Virtual Poster Session

Welcome to the Virtual Poster Session, a new and powerful tool for networking and information exchange. Here you can share your work, search though the poster library, and start a dialogue with others in your field. Each uploaded poster that pertains to force measurement and testing can currently be used to apply for an academic travel scholarship; please see the Scholarships page for application details and deadlines.

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Name: clachanc

Compliant flooring is a promising intervention for reducing fall-related injuries among long-term care residents but may increase the forces required for direct care staff to perform pushing tasks. We analyzed initial and sustained hand forces required for care staff to push a wheelchair (n=14) or two floor-based lifts (traditional manual and motor-driven) (n=14), loaded with average and ninetieth percentile resident weights, over four flooring systems. Compliant subflooring increased push forces compared to concrete subflooring, especially with vinyl overlay, but pushing over a compliant subfloor with vinyl overlay did not require more force than pushing over a concrete subfloor with carpet overlay. Compared to the traditional lift, the motor-driven lift substantially reduced push forces on all flooring systems. With the motor-driven lift only, resident weight did not influence push forces. These results provide new knowledge about the effects of compliant flooring and motor-driven lifts on push forces in long term care.

Listed In: Other
Name: dyocum

Purpose: An increased likelihood of developing obesity-related knee osteoarthritis may be associated with increased peak internal knee abduction moments. Increases in step width may act to reduce this moment. The purpose of this study was to determine the effects of increased step width on knee biomechanics during stair ascent of healthy-weight and obese participants. Methods: Participants ascended stairs while walking at their preferred speed in two different step width conditions – preferred and wide. A 2 x 2 (group x condition) mixed model analysis of variance (ANOVA) was performed to analyze differences between groups and conditions (p<0.05). Results: Increased step width decreased the loading-response peak vertical ground reaction force (GRF), loading-response knee abduction moment, knee extension ROM, and knee abduction ROM in both groups. However, it also increased loading and push-off peak mediolateral GRF, and peak knee abduction angle in both groups. Obese participants experienced a disproportionate increase in loading and push-off peak mediolateral GRF, and peak knee abduction angle compared to healthy. Conclusion: Increased SW successfully decreased loading-response peak knee abduction moment. Implications of this finding are that increased SW may decrease likelihood of developing medial compartment knee osteoarthritis. This study shows that this gait modification affects obese and healthy-weight differently, and the influence of body mass on knee biomechanics.

Listed In: Biomechanics
Name: meadowkd

Disc function is mechanical, and measures of disc mechanical function are important to address spine function, degenerative disc disease, and low back pain. In vivo measures of disc mechanical function are needed, however the current standard in disc imaging is to acquire a single static image and classify the disc’s appearance using qualitative integer scales for degree of degeneration. Current grading standards are acknowledged as insufficient to identify symptomatic discs for treatment. In addition, static T2 weighted MRI cannot provide mechanical function information – mechanics must be measured as the change following a load or deformation perturbation. Because the disc experiences significant compression and height loss throughout the day, and because flexion-extension postures are often associated with low back pain, these physiological mechanical perturbations have potential to be used to quantify disc mechanics in vivo. The objective of this study was to use MRI-based methods to quantify in vivo disc function by measuring changes in disc geometry and T2 relaxation time with diurnal changes and with controllable posture. Quantification of in vivo disc mechanics by using diurnal loading or prescribed posture changes has potential to improve our ability to identify, evaluate, and treat degenerative disc disease. Symptomatic discs may have aberrant mechanics; if so, in vivo measurements of mechanical function may, with continued development, facilitate diagnosis of pathological discs.

Name: asondall

The purpose of the study was to determine whether increasing trunk flexion (TF) and whole body inclination (WBI) angles influences peak knee, hip, and trunk kinematics and kinetics during running. Nineteen participants ran over ground at a self-selected speed under three postures: self-selected normal (SSN), TF, and WBI. Analyses revealed significant differences between conditions for peak knee, hip, and trunk flexion angles and peak knee and hip extension moments. Both TF and WBI postures are effective strategies for reducing peak knee extension moments during running with more load distributed to the hips. This may reduce PFJ stress and therefore aid in knee injury prevention and management. Individual preference of either altered running posture should be utilized in a clinical setting.

Listed In: Biomechanics
Name: deluccaj27

Residual stresses are known to exist in human intervertebral discs but have not been incorporated in finite element models. A multigeneration model was applied to the annulus fibrosus of the intervertebral disc to simulate residual stresses arising from growth and remodeling. The intervertebral disc shape and compressive creep were used to verify that the multigeneration approach generates realistic values of residual stress. The model was then validated by comparing its 6 degree-of-freedom mechanical response to experimental data. Human intervertebral discs were tested in a custom-built hexapod in all 6 degrees-of-freedom (lateral shear, anterior-posterior shear, torsion, bending, flexion, and compression). Incorporating residual stresses resulted in a finite element model which can predict 4 degrees-of-freedom while excluding residual stresses produces a finite element model that can only predict 2 degrees-of-freedom.

Name: danialkia

Knowledge of ligamentous contributions to joint stability is essential to restore normal joint range of motion and functionality through reconstruction procedures. Although, there has been numerous studies on the pathomechanics of the elbow joint, there have been very few rigorous and systematic attempts to characterize the roles of soft tissues during clinically relevant motions.
Five fresh frozen cadaveric elbows from three male subjects were used for this study. In-vitro simulations were performed using a VIVO six degree-of-freedom (6-DOF) joint motion simulator (AMTI, Watertown, MA) capable of virtually simulating the effects of soft tissue constraints (virtual ligaments). This study introduces a unique, hybrid experimental-computational technique for measuring and simulating the biomechanical contributions of ligaments to elbow joint kinematics and stability. In vitro testing of cadaveric joints is enhanced by the incorporation of fully parametric virtual ligaments, which are used in place of the native joint stabilizers to characterize the contribution of elbow ligaments during simple flexion-extension motions using the principle of superposition.
our results demonstrate the importance of AMCL and RCL structures as primary stabilizers under valgus and varus loading respectively. Virtual ligaments demonstrate the ability to restore the VV stability of the joint in the absence of any soft tissues attached to the osseous structures. This demonstrates the effectiveness of “virtual” ligaments for in vitro testing of elbow joint biomechanics, with applications in pre-clinical assessment of elbow implants.

Name: Patrick Carden

Analysis of lower limb biomechanics during jumping and landing tasks are often used to assess lower limb injury risk in research and applied practice within professional team sports. However, there are limited instances of these movements being incorporated into research focusing on Achilles tendinopathy development. PURPOSE: To investigate whether differences existed in lower limb motion and moments during jumping and landing between individuals who develop Achilles tendinopathy and those who remain injury free. METHODS: Male professional Rugby Union players without lower limb injury (n = 43) were compared to players who sustained Achilles tendinopathy (n = 8). Five single-leg drop vertical jumps per leg were performed at the start of their pre-season training. Motion of the lower limbs were recorded synchronously with ground reaction force. RESULTS: Players who sustained Achilles tendinopathy demonstrated significantly increased rear-foot inversion-eversion range of motion (p = 0.03), a reduction in dorsi-plantarflexion range of motion (p = 0.01) and knee flexion-extension range of motion (p = 0.03). Peak dorsiflexion velocity (p = 0.02) and peak knee flexion velocity were also reduced in those with Achilles tendinopathy (p = 0.03). No differences in hip joint kinematics were observed. Controls displayed slightly larger peak plantarflexion moments; however this difference was not statistically significant (p = 0.15, g = 0.60). CONCLUSIONS: The findings indicated that players who subsequently developed Achilles tendinopathy displayed an altered single leg landing strategy when compared to players who did not sustain injury; with motion of the ankle joint and rear-foot most influenced.

Name: catelli

INTRODUCTION: Cam femoroacetabular impingement (FAI) is characterized by an osseous overgrowth on the femoral head-neck junction [1], leading to pain and limited range of motion (ROM) during daily life activities [2]. Corrective surgery is highly recommended and performed in order to reduce or eliminate pain and further development of osteoarthritis (OA). However, it is still unclear whether it would lead to improved functional mobility. The purpose was to compare kinematic variables of the operated limb between FAI patients when performing a squat task pre-surgery and at around 2-year follow-up. A secondary objective consisted of express the results in a biomechanical functional score to quantify the joint kinematics of FAI patients compared to healthy control (CTRL) participants.
METHODS: Eleven male patients (7 arthroplasty: 34.6±8.1 years, 25.7±3.2 kg/m2; 4 open: 33.3±7.1 years, 24.9±1.9 kg/m2) and 21 CTRL (2F/19M, 33.4±6.7 years, 25.4±3.3 kg/m2) participants were recruited from the orthopaedic surgeon’s clinical practice. Patients were assigned to either an arthroplasty or open FAI surgery correction. The participants signed prior to their participation a consent form approved by the hospital and university ethics board. Patients agreed to undergo motion analysis prior to and 2 years after the surgery. The CTRL were selected based on similar age and BMI as the FAI group and underwent the same motion analysis protocol.
At the local hospital, CT scan was performed in all participants to confirm an alpha-angle higher than 55º and also establish their pelvic and knee bony landmarks. At the motion laboratory, the participants were outfitted with 45 reflective markers and performed a minimum of five trials of deep squat at a self-selected pace. Three-dimensional joint kinematics (200 Hz) of the lower limbs were captured using a ten-camera motion analysis system (Vicon, UK). Kinematics data were processed in Nexus 1.8.3 (Vicon, UK) using a modified Plug-In-Gait model and exported with a custom MATLAB script (Mathworks, USA) to calculate group averages and extract relevant variables. All trials were time-normalized based on a full squat cycle (descent and ascent phases) and individual averages for each participant were calculated across the trials.
Four kinematic variables were included in the analysis: pelvis, hip, knee, and ankle sagittal angles. The normalized root-mean-square deviation (nRMSD) was calculated between the FAI and the CTRL groups for both pre- and post-surgery conditions, expressed by

Name: emesserschmidt

Title:  Head Acceleration During Girls Youth Soccer Using Real Time Data
Emily Messerschmidt, Katlyn Van Patten, Ryan Lee, Srikant Vallabhajosula

Purpose/Hypothesis: While the acute effects of concussion have been the focus of research in the past, there is a new emphasis toward following the cumulative effects of sub-concussive head accelerations in athletics. This is especially important in youth athletes because the developing brain is more vulnerable to injury from head trauma in sports like soccer due to techniques such as heading, that can result in numerous head impacts throughout play. There is a current lack of evidence on the magnitude and frequency of head accelerations that occur during real-time youth sports, including soccer, and whether these accelerations have a detrimental cumulative effect. The purpose of the current study was to measure the head acceleration that youth athletes experience during real-time soccer games.
Number of Subjects: 31 under-15 girls club soccer participants. 11 players monitored each game.
Materials/Methods: 3 season games were observed. Triax Smart Impact Monitor headband accelerometers were worn during gameplay to collect real-time head impact data. Forces >10g were recorded. Games were video recorded for further analysis. Head impacts were categorized by type of impact: purposeful header (PH), player to player (PP), player to ground (PG), and ball to head (BH). Data was analyzed using descriptive statistics.
Results: A total of 171 impacts were observed (PH=20, PP=113, PG=36, BH=2). Only one impact recorded was above the concussion threshold of 70g. The majority (77%) of impacts observed were <10g. Of the accelerations recorded, PH resulted in the largest average acceleration (36.8±14.9g) followed by PG (20.5±4.2g), and PP (19.5±4.6g). The maximum accelerations for PH, PG and PP were 73g, 26g and 30g respectively. No BH accelerations were recorded >10g.
Conclusions: While PH yielded the highest average acceleration, it was one of the least frequently occurring impacts. PP impacts were most common however the majority produced little to no head acceleration. While there was variability of head acceleration that occurred within each type of impact, none produced consistently dangerous (≥70g) accelerations.

Clinical Relevance: This study provides preliminary evidence of the impacts sustained during girls youth soccer games for athletic trainers or sports physical therapists who are monitoring athletes for concussions. The findings reveal that the use of headband accelerometers to measure real-time data can be a useful tool to monitor multiple players on the field. There remains a need for further research into the effect of cumulative sub-concussive impacts during soccer in youth athletes with larger sample size. Further studies should investigate the impacts players sustain over multiple seasons to observe if those who experience multiple sub-concussive impacts report concussion-like symptoms or show concussion-like signs. Additionally, this study adds evidence to the existing literature that the use of video analysis to confirm the occurrence of impacts and to correctly categorize them is highly beneficial to ensure reliability in future studies.

Name: kvalenzu

Stair negotiation is one of the more difficult daily activities reported by total knee replacement (TKR) patients. Dissatisfied TKR patients have reported increased difficulty with stair negotiation, however it is unknown what the underlying mechanical issues are for this population. Therefore, the purpose of this research was to examine the knee joint biomechanics of dissatisfied TKR patients during stair descent. Nine dissatisfied TKR patients (34.6±14.3 months from surgery), 15 satisfied TKR patients (29.3±12.8 months from surgery), and 15 healthy participants performed stair descent trials on a five-step instrumented staircase at a preferred gait speed. The dissatisfied group showed lower knee extension and abduction moments in their replaced limb. The 2nd peak vertical ground reaction force (VGRF) and 1st and 2nd peak knee internal rotation moments showed lower moments for replaced limbs compared to non-replaced limbs. First peak VGRF was reduced for dissatisfied group compared to satisfied and healthy groups. The dissatisfied TKR group had significantly increased pain levels on their replaced limb compared to all other groups and limbs. The dissatisfied group had reduced gait speed compared to the satisfied and healthy groups. Increased pain levels lead to reduced descent speed and peak loading-response and pushoff sagittal plane knee joint moments in dissatisfied total knee replacement patients during stair descent. This creates an asymmetry in the extension loading response moment for the dissatisfied group, with the non-replaced limb showing increased joint moments whereas the satisfied and healthy groups do not have that imbalance.

Listed In: Biomechanics