Approach Considerations
Obtain prereduction and postreduction radiographs to rule out any osteochondral fractures, if such lesions are suspected on the basis of mechanism of injury or findings from physical examination.
Computed tomography (CT) can detect small bony fragments that result from patellar dislocation. These fragments often are not seen on standard radiographs. CT should be considered in first-time dislocation patients and in dislocations that result from significant forces. [13]
Magnetic resonance imaging (MRI) may be considered in patients with acute traumatic patellar dislocations to help determine the nature of any osteochondral and soft-tissue injury. [14, 6] It may be useful for evaluating the anatomic sequelae of the dislocation, assessing the risk of recurrence, and determining whether conservative or surgical management is warranted in the acute setting.
Controversy has been reported in the literature regarding which patients should undergo operative repair of primary dislocations. Most patients do well with a short course of immobilization followed by physical therapy. [15, 16]
Medial patellofemoral ligament injury typically results from patellar dislocation [17] ; thus, follow-up with an orthopedic surgeon is recommended for all patients with patellar dislocations. [18, 19, 20, 21, 22]
Some evidence suggests that reduction of acute patellar dislocation can be performed by emergency medical services providers in the prehospital setting and can provide significant pain relief with low complication rates.
Patellar Reduction
Stand on the lateral side of the leg on which the patellar reduction is to be done. (See the video below.) Slightly flex the injured leg at the hip to decrease tension on the quadriceps muscles. Extend the knee while applying gentle anteromedially directed force on the lateral patellar edge to lift the patella over the femoral condyle. For a medial dislocation, use the same technique, but stand medial to the dislocation and apply an anterolateral force.
When reduction is complete, apply a knee immobilizer so that the knee is in full extension.
Arrange a follow-up appointment for the patient with an orthopedic surgeon. Some patients with complete dislocation may require surgery to prevent recurrence.
Complications
Osteochondral fractures are a very uncommon complication of reduction of a patellar dislocation. Related complications of the dislocation itself may include recurrent dislocations, degenerative arthritis, or osteochondral fractures.
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Conducting patellar reduction.
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Positioning for lateral patellar reduction.
