BACKGROUND: The Abbreviated Injury Scale (AIS) is an anatomical-based coding 
system created by the Association for the Advancement of Automotive Medicine, 
utilized to classify and code injuries resulting from trauma, in order of 
severity. According to the latest version, all Thoraco-Lumbar Compression 
Fractures (TLCF), even without injury to other spine components and with >20% 
loss of height, were branded AIS 3 injuries, reflecting a serious threat to life 
or permanent disability. Advances in spine imaging, recent biomechanical 
studies, and long-term outcomes research offer the opportunity to consider these 
injuries differently.
OBJECTIVE: To re-evaluate the percent compression threshold of TLCF of the spine 
from motor vehicle crashes (MVC) for serious risk to life identified as surgical 
treatment, delineating a reliable cut-off for fracture severity and morbidity. 
Little national data considers degree of compression and provides adequate 
followup imaging to determine degree of compression, justifying this effort.
METHODS: Charts and radiographs of patients admitted to our institution due to 
vehicle crashes with isolated (vertebral body only) TLCF between 2008 and 2015 
were reviewed. Data were collected on degree of compression, treatment, and 
long-term outcomes to determine the threshold of permanent injury. Vertebral 
bodies at the level of fracture were measured both anteriorly and posteriorly, 
and compared to adjacent segments; percentage compression was calculated.
RESULTS: 1470 patient records with diagnoses of spine trauma were reviewed; 695 
isolated compression fractures were identified, of which 194 were in vehicle 
crashes and had adequate imaging and follow-up. Ages ranged from 19 to 82, with 
a male: female ratio of 60:40. No patient with vertebral body compression of 
less than 30% underwent surgery unless presenting with a neurological deficit. 
All 22 surgical patients demonstrated significant retropulsion of bone into the 
spinal canal. Five surgical patients suffered eight complications; there were no 
adverse outcomes in the nonsurgical group.
CONCLUSIONS: These results are consistent with evolving clinical thinking, 
resulting in decreasing surgical incidence and orthosis use. Our data strongly 
suggests that isolated compression fractures in the absence of neurologic 
deficit or severe cord compression due to retropulsed bone are self-limiting. 
Therefore, the AIS scores for these common injuries could be reconsidered and 
reflect their relatively benign outlook.