Derang of post horn of med mensc d/t old tear/inj, unsp knee

This code signifies a chronic internal derangement of the medial meniscus, specifically involving the posterior horn, resulting from a prior tear or injury. The condition affects an unspecified knee, indicating that laterality (left or right) is not documented. It implies ongoing symptoms or mechanical issues stemming from the old meniscal damage.

Use this code when documentation clearly states a "derangement" or "internal derangement" of the posterior horn of the medial meniscus due to an "old tear," "chronic tear," or "prior injury." This code is appropriate when the specific knee (left or right) is not specified in the medical record. Supporting documentation would include imaging reports (MRI) confirming an old meniscal tear and clinical notes describing persistent symptoms related to the derangement.

• Do not use this code for acute meniscal tears; specific acute tear codes exist.
• Ensure documentation specifies "posterior horn" and "medial meniscus" to justify this code.
• If laterality is documented (left or right knee), a more specific code (M23.221 or M23.222) should be used instead.