Loose body in 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, pain, and effusion, interfering with normal knee function.

Apply this code when documentation explicitly states the presence of a loose body within the knee joint. This diagnosis is typically supported by imaging studies (e.g., X-ray, MRI) confirming the free-floating fragment, or by direct visualization during arthroscopy.

• Differentiate from osteochondritis dissecans (OCD) where the fragment is still partially attached.
• Consider laterality if specified in the documentation (e.g., right or left knee).
• Sequence as a primary diagnosis when the loose body is the main reason for the encounter or procedure.