Derang of post horn of lat mensc due to old tear/inj, l knee

This diagnosis code indicates a chronic internal derangement of the posterior horn of the lateral meniscus in the left knee. It signifies that the meniscal damage, specifically a tear or injury, is not acute but rather an older, pre-existing condition causing ongoing mechanical symptoms or dysfunction.

Use this code when documentation explicitly states an "old" or "chronic" tear or injury affecting the posterior horn of the lateral meniscus of the left knee, leading to derangement. This is appropriate for patients presenting with persistent knee pain, locking, or instability attributable to a previously sustained meniscal injury that has not fully resolved.

• Ensure documentation specifies "old" or "chronic" to differentiate from acute tears.
• Verify laterality (left knee) is clearly stated in the medical record.
• Distinguish from derangements of the medial meniscus or other parts of the lateral meniscus.