Department of the Army #W81XWH-08-1-0587, #W81XWH-15-1-0006; Ball State University 2010 ASPiRE grant.

The experiment was conducted under the Helsinki Declaration. Prior to data collection, the subject reviewed and signed the consent form approved by the University Institutional Review Board before participating in the study.
1. CT Imaging Protocol
<ol>
	<li>Take the participant to a facility where a CT scanner is housed. Prior to the CT scan, configure the CT machine with the following parameters: CT slice thickness of 0.625 mm, CT field of view of 15 cm x 15 cm, and auto setting for paramet...

<ol>
	<li>Brukner, P., Bennell, K., Matheson, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Stress fracture. , (1999).</li><li>Zadpoor, A., Nikooyan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+relationship+between+lower-extremity+stress+fractures+and+the+ground+reaction+force:+A+systematic+review.">The relationship between lower-extremity stress fractures and the ground reaction force: A systematic review.</a> Clin Biomech. 26, 23-28 (2011).</li><li>Matheson, G. O., Clement, D. B., McKenzie, D. C., Taunton, J. E., Lioyd-Smith, D. R., Maclntyre, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stress+fractures+in+athletes.+A+study+of+320+cases.">Stress fractures in athletes. A study of 320 cases.</a> Am J Sports Med. 15, 46-58 (1987).</li><li>Bennell, K., Grimston, S., Burr, D., Milgrom, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Risk+factors+for+developing+stress+fractures.">Risk factors for developing stress fractures.</a> Musculoskeletal fatigue and stress fractures. , 15-33 (2001).</li><li>Milgrom, C., Giladi, M., Stein, M., Kashtan, H., Margulies, J. Y., Chisin, R., Stenberg, R., Aharonson, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stress+fractures+in+military+recruits.+A+prospective+study+showing+an+unusually+high+incidence.">Stress fractures in military recruits. A prospective study showing an unusually high incidence.</a> J Bone Joint Surg Br. 67, 732-735 (1985).</li><li>Almeida, S. A., Williams, K. M., Shaffer, R. A., Brodine, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiological+patterns+of+musculoskeletal+injuries+and+physical+training.">Epidemiological patterns of musculoskeletal injuries and physical training.</a> Med Sci Sports Exerc. 31, 1176-1182 (1999).</li><li>Jones, B. H., Knapik, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical+training+and+exercise-related+injuries,+surveillance,+research+and+injury+prevention+in+military+populations.">Physical training and exercise-related injuries, surveillance, research and injury prevention in military populations.</a> Sports Med. 27, 111-125 (1999).</li><li>Jones, B. H., Thacker, S., Gilchrist, J., Kimsey, C. D., Sosin, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevention+of+lower+extremity+stress+fractures+in+athletes+and+soldiers:+a+systematic+review.">Prevention of lower extremity stress fractures in athletes and soldiers: a systematic review.</a> Epidemiol Rev. 24, 228-247 (2002).</li><li>Voloshin, A., Wosk, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+in+vivo+study+of+low+back+pain+and+shock+absorption+in+the+human+locomotor+system.">An in vivo study of low back pain and shock absorption in the human locomotor system.</a> J Biomech. 15, 21-27 (1982).</li><li>Burr, D. B., Milgrom, C., Fyhrie, D., Forwood, M., Nyska, M., Finestone, A., Hoshaw, S., Saiag, E., Simkin, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+measurement+of+human+tibial+strains+during+vigorous+activity.">In vivo measurement of human tibial strains during vigorous activity.</a> Bone. 18, 405-410 (1996).</li><li>Ekenman, I., Halvorsen, K., Westblad, P., Fellander-Tsai, L., Rolf, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+reliability+and+validity+of+an+instrumented+staple+system+for+in+vivo+measurement+of+local+bone+deformation.+An+in+vitro+study.">The reliability and validity of an instrumented staple system for in vivo measurement of local bone deformation. An in vitro study.</a> Scand J Med Sci Sports. 8, 172-176 (1998).</li><li>Lanyon, L. E., Hampson, W. G., Goodship, A. E., Shah, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone+deformation+recorded+in+vivo+from+strain+gauges+attached+to+the+human+tibial+shaft.">Bone deformation recorded in vivo from strain gauges attached to the human tibial shaft.</a> Acta Orthop Scand. 46, 256-268 (1975).</li><li>Ekenman, I., Halvorsen, K., Westblad, P., Tsai, L. F., Rolf, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Local+bone+deformation+at+two+predominant+sites+for+stress+fractures+of+the+tibia:+an+in+vivo+study.">Local bone deformation at two predominant sites for stress fractures of the tibia: an in vivo study.</a> Foot Ankle Int. 19, 479-484 (1998).</li><li>Milgrom, C., Finestone, A., Levi, Y., Simkin, A., Ekenman, I., Mendelson, S., Millgram, M., Nyska, M., Benjuya, N., Burr, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Do+high+impact+exercises+produce+higher+tibial+strains+than+running?.">Do high impact exercises produce higher tibial strains than running?.</a> Br J Sports Med. 34, 195-199 (2000).</li><li>Milgrom, C., Finestone, A., Simkin, A., Ekenman, I., Mendelson, S., Millgram, M., Nyska, M., Larsson, E., Burr, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-vivo+strain+measurements+to+evaluate+the+strengthening+potential+of+exercises+on+the+tibial+bone.">In-vivo strain measurements to evaluate the strengthening potential of exercises on the tibial bone.</a> J Bone Joint Surg Br. 82, 591-594 (2000).</li><li>Al Nazer, R., Rantalainen, T., Heinonen, A., Sievanen, H., Mikkola, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flexible+multibody+simulation+approach+in+the+analysis+of+tibial+strain+during+walking.">Flexible multibody simulation approach in the analysis of tibial strain during walking.</a> J Biomech. 41, 1036-1043 (2008).</li><li>Al Nazer, R., Klodowski, A., Rantalainen, T., Heinonen, A., Sievanen, H., Mikkola, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+full+body+musculoskeletal+model+based+on+flexible+multibody+simulation+approach+utilised+in+bone+strain+analysis+during+human+locomotion.">A full body musculoskeletal model based on flexible multibody simulation approach utilised in bone strain analysis during human locomotion.</a> Comput Method Biomec. 14, 573-579 (2011).</li><li>Johnson, M. A., Moradi, M. H., Crowe, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> PID control: new identification and design methods. , 543 (2005).</li><li>Craig, R. R., Bampton, M. C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coupling+of+substructures+for+dynamics+analysis.">Coupling of substructures for dynamics analysis.</a> American Institute of Aeronautics and Astronautics Journal. 6, 1313-1319 (1968).</li><li>Wasfy, T. M., Noor, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computational+strategies+for+flexible+multibody+systems.">Computational strategies for flexible multibody systems.</a> Appl Mech Rev. 56, 553-613 (2003).</li><li>Kadaba, M. P., Ramakrishnan, H. k., Wootten, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+lower+extremity+kinematics+during+level+walking.">Measurement of lower extremity kinematics during level walking.</a> J Orthop Res. 8, 383-392 (1990).</li><li>Schwartz, M. H., Rozumalski, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+method+for+estimating+joint+parameters+from+motion+data.">A new method for estimating joint parameters from motion data.</a> J Biomech. 38, 107-116 (2005).</li><li>Devita, P., Skelly, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+landing+stiffness+on+joint+kenetics+and+energetic+in+the+lower+extremity.">Effect of landing stiffness on joint kenetics and energetic in the lower extremity.</a> Med Sci Sports Exerc. 24, 108-115 (1992).</li><li>Dong, X. N., Guo, X. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+dependence+of+transversely+isotropic+elasticity+of+human+femoral+cortical+bone+on+porosity.">The dependence of transversely isotropic elasticity of human femoral cortical bone on porosity.</a> J Biomech. 37, 1281-1287 (2004).</li><li>Schileo, E., Taddei, F., Malandrino, A., Cristofolini, L., Viceconti, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subject-specific+finite+element+models+can+accurately+predict+strain+levels+in+long+bones.">Subject-specific finite element models can accurately predict strain levels in long bones.</a> J Biomech. 40, 2982-2989 (2007).</li><li>Pattin, C. A., Caler, W. E., Carter, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclic+mechanical+property+degradation+during+fatigue+loading+of+cortical+bone.">Cyclic mechanical property degradation during fatigue loading of cortical bone.</a> J Biomech. 29, 69-79 (1996).</li><li>Lifemodeler, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Lifemod Manual. , (2010).</li></ol>

The authors declare that they have no competing financial interests.

The purpose of this study was to develop a non-invasive method to determine tibia deformation during high impact activities. Quantifying tibia strain due to impact loading will lead to a better understanding of tibia stress fracture. In this study, a subject-specific musculoskeletal model was developed, and computer simulations were run to duplicate the drop-landing movements performed in a laboratory setting. The effect of drop-landing height on tibial strain was examined. In this study, we observed that as the drop-lan...

Bone stress injuries, such as stress fractures, are severe overuse injuries requiring long periods of recovery and incurring significant medical cost1,2. Stress fractures are common both in athletic and military populations. Among all sports related injuries, stress fractures account for 10% of the total3. In particular, track athletes face a higher injury rate at 20%4. Soldiers also experience a high rate of stress fractures. For instance, a 6% injury rate was reported for the US Army1 and a 31% injury rate was reported in the Israeli Army5. Among all reported stress fractures, tibia stress fracture is the most common one6,7,8.
Sports and physical trainings with a higher risk of tibia stress fracture are normally associated with high ground impacts (e.g., jumping, landing, and cutting). During locomotion, a ground impact force is applied to the body when the foot contacts the ground. This impact force is dissipated by the musculoskeletal system and footwear. The skeletal system serves as a series of levers allowing muscles to apply forces to absorb the ground impact9. When the leg muscles cannot adequately reduce the ground impact, lower-body bones must absorb the residual force. Bone structure will experience deformation during this process. Repetitive absorption of residual impact force may result in microdamages in the bone, which will accumulate and become stress fractures. To date, information related to bone reaction to external ground impact forces is limited. It is important to study how the tibia bone responds to the mechanical load introduced by high impact forces during dynamic motions. Examining tibia bone deformation during high impact activities could lead to a better understanding of the mechanism of tibia stress fracture.
Conventional techniques used to measure bone deformation in vivo rely on instrumented strain gauges10,11,12,13,14,15. Surgical procedures are needed to implant strain gauges on bone surface. Due to the invasive nature, in vivo studies are limited by a small sample of volunteers. In addition, the strain gauge can only monitor a small region of the bone surface. Recently, a non-invasive method utilizing computer simulation to analyze bone strain was introduced16,17. This methodology allows for the ability to combine musculoskeletal modeling and computational simulations to study bone strain during human movement.
A musculoskeletal model is represented by a skeleton and skeletal muscles. The skeleton consists of bone segments, which are rigid or non-deformable bodies. Skeletal muscles are modeled as controllers using the progressive-integral-derivative (PID) algorithm. The three-term PID control uses errors in estimation to improve the output accuracy18. In essence, PID controllers representing muscles try to duplicate body movements by developing necessary forces to produce length changes of the muscles over time. The PID controller uses the error in the length/time curve to modify the force for reproducing the movement. This simulation process creates a feasible solution to coordinate all muscles to work together to move the skeleton and produce the body movement.
One or more segments in the skeleton of the musculoskeletal model can be modeled as flexible bodies to allow measurement of deformation. For instance, the tibia bone can be broken down into a finite number of elements, which consists of thousands of elements and nodes. The effect of mechanical loading on the flexible tibia can be examined through finite element (FE) analysis. The FE analysis calculates the loading response of individual elements over time. As the number of bone elements and nodes increase, the computation time of the FE analysis will significantly increase.
To reduce computational cost with accurate evaluation of flexible bodies&#39; deformation, modal FE analysis has been developed and used within the automotive and aerospace industry19,20. Instead of analyzing individual FE elements&#39; responses to mechanical load in the time domain, this procedure assesses an object&#39;s mechanical responses based on different vibrational frequencies in the frequency domain. This method results in a significant reduction in computation time while providing accurate measurement of deformation20. Although modal FE analysis has been widely used to study mechanical fatigue in automotive and aerospace areas, the application of this method has been very limited in human movement science. Al Nazer et al., used a modal FE analysis to examine tibial deformation during human gait and reported encouraging results16,17. However, their method was greatly affected by only using limited kinematic data from an experiment to drive the computer simulations; There were no real ground impact forces used to assist the simulations. This approach may be reasonable for studying low impact slow motions such as walking, but it is not a feasible solution to study high ground impact movements. Thus, in order to examine lower-body bone reactions during dynamic high impact activities, it is essential to develop an innovative approach to address the limitations associated with the previously reported method. Specifically, a method utilizing accurate experimental kinematic data and real ground impact forces must be developed. Therefore, the goal of this study was to develop a subject-specific musculoskeletal model to perform multibody dynamic simulations with modal FE analysis to examine tibial strain during high impact activities. A dynamic high impact movement represented by drop-landings from different heights was selected to test the method.

<table border="0" cellpadding="0" cellspacing="0" width="575">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:143px;">CT Scanner</td>
			<td style="width:123px;">GE Medical System</td>
			<td style="width:107px;">N/A</td>
			<td style="width:203px;">Light Speed VCT. For performing tibia CT scan.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Motion Capture System</td>
			<td>Vicon Inc</td>
			<td>N/A</td>
			<td>Vicon FX40 high speed cameras. For performing 3D motion capture.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Force plates</td>
			<td>AMTI Inc</td>
			<td>N/A</td>
			<td>Collecting 3D ground reaction forces</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Vicon Nexus</td>
			<td>Vicon Inc</td>
			<td>N/A</td>
			<td>Motion capture software program. For processing visual marker trajectory data.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Visual 3D</td>
			<td>C-Motion Inc</td>
			<td>N/A</td>
			<td>Biomechanics analysis software. For computing 3D kinematics and kinetics of human movements.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MATLAB</td>
			<td>Mathworks Inc</td>
			<td>N/A</td>
			<td>Computer programming software. For performing raw data filtering, data conversion, and data processing.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">ADAMS 2012</td>
			<td>MSC Software Inc</td>
			<td>N/A</td>
			<td>Multibody dynamic computer simulation program.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">LifeMOD</td>
			<td>Lifemodeler Inc</td>
			<td>N/A</td>
			<td>A software Plug-in in ADAMS. For building human body musculo-skeletal models.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MIMICS 13</td>
			<td>Materialise Inc</td>
			<td>N/A</td>
			<td>Image processing program. A 3D modeling tool to process imaging data. For creating 3D tibia model from CT scans.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MARC 2012</td>
			<td>MSC Software Inc</td>
			<td>N/A</td>
			<td>Finite element analysis software. For performing volumn meshing, generating tibia FE model, and running modal FE analysis.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">SPSS 19</td>
			<td>IBM Inc</td>
			<td>N/A</td>
			<td>Statistical analysis software.</td>
		</tr>
	</tbody>
</table>

subject-specific musculoskeletal model for studying bone strain during dynamic motion

Bone stress injuries are common in sports and military trainings. Repetitive large ground impact forces during training could be the cause. It is essential to determine the effect of high ground impact forces on lower-body bone deformation to better understand the mechanisms of bone stress injuries. Conventional strain gauge measurement has been used to study in vivo tibia deformation. This method is associated with limitations including invasiveness of the procedure, involvement of few human subjects, and limited strain data from small bone surface areas. The current study intends to introduce a novel approach to study tibia bone strain under high impact loading conditions. A subject-specific musculoskeletal model was created to represent a healthy male (19 years, 80 kg, 1,800 mm). A flexible finite element tibia model was created based on a computed tomography (CT) scan of the subject&#39;s right tibia. Laboratory motion capture was performed to obtain kinematics and ground reaction forces of drop-landings from different heights (26, 39, 52 cm). Multibody dynamic computer simulations combined with a modal analysis of the flexible tibia were performed to quantify tibia strain during drop-landings. Calculated tibia strain data were in good agreement with previous in vivo studies. It is evident that this non-invasive approach can be applied to study tibia bone strain during high impact activities for a large cohort, which will lead to a better understanding of injury mechanism of tibia stress fractures.

A healthy Caucasian male (19 years, height 1,800 mm, mass 80 kg) volunteered for the study. Prior to data collection, the subject reviewed and signed the consent form approved by the University Institutional Review Board before participating in the study. The experiment was conducted under the Helsinki Declaration. The experiment was performed based on the following protocol.
In order to verify the accuracy of the forward dynami...

Watch this Scientific Journal Video about Subject-specific Musculoskeletal Model for Studying Bone Strain During Dynamic Motion at JoVE.com

Subject-specific Musculoskeletal Model for Studying Bone Strain During Dynamic Motion

During landing, lower-body bones experience large mechanical loads and are deformed. It is essential to measure bone deformation to better understand the mechanisms of bone stress injuries associated with impacts. A novel approach integrating subject-specific musculoskeletal modeling and finite element analysis is used to measure tibial strain during dynamic movements.

Bone stress injuries are common in sports and military trainings. Repetitive large ground impact forces during training could be the cause. It is ...

The overall goal of this procedure is to create a Subject-specific Musculoskeletal Model for Bone Strain analysis. This method can help answer key questions in the biomedical engineering field such as quantifying human bone deformation during dynamic motion. The main advantage of this technique is that a non-invasive approach is implemented to study bone strength during dynamic physical activities.Demonstrating the procedure will be Marisa Loo and Kerstyn Hall, graduate students from my laboratory. To begin this procedure perform CT scanning and anthropometric measurement on the subject. After this, place 14mm reflective markers on the participants'body as outlined in the text protocol.Place semi rigid plastic plates with four marker clusters on the participants'thighs and shanks. After entering the subjects'information into the motion capture program, ask them to stand motionless in the center of the calibrated room with their feet shoulder width apart. Then ask them to extend their upper extremities laterally so that all of the reflective markers are well exposed to the cameras.In the main program window, open the tools pane, click the subject preparation tab. In the subject capture section, click start to record a three second motion trial to be the static calibration trial. To begin determining the functional hip joint center, ask the participant to stand on one leg while fully extending the other leg slightly forward.Instruct the participant to move the extended leg around the hip joint anteriorly and return to neutral. Anterior laterally and return to neutral. And then laterally and return to neutral.After this have the participant move the same leg around the hip joint posterior laterally and return to neutral. Posteriorly and return to neutral. And then in a circumduction motion.In the main program window, open the tools pane, click the capture tab, then in the capture section click start to record a motion trial for each functional hip motion. To begin determining the functional knee joint center, ask the participant to stand on one leg while maintaining a 30 degree hip hyperextension of the other leg. Next, instruct the participant to perform a 45 degree knee flexion with the non weight bearing leg.Have them repeat this five times. In the capture section of the tools pane, click start to record a motion trial for each functional knee motion. Place the height adjusted wood box on an area of the floor covered by a rubber mat, making sure that it is approximately 11cm from the edges of the force plates.Next, ask the participant to stand on top of the box. Instruct the participant to extend their dominant foot directly in front of the box, then have them shift their weight forward and step off the box. Both of the participants legs should land on the ground at the same time with each foot striking a separate force plate, ask the participant to remain standing until the motion capture of the trial is complete.Repeat the motion capture three times to collect three motion trials for each height. First, open a motion capture software program. In the main window, go to the communications pane, click the data management tab and select one of the recorded motion trials.Open the trial data in the program. In the tools pane, click the pipeline tab. From the current pipeline list, select the reconstruct pipeline, click the run button to start reconstruction process to obtain three dimension trajectories of the reflective markers.Navigate to the tools pane and click the label edit tab, in the manual labeling section select individual marker names and label the corresponding 3D trajectories. When labeling is complete, click the save button on the tool bar. To begin creating a lower body skeletal model, open the multi-body dynamic simulation software program with the human body modeling plug in installed.At the splash screen, double click the new model icon to open the model building control panel, in the anthropometric database library section of the main modeling panel, choose the generic body from the drop down list, specify the body mass, body height, gender and age. In the body configuration section of the main modeling panel click the lower body radio button, in the units drop down list select mm, kg, Newton;click the apply button in the create body measurement table section to accept the body measurements. Continue to click the apply button in the create human segment section to create a lower body skeletal base model.To begin modeling the lower body joints, open the main menu drop down list in the main modeling panel and select joints to open the joint configuration panel. In the joint rotation element section of the joint configuration panel, click the button next for prepare model with recording joints. In the spring dampers and joint limits properties section enter the parameters for nominal joint stiffness, nominal joint damping and joint stop stiffness as shown here.Continue to select left leg and right leg by checking corresponding radio buttons, click the apply button to accept the joint configurations. After this, open the main menu drop down list in the main modeling panel and select workflow, in the sub menus drop down list select gait and calibrate, in the joint center data section enter the participants lower body joint center file. Then click the load button to import the data and modify the locations of the joint centers, in the load static trial section enter the static calibration motion capture trial.Click the load button to import the file and parametrize the lower body skeletal model. To begin modeling the skeletal muscles, open the main menu drop down in the main modeling panel and select soft tissues, after this open the sub menu drop down and select create base tissue set. In the muscle contract tile element section, click prepare model with recording muscle elements.Next, in the global recording element muscle properties section, click the radio button corresponding to updated 45 muscle set then accept the default settings for muscle properties as shown here. Check the radio buttons for left leg and right leg for muscle assignments, then click the apply button to accept the configurations. In this study, a non-invasive method is used to determine tibia deformation during high impact activities.The accuracy of the forward dynamic simulation is verified by comparing the lower body joint angles from the simulation to the corresponding joint angles as measured for motion capture data. These comparisons are completed for the ankle angle, knee angle and hip angle at all three drop heights where the vertical lines represent moments of impact. As can be seen, the simulation and experimental data largely agree, demonstrating that the simulation itself has a high degree of accuracy.Statistical analysis software is then used to calculate the cross-correlation coefficients between the experimental and simulation joint angles at zero lag. The peak strains at the antero medial region of the mid tibial shaft are recorded while the subject lands from three different heights. The 52cm landing condition demonstrates the largest peak maximum principal, peak minimum principal and peak maximum shear strains.The peak maximum principal strains are also seen to increase as the drop height increases. After it's development, this technique paved the way for researchers in the field of biomedical engineering, to explore mechanisms of bone stress injuries in athletes and military trainees.

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Unit 1

Transformations of Stress and Strain

Musculoskeletal System

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9.6K 조회수.  Ball State University. The overall goal of this procedure is to create a Subject-specific Musculoskeletal Model for Bone Strain analysis. This method can help answer key questions in the biomedical engineering field such as quantifying human bone deformation during dynamic motion. The main advantage of this technique is that a non-invasive approach is implemented to study bone strength during dynamic physical activities.Demonstrating the procedure will be Marisa Loo and Kerstyn Hall, graduate students from m...