Airbag protection versus compartment intrusion effect determines the pattern of injuries in multiple trauma motor vehicle crashes

Objective: A prospective study of the interaction between airbag (AB) and seat-belt (Bt) protection versus vehicular compartment (VC) intrusion effects on injury patterns in motor vehicle crash (MVC) trauma patients. Methods: Two hundred MVC patients, nonejected drivers or front seat passengers with multiple trauma or severe lower extremity (LE) trauma admitted to two Level I trauma centers. Results: In frontal crashes, airbags (AB) more than Bt reduced Glasgow Coma Scale severity in brain injury, face fracture, shock, and the need for MVC extrication (all p < 0.05). Frontal AB also had a protective effect on LE fractures (41% vs. 66%, p < 0.01), but had no significant protective effect on pelvic fractures. When AB protection was present, it prevented brain and face fracture injuries caused by impact contacts and reduced the incidence of these injuries resulting from VC intrusions (p < 0.05). Thoracoabdominal injuries resulting from steering wheel intrusion showed AB protection against intrusions of twice the magnitude of those seen in non-AB vehicles (p < 0.05). In frontal MVCs, AB reduced LE fracture contact injuries but did not prevent LE fractures resulting from intrusions of instrument panel, toepan, or floor pedal structures. In lateral MVCs, Bt did not protect against brain, face, thorax, or pelvic injuries. Conclusion: Safety measures beyond frontal airbags must address frontal crash LE injuries induced by steering wheel, instrument panel, and toepan passenger compartment structure intrusions. Lateral crash injuries may profit from side AB supplemental restraint protection.