Derang of post horn of medial mensc d/t old tear/inj, r knee

This diagnosis code signifies a structural disruption of the posterior horn of the medial meniscus in the right knee, specifically attributed to a previously sustained tear or injury. This derangement implies an abnormal mechanical function of the meniscus, often leading to symptoms like pain, locking, or instability.

Use this code when documentation clearly indicates a chronic or old tear of the posterior horn of the right medial meniscus causing current symptoms of derangement. This is typically supported by imaging studies (e.g., MRI) confirming an old tear and clinical findings consistent with meniscal pathology.

• Ensure documentation specifies "old tear" or "old injury" to differentiate from acute tears.
• Laterality (right knee) is crucial for accurate code selection.
• Do not use for acute meniscal tears; separate codes exist for acute injuries.