Basilar, skull and facial fractures in 2 row occupants by crash type with a focus on side and rear impacts.

Objective: Field data was analyzed to assess the risk of basilar, skull and facial fractures in 2 row occupants by crash type. The study determined the rate of fractures in seriously injured (MAIS 3 + F) occupants to establish priorities for 2 row occupant safety.

Methods: Field accident data on seriously injured (MAIS 3+) occupants was determined using 1993-2015 NASS-CDS and 2017-19 CISS by crash type identified with damage area variables for non-ejected occupants in the 2 row. Occupants with serious head and face injuries (AIS 3+) were subdivided by fractures to the skull, basilar skull and face. Moderate-to serious (AIS 2+) orbit fractures were included. The rate of injury was determined. Individual electronic cases were analyzed for occupants with basilar fracture in rear and side impacts.

Results: The proportion of 2 row occupants with AIS 3+ head and face injury was highest at 73.7% in rear impacts followed by side impacts at 54.2% for those with MAIS 3 + F injury. Basilar fractures (AIS 3+) occurred in 53.9% of 2 row occupants with skull fracture in rear impacts but only 20.3% in side impacts. Overall, basilar fractures occurred in 10.8% of 2 row occupants with serious injury (MAIS 3 + F) in rear impacts and 2.7% in side impacts. The frequency of AIS 3+ facial fractures was highest in side impacts (40.2%) and lowest (7.6%) in rear impacts.

Conclusions: While basilar skull fractures are rare in 2 row occupants, at 0.083% in rear and 0.044% in side impacts, they represent 53.9% of 2 row occupants with a skull fracture and serious injury in rear impacts and 20.3% in side impacts. The mechanism of injury is different in rear and side impacts, but frequently involves multi-impact crashes, severe impacts, intrusion into the seating area and head impact on hard surfaces.