Derang of medial meniscus due to old tear/inj, right knee

This diagnosis code signifies a chronic or old injury to the inner (medial) meniscus of the right knee, leading to its functional impairment or displacement. It indicates a pre-existing tear or injury that is now causing symptoms or mechanical issues within the knee joint. This is distinct from an acute, recent meniscal tear.

Apply this code when documentation specifies a derangement of the right medial meniscus resulting from a past tear or injury, rather than a new, acute event. Supporting documentation should clearly indicate the chronicity of the meniscal issue, often through terms like "old tear," "chronic injury," or "due to prior trauma." This code is appropriate when the patient presents with symptoms like locking, clicking, or instability attributable to this long-standing meniscal pathology.

• Differentiate carefully between acute (new) and chronic (old) meniscal tears; this code is specifically for chronic/old injuries.
• Ensure laterality is clearly documented as "right knee" to support this specific code.
• Consider sequencing this code with an external cause code if the original injury's cause is known and relevant to the current encounter.