Cystic meniscus, post horn of medial meniscus, unsp knee

This diagnosis code signifies the presence of a fluid-filled sac (cyst) within the posterior portion of the medial meniscus, a C-shaped cartilage in the knee that acts as a shock absorber. This condition can lead to pain, swelling, and mechanical symptoms in the knee joint. The "unspecified knee" indicates that the laterality (left or right) of the affected knee is not documented.

Apply this code when documentation confirms a cystic lesion specifically located in the posterior horn of the medial meniscus, and the medical record does not specify which knee is affected. This diagnosis is typically made based on imaging studies such as MRI, often following patient complaints of knee pain or discomfort.

• Ensure the documentation clearly specifies "posterior horn" and "medial meniscus" to support this code.
• Avoid using this code if the laterality (left or right knee) is known; instead, use the more specific codes for left (M23.021) or right (M23.022) knee.
• Do not confuse this with meniscal tears without cyst formation, or cysts in other parts of the meniscus or knee joint.