ICD-10 Coding for Degenerative Knee Changes with Bilateral Meniscal Tears
The appropriate ICD-10 codes for this case are M17.0 (Bilateral primary osteoarthritis of knee) as the primary diagnosis, with M23.203 (Derangement of unspecified meniscus due to old tear or injury, unspecified knee, bilateral) as a secondary code to capture the bilateral meniscal pathology.
Primary Diagnosis Code
- M17.0 (Bilateral primary osteoarthritis of knee) is the most accurate primary code because the imaging demonstrates degenerative changes affecting all three compartments (medial tibiofemoral, lateral tibiofemoral, and patellofemoral) with characteristic features of osteoarthritis including narrowed joint spaces, irregular articular surfaces, subchondral marrow edema, and marginal osteophytes 1.
Secondary Diagnosis Code
- M23.203 (Derangement of unspecified meniscus due to old tear or injury, unspecified knee, bilateral) should be added as a secondary code because the imaging reveals branching tears of both the medial and lateral menisci in both horns and body segments 1, 2.
- The meniscal tears in this context are degenerative rather than acute traumatic tears, as evidenced by the extensive degenerative changes throughout the joint and the complex branching pattern described 2.
Additional Coding Considerations
- M25.469 (Effusion, unspecified knee, bilateral) may be considered if the periarticular soft tissue edema represents significant joint effusion, as effusion is associated with increased knee pain and progression of osteoarthritis 1, 3.
- M25.569 (Pain in unspecified knee, bilateral) can be added if documenting the symptomatic nature of the condition for billing purposes, though this is often implied by the primary diagnosis 1.
Bone Marrow Edema Documentation
- The subchondral marrow edema noted in the medial compartment is a significant finding that indicates active disease and is associated with increased knee pain 1, 4.
- Bone marrow lesions (BMLs) are readily depicted on MRI and new or increasing BMLs are associated with increased knee pain and risk of progression 1.
- While bone marrow edema is captured within the osteoarthritis diagnosis, documenting its presence in clinical notes is important as it may influence treatment decisions and prognosis 4, 5.
Common Coding Pitfalls to Avoid
- Avoid using M23.2 codes for acute meniscal tears when the clinical and imaging context clearly indicates degenerative meniscal pathology associated with osteoarthritis 2.
- Do not code each compartment separately (M17.2 for medial, M17.3 for lateral) when bilateral disease affecting multiple compartments is present; M17.0 is more appropriate 1.
- Avoid omitting the bilateral designation when both knees are affected, as this impacts treatment planning and reimbursement 1.