ICD-10 Code M00.86 – Arthritis due to other bacteria, knee (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M00.86 – Arthritis due to other bacteria, knee
What it is
M00.86 identifies bacterial arthritis affecting the knee joint when the causative organism is not one of the specific code-listed pathogens. Use this code for a documented bacterial infection of the knee joint.
Clinical signs
Typical findings include a painful, swollen, warm knee with limited range of motion. Clinical features vary; refer to documentation for the organism, laterality, and whether the diagnosis is confirmed.
When to use this code
Use M00.86 when the provider documents septic or infectious arthritis of the knee due to other bacteria. It applies when the knee is the involved joint and the organism is identified as bacterial but not otherwise specified in a more exact code.
Choose this code only when the record supports an active bacterial joint infection, not a history of infection or nonspecific knee pain. Check documentation if the note does not clearly identify the knee or the bacterial cause.
Do not use for
Do not use this code for noninfectious arthritis, such as osteoarthritis or rheumatoid arthritis. Also avoid it when the joint involved is not the knee or when the documentation does not support bacterial infection.
Coding tip
Verify the organism and joint site in the provider note before assigning M00.86.