Loose body is the term applied to small fragments of articular cartilage that break off in the knee joint as a result of a knee injury or degeneration. Loose bodies float around within the knee joint and cause pain, catching, locking, or swelling depending upon where the fragments migrate. These fragments of bone and cartilage can come in all sizes and shapes, and can also occur as the result of long-term wear and tear to the knee. When a loose body becomes lodged within the knee joint, pain and instability will follow. This tends to recur until the loose pieces of cartilage are removed through surgery.

Symptoms and Diagnosis

Pain and a catching sensation within the knee are the primary symptoms of a loose body within the knee joint. Swelling usually follows. Some cases are associated with locking or buckling. Your physician will review the patient history and will ask about previous injuries and surgeries, and will also conduct a series of physical examination tests. An X-ray may show large, bony loose bodies, but an MRI is required to evaluate for loose cartilage without bone. Often, small loose bodies may be missed using MRI, and it is necessary to treat a patient with symptoms. The arthroscopic camera is the ultimate standard for confirming the location, size, and severity of loose bodies.


Your physician will perform an arthroscopic knee surgery. Tiny incisions will be made and a camera will be used to visualize the inside of the knee joint. Then, your physician will begin to remove the loose fragments and smooth or perform restoration to the damaged cartilage (bone lining from where the loose bodies broke off or came free). In patients who have symptoms as a result of loose bodies, surgery is usually the only way to provide relief. If left untreated, the loose fragments in the joint may lead to further deterioration of the articular cartilage. In the majority of cases, surgery is very successful and thus knee pain and mobility are improved tremendously.


Your physician will provide a detailed rehabilitation and physical therapy program during your first post-op visit following arthroscopic knee surgery. Therapy will focus on slowly returning motion back to the injured knee, followed by a progressive strengthening program to protect the repaired joint. Most patients walk normally within 7 days and return to full activity in less than 4 weeks. Others with more complicated conditions may require crutches, or a slower rehabilitation.