Idiopathic aseptic necrosis of unspecified femur

This code signifies the death of bone tissue in an unspecified femur due to a lack of blood supply, without an identifiable cause such as trauma or infection. This condition, also known as avascular necrosis or osteonecrosis, leads to bone collapse and subsequent joint destruction. It is considered idiopathic when no underlying etiology can be determined.

Apply this code when documentation clearly states idiopathic avascular necrosis affecting the femur, and the specific side (left or right) is not specified. This diagnosis is typically made based on imaging studies (e.g., MRI, X-ray) and clinical presentation of hip pain and limited range of motion, in the absence of other contributing factors.

• Ensure documentation explicitly states "idiopathic" and "femur" to support this code.
• Avoid using this code if a specific cause (e.g., steroid-induced, post-traumatic) or a specific side of the femur is documented; instead, use a more specific code from the M87.1 or M87.2 subcategories.
• If the laterality is known (left or right femur), select the appropriate M87.051 or M87.052 code.