Which Thoracolumbar AO fracture subtype MRI would have the highest chance to change decision-making?
The impact of MRI in decision-making depends on the neurological status, degree of bony instability, and posterior ligamentous status.
In neurologically intact patients, the impact of MRI depends on the chance of MRI changing PLC status vs. bony instability.
In A4 fractures there is a higher chance of MRI changing the PLC status but the impact on decision making is less because of the higher degree of bony instability which can independently predict the need for surgery.
In A3 because there is less degree of bony instability any change in PLC status would be translated into a change in surgical decision making.
A3 and a4 fractures in neuro intact patients may be classified as B2 injuries and change initial treatment. I think for A3 and A4 when considering non operative management an Mri is highly recommended.
Dr. Joaquim I entirely agree with your answer!
In addition, A4 fractures have a higher incidence to change the classification after MRI than A3. But when it comes to change decisions A3 are more likely to change decisions because they are usually treated conservatively based on their mild bony instability. In contrast, A4 is more likely to be treated surgically regardless.
the M1 modifier as defined by a single positive CT finding helps to assess the CHANCE OF MRI CHANGING THE CLASSIFICATION AND need for MRI.
A3M0 the chance of MRI changing classification is 0% compared to 20% for A3M1. A4M0 the chance of changing classification is 7% compared to 32% for A4M1.
The absence of M1 ( M0, negative CT) is very reassuring that MRI is not needed esp for A3. M1is an indication for MRI. Please note that Vertical laminar fractures and facet joint widening are not counted as positive CT findings as they lack independent association with PLC injury in MRI. THESE 2 SIGNS ARE COMMON IN A4 fractures and are responsible for a great deal of confusion!