Basilar, skull and facial fractures in 2nd 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(nd) row occupants by crash type. The study determined the rate of fractures in seriously injured (MAIS 3 + F) occupants to establish priorities for 2(nd) 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(nd) 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(nd) 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(nd) row occupants with skull fracture in rear impacts but only 20.3% in side impacts. Overall, basilar fractures occurred in 10.8% of 2(nd) 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(nd) row occupants, at 0.083% in rear and 0.044% in side impacts, they represent 53.9% of 2(nd) 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.