Loose Body in the Knee

What Is It?

A loose body is a fragment of cartilage or bone that has broken free and is floating inside the knee joint. Because it can drift, it may wedge between the joint surfaces and interfere with smooth motion.

Loose bodies range from a few millimeters to over a centimeter, and there may be one or several. On X-ray a bony fragment is often visible; purely cartilage fragments may need an MRI to find.

How It Happens

Most loose bodies come from a cartilage injury, osteochondritis dissecans (a fragment of bone and cartilage that separates), a prior injury or dislocation, arthritis wear, or an inflamed joint lining that forms small cartilage nodules (synovial chondromatosis).

What It Feels Like

The classic symptoms are catching, clicking, and episodes of true locking — the knee briefly gets stuck and then releases. Many patients feel something moving inside the knee, with intermittent sharp pain and swelling after activity. Between episodes the knee may feel entirely normal.

How Long Recovery Takes

Arthroscopic removal of a loose body is an outpatient procedure through two small incisions. Most patients walk immediately, return to desk work within a few days, and return to sport in 2–6 weeks depending on what is found and treated at the same time.

If the fragment came from a fresh cartilage defect, treating the source (chondroplasty, microfracture, or a cartilage restoration procedure) can change the recovery plan — Dr. Pettit will review this with you.

Treatment

A loose body that is causing locking or recurrent swelling generally should be removed — mechanical symptoms tend to persist, and a hard fragment can scuff healthy cartilage over time. Knee arthroscopy allows Dr. Pettit to remove the fragment, inspect the whole joint, and treat the source of the fragment at the same sitting.

If the loose body was an incidental finding and is not causing symptoms, observation is reasonable — activity modification and anti-inflammatory medicine as needed.

Returning to Sport

After a straightforward removal, return to sport typically takes 2–6 weeks: comfortable walking first, then cycling and straight-line jogging, then cutting and jumping once swelling is gone and strength is symmetric.

Preventing the Next One

Address the source: cartilage defects and osteochondritis dissecans lesions are followed with imaging and treated when unstable. Keep the quadriceps and hips strong, manage body weight, and treat swelling episodes early.

When to Call Us

Call the office at (513) 354-3700 for a knee that locks and will not release, rapidly increasing swelling, fever over 101°F, or pain that is not controlled with medicine. A truly locked knee should be seen promptly.