Idiopathic aseptic necrosis of unspecified carpus

This code signifies the death of bone tissue in an unspecified carpal bone due to a lack of blood supply, without an identifiable cause (idiopathic) and without infection (aseptic). This condition, also known as avascular necrosis, leads to bone collapse and subsequent arthritis if left untreated.

Apply this code when documentation clearly indicates idiopathic aseptic necrosis affecting a carpal bone, and the specific carpal bone involved is not identified. Supporting documentation would include imaging reports (e.g., X-ray, MRI) confirming avascular necrosis and clinical notes ruling out trauma, infection, or systemic diseases as the cause.

• Ensure the documentation explicitly states "idiopathic" or "avascular necrosis of unknown etiology" to support the aseptic and idiopathic components.
• If a specific carpal bone is identified (e.g., lunate, scaphoid), use the more specific code from the M87.03- subcategory.
• Do not use this code if the necrosis is due to trauma (e.g., fracture) or a known underlying condition; instead, code the primary cause.