These fractures are usually caused by a direct impact to the front of the knee and are some of the most difficult fractures to treat. They are classified by the AO/OTA as 34C3 fractures.
The surgeon will often underestimate the complexity of the injury and will therefore not be prepared for a very challenging osteosynthesis.
The articular injury is usually much more severe than predicted from the radiographs. The patellofemoral joint surface injury may be associated with impaction deformation of the patellar joint surface that can be impossible to restore anatomically and stably. Patellar fractures are important for two reasons:
they generally disrupt the extensor mechanism and
they are associated with a significant articular injury to the patellofemoral joint