«Lesión de columna vertebral y médula en choques de automóvil: Una función del cambio en la velociadad y la disipación de energía en el impacto con respecto a la dirección del choque.»
Smith, Joyce A. MS; Siegel, John H. MD; Siddiqi, Shabana Q. MD
Objective: To examine the effect of change in velocity ([DELTA]V) and energy dissipation (IE) on impact, above and below the test levels for Federal MVC Safety Standards, on the incidence of spine fractures (SF), spinal cord injury (SCI)), SF mortality and the associated injury patterns in Frontal (F) and Lateral (L) MVCs. Comparison of 214 patients with SF or SCI with 938 patients who did not have SF or SCI.
Methods: 1152 MVC adult drivers or front-seat passengers (701 F & 451 L) evaluated at 10 Level I CIREN study Trauma Centers together with vehicle and crash scene engineering reconstruction. Patient seat belt (SB) and/or airbag (AB) use correlated with clinical, or autopsy findings.
Results: The relationship between [DELTA]V and IE rose exponentially as [DELTA]V increased. Of the 1152 patients, all with AIS>=3 injuries, there were 214 patients with spine fractures of AIS >=2. In FMVCs there were more SF patients with Cervical SF than in LMVCs (68F versus 64 L) and more Thoracic (35F versus 21L) and Lumbar (39F versus 16L) SF. However, the incidence of spinal cord injury was greatest in the Cervical SF (33%), compared with the Thoracic SF (18%), or Lumbar SF (2%). Most important, in FMVCs 49% of SF, 47% of SCI and 71% of the SF deaths (p < 0.05) occurred at > mean of 47.4 kph. In contrast, in LMVCs 51% of SF, 52% of SCI and 67% of the SF deaths occurred at [DELTA]V > mean of 35.3 kph. However, 80% of all deaths in SCI occurred in Cervical SF cases, in these 74% also had a brain injury. In contrast, the deaths in Thoracic SF were due to combinations of brain (45%), thorax (95%) or associated pelvic fracture injuries (50%). Airbag (AB), or Seat belt (SB) restraints appeared to protect FMVC SF patients from SCI at lower [DELTA]V, but 84% of Cervical SCI patients at [DELTA]V > 47 kph had AB protection and in a few cases the AB appeared responsible for the SCI. In contrast, 82% of Lumbar SF patients had SB, but in FMVCs where jackknifing due to backloading occurred, improper SB positioning may have contributed to the SF.
Conclusions: The implication for SCI in both front seat drivers and passengers in either FMVC or LMVC crashes above their respective [DELTA]V means is that improved spine fracture protection is necessary at higher [DELTA]V levels. More effective safety systems to prevent Cervical SCIs should be developed using two-level frontal and side AB & SB+pretensioner devices, which protect against SF at [DELTA]V both at and 1SD above the FMVC (47 & 72 kph = 30 & 45 mph) and LMVC (35 & 54 kph =22 & 34 mph) means.
Journal of Trauma-Injury Infection & Critical Care. 59(1):117-131, July 2005.