Patella dislocation: Difference between revisions
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==Background== | ==Background== | ||
* | [[File:Knee diagram2.png|thumb|Anatomy of anterolateral aspect of right knee.]] | ||
*Acute | *Usual mechanism is blow to extended knee with externally rotated foott<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> | ||
*Chronic | *May also occur with sudden lateral cut or twisting at the ankle or knee | ||
* | *Acute traumatic dislocations more common in males<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 dislocation seen more commonly in women/teenage girls, typically little or no swelling<ref name="epi"></ref> | |||
**May be associated with hemarthrosis | |||
*Chronic dislocation more common in females | |||
**Typically little or no swelling | |||
==Clinical Features== | ==Clinical Features== | ||
*Patella | [[File:Patellar dislocation.jpg|thumb|patella dislocates laterally]] | ||
* | *Patella usually displaced laterally | ||
*Knee held in flexion | |||
*Pain | |||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
{{Knee DDX}} | {{Knee DDX}} | ||
== | ==Evaluation== | ||
[[File:Patellaluxation ap 001.png|thumb]] | |||
* | *Clinical diagnosis | ||
* | *May consider pre-reduction x-ray if concern for fracture (not required) | ||
* | |||
**Medial | ==Management== | ||
[[File:Patellar Dislocation Relocation.jpg|thumb|Relocation with lateral pressure on dislocated patella]] | |||
*Reduce | |||
**Generally do not need x-rays prior to reduction | |||
**Sedation rarely required | |||
***Single dose of pain medication may facilitate relaxation | |||
===Techniques for closed reduction=== | |||
*Single operator | |||
#Place the hip in mild flexion by raising head of bed | |||
#*This facilitates relaxation of the quadriceps | |||
#Gently extend the knee with one hand while pushing the patella back in place with the other hand | |||
*Two operators | |||
#One provider applies slow downward pressure over quadriceps | |||
#*This stretches the muscle and slowly straightens the leg | |||
#Second provider gently rotates the patella lateral to anterior | |||
*Place patient in knee immobilizer | |||
*Provide NSAIDs | |||
*Obtain radiographs to rule out associated fracture (consider including sunrise view) | |||
*Allow weight-bearing as tolerated | |||
==Complications== | |||
*Commonly associated fractures: | |||
**Medial patellar facet | |||
**Lateral femoral condyle | **Lateral femoral condyle | ||
== | ==Disposition== | ||
* | *If unable to reduce or if fracture or loose bodies (i.e. osteochondral fracture) are seen on post-reduction radiographs, consult orthopedic surgery | ||
*If patella successfully reduced, discharge with knee immobilizer and orthopedic follow up within 1 - 2 weeks | |||
* | |||
==References== | ==References== | ||
Revision as of 21:42, 21 May 2020
Background
- Usual mechanism is blow to extended knee with externally rotated foott[1]
- May also occur with sudden lateral cut or twisting at the ankle or knee
- Acute traumatic dislocations more common in males[2]
- Chronic dislocation seen more commonly in women/teenage girls, typically little or no swelling[2]
- May be associated with hemarthrosis
- Chronic dislocation more common in females
- Typically little or no swelling
Clinical Features
- Patella usually displaced laterally
- Knee held in flexion
- Pain
Differential Diagnosis
Knee diagnoses
Acute knee injury
- Knee dislocation
- Knee fractures
- Meniscus and ligament knee injuries
- Patella dislocation
- Patellar tendonitis
- Patellar tendon rupture
- Quadriceps tendon rupture
Nontraumatic/Subacute
- Arthritis
- Gout and Pseudogout
- Osgood-Schlatter disease
- Patellofemoral syndrome (Runner's Knee)
- Patellar tendonitis (Jumper's knee)
- Pes anserine bursitis
- Popliteal cyst (Bakers cyst)
- Prepatellar bursitis (nonseptic)
- Septic bursitis
- Septic joint
- DVT
Evaluation
- Clinical diagnosis
- May consider pre-reduction x-ray if concern for fracture (not required)
Management
- Reduce
- Generally do not need x-rays prior to reduction
- Sedation rarely required
- Single dose of pain medication may facilitate relaxation
Techniques for closed reduction
- Single operator
- Place the hip in mild flexion by raising head of bed
- This facilitates relaxation of the quadriceps
- Gently extend the knee with one hand while pushing the patella back in place with the other hand
- Two operators
- One provider applies slow downward pressure over quadriceps
- This stretches the muscle and slowly straightens the leg
- Second provider gently rotates the patella lateral to anterior
- Place patient in knee immobilizer
- Provide NSAIDs
- Obtain radiographs to rule out associated fracture (consider including sunrise view)
- Allow weight-bearing as tolerated
Complications
- Commonly associated fractures:
- Medial patellar facet
- Lateral femoral condyle
Disposition
- If unable to reduce or if fracture or loose bodies (i.e. osteochondral fracture) are seen on post-reduction radiographs, consult orthopedic surgery
- If patella successfully reduced, discharge with knee immobilizer and orthopedic follow up within 1 - 2 weeks
References
- ↑ 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
- ↑ 2.0 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