Idiopathic aseptic necrosis of left femur

This code signifies the death of bone tissue in the left 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 arthritis if untreated.

Apply this code when documentation explicitly states idiopathic avascular necrosis or osteonecrosis affecting the left femur. It is appropriate for cases where no underlying systemic disease, steroid use, or traumatic event is identified as the cause.

• Ensure laterality is clearly documented as "left femur" to support this specific code.
• Distinguish from secondary avascular necrosis (e.g., due to steroid use, trauma, or sickle cell disease), which would require different codes.
• Look for terms like "idiopathic," "primary," or "spontaneous" to confirm the absence of an underlying cause.