Eight whole fresh-frozen cadavers (6 female, 2 male) that were elderly and/or female were laterally impacted using UMTRI's dual-sled side-impact test facility. Cadavers were not excluded on the basis of old age or bone diseases that affect tolerance. A thinly padded, multi-segment impactor was used that independently measured force histories applied to the shoulder, thorax, abdomen, greater trochanter, iliac wing, and femur of each PMHS. Impactor plates were adjusted vertically and laterally toward the subject so that contact with body regions occurred simultaneously and so that each segment contacted the same region on every subject. This configuration minimized the effects of body shape on load sharing between regions.
Prior to all tests, cadavers were CT scanned to check for pre-existing skeletal injuries. Cadavers were excluded if they had pre-existing rib fractures or had undergone CPR. Cadavers were instrumented with strain gages at the posterolateral, lateral, and anterolateral portions of the struck-side ribs, and chestbands were positioned on the upper and lower thorax. Cadavers were first impacted at 3 m/s. If two or fewer rib fractures occurred, as determined using strain gage data and a post-test CT scan, a second impact was performed at 6 m/s on the contralateral side of the body.
Five of the eight 3-m/s tests produced AIS 3+ level injuries. All three of the 6-m/s tests produced AIS 3+ injury. Response corridors were developed for each body region using the Maltese alignment method with impulse-momentum normalization. Corridors describing upper and lower thorax deflection were generated from chestband data. An injury risk curve developed from the deflections associated with AIS 3+ injury associates a 50% probability of AIS 3+ rib fracture with 25.6% half-thorax deflection for the population used in this study.