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: arielpelletier

Introduction: Running is a popular form of physical activity linked to various lower extremity injuries. A commonly used technique for injury prevention and rehabilitation is taping. There is considerable research investigating running biomechanics, however, there has been limited to no research examining the effects of gender, speed, and the type of tape used on two-dimensional lower extremity kinematics. Therefore, the purpose of this pilot study was to investigate the effects of gender, speed, and tape on two-dimensional lower extremity kinematics and stride characteristics during running.

Method: Eight healthy runners participated (4 males, 4 females). Taping interventions (Leukotape, Kinesio Tape, no tape) and speeds (2.35 m/s, 3.35 m/s) were randomized and lower extremity stride kinematics were obtained using the Peak Motus System at initial contact, midstance, and toe off of running. Comparisons were made using descriptive statistics.

Results: Females exhibited greater hip (FIC= 164.04+1.99°; MIC= 167.54+2.12°) and knee flexion (FIC= 167.73+0.93°; MIC= 170.42+1.65°; FPK= 142.83+1.28°; MPK= 146.35+1.21°), while males had greater ankle dorsiflexion (FIC= 88.60+1.00°; MIC= 84.14+1.08°) and plantarflexion (FTO= 51.90+1.01°; MTO= 55.99+0.825°). Females spent more time in support (FCT= 0.28+0.03s; MCT= 0.26+0.02s) while males spent more time in the air (FFT= 0.45+0.02s; MFT= 0.48+0.01s). Faster speed was associated with greater hip flexion and extension (SIC= 167.57+1.95°; FIC= 164.01+2.11°; STO= 197.14+1.23°; FTO= 201.28+0.74°), peak knee flexion (SPK= 145.39+1.82°; FPK= 143.79+2.39°), and less time during contact (SIC = 0.30+0.01s; FIC= 0.25+0.00s).

Conclusion: Gender and speed seem to have effects on lower extremity stride kinematics, whereas type of tape does not.


Listed In: Biomechanics, Gait, Other
Name: ADiffendaffer

Peripheral arterial disease (PAD) is a vascular disease characterized by atherosclerotic blockages restricting blood flow to the lower extremities causing pain and discomfort with physical activity. Several studies have previously found decrements in ambulation associated with PAD, such as decreased joint moments and powers before and after the onset of claudication pain [1]. With decreases in moments and powers, the joint work may also be decremented as well. Thus, the purpose of this study was to investigate the positive and negative work at the ankle, knee and hip of PAD patients in a pain-free condition and compare them to gait-velocity matched controls.

Five patients with PAD and five healthy older controls were consented for participation. Subjects walked along a 10-meter walkway at their own self-selected speed while kinematics and kinetics were recorded. Each subject rested one minute between trials to mitigate fatigue and prevent ischemic pain. The positive and negative joint work for the PAD patients’ affected limb and the right limb of each control were analyzed and compared through independent t-tests (α=0.05).

Five PAD patients (66.6 + 6.2 years; 178.2 + 9.3 cm; 102.6 + 18.5 kg; 1.16 + 0.07 m/s) and five controls (69 + 4.6 years; 174.5 + 1.6 cm; 79.4 + 8.14 kg; 1.30 + 0.09 m/s) were used for analysis.

From this study it was found that patients with PAD exhibit a 26% reduction in positive ankle joint work during stance phase than their healthy counterparts (p=0.012).


Listed In: Biomechanics
Name: mmansfi1

Physical testing of TKR systems to assess stability is an important aspect in screening candidate TKR designs which can be expensive and time consuming. Costs can be reduced by utilizing 3D printed plastic components. The objective is to compare the kinematics and intrinsic constraint of metal-on-plastic (M-P) and plastic-on-plastic (P-P) implants under physiologically relevant loading, with and without simulated ligament contributions, in order to elucidate the effects of material pairings. A cruciate retaining TKR implant was created by combining a 3D printed ABS plastic tibial component with the standard cobalt chrome femoral component, as well as a 3D printed ABS plastic replica femoral component. This results in both M-P and P-P articulations that were mounted to a VIVO 6-DOF joint motion simulator (AMTI, Watertown, MA), which was used for in vitro constraint testing using functional laxity tests. Anterior-posterior (AP) and internal-external (IE) constraint was measured based on resulting deviations from the normal path when superimposed AP and IE loads were applied. Ligaments were simulated as tension-only point-to-point springs using the soft tissue modelling capabilities of the VIVO. Different kinematics were observed between the M-P and P-P implants which could be the result of different initial implant positioning on the joint motion simulator or due to “stiction” of the P-P implant. The functional laxity of the implant system tested appears to be relatively insensitive to the material pairing and ligament presence. These relationships are complex and hard to predict, which underscores the importance of pre-clinical in vitro testing.


Name: ulmans22

Multi-segmented foot and ankle (FandA) models provide more information regarding intrinsic foot motion compared to rigid-body models due to additional markers on bony landmarks of the foot. Marker placement sensitivity is a concern, especially in patients with bony abnormalities, because kinematics vary with marker placement deviations. PURPOSE: Assess kinematic changes due to marker placement error using the TSRHC multi-segmented FandA model. METHODS: Our participant was an 18yo female lacking any prior orthopedic conditions. The Plug-in-Gait model was used with the TSRHC model. An experienced clinician executed all marker placements, systematically moving each marker approximately 2.5mm within two planes. Three dynamic trials were collected for each condition, and static trials were used to calculate exact distances markers moved. Six force plates (AMTI) were utilized to confirm a consistent walking pattern. Graphs analyzed included: 1)PIG–ankle dorsiflexion, foot rotation, foot progression angle, 2)TSRHC–hindfoot, forefoot, FF-tibia. For each condition, the peaks of affected kinematic graphs were compared to assess correlations. Intra-trial error was determined by the maximum difference across walking trials. CONCLUSION: The hindfoot was most sensitive to transverse plane marker placement errors. Markers on metatarsals periodically rose vertically when moved laterally due to foot curvature causing errors in the sagittal plane as well. The forefoot also had transverse plane errors when metatarsal markers were moved. This case study illustrates the importance of proper marker placement training when utilizing a multi-segmented foot model. A thorough understanding of a utilized model is imperative, including how sensitive the model is to marker placement.


Name: Jrfoster

A period of incoordination and fatigue is commonly associated with the transition run in triathletes, in which running mechanics are thought to be altered. Few studies have examined the changes in ground reaction forces and vertical loading rate during the transition run. Our purpose was to assess the changes that occur in ground reaction forces during a fatigued transition run in triathletes. 13 recreational male triathletes (34 ± 4.2 years) performed an incremental cycling test and a cycle to run transition on separate testing sessions. A 15-camera Vicon motion capture system collecting at 200 Hz and an AMTI force instrumented treadmill collecting at 2000 Hz were used in conjunction with a modified Plug-In Gait marker to collect trajectory and analog data for pre and post-cycling running trials. Ground reaction forces and temporal spatial parameters were assessed during stance of all running trials using Visual 3D software. Peak vertical ground reaction force and step length decreased significantly from pre-cycling to immediate post-cycling measures (p=.003, p<.001), no difference existed for either variable for pre-cycling vs. 10min post-cycling. Instantaneous peak vertical loading rate (IVLR) and step rate increased significantly from pre-cycling to immediate post-cycling measures (p=.05, p<.001), no difference existed for stride rate for pre-cycling vs. 10min post-cycling. IVLR remained significantly increased at the 10 min post-cyling (p=.035). The study findings suggest that fatigue from prolonged cycling can negatively impact triathletes’ ability to attenuate ground reaction forces in subsequent running.


Name: rlkrup

Calculating and interpreting joint moments using marker position and ground reaction force (GRF) data is a fundamental part of gait biomechanics research. Due to noise in marker positions, these data are low-pass filtered prior to performing inverse dynamics. Traditionally, kinematic data are filtered at low cutoff frequencies (~6 Hz) and kinetic data are filtered at high frequencies (~30-100 Hz). This technique can result in joint moment impact peaks, particularly during high-impact movements. Filtering marker and GRF data at the same cutoff frequency has been suggested to attenuate these impact artefacts. The effect of various filtering approaches on joint moments in walking is unknown. The purpose of this study was to compare the effect of low-pass filtering cutoff frequencies on joint moments during walking. We hypothesized that filtering would not affect peak joint moments during walking due to smaller violations of the rigid body assumption compared to high-impact movements. Kinetic and kinematic data were collected for twenty-four health adults walking at self-selected speed. Marker position and GRF were smoothed using a 4th-order dual-pass Butterworth filter with cutoff frequencies of 6/45 Hz, 6/6 Hz, 10/10 Hz, for markers and GRF, respectively. A one-way repeated measures ANOVA tested for the effect of filter frequency on peak hip and knee joint moments. Peak hip and knee moments were greater when filtered at 10/10 Hz compared to 6/45 Hz. Although there were differences between cutoff frequency conditions, the effect sizes were small, suggesting that the differences are not large enough to have a meaningful effect.


Listed In: Biomechanics
Name: afalaki

Over the past years, we have developed a test for postural stability based on the theory of synergies stabilizing salient performance variables. In this study, effects of Parkinson's disease (PD) and dopamine-replacement therapy on multi-muscle synergies stabilizing the center of pressure (COP) coordinate were explored between: (1) a cohort of 11 patients without clinically identifiable postural problems (Hoehn-Yahr stage II) and 11 age-matched controls, and (2) a cohort of 10 patients tested off- and on-medication, with and without postural problems (stage II and III, n = 5 per stage). Participants stood on a force platform and performed cyclical body sway at 0.5 Hz along the anterior-posterior direction. Electromyographic signals from 13 leg and trunk muscles were used to compute: (1) the amount of inter-cycle variance that did not affect (VUCM) and affected (VORT) COP coordinate, and (2) the magnitude of the cycle-to-cycle motion that did not change (motor equivalent: ME) and changed (non-motor equivalent: nME) the COP coordinate. We hypothesized that both methods would produce indices sensitive to PD and dopaminergic medications. Compared to controls, patients showed significantly smaller inter-cycle VUCM and ME components suggesting a less flexible, and hence less stable, behavior. Moreover, inter-cycle variance within/orthogonal to the UCM correlated with ME/nME displacements. Results suggest clinical utility of variance and motor equivalence analyses of postural instability in early stages of PD and quantifying the effects of dopamine-replacement drugs. The analysis of motor equivalence is particularly attractive because it requires only a handful of trials (observations).


Listed In: Neuroscience
Name: presidentk

People with diabetes mellitus (DM) have been reported of increased ground reaction force (GRF) and plantar propulsion force (PPF) that will worsen the formation of plantar ulcer. The reliance of perception of self-motion has been previously addressed for maintaining stability during locomotion in DM. Therefore, we speculate that perception of self-motion will affect DM’s plantar force adjustment by decreasing GRF/PPF along with reducing of variability (CV). We recruited five DMs and three healthy controls to walk on an instrumented treadmill with their self-selected pace. All subjects went through three no self-motion and three self-motion walking trials (120s/trial). The self-motion was generated by presenting a virtual corridor that moved toward subjects with their matched velocity. Three-axis force data were recorded at 300 Hz. Two-factor ANOVA with repeated measures were conducted to examine the role of visual cue impacts GRF/PPF in DM and age-matched healthy. The visual cue and group factors show significant interaction on PPFPeak and PPFCV. The following comparisons showed significant visual effect on reducing: (1) PPFPeak in healthy controls; (2) PPFCV in DM patients. Generally, the decreased PPFPeak and PPFCV founded in this study were in line with previous study and can be explained as the optimization of neuromuscular locomotor system in the anteroposterior direction. Furthermore, visual perception of self-motion shows its effect on reducing PPFPeak during toe-off in healthy controls. Lastly, the significant decreased PPFCV of DM versus healthy stands for the reduced human movement variability observed in DM’s neuromuscular locomotor system when perception of self-motion is provided.


Name: claesamy

Nucleotomy is a surgical procedure following herniation and also simulates the reduced nucleus pulpousus (NP) pressure that occurs with disc degeneration. Internal disc strains are an important factor in disc function, yet it is unclear how internal strains are affected by nucleotomy. Grade II L3-L4 human cadaveric discs (n=6) were analyzed intact and after a partial nucleotomy that removed 30-50% of the NP through a left posterolateral incision (incision) while the contralateral side remained intact (uninjured). Two cycles of stress-relaxation testing were performed for reference (50N) and loaded (0.70MPa) configurations. After each 8hour equilibration period, the reference and loaded discs were imaged separately in a 7T MRI scanner (0.3mm isotropic resolution). The reference and loaded images were registered to calculate internal strain within the annulus fibrosus (AF) lamellae and discs were averaged to create anatomical templates. Circumferential, radial, and axial strains for each disc were transformed to the average templates, effectively normalizing the strains. Five circumferential regions were defined within the mid-third of the templates. Nucleotomy altered disc strains on both the incision and uninjured sides from the intact state. Strain fields were inhomogeneous through the five regions. Mean circumferential strain was unaffected by nucleotomy on the uninjured side, but decreased with incision, showing hoop strains through the AF were disrupted. Mean compressive axial strains were higher after nucleotomy, effectively reducing AF stiffness, and mean radial strains were unaltered after partial nucleotomy. These findings are important to address etiology and progression of degeneration, and to develop and evaluate therapeutic interventions.


Name: sfray9292

The purpose of this study was to quantify adaptation to a new prosthesis in terms of mechanical work profiles. Currently, there is a lack of knowledge on how individuals adapt to a new prosthesis, with many studies investigating different prosthetic feet but not adaptation over time. Thus, there is a need for objective measures to quantify the process of adaptation. Mechanical power and work profiles are a prime subject for modern energy-storage-and-return type prostheses, as the amount of energy a prosthesis stores and returns (i.e., positive and negative work) during stance is directly related to how a user loads and unloads the limb. 22 individuals with unilateral, transtibial amputation were given a new prosthesis at their current mobility level (K3 or above) and wore it for a three-week adaptation period. Kinematic and kinetic measures were recorded from walking on overground force plates at 0, 1.5, and 3 weeks into the adaptation period. Positive and negative work done by the prosthesis and intact ankle-foot was calculated using a unified deformable segment model. Positive work from the prosthesis side increased by 6.1% and intact side by 5.7% after 3 weeks (p = .041, .036). No significant changes were seen in negative power from prosthesis or intact side (p = .115, .192). Analyzing work done by a prosthesis may be desirable for tracking a patient’s gait rehabilitation over time. Future work may analyze how mechanical work profiles relate to more traditional clinical measures.