Merck Manual

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How To Reduce a Lateral Patellar Dislocation


Matthew J. Streitz

, MD, San Antonio Uniformed Services Health Education Consortium

Last full review/revision Dec 2019| Content last modified Dec 2019
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Manual manipulation of the patella is used to reduce a lateral patellar dislocation. Analgesia is usually not needed.


  • Lateral dislocation of the patella

Patellar dislocations are almost always lateral.


There are no contraindications to lateral patellar dislocation reduction. However, consultation with an orthopedic surgeon should be obtained prior to reduction if an associated proximal tibial or distal femoral fracture (including osteochondral fracture) is present.


  • Complications are rare when reduction is done gently.


  • Knee immobilizer or splinting material

  • Crutches

Additional Considerations

  • Pre-procedure x-rays are recommended to identify coexisting patellar fractures, other bony abnormalities, or foreign bodies.

  • The patella often reduces spontaneously (eg, before hospital arrival) or when the knee is incidentally extended.


  • Position the patient supine on the stretcher.

Step-by-Step Description of Procedure

  • Do a pre-procedure neurovascular examination, including posterior tibial and dorsalis pedis pulses, capillary refill time (normally < 2 seconds).

  • Analgesia is usually unnecessary. Patients with significant pain or anxiety may be offered procedural sedation and anesthesia (PSA).

  • Cradle the affected lower leg in one arm.

  • Slightly flex the hip (relaxes quadriceps tension).

  • Gently extend the lower leg. The patella may reduce spontaneously.

  • If the patella has not reduced, use your other hand to apply gentle force to the outermost edge of the displaced patella, and push the patella back to its normal location between the femoral condyles.

  • Successful reduction may be accompanied by a perceptible “clunk.”


  • Successful reduction is preliminarily confirmed by visible restoration of a normal knee contour and by decreased pain.

  • Immediately immobilize the knee in full extension with a knee immobilizer or splint. The immobilizer should be worn for 3weeks.

  • Repeat the neurovascular examination.

  • Do post-procedure x-rays to confirm proper reduction and identify any coexisting fractures.

  • Arrange orthopedic follow-up.

Warnings and Common Errors

  • A patella may reduce spontaneously prior to evaluation. Be sure that the injury was not actually a knee dislocation.

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NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
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