Oblique and lateral impact response of the PMHS thorax.

This study characterizes the PMHS thoracic response to blunt impact in oblique and lateral directions. A significant amount of data has been collected from lateral impacts conducted on human cadavers. Substantially less data has been collected from impacts that are anterior of lateral in an oblique direction. In the past, data collected from the handful of oblique impact studies were considered to be similar enough to the data from purely lateral impacts such that the oblique data were combined with data from lateral impacts. Defining the biomechanical response of the PMHS thorax to oblique impact is of great importance in side impact vehicle crashes where the loading is often anterior-oblique in direction. Data in this study was obtained from a chestband placed on the thorax at the level of impact to measure thoracic deflection. Two low energy impacts were conducted on each of seven subjects at 2.5 m/s, with one lateral impact and one oblique impact to opposite sides of each PMHS. Data was normalized using the Mertz-Viano method for a two mass system to allow for inter-subject comparisons. Force versus deflection response corridors were generated for the two impact types using an objective mathematical approach and compared to one another. Results were also compared to existing data for oblique and lateral thoracic impacts. The oblique thoracic response in low speed pendulum impacts was found to be different than the lateral thoracic response, in terms of force and deflection. Specifically, the lateral force was greater than the oblique force, and oblique deflection greater than lateral deflection for equal energy impacts.

Shoulder impact response and injury due to lateral and oblique loading.

Little is known about the response of the shoulder complex due to lateral and oblique loading. Increasing this knowledge of shoulder response due to these types of loading could aid in improving the biofidelity of the shoulder mechanisms of anthropomorphic test devices (ATDs). The first objective of this study was to define force versus deflection corridors for the shoulder corresponding to both lateral and oblique loading. A second focus of the shoulder research was to study the differences in potential injury between oblique and lateral loading. These objectives were carried out by combining previously published lateral impact data from 24 tests along with 14 additional recently completed lateral and oblique tests. The newly completed tests utilized a pneumatic ram to impact the shoulder of approximately fiftieth percentile sized cadavers at the level of the glenohumeral joint with a constant speed of approximately 4.4 m/sec. Of the 14 tests, four of them were conducted lateral to the shoulder along the subject's y-axis, four of them were conducted 15 anterior to this axis, and six were conducted 30 anterior to the subject's y-axis. As in the previous testing, the first thoracic vertebrae and both shoulders of the subject were instrumented with tri-axial linear accelerometers on the sternum, clavicle, acromion process, and inferior angle of the scapula. The impacting mass was instrumented with an accelerometer and displacement transducer. In addition to this instrumentation, the tests were documented by high-speed digital imagery. Radiographs (x-rays), magnetic resonance images (MRIs), and autopsies were used to document injury to the subjects. The results from the tests revealed differences between the stiffness of the shoulder when loaded laterally to that when it is loaded obliquely. The shoulder was found to deflect twice as much medially when loaded obliquely then when it is loaded laterally. This can be attributed to the ability of the scapula to slide posteriorly around the thoracic cage. The ability of the shoulder to displace medially while simultaneously deflecting posteriorly in oblique impact is important to replicate in the ATDs because it results in the load being transmitted to the upper thoracic cage.