Patella fractures are typically due to direct trauma as in a fall or direct blow to the knee.

Fractures may be missed on the AP view or misdiagnosed as a bipartate fracture.  To avoid these pitfalls look closely at the lateral view and consider getting a sunrise view of the knee (better visualizes the patella).  Finally,  unilateral bipartate patella are very rare so consider an x-ray of the contralateral knee if you are considering this as your diagnosis.

Surgery should be considered for:

• Fractures with displacement greater than 3 mm.
• Individuals that have lost there externsor mechanism as it is indicative of a tear in the extensor retinacula.