ICD-10 Code M00.869 – Arthritis due to other bacteria, unspecified knee (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M00.869 – Arthritis due to other bacteria, unspecified knee
What it is
This code identifies bacterial arthritis affecting the knee when the organism is not one of the specifically named causes in ICD-10-CM. It is used when the knee is documented, but the side is not specified.
Clinical signs
Typical findings include an acutely painful, swollen, warm knee with limited range of motion. Clinical features vary; refer to documentation, and confirm that the record supports bacterial joint infection rather than another cause of arthritis.
When to use this code
Use M00.869 when the provider documents arthritis due to other bacteria in the knee and does not specify left or right. It also fits when the causative bacteria is identified as another bacterial agent, but the knee laterality is absent. Check documentation if the joint infection is described only generally.
Do not use for
Do not use this code for viral, fungal, or noninfectious arthritis, or for septic arthritis caused by a specifically named organism that has a different ICD-10-CM code. Do not assign it when the knee side is documented and a more specific laterality code is available.
Coding tip
Code the organism and laterality exactly as documented, and query the provider if the note does not clearly support “other bacteria” or an unspecified knee.