Causes of scapula fractures differ from other shoulder injuries in occupants seriously injured during motor vehicle crashes.

PURPOSE: Current motor vehicle safety systems primarily focus on preventing life-threatening and serious injury during crashes, but occupants may still sustain less serious injury. Upper extremity injury is common in occupants involved in motor vehicle crashes. The purpose of this study was to compare occupants with scapula fractures to occupants with other shoulder injuries.

METHODS: We used data from the Crash Injury Research and Engineering Network (CIREN) database (1997-2008) to compare two groups of occupants: (1) occupants with only scapula fractures and (2) occupants with shoulder injury not involving the scapula. We hypothesised that there were no differences in demographics, vehicle, crash characteristics and causes of shoulder injury in these two groups.

RESULTS: Of the 3370 occupants studied, 54 occupants (1.6%) had only a scapula fracture in the shoulder region and 342 (10.1%) occupants had other shoulder injuries. There were significant differences between gender, height and weight, maximum Abbreviated Injury Scale (AIS) severity and the crash type. Occupants with scapula fractures were 3 times more likely to be male (odds ratio (OR)=3.30) and were significantly taller and weighed more than occupants with other shoulder injuries. Occupants with other shoulder injuries had significantly greater injury severity (based on maximum AIS for any injury) than those with scapula fractures. There was a significant difference between scapula fractures and clavicle fractures (OR=1.87) and joint dislocations/separations (OR=2.79) comparing the cause of injury (vehicle side interior vs. other causes). Safety belts are the single most important safety system in motor vehicles and should always be worn. However, we found no differences in the cause of scapula fractures comparing occupants wearing their safety belt with those not wearing the belt.

CONCLUSION: This study provides information showing that scapula fractures occur during different types of impacts and have different causes other than shoulder injuries.