Patella dislocation

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Revision as of 16:42, 9 May 2017 by Jdiamond (Talk | contribs) (Management)

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Background

  • Occurs with trauma to an extended knee with externally rotated foot and twisting motion[1]
  • Acute: in traumatic injury, occurs equally in men/women [2]
  • Chronic: women/teenage girls[2]
  • Commonly lateral displacement and unable to extend knee

Clinical Features

patella dislocates laterally
  • Patella is usually displaced laterally; knee is held in flexion
  • Acute: often with large hemarthrosis
  • Chronic: little to no swelling

Differential Diagnosis

Knee diagnoses

Acute Injury

Nontraumatic/Subacute

Evaluation

Patellaluxation ap 001.png
  • Xray if traumatic mechanism to rule out fracture
  • Do not need xay prior to reduction if chronic
  • Post-reduction x-ray: confirm reduction, eval for fractures and loose bodies (avulsions, misalignment, etc)[3]
  • Common associated fractures
    • Medial patella facet
    • Lateral femoral condyle

Management

Relocation with lateral pressure on dislocated patella
  • Reduce; do not need x-rays prior to reduction. Rarely need any sedation though a dose of IV pain medication can help relax the patient
    • Option #1:
      • Mild flexion of hip (20-30 degrees by raising head of bed, not by propping the leg up off the bed) to relax quadriceps
      • Slowly extend and slightly hyperextend the knee and slide patella back into place.
    • Option #2
      • One provider applies slow downward pressure over the quads. This stretches out the muscle and slowly straigttens the leg
      • At the same time, second pulls gentle traction of the patella outward while rotating the patella back over from lateral to anterior
    • Knee immobilizer, NSAIDs, weight-bearing as tolerated

Disposition

References

  1. Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
  2. 2.0 2.1 Fithian DC, Paxton EW, Stone ML, Silva P, Davis DK, Elias DA, White LM. Epidemiology and natural history of acute patellar dislocation. AJSM 2004;32:1114-1121
  3. Krause E A. et al. Pediatric lateral patellar dislocation: is there a role for plain radiography in the emergency department? J Emerg Med. 2013 Jun;44(6):1126-31

See Also

Knee (Main)