ICD-10 Code M02.369 – Reiter’s disease, unspecified knee (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M02.369 – Reiter’s disease, unspecified knee
What it is
M02.369 identifies reactive arthritis, historically called Reiter’s disease, affecting an unspecified knee. Use it when the record shows this inflammatory joint condition in the knee but does not specify left or right.
Clinical signs
Typical findings include painful, swollen, and stiff arthritis with reduced range of motion. Clinical features vary; refer to documentation, especially when the diagnosis is based on a known reactive arthritis pattern.
When to use this code
Use this code when the provider documents Reiter’s disease or reactive arthritis involving a knee and laterality is not stated. It also fits when the chart confirms knee involvement but does not identify the affected side. If the note names a specific knee, choose the laterality-specific code instead.
Do not use for
Do not use it for nonspecific knee pain, osteoarthritis, or other inflammatory arthropathies without documentation of reactive arthritis. Check documentation if the record does not clearly link the knee findings to Reiter’s disease.
Coding tip
Verify both the diagnosis and laterality in the note before assigning M02.369.