decompression may be indicated for a progressive syrinx.
• Largely supportive joint care. Protect the joint, manage symptoms and maintain function; activity modification and bracing have a role.
• Surgery is selective and unreliable. Charcot joints have high surgical complication and failure rates; arthrodesis is difficult and often fails, and arthroplasty is reserved for carefully selected cases, ideally after the neurological process is addressed, within a multidisciplinary team.