Alison McDonald      

About Alison:

Academic Institution:  McMaster University

Academic Department: Science - Department of Kinesiology

Major: PhD in Kinesiology-Biomechanics

Advisor:  Dr. Peter Keir

As an undergraduate student I studied Kinesiology at the University of Waterloo (Waterloo, Ontario).  Here, I had the opportunity to apply my studies during ergonomics work placements, and a research assistantship in occupational biomechanics.  My interest in biomechanics research started while I was an undergraduate student, working in Dr. Clark Dickerson’s Digital Industrial Ergonomics and Shoulder Evaluation Laboratory.  During this time, not only did I develop research skills and gain valuable experience, but also I developed a strong interest and passion for occupational biomechanics research.  I decided to continue in this field of occupational upper extremity biomechanics, and pursue a master’s degree in the McMaster Occupational Biomechanics Laboratory in the Department of Kinesiology at McMaster University (Hamilton, Ontario), under the supervision of Dr. Peter Keir. After my first year of graduate school I accelerated into the PhD program.

Alison's Research:

The focus of my research is to improve understanding of the muscular and kinematic response to fatigue in the shoulder complex, and investigate how workers adapt to recover while on the job.  Musculoskeletal injuries resulting from repetitive work is a common cause of industrial workplace injuries.  While performing repetitive work tasks, workers experience fatigue acting to reduce their muscle capacity, however, we know they will adapt to continue performing their required tasks.  The musculature and kinematic degrees of freedom in the shoulder create a large range of motion for the arm, and opportunities to vary kinematic and muscular strategies to continue working. This makes it challenging to predict how people will respond to fatigue, and how task performance will change throughout the workday.  Understanding how these responses change over time will give us insight into mechanisms of cumulative workplace injuries. To achieve this, I am in the process of completing three studies aimed at eliciting and evaluating changes with repetitive work.  My thesis work uses multi-axial force measurement to simulate repetitive work tasks, and examine changes in kinematics, muscle activity and task performance.  Musculoskeletal modeling will be done concurrently to help explain the strategic mechanisms behind changes observed. 

Multi-axis Testing in my Research:

The shoulder is a six-degree of freedom complex, allowing the hand to exert forces in many directions.  This flexibility means that for a thorough evaluation of workplace tasks, forces and moments need to be measured in multiple axes; making the use of multi-axial force transducers essential to answering my research questions. Multi-axial measurement tools allow me to measure and control the directions, magnitudes and locations of exertions, and is vital to furthering our understanding of the complex mechanisms leading to workplace injuries.  Using a 6-degree of freedom force plate allows me to measure changes in center of pressure with fatigue, giving insights into whole body compensations to continue performing work tasks.  Using one-dimensional and single axis methods could lead to over simplification and misinterpretation of results.  

Erin Futrell 

About: Erin:

Academic Institution: MGH Institute of Health Professions

Academic Department: Center for Interprofessional Studies and Innovation

Major: PhD in Rehabilitation Sciences

Advisor: Dr. Irene Davis

Erin studied Exercise Physiology as an undergraduate student at Georgia State University.  She then went on to earn a Master’s degree in Physical Therapy in 2007, and became an Orthopedic Certified Specialist in 2010.  After several years of working in outpatient orthopedic physical therapy, she decided to pursue a PhD with the goal of becoming an educator of future physical therapists and a researcher promoting evidence-based practice. This led her to studying running biomechanics at the Spaulding National Running Center in Cambridge, MA.  This unique facility allows biomechanists, engineers, physical therapists, and physicians to collaborate toward expanding the current understanding of running-related musculoskeletal injuries, and to use this understanding to provide patients with the most effective treatments and prevention strategies. Erin’s dissertation work for her PhD focuses on gait retraining interventions aimed at reducing impact loads in runners.

Erin’s Research:

 Running is an activity that promotes overall health and is one of the most popular fitness activities in the US with over 20 million regular participants annually. Unfortunately up to 79% of runners will have an injury in a given year and up to 46% will be recurrences.Despite advancements in technology and footwear design, running equipment and current interventions have not reduced the overall incidence of running injuries. While the etiology of running injuries is multifactorial, impact mechanics have been related to a number of common running-related injuries.  It has been reported that 89% of shod runners land with a rear foot strike pattern resulting in an impact force that has been related to injury. Two alterations in gait mechanics have been promoted to reduce these impact forces. The first involves increasing step rate, or cadence, by 5-10%.  The second involves transitioning to landing on the ball of the foot, or a forefoot strike pattern. To date, these two gait styles have not been compared in the same study design to determine which results in the greatest reduction in impact forces. Further, there has been no evidence that persons receiving gait retraining can maintain a new gait pattern when fatigued, or whether these patterns will persist in the long term. If gait retraining is to be a worthwhile intervention to reduce the risk of future running injury, long-term use is key. Therefore, the purpose of this investigation is to determine the comparative effectiveness of two gait-retraining interventions for the reduction of impact forces, and their persistence under fatigue and permanence over time.

To effectively reduce injury risk, these interventions need to significantly reduce impacts in a way that persists in the long term. Identifying which of these two is the more efficacious intervention will help guide physical therapists in their approach to treating and preventing running injuries. This may reduce future musculoskeletal injuries associated with running by reducing the impacts that have been linked to these injuries. This will be the first study known to the author to investigate the extent of impact reduction of these two gait -retraining methods. In addition, this will be the first known study to investigate the long-term permanence of any type of running gait retraining after a period of 6 months.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

 The Spaulding National Running Center is dedicated to using the most advanced motion analysis equipment to allow researchers and clinicians to expand the understanding of running-related musculoskeletal injuries.  Running is a dynamic activity with simultaneous motions in multiple planes.  Multi-axis force measurement will be used for the analysis of the primary variables of interest for this study.  Ground reaction force data will detect the effectiveness of two gait-retraining interventions meant to reduce impact forces during running. Often in running research, the vertical ground reaction force is of primary interest. However, during running the body experiences load rates and forces in multiple directions, not just the vertical.  This study is unique in that the load rates of the resultant force will be analyzed. Thus, multi-axis force measurement is a valuable and essential tool of this investigation.

Sijia Zhang

About Sijia:

Academic Institution: University of Pennsylvania

Academic Department: Department of Bioengineering

Major: PhD Candidate in Bioengineering

Advisor: Prof. Beth A. Winkelstein

I first started to learn and investigate mechano-biology of the sensory system as an undergraduate student, working in Dr. Jong-Hoon Nam’s lab at University of Rochester. After graduating summa cum laude with a degree in Biomedical Engineering, I proceeded to pursue my PhD in Bioengineering. My interest in the interface between biomechanics and  neuroscience led me to work under Dr. Beth Winkelstein at University of Pennsylvania to study mechanisms of pain after traumatic neck injury. My current research focuses on defining the relationships between tissue mechanics and neuronal dysfunction in ligament pain using integrated experimental and computational approaches. My recent studies measuring the multi-scale tissue mechanics in the context of pain were published in the Journal of Biomedical Engineering and the Journal of the Royal Society Interface.

Sijia's Research:

My research focuses on the important and significant health problem of trauma-induced neck and low back pain. The facet capsular ligament (FCL) encloses the bilateral facet joints at each spinal level and is a common source of pain especially from complex FCL loading because that ligament is innervated by mechanoreceptive and pain nerves. Only recently has biomechanical attention been focused on the FCL, with advances in imaging systems and increased surgical interventions for spine treatment. Since the FCL exhibits regions of irregular and parallel collagen fibers, the mechanically-vulnerable nerves embedded in the FCL experience a range of local mechanical environments, with varied risks for injury. Because of the unique anatomy of the facet joints and their potential for loading in all directions during the complicated multi-axial spinal motions and loads, the FCL can be injured under many different scenarios.

I hypothesize that excessive tissue loading regulates the pain-related mechanotransduction pathways of nerves within the FCL, via modified local biomechanics of the collagen matrix. I have developed an in vitro neuron-collagen construct system that enables integration of prescribed collagen fiber orientation, measurement of neuronal responses, and quantification of the multi-scale tissue mechanics. So far, I have only investigated relationships using uniaxial tension known to be painful. I propose to impose multi-axial loading of the FCL simulating the complicated in vivo conditions and define effects on neuronal responses. Coordinated with characterizing the bulk tissue mechanics, I will measure the microscopic mechanics through quantitative polarized light imaging that I have integrated with a testing device. That work will enable measuring real-time collagen fiber kinematics during multi-axial loading, which are likely different from what was observed under uniaxial tension. To predict microscopic tissue and neuronal stresses and strains, I am developing a computational model of the innervated FCL that accommodates a variety of loading conditions. Lastly, pain pathways are interrogated with pharmacological approaches to identify those initiated by complex FCL loading.

The novelty of my research lies in its defining the biomechanical mechanisms that bridge tissue-level loading and pain-related neuronal responses during the multi-axis real injury scenarios. The innovative integration of mechanical testing, cell culture systems, advanced imaging, and computational modeling enables coordinated evaluation of mechanics of tissue and pain fibers during spinal loading. My research not only has the potential to improve knowledge about spinal pain, but uses innovative approaches to understanding mechanical ligament injury beyond facet-mediated pain.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

My research focuses on a spinal ligament, which encloses a 3D joint and physiologically constrains highly coupled and multi-axial vertebral motions. In spinal regions like the neck, where the joint kinematics can be exaggerated during trauma, this ligament can be injured. During injurious loading, sub-regions of the same ligament experience combined shear, tension, and bending, altering the regional strains. The resultant loading to the embedded nerves also varies due to differences in the tissue’s microstructure and the local biomechanical environment. This ligament has only been experimentally characterized in simple tension or shear, which dramatically simplifies the actual loading experienced in the spine. To best define relationships between tissue deformations and local collagen and nerve responses, tests must accurately simulate and measure the multi-axis loading. Six-degree-of-freedom loading of the joint and biaxial testing of engineered cell-tissue constructs, along with imaging, enable the appropriate and necessary multi-scale characterization of this ligament system.

NICOLE RAMO

Academic Institution: Colorado State University

Academic Department: School of Biomedical Engineering

Major(s): PhD student in Bioengineering

Advisor: Prof. Christian Puttlitz

About Nicole:

As an undergraduate mechanical engineering student at Kettering University (Flint, MI), I was given the opportunity to work as a research assistant in the Bone and Joint Research Center of Henry Ford Hospital (Detroit, MI). It was there that I was first introduced to multi-axis measurement and testing as I assisted in the study of dynamic three-dimensional in-vivo joint motion. In the array of projects on which I worked I found the challenges and complexity of spinal research particularly interesting. For my undergraduate thesis I worked with researchers, a neurological surgeon, and patients to study the effects of cervical level spinal-fusion on vertebral motion. My interest in spinal biomechanics led me to pursue graduate research at Colorado State University under Dr. Christian Puttlitz, who is well-known for his work in mathematical and computational modeling of spinal tissues.

Nicole's Research:

I joined the Puttlitz research group of Colorado State University at an especially exciting time as they were beginning to investigate spinal cord injuries (SCIs) by mechanically characterizing and modeling the tissues of the spinal cord-meningeal complex (SCM). The majority of SCIs occur during high-speed impact events such as vehicular accidents, falls, or sports injuries where the SCM is loaded, often along multiple axes, to the point of sub-failure or full thickness damage. Computational models are an important economical and ethical way to study SCIs and assess the effectiveness of new safety features and the implications of clinical interventions. However, utilizing these models requires sophisticated characterization of the SCM components (i.e. the dura mater, pia mater, and cord tissue).

Despite their known importance in injury prevention, many models either do not include the dura and pia maters or make simplifying assumptions about their properties, both of which have a significant effect on model predictions. Although numerous groups have reported properties of fresh dura, there is only one study to date on the behavior of isolated pia mater. Additionally, the strain rates utilized in these studies are typically far below those estimated to occur during SCI. Therefore, the overall goal of my research is to provide a more complete characterization of the spinal dura and pia maters for use in studies of SCIs through mechanical testing at high strain rates, along multiple axes, and within the sub-failure and failure domains, then implement these data into a finite element model to investigate SCI mechanics.

The unique features of my work are its focus on paediatric subjects, the frequency of data collection sessions, the integration of muscle activity, force and motion data and the breadth of functional activities studied. Our pilot work supports previous adult studies from other centres showing persistent kinematic and kinetic differences post-ACL reconstruction, particularly during high demand activities. This novel data set, combined with advanced multivariate pattern recognition techniques will hopefully yield new insights regarding factors affecting recovery from ACL reconstruction.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

Physiologically, the tissues of the spinal cord-meningeal complex (SCM) experience loading in the circumferential and longitudinal directions simultaneously. Circumferential stresses/strains are produced by the pulsatile flow of cerebrospinal fluid while longitudinal stresses/strains are produced by movement of the head/neck.  During the complex loading scenarios of spinal cord injuries, this simultaneous multi-axis loading can be significant. Therefore, in order to study the response of the tissues of interest under the most applicable conditions, it is imperative that the tissues be mechanically tested in multiple directions simultaneously. Unlike single-axis methods, biaxial testing allows for the inclusion of the interaction of the longitudinal and circumferential stresses in studies of the overall mechanical behavior of the tissues of interest. Therefore, multi-axis testing is important in characterizing the behavior of spinal tissues under physiological and injurious conditions.

ROBERT ZONDERVAN

Academic Institution: Michigan State University

Academic Department: Osteopathic Medicine/Physiology

Major(s): Doctor of Osteopathic Medicine/PhD in Physiology

Advisor: Prof. N. Peter Reeves

Impact of spinal surgical instrumentation on adjacent segment dynamic behavior.

About Robert:

Mr. Zondervan studied neuroscience as an undergraduate at Colby College in Waterville, Maine.  He then worked in Boston, Massachusetts at Dana-Farber/Harvard Cancer Center (DF/HCC) as an imaging analyst for oncology clinical trials.  His responsibilities included assessing tumor burden and response using PET, CT, and MRI imaging.  During his time at DF/HCC Mr. Zondervan also studied the risk of radiation-induced cancer from CT scanning.  His work, which studied 22,000 patients, was published in Radiology and Journal of the American College of Radiology. From Boston, Mr. Zondervan entered medical school at the University of New England in Biddeford, Maine.  He then transferred to Michigan State University to also pursue a PhD where he now studies spine dynamics at the Center for Orthopedic Research. Mr. Zondervan’s dissertation investigates the impact of spinal surgical instrumentation on degeneration in the spine.  As a dual-degree student, his focus is on translational research – bringing laboratory findings into clinical practice.  After completion of his medical degree and PhD he plans on practicing as an orthopedic surgeon and serving as a principal investigator of a biomechanical research laboratory.

Roberts's Research:

Despite extensive research efforts in the past 20 years, current management of low back pain (LBP) is unsatisfactory.  In fact, efficacy studies have shown an increase in LBP treatment, but worse outcomes.  Typically, LBP sufferers are diagnosed with nonspecific pathology, which leads to nonspecific treatment, which not surprisingly, results in poor clinical outcomes.  Since the introduction of total disc replacement surgery (arthroplasty) as an alternative to interbody fusion (arthrodesis), there has been a rapid growth in procedures performed.  However, despite claimed mechanical improvements over arthrodesis, arthroplasty outcomes have been similarly poor.  Previous research has failed to identify the cause of such poor outcomes, but suggest that altered spine mechanics at the site of implant are implicated in the disease pathophysiology. 

Solutions to complex problems, such as LBP, require a detailed knowledge of how the spine system functions. One of the main shortcomings in LBP research an emphasis on static properties of spine biomechanics. Current analysis used to assess the impact of spine surgical devices on biomechanics has significant limitations in predicting system response while in motion or under time-varying load.  Given that the in vivo spine is a dynamic system, in vitro dynamic analysis of the spine is indicated. Therefore, the overall goal of my research is to apply dynamic systems theory to develop a new standard for multi-axis in vitro spine testing, thus overcoming a critical gap in knowledge and allowing for a more comprehensive understanding of spine biomechanics. Using this new testing standard, I am developing biomechanical data sets to demonstrate the mechanical effects of surgical intervention on the lumbar spine; specifically, I will apply the new approach to study the dynamic properties of spines after undergoing arthroplasty and arthrodesis in 6 degrees of freedom.  Overall, this research will provide an essential tool to standardize spine multi-axis testing and progress research in LBP.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

The Michigan State University Center for Orthopedic Research uses systems science to advance understanding of healthy and diseased spines.  To approach the complexities of the spine system, investigations involve a combination of in vivo testing, in vitro testing, and systems modeling.  To construct an accurate model of the spine system, it is essential to test the in vitro spine in a condition that is most similar to the in vivo condition.   The human spine is not constrained to one degree of freedom; it flexes, extends, side bends, rotates, translates, and compresses. Intuitively, testing in only one degree of freedom would yield an incomplete model and limit the usefulness of acquired data.  Therefore, multi-axis testing is essential for convergence on an accurate spine system model, developed from in vivo and in vitro investigations.

PARIS VAKIL

Academic Institution: University of Calgary

Academic Department: Civil Engineering

Major(s): PhD Student in Civil Engineering

Advisor: Prof. Nigel Shrive

About Paris:

After achieving honors and graduating from McGill University with a degree in Civil Engineering, I proceeded to work in the oil and gas industry for over a year, before ultimately deciding to further my education.  I chose the University of Calgary to pursue a degree in Civil engineering with a specialization in Bio-medical engineering, and am currently working towards attaining my PhD. I currently conduct research in the field of arthritis, specifically the effect of stress in the cartilage on the onset of arthritis due to changes in gait, after an injury.

Paris's Research:

Knee joint injuries involving rupture of the anterior cruciate ligament (ACL) and/or meniscal tears often lead to the development of post- traumatic osteoarthritis (PTOA). Abnormal joint motions resulting from such severe knee injuries possibly initiate PTOA and contribute to disease progression. Patients with ACL tears are advised to undergo reconstructive surgery aimed at restoring normal joint function. However, despite successful reconstruction of the ACL there is evidence of joint degeneration leading to OA over time.

Different techniques have been used to capture the alterations in knee joint motions and tissue loads following injury or surgery. The non invasive techniques use skin surface markers but are limited in terms of accuracy and motion specificity. We have developed anovel testing platform combining an instrumented spatial linkage for in vivo kinematic assessments and a unique 6-DOF parallel robotic system for accurate reproduction of in vivo joint motions and measurement of in situ joint/tissue loads We are now poised to determine the subtle changes observed in the joint motions following injury or surgery that cause changes in the surface interactions of the cartilage covering the knee joint, thus initiating or causing progression of PTOA. 

We hypothesize that alterations in relative surface configuration affect contact stresses on the articulating surfaces of the knee joint and play a role in PTOA pathogenesis. To identify the location and magnitude of these changes in the early stages of disease we aim to apply fiber-optic sensor technology in conjunction with the parallel robot. The paradigm that we are testing is that is that cartilage is unable to adapt to a large change in stress and will begin to degrade in a process exacerbated by continual application of the abnormal stress.

The technique of using the fiber-optic system will be unique in determining the altered joint loads resulting from even subtle changes in joint motion. Once the technique is well established, we aim determine the changes in shear and normal stress in the knee joint after transection of the ACL and relate these to the damage observed to the cartilage of those joints in an ovine model.

ELIZABETH HASSAN

Academic Institution: Queen's University, Canada

Academic Department: Mechanical Engineering

Major(s): PhD in Mechanical Engineering

Elizabeth's website

Advisor: Prof. Kevin Deluzio

Evaluation of semitendinosus-only ACL reconstruction

About Elizabeth:

I returned to Queen’s for my PhD after working in forensic engineering and obtaining Masters’ degrees in both mechanical engineering and design. I’ve had some diverse work experiences: measuring the acoustics of guitars, reconstructing motorcycle collisions, running medical simulations and studying elbow motion. It makes me well rounded, (I love photography, art and travel) and I have become proficient at sharing technical information with non-engineers, including the surgeons I work with. My ongoing dissertation work combines biomechanical data with multivariate statistics to detect subtle differences due to surgical technique. I hope that this work will eventually help patients return to their sport and leisure activities more quickly after surgery and improve their quality of life.

Elizabeth's Research:

I am studying the biomechanics of patients after anterior cruciate ligament (ACL) reconstruction surgery, in collaboration with orthopaedic surgeons at Kingston General Hospital. We are collecting data to compare a conventional surgical technique with a new suspension technique, and develop functional assessment methods for a post-ACL reconstruction population. Although my work is focused on paediatric patients, this work is significant for ACL reconstruction in general because objective, functional outcome measures for post-operative performance do not currently exist. Existing subjective measures, such as the IKDC score, and static laxity measures are poorly correlated with return to sporting activities. Once developed, these new objective measures could be used to verify whether new techniques yield clinically meaningful improvements in dynamic function.

The unique features of my work are its focus on paediatric subjects, the frequency of data collection sessions, the integration of muscle activity, force and motion data and the breadth of functional activities studied. Our pilot work supports previous adult studies from other centres showing persistent kinematic and kinetic differences post-ACL reconstruction, particularly during high demand activities. This novel data set, combined with advanced multivariate pattern recognition techniques will hopefully yield new insights regarding factors affecting recovery from ACL reconstruction.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

Anterior cruciate ligament (ACL) injuries generally occur during multi-planar movements, such as rapid cuts or landings from a jump. Similarly, recovery occurs across multiple planes and modalities; for example, injured subjects exhibit increased thigh muscle co-contraction combined with increased tibial rotation and reduced flexion moment.

Therefore, a uniaxial or purely saggital plane analysis would not be sufficient to capture either injury mechanism or recovery. My study involves rapid, demanding, multi-planar activities (jumping and cutting) that mimic the sporting activities that paediatric subjects wish to return to. This makes multi-axial force plates with a large load capacity and high data capture rate critical to capturing these activities accurately.

PENNY ATKINS

Academic Institution: University of Utah

Academic Department: Bioengineering

Major(s): PhD Student in Bioengineering

Advisor: Prof. Andrew Anderson

Biomechanics of femoroacetabular impingement

About Penny:

As an undergraduate, I studied Industrial Engineering at Montana State University and completed my first research project utilizing a virtual driving simulator. After working in industry for four years, I decided to continue my passion for research and education in Bioengineering at the University of Utah.

Penny's Research:

My research focuses on the kinematics and load transfer across hips affected by femoroacetabular impingement (FAI), a condition affecting an estimated three million young, active adultsin the USA. I will be applying a combined experimental and computational modeling protocol to measure kinematics and estimate muscle forces/hip joint reaction forces in-vivo. Kinematics at the hip joint are measured using a technique termed “dual fluoroscopy and model-based tracking”. This system utilizes two x-rays placed at roughly 90 degrees to image joints moving in-vivo in real-time, multi-axis force plates, a motion camera system, and EMG data in combination with 3D models generated from CT scans of the person’s hip joint. This system allows for nearly identical recreation of the in-vivo motion within the hip joint, and estimation of joint reaction forces and muscle forces. Together, these biomechanical data will elucidate the mechanisms of hip osteoarthritis in FAI patients, which may provide motivation to develop alternative strategies to diagnose and treat this disorder.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

Multi-axis force measurements, along with the kinematic measurements from the dual-fluoroscopy system, will be fed into the muscle modeling software to predict muscle activation and joint reaction forces. As the dual fluoroscopy system measures hip kinematics in all three axes, it is important to include measurements of forces for all six components into the muscle models. Muscle models use static optimization to predict muscle forces; thus, it is imperative that force measurements be accurate, and in all six degrees of freedom. The chosen loading activities herein are complex. Single-axis force measurements would not provide relevant data to be used in the quantification of these hip joint reaction forces. Multi-axis force measurements, on the other hand, allow for the documentation of external forces which can then be translated into internal joint reaction forces. These internal forces can be used with the imaging data to determine the effects and progression of FAI.

MICHAEL GRANATOSKY

Academic Institution: Duke University

Academic Department: Evolutionary Anthropology

Major(s): PhD in Evolutionary Anthropology

Advisor: Prof. Daniel Schmitt

AXEL MOORE

Academic Institution: University of Delaware

Academic Department: Biomedical Engineering

Major(s): Biomedical Engineering

About Axel:

My research interest in articular cartilage mechanics began with my undergraduate study of marine engineering.  I first gained an appreciation for the impact of lubrication (or lack thereof) when I experienced a 900 kW diesel generator failure due to oil contamination.  The speed at which the problem manifested was so great that by the time engine was secured we had effectively destroyed the crankshaft.  These experiences combined with a family member suffering from joint pain sparked a fascination of human joint and cartilage lubrication.  My experiences and education suggested that a slow moving joint like the knee would be very poorly lubricated. What surprised me was not that cartilage sometimes fails, but that healthy cartilage survives and in fact thrives in this difficult mechanical environment.  Understanding how this happens is essential to understanding why and under what conditions failure occurs.  

Axel's Research:

The motivation for my research is osteoarthritis (OA), a leading cause of severe disability in the U.S.  OA is characterized by the progressive degradation of articular cartilage. Although the causes and mechanisms of the disease remain poorly understood, impact and other insults to the joint are known to initiate OA.

Healthy articular cartilage functions without significant wear under normal physiological conditions because of a unique biphasic tissue structure which induces interstitial fluid pressurization in response to contact and sliding. In my current research project I aim to demonstrate that localized cartilage damage can disrupt lubrication and initiate progressive OA.  I anticipate that local cartilage defects will facilitate the spread of damage by compromising fluid pressure locally and increasing the stresses on surrounding tissue.  This objective of this study is to: 1) demonstrate whether OA has a purely biomechanical pathway, 2) elucidate the nature of the responsible mechanism, and 3) provide the working understanding necessary for the design of controlled studies of OA progression and treatment.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

Multi-axis force sensing is an essential part of a friction coefficient measurement. Furthermore, it is important to recognize that the surface normal direction and the corresponding axis of the load cell are misaligned; this is especially true for cartilage, which is curved. Three-axis force sensing vastly improves measurement accuracy by enabling correction for axis mismatches between the sample and load cell. Additionally, accurate measurements of normal force and penetration depth are necessary for measurements of interstitial load support, fluid pressure, and lubrication. This combination of accurate friction coefficient and interstitial pressure measurements gives us the unique ability to quantify friction while directly probing the primary lubrication mechanism.

MINWOOK KIM

Academic Institution: University of Pennsylvania

Academic Department: School of Engineering and Applied Science

Major(s): Bioengineering

Minwook's website

About Minwook:

I was born and grew up in Seoul, South Korea. I received a bachelor’s degree from Myong Ji University in mechanical engineering and a master’s degree from the City College of New York in biomedical engineering. My research is focused on engineering of musculoskeletal tissues particularly articular cartilage. Outside of the lab, I enjoy traveling, playing soccer, drums and spending time with kids. 

Minwook's Research:

My main research interests lie in studying cartilage tissue engineering, especially developing tissue engineered cartilage using different types of hydrogels, which properties can be enhanced by mechanical stimulation, growth factors and culture conditions, and improving an integrative capability of engineered constructs in cartilage repair and regeneration to intervene musculoskeletal disease and restore natural function and morphology of articular cartilage. 

Over the past year, my research was aimed at developing perfusion-based tissue engineered cartilage grown in a hollow fiber bioreactor (HFBR) and evaluating the tissue growth and quality by using fourier transform infrared imaging spectroscopy (FT-IRIS), and also at developing tissue engineered cartilage we refer as “cartilage tissue analog” (CTA) by self aggregating suspension culture (SASC) method. 

Currently, I have begun investigations regarding functional cartilage tissue engineering using mesenchymal stem cells (MSCs) in hyaluronic acid (HA) hydrogels to evaluate cellular behavior of MSCs with long term dynamic loading and integrative cartilage repair using an in vitro model. The aim of this research is to acquire a mechanistic understanding of cellular behavior and functional adaptation of MSCs in association with HA hydrogels and how MSCs in hydrogels respond to mechanical stimulation. This understanding will be crucial to the development of tissue engineered cartilage that will be utilized to fill the defect and replace functions of normal cartilage. 

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

In this research, I have utilized a sliding contact bioreactor to mimic the mechanical stimuli arising from native joint motion. The recapitulation of depth-dependent properties is partially driven by mechanical forces; mechanical loading with motion induces remodeling of the immature matrix, leading to increases in compressive and tensile properties. The organization and orientation of collagen fibers influence tensile properties, which are highest in the superficial zone (the highest collagen content). The increases in tensile properties correlate with increases in collagen content and integrity. By introducing multiaxial loading that mimics the native environment, the engineered construct can experience compression through the depth and tension through the surface, simultaneously. This multi-axis stimulation bioreactor is unique to the field of cartilage tissue engineering. 

MAMIKO NOGUCHI

About Mamiko:

I was born in Japan, grew up in Malaysia, and have been studying at the University of Waterloo in Canada since 2006. I studied Kinesiology as an undergraduate, and during those years, I completed several work placements as an ergonomist, where I was first exposed to dealing with workplace injuries, particularly low back pain. I have been heavily involved in athletics as well – from paddling to running to cycling – and dealing with injuries over the years has taught me the importance of understanding the injury mechanisms with the goal of preventing injuries from happening in the first place.

Mamiko's Research:

My research interests lie in understanding the relationship between the mechanical environment and the biological responses of the intervertebral disc cells (IVD) in animal models. Eighty percent of the population will experience low back pain at some point in their lives: it is the most prevalent and costly musculoskeletal problem in North America. Low back pain is primarily linked to intervertebral disc degeneration involving both biological and structural changes. Since mechanical loading within the normal physiological range naturally triggers biologic cell responses (e.g. inflammation response) – which could negatively affect the structural integrity of the tissue in the long term – the onset of degeneration is difficult to identify. Current IVD models lack this time-varying biologic cell response associated with cumulative mechanical exposure, which could potentially indicate when and how degeneration initiates and progresses. Hence, my research will aim to develop a novel IVD model which enables prediction of biomechanical and biological responses from cumulative mechanical exposure. The results will provide a powerful and novel contribution to the development of methods to assess work tasks and set exposure limits, and will ultimately help prevent low back injuries.

Over the past year, as a part of my Master’s degree, I have been developing a new pressure sensor system that allows measurement of time-varying intradiscal pressure. Our laboratory has a vast amount of time-varying mechanical tissue response data (e.g. torque, specimen height, single and multiple lamellae stress-strain) collected using a multi-axial testing system, and intradiscal pressure was one of the measures necessary to help explain the onset of internal disc disruption.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

It has been shown that uni-axial loading (i.e. compression) increases the production of cells related to intervertebral disc degeneration. In addition, previous studies in our laboratory have demonstrated that multi-axial loading increases the magnitude of tissue damage. Therefore, with this award, we plan to build pressurized chamber bladders, a system that simulates physiological loading experienced in-vivo, which can be implemented in live animal models. The addition of time-varying biologic data (e.g. apoptotic, proteoglycan, collagen contents) using this multi-axial loading system will enable development of a novel intervertebral disc degeneration model.

ADAM FOSTER

Academic Institution: University of Arizona

Academic Department: School of Anthropology

Major(s): Anthropology

Adam's Website

About Adam:

I am a Ph.D. candidate in the School of Anthropology at the University of Arizona.  My interests center on using experimental and comparative methods to tease apart form and function in order to understand how and why selection-shaped component parts of bipedal morphology and physiology.  

Adam's Research:

My dissertation research takes an evolutionary developmental approach by examining the links between ontogeny, plasticity and the bipedal phenotype using rats as an animal model.  In this study, I induce a locomotor shift in a rat model using a custom harness system mounted over a treadmill.  Here I examine the role that a shift from quadrupedal to bipedal standing and locomotion has in generating adaptive morphology in the postcranial skeleton of a quadruped during ontogeny and adulthood.

Skeletal development will be tracked through regular µCT scans. Kinematic, kinetic and energetic data will be collected to link changes in morphology to changes in locomotor performance. The findings of this study will help us identify how behavior drives morphological adaptation and which morphologies may have been the first to evolve in response to a shift to bipedalism in the earliest hominins. 

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

Using a multi-axis fore plate is an important component in this study because it provides crucial data to link the kinematic data to morphological changes throughout ontogeny. Having multi-axis capabilities is important as walking involves extensor, flexor, and stabilizer muscles that necessarily function differently when shifting from quadrupedal to bipedal locomotion. Single-axis methods would not be able to fully capture the data required to link kinematic changes with morphological changes. In this study, multi-axis force data will be used to examine the amount of muscle force produced over a step. These data can be used to link changes in muscle activity to changes in skeletal morphology and to estimate the cost of locomotion using a muscle force production model (e.g. Pontzer et al. 2009).

JOHN MARTIN

Academic Institution: University of Pennsylvania

Academic Department: Mechanical Engineering and Applied Mechanics

Major(s): Mechanical Engineering

John's Website

About John:

I grew up in Delran, NJ and was first exposed to mechanical engineering as an undergraduate at The College of New Jersey. I continued my education in engineering as a graduate student at the University of Pennsylvania because I enjoy the challenge the classes and research present. I am currently a third year PhD student in the Mechanical Engineering and Applied Mechanics department.

John's Research:

My current research is focused on intervertebral disc degeneration and re-establishing healthy intervertebral joint mechanical function. In particular, our lab has developed a nanofiber based engineered disc replacement that we seed with cells and implant into the rat spine. We believe tissue engineering will one day be beneficial to populations that are susceptible to advanced disc degeneration especially military service members.

Our lab has previously demonstrated that cells seeded on engineered materials increase the production of important structural proteins when the material is mechanically loaded. With this award, we plan to build a bioreactor, a machine that reproduces the in vivo ambient conditions and multiaxial forces experienced by the intervertebral disc, in order to stimulate cells within a tissue engineered disc replacement.

The importance of multi-axis force measurement and/or testing machines to your research (as compared to single-axis methods):

In my research I have utilized compression and torsion loading orientations to evaluate functional properties of the intervertebral disc. In compression, the nucleus pulposus generates hydrostatic pressure that is confined circumferentially by the annulus fibrosus and axially by the endplates of adjacent vertebral bodies. In torsion, since the nucleus pulposus is the consistency of a gel, only the annulus fibrosus and vertebral bodies are involved. By testing in these two orientations, the disc as a structure can be assessed in compression while the mechanical response of the annulus fibrosus can be isolated in torsion. In this manner I have been able to examine the mechanical response of the intervertebral disc in two animal models of disease. First, I have investigated the progression of common intervertebral disc degeneration in a mouse model of the disease, and second I have studied the genetic disorder MPS VII in a dog model.