Creation and Validation of a Dynamic, EMG-Driven Cervical Spine Model

Biomechanical modeling is one of the ways to assess the risk of pain and injury to an individual. Injuries and pain are becoming more common in the cervical spine. There are many cervical spine models available, but almost all of them were made to study impact loading (whiplash), which makes them unsuitable for studying activities of daily living. A personalized, dynamic, EMG-driven model is very important, because everybody activates their muscles differently, and that different activation will cause different loading patterns. The goal of this study was to create and evaluate a dynamic, EMG-driven cervical spine model that tracks motion and calculates spinal loads in the cardinal planes.The cervical spine model was created in MSC Adams™ and included vertebrae, intervertebral discs, ligaments, and muscles. The vertebrae (C1-C7) were harvested from a cadaver, and using a white light scanner, were turned into 3D models. The discs were modeled as bushing forces. The ligaments were modeled as single vector forces. Each ligament consisted of three vectors, which enables the model to calculate shear as well as force on the ligament. The muscles were modeled as straight line force vectors between the origin and insertion points. The loads on the discs were calculated using moment arms and force vectors from the ligaments and muscles, as well as velocity and acceleration of the vertebrae and skull.Three subjects were used to evaluate the model. Subjects completed sagittal flexion and lateral flexion trials. Electromyography data, optical data, and force plate data were collected. The internal load, calculated using the EMG and optical data, was compared to the external load, calculated with the force plate. The trials in the sagittal plane performed well (r2 = .70, AAE = 1.65 N), while some of the trials in the lateral plane worked well and some did not perform as well (r2 = .48, AAE = 1.74 N). There was significant co-activation in the muscles during the trials. The loads on the discs were reasonable. The sagittal trials had an average compression load of 130.94 N on the discs, an average lateral shear load of 70.52 N on the discs, and an average anterior-posterior shear load of 52.72 N on the discs. The lateral trials had an average compression load of 234.21 N on the discs, an average lateral shear load of 136.78 N on the discs, and an average anterior-posterior shear load of 84.61 N on the discs. This model met its goals reasonably well, it was able to track motion, predict moments on the cervical spine, and calculate loads on the discs. The co-activation in the muscles was expected, as all of the muscles were needed to maintain balance of the head and complete the motion. The loads on the discs were plausible; they were well below established failure tolerances, as well as below the loads on the discs in the lumbar spine during similar trials. With improvements, this model will be able to accurately predict the loads on the discs during many different tasks.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Industrial and Systems Engineering

Grantor dc:publisher

The Ohio State University

Year dc:date

2013

Author dc:creator

• Huber, Zach Elijah

Contributors dc:contributor

• Marras, William

• Biomechanics
• Biomedical Research
• Occupational Safety
• cervical spine
• biomechanical model
• cervical model
• cervical disc loads, EMG

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1365680628

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1365680628