ICD-10 Code M00.879 – Arthritis due to other bacteria, unspecified ankle and foot (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M00.879 – Arthritis due to other bacteria, unspecified ankle and foot
What it is
M00.879 identifies septic arthritis of the ankle or foot caused by bacteria other than the common specified organisms, when the exact ankle or foot site is not further defined. Use it for a documented bacterial joint infection in this region.
Clinical signs
Typical findings include a painful, swollen, warm joint with reduced range of motion, and clinical features may vary; refer to documentation. Fever or surrounding inflammation may be present, but the record should support infectious arthritis.
When to use this code
Use this code when the provider documents bacterial arthritis affecting the ankle or foot and does not name the exact site more specifically. It also fits cases where the organism is other than the usual coded causes and the chart supports infection of the joint.
If the note only says “joint pain,” “cellulitis,” or another non-articular infection, you should not assign this code. Check documentation for the joint involved and whether the arthritis is confirmed as bacterial.
Do not use for
Do not use it for noninfectious arthritis, traumatic joint pain, or soft-tissue infection without joint involvement. If the organism or anatomic site is specified more precisely, choose the more specific code.
Coding tip
Confirm both infection and joint location in the provider note before coding, and code the most specific site available.