A new biomechanically-based criterion for lateral skull fracture.

This work develops a skull fracture criterion for lateral impact-induced head injury using postmortem human subject tests, anatomical test device measurements, statistical analyses, and finite element modeling. It is shown that skull fracture correlates with the tensile strain in the compact tables of the cranial bone as calculated by the finite element model and that the Skull Fracture Correlate (SFC), the average acceleration over the HIC time interval, is the best predictor of skull fracture. For 15% or less probability of skull fracture the lateral skull fracture criterion is SFC < 120 g, which is the same as the frontal criterion derived earlier.

Response corridors of the human head-neck complex in rear impact.

In recent years, anatomically accurate dummies were developed to produce a more biofidelic response to rear impacts. The detailed dummy geometry permits more comprehensive kinematic validation, which is typically accomplished through response corridors developed using human volunteers and cadavers. In the present investigation, ten intact head-neck cadaver specimens were subjected to 1.

Gender- and region-dependent local facet joint kinematics in rear impact: implications in whiplash injury.

Study Design: Localized facet joint kinematics resulting from whiplash acceleration were analyzed in the dynamic domain during the time of cervical S-curvature using intact head and neck specimens and a pendulum mini-sled loading apparatus.

Objectives: To determine the effects of gender, impact severity, cervical level, and anatomic joint region on shear and distraction motion of lower cervical facet joints.

Summary Of Background Data: Clinical and experimental studies identify cervical facet joints to be a likely location of whiplash injury.

Validation of a head-neck computer model for whiplash simulation.

A head-neck computer model was comprehensively validated over a range of rear-impact velocities using experiments conducted by the same group of authors in the same laboratory. Validations were based on mean +/- 1 standard deviation response curves, i.e.

Influence of muscle contraction on whiplash kinematics.

It is unclear whether reflexive muscle contraction in unaware occupants can alter spinal kinematics to mitigate injury in the unaware occupant subjected to whiplash loading. Whiplash injury likely occurs during the non-physiologic S-curvature phase of spinal kinematics, present during the first 100 msec after the initiation of T1 acceleration. Experimental investigations using human volunteers have reported 45 to 60 msec delays prior to electrical activity of the sternocleidomastoid.

Biomechanics of temporo-parietal skull fracture.

Unlabelled: This paper presents an analysis of research on the biomechanics of head injury with an emphasis on the tolerance of the skull to lateral impacts. The anatomy of this region of the skull is briefly described from a biomechanical perspective. Human cadaver investigations using unembalmed and embalmed and intact and isolated specimens subjected to static and various types of dynamic loading (e.

Rear impact responses of different sized adult Hybrid III dummies.

Rear impact sled tests were conducted using 5th, 50th, and 95th percentile Hybrid III dummies to evaluate proposed injury criteria. Different head restraint height (750, 800 mm) and backset (0, 50, 100 mm) positions were used to determine axial and shear forces, bending moments, and injury criteria (NIC, N(ij), and N(km)). The time sequence to attain each parameter was also determined.

Exposure to pulsed magnetic fields enhances motor recovery in cats after spinal cord injury.

Study Design: Animal model study of eight healthy commercial cats was conducted.

Objective: To determine whether pulsed electromagnetic field (PMF) stimulation results in improvement of function after contusive spinal cord injury in cats.

Summary Of Background Data: PMF stimulation has been shown to enhance nerve growth, regeneration, and functional recovery of peripheral nerves.

Anatomic study of the morphology of human cervical facet joint.

Study Design: Geometrical properties of the facet joint including cartilage thickness and gap were obtained using human cadaver cervical spinal columns and cryomicrotomy techniques.

Objectives: To determine the existence of level or gender dependency on facet joint morphology in the human cervical spine.

Background Data: Although measurements of the human cervical spine have been reported in literature, to the best of knowledge of the authors, geometrical data on the facet joint structures such as the cartilage are not available.

Statistically and biomechanically based criterion for impact-induced skull fracture.

This work developed a skull fracture criterion for impact-induced head injury, using post mortem human subject tests, anatomical test device measurements, statistical analyses, and finite element modeling. It is shown that skull fracture correlates with the tensile strain in the outer table of the cranial bone, and an index termed the Skull Fracture Correlate (SFC) predicts injury. SFC offers several advantages as a protection criterion.

Gender dependent cervical spine segmental kinematics during whiplash.

Clinical and epidemiological studies have frequently reported that female occupants sustain whiplash injuries more often than males. The current study was based on the hypothesis that segmental level-by-level cervical intervertebral motions in females are greater than in males during rear impact. The hypothesis was tested by subjecting 10 intact human cadaver head-neck complexes (five males, five females) to rear impact loading.

Kinetics of the head-neck complex in low-speed rear impact.

A comprehensive characterization of the biomechanics of the cervical spine in rear impact will lead to an understanding of the mechanisms of whiplash injury. Cervical kinematics have been experimentally described using human volunteers, full-body cadaver specimens, and isolated and intact head-neck specimens. However, forces and moments at the cervico-thoracic junction have not been clearly delineated.

Biophysics of cochlear implant/MRI interactions emphasizing bone biomechanical properties.

Objective/hypothesis: The forces exerted during a 1.5-Tesla MRI evaluation on the internal magnet of a cochlear implant (CI) raise concern about the safety for CI recipients. This study determines the magnitude of force required to fracture the floor of a CI receiver bed.

Small female and large male responses in rear impact.

The objective of this study was to conduct rear impact sled tests using 5(th), 50(th), and 95(th) percentile Hybrid III dummies and evaluate proposed injury criteria. Head restraint positions of differing height (750, 800 mm) and backset (0, 50, 100 mm) were used to determine axial and shear forces, bending moments, and injury criteria (NIC, N(ij), and N(km)). The time sequence to attain each parameter was also determined.

Biomechanical analyses of whiplash injuries using an experimental model.

Neck pain and headaches are the two most common symptoms of whiplash. The working hypothesis is that pain originates from excessive motions in the upper and lower cervical segments. The research design used an intact human cadaver head-neck complex as an experimental model.

Preinjury cervical alignment affecting spinal trauma.

Object: The authors tested the hypothesis that initial alignment of the head-neck complex affects cervical spine injury mechanism, trauma rating, injury classification based on stability, and fracture pattern.

Methods: Thirty intact human cadaveric head-neck complexes were prepared by fixing the thoracic end in polymethylmethacrylate. The cranium was unconstrained.

Intervertebral rotations as a function of rear impact loading.

Rear impact loading of the cervical spine results in a complicated biomechanical problem due to the complex geometry and viscoclastic material properties of this anatomy. Although a number of investigations have been performed to understand the biomechanics of rear impact, the dependence of segmental kinematics on cervical level and input velocity has not been clearly outlined. An experimental investigation was performed for this purpose using 10 isolated head-neck specimens.

Orbital blowout fractures: experimental evidence for the pure hydraulic theory.

Background: The mechanism of injury and the underlying biomechanics of orbital blowout fractures remain controversial. The "hydraulic" theory proposes that a generalized increased orbital content pressure results in direct compression and fracturing of the thin orbital bone.

Objective: To examine the pure hydraulic mechanism of injury by eliminating the factor of globe-to-wall contact and its possible contribution to fracture thresholds and patterns.

Whiplash injury determination with conventional spine imaging and cryomicrotomy.

Study Design: Soft tissue-related injuries to the cervical spine structures were produced by use of intact entire human cadavers undergoing rear-end impacts. Radiography, computed tomography, and cryomicrotomy techniques were used to evaluate the injury.

Objectives: To replicate soft tissue injuries resulting from single input of whiplash acceleration to whole human cadavers simulating vehicular rear impacts, and to assess the ability of different modes of imaging to visualize soft tissue cervical lesions.

Experimental trauma to the malar eminence: fracture biomechanics and injury patterns.

Objectives: To document patterns of facial fractures after trauma to the malar eminence and to elucidate biomechanical factors relevant to the injury patterns.

Study Design And Setting: Studies were conducted on 14 cadaver heads. Study variables included impact velocity, contact area, impact force, and zygomatic skin thickness.

Contribution of disc degeneration to osteophyte formation in the cervical spine: a biomechanical investigation.

Cervical spine disorders such as spondylotic radiculopathy and myelopathy are often related to osteophyte formation. Bone remodeling experimental-analytical studies have correlated biomechanical responses such as stress and strain energy density to the formation of bony outgrowth. Using these responses of the spinal components, the present study was conducted to investigate the basis for the occurrence of disc-related pathological conditions.

Patterns of abdominal injuries in frontal and side impacts.

Public awareness for safety and vehicle improvements has contributed to significant reduction in injuries secondary to motor vehicle crashes. The spectrum of trauma has shifted from one region of the body to another with varying consequences. For example, airbags have minimized head and neck injuries for adults while emphasizing the lower regions of the human body.

Airbag effectiveness on brain trauma in frontal crashes.

The purpose of this study was to evaluate the effectiveness of frontal restraint systems in reducing the potential for head injuries, specifically brain injuries and skull fractures. The US DOT NASS database files from 1991-1998 were evaluated for drivers and right front seat occupants in frontal crashes. Of the total driver and right front seat occupants in this data set, 3.

Biomechanics of calcaneal fractures: a model for the motor vehicle.

Changes in legislation, availability of passive or active restraint systems, or both, together with increased public awareness for safety and the need for use of restraint, have shifted the spectrum of trauma in motor vehicle crashes from the head and torso to other regions. Lower extremity trauma in motor vehicle crashes continues to be a significant problem. The objective of this study was to investigate the biomechanics of the human foot and ankle complex under impact loading and replicate calcaneal fractures routinely seen in motor vehicle crashes.

Biomechanics of abdominal injuries.

Although considerable efforts have been advanced to investigate the biomechanical aspects of abdominal injuries, reviews have been very limited. The purpose of this article is to present a comprehensive review of the topic. Traumatic abdominal injuries occur due to penetrating or blunt loading.