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Load Sharing Classification Score of McCormack et al

Purpose: To evaluate a patient with a fracture involving the body of a thoracolumbar vertebra using the load bearing classification of McCormack et al.

Description

McCormack et al developed a score that reflects the load sharing in a fractured vertebral body. This can help identify a patient preoperatively who is likely to experience mechanical fracture of orthopedic screws used to stabilize the spine. The authors are from the University of Missouri-Columbia Medical Center.


Patient selection: 3 column fracture of the thoracolumbar spine

 

Outcome: fracture of stabilizing screws

 

Parameters:

(1) percent comminution of the vertebral body

(2) extent of apposition for the bone fragments on axial CT

(3) kyphotic correction in degrees in lateral radiographs

 

Parameter

Finding

Points

percent comminution

< 30% of the vertebral body

1

 

30 - 60%

2

 

> 60%

3

extent of apposition

minimal

1

 

>= 2 mm in < 50%

2

 

>= 2 mm in >= 50%

3

kyphotic correction

<= 3°

1

 

4 to 9°

2

 

>= 10°

3

 

total score =

= SUM(points for all 3 parameters)

 

Interpretation:

• minimum score: 3

• maximum score: 9

• The higher the score the more severe the fracture.

• A patient with a score <= 6 will probably not have a screw fracture.

• A patient with a score >= 7 is at risk for screw fracture.


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Specialty

Objective

ICD-10