Small fragments of cartilage or bone that may move freely around the knee in joint fluid, or synovium
Aetiology
- Trauma, osteochondritis dissecans and joint degeneration can cause a fragment of cartilage +/- bone to detach causing a loose body in the joint
Pathophysiology
- They can grow over time getting nutrition from synovial fluid and may cause painful locking or catching
- Some can stick to synovium or fat pad - no longer 'loose'
Clinical presentation
- History of mobile lump or sharp occasional pain and locking/catching suggestive of loose body
- They should not cause constant, generalised or severe pain
Investigations
- They are commonly overdiagnosed with an opacification identified on an x-ray
- A fabella is an accessory ossicle in the lateral head of gastrocnemius (usually) commonly misdiagnosed as a loose body
- MRI or serial x-rays can determine if a body is truly loose
Management
- Arthroscopic removal can help troublesome symptoms but won't help degenerative joint pain