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

This code signifies an internal derangement of the right knee's medial meniscus, specifically involving the anterior horn, resulting from a previously sustained tear or injury. This condition often presents with mechanical symptoms such as locking, catching, or instability, and can be associated with chronic knee pain.

Apply this code when documentation clearly indicates a diagnosis of an anterior horn medial meniscal derangement in the right knee, explicitly attributed to an old or pre-existing tear or injury. Supporting documentation typically includes MRI reports confirming the meniscal pathology and physician notes detailing the chronicity of the injury.

• Differentiate from acute meniscal tears; this code specifically denotes an old injury.
• Ensure laterality (right knee) is clearly documented.
• Confirm the specific location (anterior horn) and type of meniscus (medial) are explicitly stated in the clinical notes.