Jp. Albano et al., INJURY RISK FOR RESEARCH SUBJECTS WITH SPINA-BIFIDA OCCULTA IN A REPEATED IMPACT STUDY - A CASE REVIEW, Aviation, space, and environmental medicine, 67(8), 1996, pp. 767-769
Spina bifida occulta (SBO) occurs in 18-34% of the normal U.S. populat
ion. Recently, 16.5% of normal, asymptomatic male soldier volunteer ca
ndidates in a U.S. Army Aeromedical Research Laboratory ride motion st
udy were excluded from the study because they had SBO at one vertebral
level. Disqualifying this percentage of screened research subject can
didates threatened the timely completion of the schedule-intense proto
col. Although one study suggests that SBO at spinal level S1 has a hig
her incidence of posterior disc herniation, the preponderance of clini
cal literature reports that spina bifida occulta is not a medical prob
lem. The impact literature indicates that lumbosacral vertebral bodies
fracture at 7.14 kN in static compression and 20+ G during dynamic ve
rtical impacts. In this paper, we examined the human data observed in
ejection seat incidents, the rationale for excluding volunteers with s
ingle level SBO and the path of axial load transmission through the lu
mboscral spine. Based on the findings, we concluded that research volu
nteers with single level SBO are not at increased risk Tor injury and
recommended inclusion of these volunteers in future studies involving
repeated axial impacts due to ride motion.