Patella dislocation: Difference between revisions

Latest revision as of 21:07, 31 December 2020

Background

Anatomy of anterolateral aspect of right knee.

Usual mechanism is blow to extended knee with externally rotated foot^[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 dislocates laterally

Patella usually displaced laterally
Knee held in flexion
Pain

Differential Diagnosis

Knee diagnoses

Acute knee injury

Nontraumatic/Subacute

Evaluation

Clinical diagnosis
May consider pre-reduction x-ray if concern for fracture (not required)

Management

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

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

@@ Line 1: / Line 1: @@
 ==Background==
-*Occurs when pivot knee on fixed leg
+[[File:Knee diagram2.png|thumb|Anatomy of anterolateral aspect of right knee.]]
+*Usual mechanism is blow to 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>
+*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
-==Diagnosis==
+==Clinical Features==
-*Petella is usually displaced laterally; knee is held in flexion
+[[File:Patellar dislocation.jpg|thumb|patella dislocates laterally]]
+*Patella usually displaced laterally
+*Knee held in flexion
+*Pain
-==Work-Up==
+==Differential Diagnosis==
-*Post-reduction x-ray to evaluate for fx
+{{Knee DDX}}
-**Usually seen at lateral femoral condyle or medial margin of patella
-==Treatment==
+==Evaluation==
-*Reduce; do not need x-rays prior to reduction
+[[File:Patellaluxation ap 001.png|thumb]]
-**Extend knee and slide patella back into place
+*Clinical diagnosis
-*Knee immobilizer, NSAIDs, partial weightbearing
+*May consider pre-reduction x-ray if concern for fracture (not required)
+==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
 ==Disposition==
-*Ortho f/u within 1-2wks
+*If unable to reduce or if fracture or loose bodies (i.e. osteochondral fracture) are seen on post-reduction radiographs, consult orthopedic surgery
-*If unable to reduce obtain immediate ortho consult
+*If patella successfully reduced, discharge with knee immobilizer and orthopedic follow up within 1 - 2 weeks
+==References==
+<references/>
-==Source==
+==See Also==
-*Tintinalli
+[[Knee (Main)]]
-[[Category:Ortho]]
+[[Category:Orthopedics]]