What is it?

	Normal patella	Bipartite Patella

The patella or knee-cap develops from one center of bone formation (or ossification center). In some cases, a separate second center of bone formation is present. If these two centers of bone formation do not eventually fuse, a situation arises where there is an accessory bone from the second center of ossification that is attached to the patella by fibrous or cartilage tissue. This is often on the supero-lateral corner of the patella.

What are the symptoms?

Usually there are no symptoms, and the diagnosis is made incidentally when X-rays were taken for a knee injury. It may be mistakenly diagnosed as a patella fracture.

What does your doctor do about it?

If X-rays taken for a knee injury show a radiolucent line at the supero-lateral corner of the patella, a comparison view of the other knee will confirm or rule out bipartite patella, since it is usually bilateral.

Sometimes the injury involves the bipartite patella itself, which could be a separation of the fibrous or cartilage union at the bipartite patella. In those cases, a cylinder cast or knee immobilizer to rest the knee in extension for 4 to 6 weeks usually resolves the problem. In cases of persistent or recurrent pain, excision of the bipartite patella may be necessary.