Anterior cruciate ligament avulsion fracture

Anterior cruciate ligament (ACL) avulsion fracture or tibial eminence avulsion fracture is a type of avulsion fracture of the knee. This typically involves separation of the tibial attachment of the ACL to variable degrees. Separation at the femoral attachment is rare 5.

It is more common in children than adults. It has been hypothesized that this may be due to the relative weakness of incompletely ossified bone relative to ligamentous fibers 7, or relatively increased elasticity of ligament in children 8.

They are usually caused by forceful hyperextension of the knee or by a direct blow over distal end of femur with the knee flexed.

A classification initially proposed by Meyers and McKeevers in 1959, later modified by Zaricznyj in 1977 6, is the most common system for describing ACL avulsion fracture.

Under the Meyers and McKeever system, injuries are classified into four main types:

  • type 1: minimally/nondisplaced fragment
  • type 2: anterior elevation of the fragment
  • type 3: complete separation of the fragment
    • type 3a: involves small portion of eminence
    • type 3b: involves the majority of the eminence
  • type 4: comminuted avulsion or a rotation of the fracture fragment

Depending on the type, a tibial avulsion is typically seen as a fracture fragment in variable orientation involving the tibial eminence. There may be anterior translation of the femur on the tibia on the lateral view.

Fractures
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Article information

rID: 37764
Synonyms or Alternate Spellings:
  • Anterior cruciate ligament bony avulsion fracture
  • ACL avulsion fracture
  • Bony ACL avulsion
  • ACL bony avulsion
  • ACL bony avulsion fracture
  • Tibial eminence avulsion fractures
  • Tibial eminence avulsion fracture

Cases and figures

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    Figure 1: classification - diagram
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    Case 1
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    Case 9
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