Diagnosis

Complete articular, frontal/coronal multifragmentary fractures (AO/OTA 34C3)

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General considerations
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. 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:

  1. they generally disrupt the extensor mechanism and
  2. they are associated with a significant articular injury to the patellofemoral joint

Clinical examination: straight leg raise test
Injury to the patella may disrupt the extensor apparatus of the knee. In these injuries, the extension mechanism is usually intact, but because of pain from the injury, the patient may be unable to perform an active straight leg raise. If there is clinical uncertainly about the correct diagnosis of disruption of the extensor apparatus of the knee, an ultrasound scan, or MRI, of the extensor apparatus, including the quadriceps tendon and patellar tendon should be obtained, in order to elucidate the correct diagnosis.

Complete articular, frontal/coronal multifragmentary fractures (AO/OTA 34C3)
Multifragmentary fractures may need a combination of fixation techniques, such as screw fixation with tension band wiring. These are classified by AO/OTA as 34C3.

Stable anatomical restoration of the articular surface may not be possible. Excision of the patella should be avoided. If the articular surface is badly damaged, once the body of the patella has healed, some form of salvage procedure may be required.

 

X-ray by courtesy of Spital Davos, Switzerland, Dr C Ryf and Dr A Leumann.

X-ray by courtesy of Spital Davos, Switzerland, Dr C Ryf and Dr A Leumann.