Other chronic osteomyelitis, unspecified tibia and fibula

This code signifies a persistent, long-term infection of the bone marrow and bone tissue within an unspecified tibia and fibula. It indicates a non-acute inflammatory process that has been ongoing, without further specification of the affected leg.

Apply this code when documentation clearly states "chronic osteomyelitis" affecting either the tibia or fibula, or both, but does not specify laterality (left or right). This is appropriate when the physician has not identified the specific bone or side involved.

• Only use this code when laterality is truly unspecified in the medical record.
• Prioritize codes that specify laterality (e.g., M86.661 for right, M86.662 for left) if documented.
• Do not use this code for acute osteomyelitis; refer to codes in the M86.0-M86.1 series.