Loose Bodies of the Knee Joint
What Are Loose Bodies?
Loose bodies are fragments of bone and/or cartilage that freely floats inside the knee joint.
What Are the Symptoms?
- Locking or jamming of the knee
- Intermittent catching of the knee
How to Diagnose?
X-rays can sometimes show the bony fragment in the knee joint. Occasionally MRI scans are required to identify the loose bodies.
Some of these loose bodies are relatively “fixed” inside the knee (usually at the back of the knee joint) and may not float about inside the knee joint. These tend to cause less symptoms and problems.
However, some of these larger loose bodies at the back of the knee joint can fragment into smaller pieces and these smaller pieces can float into the knee joint leading to locking, pain and swelling.
How Do They Come About?
Some of these loose fragments break off from bony spurs that form in the knee joint due to wear and tear (osteoarthritis). Others can break off as an osteochondral fragment and these can be termed “osteochondritis dissecans”.
There is a condition where the synovial covering of the knee joint becomes abnormal and it forms many small pieces of bone and this is called “synovial chondromatosis”.
This is a 60 year old woman who presented with acute pain and swelling of her right knee. There was no prior injury or trauma to her right knee. She described having locking sensations of her knee followed by pain and swelling.
MRI showed a large loose body in the back of her knee joint.
Arthroscopy showed small loose body in the medial compartment of the knee joint. It most likely broke off from the large posterior loose body.
Arthroscopic removal of the loose bodies were successfully carried out with resolution of her knee pain and jamming symptoms.