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Astrologo AN, Nano S, Klemm EM, Shefelbine SJ, Dennerlein JT. Determining the effects of AR/VR HMD design parameters (mass and inertia) on cervical spine joint torques. Appl Ergon 2024; 116:104183. [PMID: 38071785 DOI: 10.1016/j.apergo.2023.104183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 10/01/2023] [Accepted: 11/19/2023] [Indexed: 01/16/2024]
Abstract
This study aimed to determine gravitational and dynamic torques and muscle activity of the neck across a series of design parameters of head mounted displays (mass, center of mass, and counterweights) associated with virtual and augmented reality (VR/AR). Twenty young adult participants completed five movement types (Slow and Fast Flexion/Extension and Rotation, and Search) while wearing a custom-designed prototype headset that varied the three design parameters: display mass (0, 200, 500, and 750 g), distance of the display's center of mass in front of the eyes (approximately 1, 3, and 5 cm anteriorly), and counterweights of 0, 166, 332, and 500 g to balance the display mass of 500 g at 7 cm. Inverse dynamics of a link segment model of the head and headset provided estimates of the torques about the joint between the skull and the occiput-first cervical vertebrae (OC1) and joint between the C7 and T1 vertebrae (C7). Surface electromyography (EMG) measured bilateral muscle activity of the splenius and upper trapezius muscles. Adding 750 g of display mass nearly doubled root mean square joint torques across all movement types. Increasing the distance of the display mass in front of the eyes by 4 cm increased torques about OC1 for the Slow and Fast Rotation and Search movements by approximately 20%. Adding a counterweight decreased torques about OC1 during the rotation and search tasks but did not decrease the torques experienced in the lower cervical spine (C7). For the flexion/extension axis, the magnitude of the dynamic torque component was 20% or less of the total torque experienced whereas for the rotation axis the magnitude of the dynamic torque component was greater than 50% of the total torque. Surface EMG root mean square values significantly varied across movement types with the fast rotation having the largest values; however, they did not vary significantly across the headset configurations.
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Affiliation(s)
| | - Sarah Nano
- Department of Bioengineering, Northeastern University, Boston, MA, USA
| | - Elizabeth M Klemm
- Department of Bioengineering, Northeastern University, Boston, MA, USA
| | - Sandra J Shefelbine
- Department of Bioengineering, Northeastern University, Boston, MA, USA; Department of Mechanical & Industrial Engineering, Northeastern University, Boston, MA, USA
| | - Jack T Dennerlein
- Sargent College of Health and Rehabilitation Sciences, Boston University, Boston, MA, USA.
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Ovsepyan AL, Smirnov AA, Pustozerov EA, Mokhov DE, Mokhova ES, Trunin EM, Dydykin SS, Vasil'ev YL, Yakovlev EV, Budday S, Paulsen F, Zhivolupov SA, Starchik DA. Biomechanical analysis of the cervical spine segment as a method for studying the functional and dynamic anatomy of the human neck. Ann Anat 2021; 240:151856. [PMID: 34793958 DOI: 10.1016/j.aanat.2021.151856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 10/11/2021] [Accepted: 11/05/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Traditionally, dynamic and functional anatomy, in particular the dynamic anatomy of the neck, is studied on cadaveric material. However, the development of in vivo visualization technologies and in silico modeling has made it possible to expand these possibilities. Despite significant progress in the study of dynamic and functional anatomy of the neck by means of in silico methods, the issues of validating the developed models and taking into account the pronounced nonlinearity of soft tissues as well as local anisotropy remain open. The aim of this study was to develop a virtual dynamic anatomical model of the human neck and reproduce the dynamic processes in the cervical spine from this model using the finite element method. MATERIALS AND METHODS Reverse engineering was used to generate a dynamic anatomical model of the neck from CT data (both male, 24 and 22 years old). Two segments of the cervical spine (C3-C5, C2-T1) were isolated from the resulting model for finite element analysis. Finite element mesh generation and contact interactions were performed using the HyperMesh software (Altair Engineering Inc, Troy, Michigan, USA). The anisotropic hyperelastic Holzapfel-Gasser-Ogden model was used to describe the material behavior of the fibrous rings of the disc. Material modeling and finite element analysis were performed using Abaqus CAE 6.14 software (Simulia, Johnston, Rhode Island, USA). RESULTS A technique for creating a virtual dynamic anatomical model of the neck was elaborated and implemented. The model includes 79 major anatomical structures of the neck segmented from radiological data. A finite element analysis of the cervical spine was performed. The results of finite element analysis of the C3-C5 segment under axial load were compared with in vitro data. The proposed model shows nonlinear deformation of the disc under static loading; the model predicted displacement values agree well with the experimental ones. The displacement of the С3-С5 central vertebra with an axial load of 800 N reaches a value of 0.65 mm. For the segment C2-T1, data on intradiscal pressure, stress plots and displacements during flexion were obtained. The maximum stress value of 10.036 MPa is observed in the C3-C4 disc. CONCLUSION Simulation results using the proposed methodology are in good agreement with experimental data. The generated biomechanical models allow describing dynamic phenomena in the cervical spine and obtaining a wide range of quantitative properties of anatomical objects, which are otherwise inaccessible to classical methods for studying dynamic and functional anatomy.
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Affiliation(s)
- A L Ovsepyan
- Saint Petersburg Electrotechnical University "LETI", Department of Bioengineering Systems, St. Petersburg, Russia
| | - A A Smirnov
- Moscow Region State University, Moscow, Russia.
| | - E A Pustozerov
- Saint Petersburg Electrotechnical University "LETI", Department of Bioengineering Systems, St. Petersburg, Russia; Almazov National Medical Research Centre, Institute of Endocrinology, St. Petersburg, Russia
| | - D E Mokhov
- North-Western State Medical University Named After I.I. Mechnikov, Department of Osteopathy, St. Petersburg, Russia
| | - E S Mokhova
- Insitute of the Osteopathy, St. Petersburg State University, Russia
| | - E M Trunin
- North-Western State Medical University Named After I.I. Mechnikov, Department of Operative and Clinical Surgery with Topographical Anatomy Named After S.A. Simbirtsev, St. Petersburg, Russia
| | - S S Dydykin
- Sechenov University, Department of Operative Surgery and Topographic Anatomy, Moscow, Russia
| | - Yu L Vasil'ev
- Sechenov University, Department of Operative Surgery and Topographic Anatomy, Moscow, Russia
| | - E V Yakovlev
- Medical Center of JSC "Admiralteyskie Verfi", St. Petersburg, Russia; Department of Psychophysiology of the Institute of Applied Psychoanalysis and Psychology of the "University at the Interparliamentary Assembly of EurAsEC", St. Petersburg, Russia
| | - S Budday
- Friedrich Alexander University Erlangen-Nürnberg, Department of Mechanical Engineering, Erlangen, Germany
| | - F Paulsen
- Sechenov University, Department of Operative Surgery and Topographic Anatomy, Moscow, Russia; Friedrich Alexander University Erlangen-Nürnberg, Institute of Functional and Clinical Anatomy, Erlangen, Germany
| | - S A Zhivolupov
- Military Medical Academy Named After S.M. Kirov of the Ministry of Defense of the Russian Federation (St. Petersburg), Department of Nervous Diseases, St. Petersburg, Russia
| | - D A Starchik
- North-Western State Medical University Named After I.I. Mechnikov, Department of Morphology, St. Petersburg, Russia
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Wolff WL, Leonardis JM, Lipps DB. The relationship between muscle activation and shear elastic modulus of the sternocleidomastoid muscle during 3-D torque production. J Electromyogr Kinesiol 2020; 55:102480. [PMID: 33157483 DOI: 10.1016/j.jelekin.2020.102480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 09/22/2020] [Accepted: 10/05/2020] [Indexed: 11/30/2022] Open
Abstract
The sternocleidomastoid (SCM) is a primary neck torque generator, but the relationship between its muscle activation and shear elastic modulus during 3-D torque production is unknown. This study examined variations in neural control and shear elastic modulus of the SCM across various 3-D isometric torques. Our primary hypothesis was that the SCM would display similar preferred directions where muscle activity and shear elastic modulus were maximal during voluntary 3-D isometric torque production. Surface electromyography (EMG) and ultrasound shear wave elastography (SWE) data were collected from the SCM in 20 participants performing 3-D isometric target-matching at two different torque amplitudes. We used spherical statistics to compare the preferred directions calculated from the SWE and EMG data at 40% and 80% torque level during 3-D isometric torque production. We demonstrated a small but significant difference between EMG and SWE preferred directions, with the SWE preferred direction oriented more towards ipsilateral bending and less towards contralateral axial rotation than the preferred direction for the EMG data. We conclude that, although small differences exist, SCM shear elastic modulus is largely driven by activation during 3-D neck torques for healthy individuals.
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Affiliation(s)
- Whitney L Wolff
- School of Kinesiology, University of Michigan, Ann Arbor, MI, USA
| | | | - David B Lipps
- School of Kinesiology, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.
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Kuo C, Fanton M, Wu L, Camarillo D. Spinal constraint modulates head instantaneous center of rotation and dictates head angular motion. J Biomech 2018; 76:220-228. [PMID: 29929891 DOI: 10.1016/j.jbiomech.2018.05.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/23/2018] [Accepted: 05/30/2018] [Indexed: 11/19/2022]
Abstract
The head is kinematically constrained to the torso through the spine and thus, the spine dictates the amount of output head angular motion expected from an input impact. Here, we investigate the spinal kinematic constraint by analyzing the head instantaneous center of rotation (HICOR) with respect to the torso in head/neck sagittal extension and coronal lateral flexion during mild loads applied to 10 subjects. We found the mean HICOR location was near the C5-C6 intervertebral joint in sagittal extension, and T2-T3 intervertebral joint in coronal lateral flexion. Using the impulse-momentum relationship normalized by subject mass and neck length, we developed a non-dimensional analytical ratio between output angular velocity and input linear impulse as a function of HICOR location. The ratio was 0.65 and 0.50 in sagittal extension and coronal lateral flexion respectively, implying 30% greater angular velocities in sagittal extension given an equivalent impulse. Scaling to subject physiology also predicts larger required impulses given greater subject mass and neck length to achieve equivalent angular velocities, which was observed experimentally. Furthermore, the HICOR has greater motion in sagittal extension than coronal lateral flexion, suggesting the head and spine can be represented with a single inverted pendulum in coronal lateral flexion, but requires a more complex representation in sagittal extension. The upper cervical spine has substantial compliance in sagittal extension, and may be responsible for the complex motion and greater extension angular velocities. In analyzing the HICOR, we can gain intuition regarding the neck's role in dictating head motion during external loading.
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Affiliation(s)
- Calvin Kuo
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Michael Fanton
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Lyndia Wu
- Department of Biomechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - David Camarillo
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA; Department of Biomechanical Engineering, Stanford University, Stanford, CA 94305, USA
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