Radiographic Imaging in Acute Knee Injuries

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Radiographic Imaging in Acute Knee Injuries

• Nick Sparler MS4

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Topics

• Basic Anatomy
• To Image or Not?
• Bony injury
• Ligamentous injury

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Anatomy
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To Image or Not?Fracture?

• Ottawa knee rules
• Age 55 years or older
• Tenderness at head of fibula
• Isolated tenderness of patella
• Inability to flex knee to 90 degrees
• Inability to walk four weight-bearing steps
  immediately after the injury and in the emergency
  department
• Pittsburgh decision rules
• Blunt trauma or a fall as mechanism of injury
  plus either of the following
• Age younger than 12 years or older than 50 years
• Inability to walk four weight-bearing steps in
  the emergency department
• In a recent prospective study, the Pittsburgh
  decision rules were 99 percent sensitive and 60
  percent specific for the diagnosis of knee
  fractures. The Ottawa knee rules were 97 percent
  sensitive and 27 percent specific for knee
  fractures

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To Image or Not?Ligament?

• History and Physical exam
• Mechanism or injury
• Lachman test, Anterior Drawer test, Gravity test
  etc
• MRI is the preferred diagnostic modality

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Bony injuries

• AP, Lateral and Oblique views should be obtained
• Lateral tibial plateau (TP) fractures are most
  common
• Patellar fractures due to trauma or forced
  contraction of quadriceps tendon
• Beware of Bi-Partite Patella
• Segond- avulsions of the LCL at Lat TP
• Think ACL or Meniscus

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Tibial Plateu Fracture
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ACL Injurywith Bony Fracture1. Hemarthrosis ACL
2. Avulsion 3. Segond Fracture
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Patella1. Bi-Partite 2.
Fracture
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Ligamentous Injury

• ACL most common
• PCL- dashboard injury, hyperextension
  associated with ACL injury
• MCL/LCL
• Meniscus

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Grading

• - Grade I (microscopic tears) ligamentous tears
  demonstrate an intact ligament of normal
  thickness surrounded to a variable degree by
  intermediate T1-weighted and high T2-weighted
  signals indicative of surrounding edema. The
  ligament remains closely applied to the
  underlying cortical bone.
• - Grade II (partial tears) tears demonstrate
  thickening and/or partial disruption of the
  fibers of the MCL with an increased amount of
  surrounding intermediate T1-weighted and high
  T2-weighted signals indicative of increased edema
  and concomitant hemorrhage.
• - Grade III (complete tear) tears demonstrate
  complete disruption of the ligament with
  corresponding surrounding hemorrhage and edema.

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ACL Injury

• Confirm in the coronal and axial planes

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PCL Injury1. Normal 2. Torn
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MCL Tear
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LCL Tear
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Meniscus1. Tear 2. Mucoid Degeneration
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Bucket- Handle Tear
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Resources

• Grainger and Allisons Diagnostic Radiology
• http//www.wikiradiography.com/page/RadiographicA
  natomy
• www.sportsdoc.umn.edu/.../normal20PCL20mri.jpg
• http//www.aafp.org/afp/991201ap/2599.html
• www.mskcases.com