Patella dislocation: Difference between revisions
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==Background==
==Background==
*Occurs with trauma to an extended knee with externally rotated foot and twisting motion<ref>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</ref>
*Typically occurs with trauma to an extended knee with externally rotated foot<ref>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</ref>
*Acute: in traumatic injury, occurs equally in men/women <ref name="epi">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</ref>
*Acute dislocation occurs with traumatic injury, M=F, may see hemarthrosis<ref name="epi">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</ref>
*Chronic: women/teenage girls<ref name="epi"></ref>
*Chronic dislocation seen more commonly in women/teenage girls, typically little or no swelling<ref name="epi"></ref>
*Commonly lateral displacement and unable to extend knee
*Common associated fractures
**Medial patella facet
**Lateral femoral condyle


==Clinical Features==
==Clinical Features==
[[File:Patellar dislocation.jpg|thumb|patella dislocates laterally]]
[[File:Patellar dislocation.jpg|thumb|patella dislocates laterally]]
*Patella is usually displaced laterally; knee is held in flexion
*Patella is usually displaced laterally; knee is held in flexion
*Acute: often with large hemarthrosis
*Chronic: little to no swelling


==Differential Diagnosis==
==Differential Diagnosis==
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==Evaluation==
==Evaluation==
[[File:Patellaluxation ap 001.png|thumb]]
[[File:Patellaluxation ap 001.png|thumb]]
*Xray if traumatic mechanism to rule out fracture
*Clinical diagnosis
*Do not need xay prior to reduction if chronic
*May consider pre-reduction x-ray if concern for fracture (not required)
*Post-reduction x-ray: confirm reduction, eval for fractures and loose bodies (avulsions, misalignment, etc)<ref>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</ref>
*Common associated fractures
**Medial patella facet
**Lateral femoral condyle


==Management==
==Management==
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***Slowly extend and slightly hyperextend the knee and slide patella back into place.  
***Slowly extend and slightly hyperextend the knee and slide patella back into place.  
**Option #2
**Option #2
***One provider applies slow downward pressure over the quads.  This stretches out the muscle and slowly straigttens the leg
***One provider applies slow downward pressure over the quads.  This stretches out the muscle and slowly straightens the leg
***At the same time, second pulls gentle traction of the patella outward while rotating the patella back over from lateral to anterior
***At the same time, second provider pulls gentle traction of the patella outward while rotating the patella back over from lateral to anterior
**Knee immobilizer, NSAIDs, weight-bearing as tolerated
*Knee immobilizer, NSAIDs, weight-bearing as tolerated


==Disposition==
==Disposition==
**Orthopedic follow-up within 1-2wks
*Obtain ortho consult if unable to reduce or fracture/loose bodies seen on post-reduction x-ray
*Unable to reduce or loose bodies/fracture on post-reduction imaging
*Otherwise may be discharged with ortho follow-up in 1-2 weeks
**Obtain immediate ortho consult


==References==
==References==

Revision as of 21:14, 9 May 2017

Background

  • Typically occurs with trauma to an extended knee with externally rotated foot[1]
  • Acute dislocation occurs with traumatic injury, M=F, may see hemarthrosis[2]
  • Chronic dislocation seen more commonly in women/teenage girls, typically little or no swelling[2]
  • Common associated fractures
    • Medial patella facet
    • Lateral femoral condyle

Clinical Features

patella dislocates laterally
  • Patella is usually displaced laterally; knee is held in flexion

Differential Diagnosis

Knee diagnoses

Acute knee injury

Nontraumatic/Subacute

Evaluation

Patellaluxation ap 001.png
  • Clinical diagnosis
  • May consider pre-reduction x-ray if concern for fracture (not required)

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 straightens the leg
      • At the same time, second provider 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

  • Obtain ortho consult if unable to reduce or fracture/loose bodies seen on post-reduction x-ray
  • Otherwise may be discharged with ortho follow-up in 1-2 weeks

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

See Also

Knee (Main)

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