Michael T Prange

Duke University, Durham, NC, United States

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Publications (11)13.1 Total impact

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    ABSTRACT: Pediatric cervical spine biomechanics have been under-researched due to the limited availability of pediatric post-mortem human subjects (PMHS). Scaled data based on human adult and juvenile animal studies have been utilized to augment the limited pediatric PMHS data that exists. Despite these efforts, a significant void in pediatric cervical spine biomechanics remains. Eighteen PMHS osteoligamentous head-neck complexes ranging in age from 20 weeks gestational to 14 years were tested in tension. The tests were initially conducted on the whole cervical spine and then the spines were sectioned into three segments that included two lower cervical spine segments (C4-C5 and C6-C7) and one upper cervical spine segment (O-C2). After non-destructive tests were conducted, each segment was failed in tension. The tensile stiffness of the whole spines ranged from 5.3 to 70.1 N/mm. The perinatal and neonatal specimens had an ultimate strength for the upper cervical spine of 230.9 +/- 38.0 N and for the lower cervical spine of 212.8 +/- 60.9 and 187.1 +/- 39.4 N for the C4-C5 and C6-C7 segments, respectively. The lower cervical segments were significantly weaker and stiffer than the upper cervical spine segments in the older cohort. For the entire cohort of specimens, the stiffness of the upper cervical spine ranged from 7.1 to 199.0 N/mm. The tolerance ranged from 173.6 to 2960 N for the upper cervical spine and from 142 to 1757 N for the lower. There was a statistically significant increase in stiffness and strength with age. The results also suggest that juvenile animal surrogates estimate the stiffness of the human cervical spine fairly well; however, they may not provide accurate estimates of pediatric cervical spine strength.
    Stapp car crash journal 12/2008; 52:107-34.
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    ABSTRACT: New vehicle safety standards are designed to limit the amount of neck tension and extension seen by out-of-position motor vehicle occupants during airbag deployments. The criteria used to assess airbag injury risk are currently based on volunteer data and animal studies due to a lack of bending tolerance data for the adult cervical spine. This study provides quantitative data on the flexion-extension bending properties and strength on the male cervical spine, and tests the hypothesis that the male is stronger than the female in pure bending. An additional objective is to determine if there are significant differences in stiffness and strength between the male upper and lower cervical spine. Pure-moment flexibility and failure testing was conducted on 41 male spinal segments (O-C2, C4-C5, C6-C7) in a pure-moment test frame and the results were compared with a previous study of females. Failures were conducted at approximately 90 N-m/s. In extension, the male upper cervical spine (O-C2) fails at a moment of 49.5 (s.d. 17.6)N-m and at an angle of 42.4 degrees (s.d. 8.0 degrees). In flexion, the mean moment at failure is 39.0 (s.d. 6.3 degrees) N-m and an angle of 58.7 degrees (s.d. 5.1 degrees). The difference in strength between flexion and extension is not statistically significant. The difference in the angles is statistically significant. The upper cervical spine was significantly stronger than the lower cervical spine in both flexion and extension. The male upper cervical spine was significantly stiffer than the female and significantly stronger than the female in flexion. Odontoid fractures were the most common injury produced in extension, suggesting a tensile mechanism due to tensile loads in the odontoid ligamentous complex.
    Journal of Biomechanics 02/2007; 40(3):535-42. · 2.72 Impact Factor
  • Forensic Science International 01/2007; 164(2-3):278-9; author reply 282-3. · 2.31 Impact Factor
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    Qiliang Zhu, Michael Prange, Susan Margulies
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    ABSTRACT: The objective of this study was to utilize tissue deformation thresholds associated with acute axonal injury in the immature brain to predict the duration of unconsciousness. Ten anesthetized 3- to 5-day-old piglets were subjected to nonimpact axial rotations (110-260 rad/s) producing graded injury, with periods of unconsciousness from 0 to 80 min. Coronal sections of the perfusion-fixed brain were immunostained with neurofilament antibody (NF-68) and examined microscopically to identify regions of swollen axons and terminal retraction balls. Each experiment was simulated with a finite element computational model of the piglet brain and the recorded head velocity traces to estimate the local tissue deformation (strain), the strain rate and their product. Using thresholds associated with 50, 80 and 90% probability of axonal injury, white matter regions experiencing suprathreshold responses were determined and expressed as a fraction of the total white matter volume. These volume fractions were then correlated with the duration of unconsciousness, assuming a linear relationship. The thresholds for 80 and 90% probability of predicting injury were found to correlate better with injury severity than those for 50%, and the product of strain and strain rate was the best predictor of injury severity (p=0.02). Predictive capacity of the linear relationship was confirmed with additional (n=13) animal experiments. We conclude that the suprathreshold injured volume can provide a satisfactory prediction of injury severity in the immature brain.
    Developmental Neuroscience 02/2006; 28(4-5):388-95. · 3.41 Impact Factor
  • Journal of Biomechanics - J BIOMECH. 01/2006; 39.
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    ABSTRACT: The adult head has been studied extensively and computationally modeled for impact, however there have been few studies that attempt to quantify the mechanical properties of the pediatric skull. Likewise, little documentation of pediatric anthropometry exists. We hypothesize that the properties of the human pediatric skull differ from the human adult skull and exhibit viscoelastic structural properties. Quasi-static and dynamic compression tests were performed using the whole head of three human neonate specimens (ages 1 to 11 days old). Whole head compression tests were performed in a MTS servo-hydraulic actuator. Testing was conducted using nondestructive quasi-static, and constant velocity protocols in the anterior-posterior and right-left directions. In addition, the pediatric head specimens were dropped from 15cm and 30cm and impact force-time histories were measured for five different locations: vertex, occiput, forehead, right and left parietal region. The compression stiffness values increased with an increase in velocity but were not significantly different between the anterior-posterior and right-left directions. Peak head acceleration during the head impact tests did not significantly vary between the five different impact locations. A three parameter model that included damping represented the pediatric head impact data more accurately than a simple mass-spring system. The compressive and impact stiffness of the pediatric heads were significantly more compliant than published adult values. Also, infant head dimensions, center of gravity and moment of inertia (Iyy) were determined. The CRABI 6-month dummy impact response was similar to the infant cadaver for impacts to the vertex, occiput, and forehead but dramatically stiffer in lateral impacts. These pediatric head anthropomorphic, compression, and impact data will provide a basis to validate whole head models and compare with ATD performance in similar exposures.
    Stapp car crash journal 12/2004; 48:279-99.
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    ABSTRACT: Rotational loading conditions have been shown to produce subdural hemorrhage and diffuse axonal injury. No experimental data are available with which to compare the rotational response of the head of an infant during accidental and inflicted head injuries. The authors sought to compare rotational deceleration sustained by the head among free falls, from different heights onto different surfaces, with those sustained during shaking and inflicted impact. An anthropomorphic surrogate of a 1.5-month-old human infant was constructed and used to simulate falls from 0.3 m (1 ft), 0.9 m (3 ft), and 1.5 m (5 ft), as well as vigorous shaking and inflicted head impact. During falls, the surrogate experienced occipital contact against a concrete surface, carpet pad, or foam mattress. For shakes, investigators repeatedly shook the surrogate in an anteroposterior plane; inflicted impact was defined as the terminal portion of a vigorous shake, in which the surrogate's occiput made contact with a rigid or padded surface. Rotational velocity was recorded directly and the maximum (peak-peak) change in angular velocity (delta theta(max)) and the peak angular acceleration (theta(max)) were calculated. Analysis of variance revealed significant increases in the delta theta(max) and theta(max) associated with falls onto harder surfaces and from higher heights. During inflicted impacts against rigid surfaces, the delta theta(max) and theta(max) were significantly greater than those measured under all other conditions. Vigorous shakes of this infant model produced rotational responses similar to those resulting from minor falls, but inflicted impacts produced responses that were significantly higher than even a 1.5-m fall onto concrete. Because larger accelerations are associated with an increasing likelihood of injury, the findings indicate that inflicted impacts against hard surfaces are more likely to be associated with inertial brain injuries than falls from a height less than 1.5 m or from shaking.
    Journal of Neurosurgery 08/2003; 99(1):143-50. · 3.15 Impact Factor
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    Michael T Prange, Susan S Margulies
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    ABSTRACT: The large strain mechanical properties of adult porcine gray and white matter brain tissues were measured in shear and confirmed in compression. Consistent with local neuroarchitecture, gray matter showed the least amount of anisotropy, and corpus callosum exhibited the greatest degree of anisotropy. Mean regional properties were significantly distinct, demonstrating that brain tissue is inhomogeneous. Fresh adult human brain tissue properties were slightly stiffer than adult porcine properties but considerably less stiff than the human autopsy data in the literature. Mixed porcine gray/white matter samples were obtained from animals at "infant" and "toddler" stages of neurological development, and shear properties compared to those in the adult. Only the infant properties were significantly different (stiffer) from the adult.
    Journal of Biomechanical Engineering 05/2002; 124(2):244-52. · 1.52 Impact Factor
  • M T Prange, D F Meaney, S S Margulies
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    ABSTRACT: No regional or directional large-deformation constitutive data for brain exist in the current literature. To address this deficiency, the large strain (up to 50%) directional properties of gray and white matter were determined in the thalamus, corona radiata, and corpus callosum. The constitutive relationships of all regions and directions are well fit by an Ogden hyperelastic relationship, modified to include dissipation. The material parameter alpha, representing the non-linearity of the tissue, was not significantly sensitive to region, direction, or species. The average value of the material parameter mu, corresponding to the shear modulus of the tissue, was significantly different for each region, demonstrating that brain tissue is inhomogeneous. In each region, mu, obtained in 2 orthogonal directions, was compared. Consistent with local neuroarchitecture, gray matter showed the least amount of anisotropy and corpus callosum exhibited the greatest degree of anisotropy. Finally, human temporal lobe gray matter properties were determined and compared to porcine thalamic properties. The results show significant regional inhomogeneity at large strains and significant anisotropy in each region tested. The extent of regional anisotropy correlated with the degree of alignment in the local neuroarchitecture. These large strain, regional and directional data should enhance the biofidelity of computational models and provide important information regarding the mechanisms of traumatic brain injury.
    Stapp car crash journal 12/2000; 44:205-13.
  • M. T. Prange, S. S. Margulies
  • M. T. Prange, S. S. Margulies

Publication Stats

353 Citations
13.10 Total Impact Points

Institutions

  • 2004–2008
    • Duke University
      • Department of Biomedical Engineering (BME)
      Durham, NC, United States
  • 2007
    • Duke University Medical Center
      • Department of Orthopaedic Surgery
      Durham, NC, United States
  • 2000–2003
    • University of Pennsylvania
      • Department of Bioengineering
      Philadelphia, PA, United States