Patella dislocation

Background

• extended knee with externally rotated foot and twisting motion
• acute: in traumatic injury, equal genders
• chronic: women/teenage girls
• commonly lateral displacement and unable to extend knee

patella dislocates laterally

Relocation with lateral pressure on dislocated patella

Diagnosis

• Patella is usually displaced laterally; knee is held in flexion
• acute: often with large hemarthrosis
• chronic: little to no swelling

Work-Up

• xray if traumatic mechanism to r/o 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)
• common associated fractures
  • medial patella facet
  • lateral femoral condyle

Treatment

• Reduce; do not need x-rays prior to reduction
  • Extend knee and slide patella back into place
  • Knee immobilizer, NSAIDs, partial weight-bearing
  • Orthopedic followup within 1-2wks
• Unable to Reduce or Loose bodies/fracture on post-reduction imaging
• Obtain immediate ortho consult

Source

• 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
• 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
• AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009

See Also

Knee (Main)