Browsing by Author "Edwards, W. Brent"

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    A biomechanical study of clamping technique on patellar tendon surface strain and material properties using digital image correlation
    (Elsevier, 2021-01-01) Firminger, Colin R.; Edwards, W. Brent
    Several clamping techniques exist for ex vivo mechanical testing of tendon. For the patellar tendon, one can choose to clamp directly to the bony attachment sites, the tendon itself, or a combination of the two; however, the influence of these techniques on localized strains and gross material properties is unknown. To this end, uniaxial tensile tests were performed on eleven porcine patellar tendons in three clamping setups while digital image correlation was used to measure axial and transverse strains, Young's modulus, and Poisson's ratio. The setups involved clamping to: 1) the patella and tibia, 2) the patella and the dissected distal tendon, and 3) the dissected proximal and distal tendon. Axial strains in the tendon-tendon clamping setup were 181% higher than patella-tibia clamping (p = 0.002) and 131% higher than patella-tendon clamping (p = 0.006). Transverse strains were not significantly different between clamping conditions (p ≥ 0.118). Young's modulus was 50% (p < 0.001) greater for patella-tibia clamping and 42% (p < 0.001) greater for patella-tendon clamping when compared to tendon-tendon clamping. For all clamping setups, the tendon illustrated auxetic behaviour (i.e., negative Poisson's ratio); however, the Poisson's ratios were 80% smaller in the patella-tibia setup (p = 0.006) and 71% smaller patella-tendon setup (p = 0.007) compared to the tendon-tendon setup. These results illustrate that discretion should be utilized when reporting material properties derived from mechanical tests involving direct clamping to the dissected patellar tendon at both ends, as this clamping technique significantly increases axial strains, reduces Young's modulus, and alters the tendon's natural auxetic behaviour.
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    Biomechanical Measures of the Muscle-Bone Unit in Postmenopausal Females: A Pilot Study
    (2016) Pangka, Aleen; Edwards, W. Brent
    Bone is a dynamic tissue that adapts its stiffness and strength to the habitual loading environment. Muscles attach to bone and the largest loads experienced by bone come from voluntary muscle contractions. The objective of this study was to quantify the relationship between functional measures of muscle loading (i.e., joint moments, isometric muscle strength, and physical activity questionnaire scores) and bone stiffness, strength, and volumetric bone mineral density (vBMD). Moderate correlations were observed between peak joint moments and bone stiffness (r=0.480, p=0.032) and strength (r=0.490, p=0.028). No relationship was observed between joint moments and vBMD, or between any bone measurements and muscle strength or physical activity. These findings suggest that muscle loading may influence bone stiffness and strength through alterations in bone quality rather than quantity, and that the functional relationship between muscle and bone may be best reflected by habitual measures of skeletal loading.
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    Bone Loss and Fracture Risk Following Spinal Cord Injury: Patient Priorities and Treatment Options
    (2024-04-22) Crack, Laura Elizabeth; Edwards, W. Brent; Gabel, Leigh; Kline, Greg
    Rapid and profound bone loss is a well-known secondary complication following spinal cord injury (SCI), occurring primarily below the level of neurological lesion due to mechanical disuse. The greatest loss of bone is experienced during the acute phase of injury, and established osteoporosis often persists into the chronic phase, with no current standard care plan for patients. The main goals of this thesis were to: (1) explore patient knowledge and awareness regarding bone loss, fracture risk and treatment options following SCI, and (2) to investigate pharmaceutical treatment options to prevent bone loss in acute SCI, as well as treat established osteoporosis in chronic SCI. Three independent studies were carried out and are presented in Chapters 3-5, respectively. Survey results demonstrated that while more than half of participants with SCI were able to correctly answer knowledge-based questions regarding bone health, less than one-fifth had received education on the topic, and approximately three-quarters were interested in learning more about treatment options. Our clinical trials demonstrated the efficacy of zoledronic acid (antiresorptive therapy) to mitigate loss of bone mineral and strength at the hip in acute SCI, regardless of one’s ability to regain ambulation following injury, and the efficacy of romosozumab (anabolic and antiresorptive monoclonal antibody therapy) to increase bone mineral and strength at the hip, but not the knee, in women with chronic SCI. These findings add to the existing body of literature suggesting zoledronic acid is a strong candidate for standard of care to mitigate bone loss during acute SCI, and indicating that further investigation is required to find a treatment that can increase bone mineral, and reduce fracture risk, at both the hip and knee during chronic SCI for those with established osteoporosis.
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    Characterizing the structure-function relationship of hand osteoarthritis using dynamic and high resolution CT imaging
    (2024-03-27) Kuczynski, Michael Tadeusz; Manske, Sarah; Ronsky, Janet; Edwards, W. Brent; Schneider, Prism
    Osteoarthritis (OA) is the most common form of arthritis and affects the trapeziometacarpal (TMC) joint. While the etiology of OA is still not fully understood, it is a multifactorial disease with biomechanical factors associated in its development. The thumb is estimated to account for over 40% of the hand’s entire function, largely due to the TMC joint. A better understanding of structural and functional changes in TMC OA may improve our understanding of this degenerative joint disease. A recent advancement in computed tomography (CT) now allows for imaging moving joints in vivo. This technique, termed dynamic CT, provides a unique opportunity to quantify joint biomechanics in vivo. In this thesis, novel methodologies are presented that improve processing of dynamic and high-resolution peripheral quantitative CT (HR-pQCT) scans. These methodologies allow for semi-automated quantification of joint space and bone mineral density (BMD) in HR-pQCT scans and biomechanical outcomes from dynamic CT. The methodologies developed in this dissertation drastically reduce processing time for dynamic CT scans compared to previous literature. A cross-sectional study is presented that utilizes HR-pQCT to measure joint space (JS) changes in hand OA, the first of its kind. Maximum JS was significantly greater in OA than controls in the second and third distal interphalangeal (DIP2, DIP3) joints (DIP2: 2.07 mm vs. 1.88 mm; DIP3: 2.01 mm vs. 1.86 mm), and decreased hand function and increased hand disability were associated with increased radiographic TMC OA. A study was conducted to characterize normal TMC joint biomechanics in vivo using the presented methodologies. BMD was computed in anatomical quadrants of the TMC joint, and it was found that the radial-volar quadrant of the first metacarpal (426 mg HA/cm3) and ulnar-volar quadrant of the trapezium (373 mg HA/cm3) were significantly greater than other quadrants. When compared with proximity maps from dynamic CT, areas with high contact corresponded to quadrants with higher BMD. The results from this dissertation provide methodologies to analyze bone and joint changes with HR-pQCT and dynamic CT to better understand hand osteoarthritis.
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    Differences in Kinetic Variables Between Injured and Uninjured Rearfoot Runners: A Hierarchical Cluster Analysis
    (2022-09) Senevirathna, Benthara Hettiarachchige Angela Madushani; Ferber, Reed; Edwards, W. Brent; Jordan, Maththew; Manske, Sarah
    Running is a popular form of physical activity with a surprisingly high incidence of running-related injuries. While the relationship between running related injuries and ground reaction forces has been investigated, a limitation of previous research is that the heterogeneity of movement patterns within a control group creates confounding factors between variables. A potential solution is to use unsupervised cluster-based analyses to group individuals with similar ground reaction force features and thus investigate differences between identified clusters. Thus, the aim of this study was to investigate whether homogenous clusters exist within a large cohort of injured and healthy runners. The results show that two homogeneous clusters were identified using hierarchical cluster analysis and no significant differences in demographic variables were observed, nor were the proportion of injured and healthy runners between the two clusters. Thus, while there appears to be evidence for two distinct homogeneous kinetic clusters within our large sample of injured and healthy runners, there is no association between these kinetic clusters and running-related injuries.
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    Dynamic In-Vivo Knee Cartilage Contact With Aging
    (2020-07-27) Kupper, Jessica C.; Ronsky, Janet L.; Boyd, Steven K.; Lichti, Derek; Edwards, W. Brent; Rainbow, Michael
    Joint contact mechanics are important to the study of cartilage health and disease. Risk factors such as aging are speculated to result in altered cartilage contact locations, magnitudes, and sliding velocities, leading to altered loading of typical cartilage contact and non-contact areas. Altered contact patterns are speculated to be an influential mechanism associated with osteoarthritis-related cartilage changes such as softening, stiffening, or swelling. It is unknown whether knee joint contact patterns differ in an asymptomatic aging population compared to their younger counterparts.This feasibility study aimed to enhance understanding of relations amongst contact mechanics, cartilage health, and functional status and aging. This work applied high-speed biplanar videoradiography and magnetic resonance imaging to non-invasively measure a weighted centroid (WC) of tibiofemoral cartilage contact during gait in participants between the ages of 20-30 years (n = 5), and 50-60 years (n = 5). Cartilage contact regions during walking were linked to cartilage-health imaging outcomes (i.e., T2 relaxometry).Assessment of techniques for calculating the WC revealed that interval-based weighting factors provided the optimal approach, showing low sensitivity to errors but high sensitivity to clinically relevant changes. In aging vs. younger participants, no significant differences were found in WC location (median difference between heel strike and first force peak of gait cycle: younger 5.21-9.69%, older 2.12-7.44%), sliding distance (at onset of terminal swing: younger 0.50-1.15 mm, older 0.74-1.84 mm), or phase plot slope (change in sliding velocity over the surface of the joint; for swing phase: younger 4.14-14.99 mm/s%, older 6.15-14.47 mm/s%). For the first time, a functional relationship was found between T2 relaxometry and the gait cycle with lower T2 values during stance compared to prior to terminal swing. No differences were detected (younger vs. older) in T2 relaxometry values (medial tibial compartment at first force peak of gait: younger 29.8-43.1 ms, older 31.0-37.6 ms). These findings could not support differences in contact mechanics in older asymptomatic tibiofemoral joints compared to younger joints. Nevertheless, some potentially atypical patterns in older participants provide motivation to better understand linkages amongst aging, contact mechanics and cartilage health status across the cartilage degeneration spectrum.
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    Effects of cyclic loading on the mechanical properties and failure of human patellar tendon
    (Journal of Biomechanics, 2021) Firminger, Colin R.; Edwards, W. Brent
    Patellar tendinopathy is a common overuse injury in sports such as volleyball, basketball, and long-distance running. Microdamage accumulation, in response to repetitive loading of the tendon, plays an important role in the pathophysiology of patellar tendinopathy. This damage presents mechanically as a reduction in Young’s modulus and an increase in residual strain. In this study, 19 human patellar tendon samples underwent cyclic testing in load control until failure, segmented by four ramped tests where digital image correlation (DIC) was used to assess anterior surface strain distributions. Ramped tests were performed prior to cyclic testing and at timepoints corresponding to 10%, 20%, and 30% of cyclic stiffness reduction. Young’s modulus significantly decreased and cyclic energy dissipation significantly increased over the course of cyclic testing. The DIC analysis illustrated a heterogeneous strain distribution, with strain concentrations increasing in magnitude and size over the course of cyclic testing. Peak stress and initial peak strain magnitudes significantly correlated with the number of cycles to failure (r2 = 0.65 and r2 = 0.57, respectively, p < 0.001); however, the rates of peak cyclic strain and modulus loss displayed the highest correlations with the number of cycles to failure (r2 = 96% and r2 = 86%, respectively, p < 0.001). The high correlation between the rates of peak cyclic strain and modulus loss suggest that non-invasive methods to continuously monitor tendon strain may provide meaningful predictions of overuse injury in the patellar tendon.
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    Evaluation of Lower Body Strength and Landing Strategy of Elite Athletes After Anterior Cruciate Ligament Reconstruction with Hamstring Tendon Autograft
    (2021-09) Lawson, Drew; Herzog, Walter; Jordan, Matt; Edwards, W. Brent; Heard, S. Mark; Bertram, John
    The purpose of this study was to identify the effects of anterior cruciate ligament reconstruction (ACLR) using the semitendinosus tendon autograft on lower body strength capacity and landing strategy in athletes who had returned to competition. Additionally, we sought to identify strength metrics that influenced landing characteristics previously identified as risk factors for primary or subsequent ACL injury. In our first study, plyometric-trained athletes performed bilateral vertical drop landings (VDLs) initiated with a step off technique with each limb serving as the leading leg. Peak vertical ground reaction force (Fzpeak) and impulse in the first 100 ms after ground contact (Impulse100ms) was calculated for each limb under each lead leg condition. We identified that lead leg selection altered force-time characteristics and between limb symmetry, which may impact return to sport decision making after injury. In our second study, we recruited athletes with ACLR, non-injured, sport performance matched controls and non-injured, sport-matched but development-level controls to perform single leg landings from 25 cm and 50 cm heights and maximum voluntary contractions to assess strength about the knee and hip joints. The ACLR limb had knee flexion strength deficits compared to the contralateral limb and was stronger in hip abduction compared to the contralateral limb. The ACLR limb did not differ in any other comparisons, including across landing kinetics and kinematics. However, we observed main effects of strength on landing variables, highlighting the importance of lower body maximal strength on landing strategy. Together, these results suggest that it is important to use caution when assessing bilateral landing technique using VDL tasks, a common practice in clinical assessments following ACLR. Furthermore, we determined that lower body strength can largely be regained following ACLR, and as such movement strategies after ACLR can mimic that of healthy, elite athlete peers.
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    Musculoskeletal loading during graded running
    (2022-09) Baggaley, Michael; Edwards, W. Brent; Millet, Guillaume; Herzog, Walter; Ferber, Reed
    Running is the most popular recreational activity in Canada, and it is associated with a myriad of physical and mental health benefits. However, running is also associated with the development of musculoskeletal injuries, which lead to lower physical activity levels and interfere with reaping the health benefits of running. Chronic running injuries are thought to result from a fatigue-failure phenomenon, where injuries develop as damage accumulates at the tissue-level over the course of many bouts of running. Damage accumulation is governed by the mechanical loading environment experienced by musculoskeletal tissues; therefore, developing running and rehabilitation programs that can reduce the risk of running injury requires knowledge of the mechanical loading environment. The stress-strain response of a tissue during running is difficult to measure in vivo; however, computational approaches have been developed to infer tissue-level loading. In vivo tissue-level loading has been well characterized during level ground running, but running outdoors often involves traversing graded terrain, which is characterized by a different gait pattern. To develop a comprehensive understanding of musculoskeletal loading during running, it is necessary to capture the mechanical loading environment of the musculoskeletal system during graded and level running. The objective of this thesis was to characterize musculoskeletal loading during running as a function of running grade. To this end, four studies were performed analyzing how individuals adapt to graded terrain as a function of running grade, speed, and step length. It was observed that graded running alters musculoskeletal tissue loading; although the pattern is dependent on many parameters such as the tissue of interest, and the speed, grade, and step length of running. For soft-tissue injuries, it is likely that downhill running may be deleterious and the effect is concomitant with the grade of running. In contrast, the risk of developing a stress fracture may not be altered by running grade, as strains were relatively constant across all grades of running. The findings of this thesis demonstrate the difficulty in capturing in vivo loading and highlight the importance of using tissue geometry to truly capture the effect of different running conditions.
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    Repeated bout effect and musculoskeletal loading during prolonged downhill running
    (2022-01-19) Khassetarash, Arash; Edwards, W. Brent; Millet, Guillaume Y.; Herzog, Walter; Stefanyshyn,Darren; Aboodarda Saied Jalal
    Running is one of the most common forms of exercise to maintain physical activity and health. Despite decades of research in the field of running biomechanics, the rate of running-related injuries remains high. A vast majority of studies investigating running biomechanics have focused on level running. However, recreational running on urban and rural terrains frequently consists of uphill and downhill running. Owing to high eccentric muscular contraction, downhill running is known to induce muscle damage and symptoms of delayed onset muscle soreness that is generally attenuated during and after a subsequent downhill running bout; a phenomenon known as the repeated bout effect. The primary objective of this thesis was to understand the physiological and biomechanical consequences of an unaccustomed eccentric-biased downhill running bout as well as how the repeated bout effect mediates these consequences. A series of studies were conducted using a model of two prolonged downhill running bouts separated by three weeks. We observed that an unaccustomed downhill run caused substantial neuromuscular fatigue (i.e., central and peripheral fatigue) that persisted up to 48 hours after the initial bout. A repeated bout effect manifested as less sever neuromuscular fatigue following the second downhill run, which was likely due to neural adaptation (i.e., less central fatigue). A repeated bout effect was also observed for downhill running biomechanics, where changes in duty factor and knee quasi-stiffness were attenuated over the course of the second bout compared to the first bout. Changes to bone strain at the lower-extremity over the course of the downhill run were then estimated using combined musculoskeletal-finite element modeling. We observed that the neuromuscular fatigue associated with prolonged downhill running did not impact tibial-fibular strains. The findings from this thesis provide new and important insight to our current understanding of the repeated bout effect in unaccustomed eccentric-biased downhill running as well as the influence of neuromuscular fatigue on bone strain during a prolonged downhill run.