Idiopathic aseptic necrosis of unspecified tibia

This code signifies the spontaneous death of bone tissue in an unspecified tibia due to a lack of blood supply, without an identifiable cause such as trauma, infection, or radiation. It represents avascular necrosis (AVN) affecting the shin bone, where the etiology remains unknown.

Apply this code when documentation explicitly states idiopathic avascular necrosis or osteonecrosis of the tibia, and the specific laterality (left or right) is not documented. Supporting documentation should include imaging reports (e.g., MRI, X-ray) confirming bone necrosis and a physician's note ruling out secondary causes.

• Ensure the documentation clearly states "idiopathic" or "primary" to differentiate from secondary AVN.
• Avoid using this code if laterality (left or right tibia) is specified; instead, select the appropriate M87.061 or M87.062 code.
• Do not confuse with osteomyelitis (M86.-) or other forms of bone necrosis with known causes.