Radiographic Imaging in Acute
Knee Injuries
Nick Sparler MS4
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Topics
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Basic Anatomy
To Image or Not?
Bony injury
Ligamentous injury
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
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
Tibial Plateu Fracture
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ACL Injury
with Bony Fracture
1. Hemarthrosis ACL 2. Avulsion
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3. Segond Fracture
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Patella
1. Bi-Partite
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2. Fracture
Ligamentous Injury
 ACL most common
 PCL- “dashboard injury”, hyperextension
associated with ACL injury
 MCL/LCL
 Meniscus
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.
ACL Injury
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 Confirm in the coronal and axial planes
PCL Injury
1. Normal
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2. Torn
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MCL Tear
LCL Tear
Meniscus
1. Tear
2. Mucoid Degeneration
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Bucket- Handle Tear
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Resources
 Grainger and Allison’s Diagnostic Radiology
 http://www.wikiradiography.com/page/Radiograph
ic+Anatomy
 www.sportsdoc.umn.edu/.../normal%20PCL%20m
ri.jpg
 http://www.aafp.org/afp/991201ap/2599.html
 www.mskcases.com