A Three-Dimensional Head-Neck Model: Validation for Frontal and Lateral Impacts

1994 ◽  
Author(s):  
M. de Jager ◽  
A. Sauren ◽  
J. Thunnissen ◽  
J. Wismans
Keyword(s):  
Model Validation ◽  
Three Dimensional ◽  
Head Neck

scholarly journals Frequency spectrum of the human head–neck to mechanical vibrations

2017 ◽  
Vol 37 (3) ◽  
pp. 611-618 ◽  
Author(s):  
Bin Yang ◽  
Zheng Shi ◽  
Qun Wang ◽  
Feng Xiao ◽  
Tong-Tong Gu ◽  
...  
Keyword(s):  
Finite Element ◽  
Frequency Spectrum ◽  
Mechanical Vibration ◽  
Three Dimensional ◽  
Human Head ◽  
Element Model ◽  
Mode Shapes ◽  
Joint Disorder ◽  
Biomechanical Responses ◽  
Head Neck

This study is based on a real finite element human head–neck model and concentrates on its numerical vibration characteristic. Frequency spectrum and mode shapes of the finite element model of human head–neck under mechanical vibration have been calculated. These vibration characteristics are in good agreement with the previous studies. The simulated fundamental frequency of 35.25 Hz is fairly similar to the published documents, and rarely reported modal responses such as “mastication” and flipping of nasal lateral cartilages modes, however, are introduced by our three-dimensional modal analysis. These additional modes may be of interest to surgeons or clinicians who are specialized in temporomandibular or rhinoplasty joint disorder. Modal validation in terms of modal shapes proposes a necessity for elaborate modeling to identify each individual part’s extra frequencies. Furthermore, it also studies the influence of damping on resonant frequencies and biomechanical responses. It is discovered that damping has an inverse proportionality between damping effect on natural frequency and that on biomechanical responses.

scholarly journals Standard Radiographic Assessment of Femoral Cam Morphology is Influenced by Neck-Shaft Angle and Femoral Version

2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0039
Author(s):  
Layla Haidar ◽  
Ryan Warth ◽  
Erinn Pemberton Annie Waite ◽  
Alfred Mansour
Keyword(s):  
Femoral Head ◽  
Alpha Angle ◽  
Three Dimensional ◽  
Neck Shaft Angle ◽  
Incremental Change ◽  
Observer Reliability ◽  
Angle Measurements ◽  
Femoral Version ◽  
Shaft Angle ◽  
Head Neck

Objectives: Cam-type femoroacetabular impingement (FAI) is a three-dimensional (3D) deformity that is still difficult to assess using traditional two-dimensional (2D) radiographic views. While measurements of alpha angle and head-neck offset are used to estimate the likelihood of actual impingement, these 2D measurements do not account for z-axis variations in femoral version (FV) and neck-shaft angle (NSA). The purpose of this qualitative proof-of-concept study was to evaluate the potential variation in alpha angle and neck-shaft offset measurements with incremental changes in NSA and FV by simulating traditional radiographic views with software-generated Digitally-Reconstructed Radiographs (DRRs). We hypothesize that incremental changes in hip morphology will produce qualitative changes in alpha angle and neck-shaft offset. Methods: 3D-CT reconstruction images were obtained from one subject with symptomatic cam-type FAI. The 3D reconstruction was cleaned to include only the femoral head, neck and subtrochanteric region along with the ipsilateral hemipelvis. Using 3D medical image processing software (Mimics; Materialise, Inc.; Belgium), the pre-processed 3D model was manipulated in a standardized manner to simulate 5-degree incremental variations in FV and NSA (-15 degrees to +15 degrees for FV; -15 degrees to +10 degrees for NSA). Negative FV reflected external rotation of the femoral head-neck unit, whereas negative NSA reflected abduction of the femoral head-neck unit. Each modified 3D model was then used to generate DRRs corresponding to traditional 2D radiographic views used for assessment of cam-FAI (Anteroposterior [AP], False Profile [FP]), Cross Table Lateral [CTL], Frog Leg Lateral [FLL], 45- and 90-degree Dunn [45D and 90D, respectively]. Alpha angle and head-neck offset were measured on each radiographic view corresponding to each incremental change in FV and NSA. All measurements utilized the perfect circle technique and were made by two independent observers for assessment of inter-observer reliability. Two-way random effects ANOVA was used for statistical assessment of inter-observer reliability and reported as intra-class correlation coefficients (κ). Comparisons between groups were performed using two-tailed paired t-tests assuming unequal variance. P-values less than 0.05 were considered statistically significant. Results: Inter-observer reliability (κ) for head-neck offset and alpha angles were 0.46 (fair) and 0.88 (excellent), respectively. Variations in head-neck offset and alpha angle with incremental variations in FV and NSA are summarized in Figure 1. There were statistically significant changes in mean alpha angles when the NSA was adjusted from Neutral to -5 degrees (p=0.01) and from -5 degrees to -10 degrees (p<0.001). There were no statistically significant differences in alpha angles or head-neck offsets between each incremental change in FV (p<0.05). Alpha angle measurements were significantly more variable than head-neck offset measurements for all variations in FV (p<0.001) and NSA (p=0.02) (Figure 2). Conclusion: Two-dimensional evaluation of three-dimensional Cam morphology (alpha angle and head-neck offset) was found to be significantly affected by alterations in femoral version and head-neck offset. Head-neck offset measurements were significantly less variable than alpha angle measurements across all FVs and NSAs within each radiographic view. Future work should be done to develop standardized procedures for routine 3D radiographic assessment of cam-type FAI. [Figure: see text][Figure: see text]

The Surgical Workstation: Surgical Planning Using Generic Software

1993 ◽  
Vol 109 (3) ◽  
pp. 434-440 ◽  
Author(s):  
David A. Wiegand ◽  
Robert B. Page ◽  
David S. Channin
Keyword(s):  
Medical Image ◽  
Surgical Planning ◽  
Medical Image Analysis ◽  
Three Dimensional ◽  
Computer Software ◽  
Medical Image Processing ◽  
Imaging Systems ◽  
Computed Tomography Scans ◽  
Further Development ◽  
Head Neck

Computer software for rendering and display of three-dimensional data is becoming readily available for all types of computers. Such programs typically accept data from any source, compute a three-dimensional volume of data, and display it with a variety of rendering options. Although not specifically designed for medical image processing, these programs can provide very detailed and finely rendered images that are useful for surgical planning. We use one such program to display data from standard computed tomography scans, which gives us a photorealistic three-dimensional view of patient anatomy. This view can be modified to render tissues transparent, translucent, or opaque, and thus allows the surgeon to selectively enhance bony architecture, tumors, or other details. Images can be rotated, sliced, and displayed in the surgical position. Image animation can be added to facilitate the display of complex anatomic relationships. Our experience with this technology suggests that such programs can provide the basis for personal surgical workstations for medical image analysis and surgical planning. Further development of such generic imaging systems should allow this useful technology to become widely available for surgical planning and education. We discuss our experience with a typical generic imaging workstation. (OTOLARYNGOL HEAD NECK SURG 1993;109:434-40.)

scholarly journals DebrisInterMixing-2.3: a finite volume solver for three-dimensional debris-flow simulations with two calibration parameters – Part 2: Model validation

2017 ◽  
Author(s):  
Albrecht v. Boetticher ◽  
Jens M. Turowski ◽  
Brian W. McArdell ◽  
Dieter Rickenmann ◽  
Marcel Hürlimann ◽  
...  
Keyword(s):  
Debris Flow ◽  
Model Validation ◽  
Material Properties ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Clay Content ◽  
Friction Angle ◽  
Angle Of Repose ◽  
Model Parameters

Abstract. Here we present validation tests of the fluid dynamic solver presented in in v. Boetticher et al. (2016), simulating both laboratory-scale and large-scale debris-flow experiments. The new solver combines a Coulomb viscosplastic rheological model with a Herschel-Bulkley model based on material properties and rheological characteristics of the analysed debris flow. For the selected experiments in this study, all necessary material properties were known – the content of sand, clay (including its mineral composition) and gravel (including its friction angle) as well as the water content. We show that given these measured properties, two model parameters are sufficient for calibration, and a range of experiments with different material compositions can be reproduced by the model without recalibration. One calibration parameter, the Herschel–Bulkley exponent, was kept constant for all simulations. The model validation focuses on different case studies illustrating the sensitivity of debris flows to water and clay content, channel curvature, channel roughness and the angle of repose. We characterize the accuracy of the model using experimental observations of flow head positions, front velocities, run-out patterns and basal pressures.

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