Loose body in knee, unspecified knee

This code signifies the presence of a detached fragment of cartilage or bone within the knee joint capsule, often referred to as a "joint mouse." These loose bodies can cause mechanical symptoms such as locking, catching, or pain during knee movement.

Use this code when documentation indicates a loose body in the knee, but the specific knee (left or right) is not specified. This diagnosis is typically made based on patient symptoms, physical examination findings, and imaging studies like X-rays or MRI.

• Avoid using this code if the laterality (left or right knee) is documented; instead, use M23.41 (right) or M23.42 (left).
• Do not confuse this with internal derangement of the knee (M23.x codes) unless a loose body is specifically identified.
• Ensure documentation clearly states "loose body" or "joint mouse" to support this diagnosis.