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Item Open Access 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. BrentSeveral 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.Item Open Access A Scoping Review Protocol on Experiential Learning in Higher Education First-Year Undergraduate Courses(2023-11) Christophe, MacKenna; Din, Cari; Hayden, K. AlixItem Open Access Absence of differences between male and female adolescents with prior sport concussion(Wolters Kluwer, 2014-01) Brooks, Brian L; Mrazik, Martin; Barlow, Karen M; McKay, Carly D; Meeuwisse, Willem H; Emery, Carolyn ASex differences following concussion are poorly understood. The purpose of this study was to examine whether male and female adolescent athletes with prior concussions differ regarding neurocognitive function and symptom reporting.Item Open Access Age-related Maintenance of Eccentric Strength: A Study of Temperature Dependence(University of Guelph, 2016-06) Herzog, Walter; Power, Geoffrey Alonzo; Dalton, Brian; Flaaten, NordanWith adult aging, eccentric strength is maintained better than isometric strength leading to a higher ratio of eccentric:isometric force production (ECC:ISO) in older than younger adults. The purpose was to investigate the ECC:ISO during electrical activation of the adductor pollicis during lengthening (20-320°∙s-1) contractions in 24 young (n=12, ~24 years) and old (n=12, ~72 years) males across muscle temperatures (Cold; ~19oC, Normal; ~30oC, Warm; ~35oC). For isometric force, the old were 20-30% weaker in the normal and cold conditions (P<0.05) with no difference for the warm condition compared to young (P>0.05). Half-relaxation time (HRT) did not differ across age for the normal and warm temperatures (P>0.05), but slowed significantly for old in the cold condition compared with young (~15%; P<0.05), as well, there was a 20 and 40% increase in muscle stiffness for the young and old, respectively. ECC:ISO was 50-60% greater for the cold condition than the normal and warm conditions. There was no age-difference in ECC:ISO across age for the normal and warm conditions (P>0.05), but for the cold, the old exhibited a 20-35% higher ECC:ISO than young for velocities above 60°∙s-1 (P<0.05). A contributing factor to the elevated ECC:ISO is an increased proportion of weakly- compared to strongly-bound cross-bridges. These findings highlight the relationship (r=0.70) between intrinsic muscle contractile speed (HRT) and eccentric strength in old age.Item Open Access Agreement Statement from the 1st international rodeo research and clinical care conference(Lippincott Williams & Wilkins, 2005-05) Butterwick, Dale J.; Brandenburg, M.A.; Andrews, D.M.; Brett, K.; Bugg, B.H.; Carlyle, K.J.; Freeman, T.R. 3rd; Hiemstra, L.; Lafave, Mark R.; Laird, J.; Lun, V.; Meyer, M.C.; Miller, C.; Mohtadi, N.; Nebergall R.; Temes, R.T.; Teochi, L.F.; Wiley, P.; Meeuwisse, Willem H.; Concussion in Rodeo GroupItem Open Access Alteration of Strain Distribution in Distal Tibia After Triple Arthrodesis: Experimental and Finite Element Investigations(Journal of Medical and Biological Engineering, 2018-06-01) Chitsazan, Ahmad; Herzog, Walter; Rouhi, Gholamreza A.; Abbasi, MostafaArthrodesis, or fusion of subtalar joints (STJs), is a well-accepted and a routine treatment in the end stage of ankle injuries or disorder, such as arthritis or fractures. Arthrodesis can restore daily life function quickly at the expense of limiting joint motion. A triple arthrodesis (TA) consists of the surgical fusion of the talocalcaneal (TC), talonavicular (TN), and calcaneocuboid (CC) joints in the foot. This study aimed at investigating the effects of TA on strain distribution around tibia near the ankle joint. A finite element (FE) model, generated using computed tomography (CT) images of the human ankle, was then used to estimate stress distribution on the ankle joint surface. Axial load was applied to a human cadaveric ankle before and after TA, and load patterns were determined in various anatomical positions by measuring strain distribution around the tibia. Therefore, the effects of fusion were investigated by comparing strain distribution obtained from experiment and from FE model before and following to fusion. A good agreement between the experiment and FE, for the mean value of experimentally measured strains per the strains determined by FEM was observed (1.4±0.32 before TA, and 1.51±0.49 after TA). Moreover, a wellaccepted point-by-point comparison between FE results and experimentally measured strains was observed with a good correlation coefficient (r=0.94). Results of this study showed that: (1) there was a significant difference in strain magnitude and strain distribution around the tibia before and after TA; (2) the strain and stress were more uniformly distributed after fusion; and (3) the peak strain and stress values were shifted to the lateral and anterolateral portion of the tibia after the fusion. Results of this investigation showed that STJs fusion reduces the average values of strains around the cortical bone through changing the pattern of load transmission at the ankle joint.Item Open Access Alterations in structural macromolecules and chondrocyte deformations in lapine retropatellar cartilage 9 weeks after anterior cruciate ligament transection(Wiley-Blackwell, 2018-01) Han, Sang Kuy; Ronkainen, Ari P.; Saarakkala, Simo J.; Rieppo, Lassi; Herzog, Walter; Korhonen, Rami K.The structural integrity and mechanical environment of the articular cartilage matrix directly affect chondrocyte deformations. Rabbit models of early osteoarthritis at 9 weeks following anterior cruciate ligament transection (ACLT) have been shown to alter the deformation behavior of superficial zone chondrocytes in mechanically loaded articular cartilage. However, it is not fully understood whether these changes in cell mechanics are caused by changes in structural macromolecules in the extracellular matrix. Therefore, the purpose of this study was to characterize the proteoglycan content, collagen content, and collagen orientation at 9 weeks post ACLT using microscopic techniques, and relate these changes to the altered cell mechanics observed upon mechanical loading of cartilage. At 9 weeks following ACLT, collagen orientation was significantly (p < 0.05) altered and proteoglycan content was significantly (p < 0.05) reduced in the superficial zone cartilage matrix. These structural changes either in the extracellular or pericellular matrix (ECM and PCM) were also correlated significantly (p < 0.05) with chondrocyte width and height changes, thereby suggesting that chondrocyte deformation response to mechanical compression in early OA changes primarily because of alterations in matrix structure. However, compared to the normal group, proteoglycan content in the PCM from the ACLT group decreased less than that in the surrounding ECM. Therefore, PCM could play a key role to protect excessive chondrocyte deformations in the ACLT group. 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:342350, 2018.Item Open Access Altered mechanical properties of titin immunoglobulin domain 27 in the presence of calcium(European Biophysics Journal, 2013-04) DuVall, Michael M.; Gifford, Jessica L.; Amrein, Matthias W.; Herzog, WalterTitin (connectin) based passive force regulation has been an important physiological mechanism to adjust to varying muscle stretch conditions. Upon stretch, titin behaves as a spring capable of modulating its elastic response in accordance with changes in muscle biochemistry. One such mechanism has been the calcium-dependent stiffening of titin domains that renders the spring inherently more resistant to stretch. This transient titin-calcium interaction may serve a protective function in muscle, which could preclude costly unfolding of select domains when muscles elongate to great lengths. To test this idea, fluorescence spectroscopy was performed revealing a change in the microenvironment of the investigated immunoglobulin domain 27 (I27) of titin with calcium. Additionally, an atomic force microscope was used to evaluate the calcium-dependent regulation of passive force by stretching eight linked titin I27 domains until they unfolded. When stretching in the presence of calcium, the I27 homopolymer chain became stabilized, displaying three novel properties: (1) higher stretching forces were needed to unfold the domains, (2) the stiffness, measured as a persistence length (PL), increased and (3) the peak-to-peak distance between adjacent I27 domains increased. Furthermore, a peak order dependence became apparent for both force and PL, reflecting the importance of characterizing the dynamic unfolding history of a polymer with this approach. Together, this novel titin Ig-calcium interaction may serve to stabilize the I27 domain permitting titin to tune passive force within stretched muscle in a calcium-dependent manner.Item Open Access Analysis of serum cortisol to predict recovery in paediatric sport-related concussion(2018-02-05) Ritchie, E V; Emery, C; Debert, C TTo study the relationship between acute serum cortisol following pediatric sport-related concussion (SRC) and clinical outcome measures of symptom burden and length to return to sport (RTS) Methods: Prospective observational study of ice hockey players ages 11-12 recruited prior to the hockey season. Players sustaining a SRC were assessed by a sports medicine physician completed a child Sport Concussion Assessment Tool-3 (childSCAT-3) and serum cortisol samples.Item Open Access Are subject-specific models necessary to predict patellar tendon fatigue life? A finite element modelling study(Taylor & Francis, 2021-09-11) Firminger, Colin R.; Haider, Ifaz T.; Bruce, Olivia L.; Wannop, John W.; Stefanyshyn, Darren J.; Edwards, W BrentPatellar tendinopathy is an overuse injury that occurs from repetitive loading of the patellar tendon in a scenario resembling that of mechanical fatigue. As such, fatigue-life estimates provide a quantifiable approach to assess tendinopathy risk and may be tabulated using nominal strain (NS) or finite element (FE) models with varied subject-specificity. We compared patellar tendon fatigue-life estimates from NS and FE models of twenty-nine athletes performing countermovement jumps with subject-specific versus generic geometry and material properties. Subject-specific patellar tendon material properties and geometry were obtained using a data collection protocol of dynamometry, ultrasound, and magnetic resonance imaging. Three FE models were created for each subject, with: subject-specific (hyperelastic) material properties and geometry, subject-specific material properties and generic geometry, and generic material properties and subject-specific geometry. Four NS models were created for each subject, with: subject-specific (linear elastic) material properties and moment arm, generic material properties and subject-specific moment arm, subject-specific material properties and generic moment arm, and generic material properties and moment arm. NS- and FE-modelled fatigue-life estimates with generic material properties were poorly correlated with their subject-specific counterparts (r2≤0.073), while all NS models overestimated fatigue life compared to the subject-specific FE model (r2≤0.223). Furthermore, FE models with generic tendon geometry were unable to accurately represent the heterogeneous strain distributions found in the subject-specific FE models or those with generic material properties. These findings illustrate the importance of incorporating subject-specific material properties and FE-modelled strain distributions into fatigue-life estimations.Item Open Access Are titin properties reflected in single myofibrils?(Journal of Biomechanics, 2012-07-26) Herzog, Jens A.; Leonard, Timothy R.; Jinha, Azim; Herzog, WalterTitin is a structural protein in muscle that spans the half sarcomere from Z-band to M-line. Although there are selected studies on titin's mechanical properties from tests on isolated molecules or titin fragments, little is known about its behavior within the structural confines of a sarcomere. Here, we tested the hypothesis that titin properties might be reflected well in single myofibrils. Single myofibrils from rabbit psoas were prepared for measurement of passive stretch-shortening cycles at lengths where passive titin forces occur. Three repeat stretch-shortening cycles with magnitudes between 1.0 and 3.0μm/sarcomere were performed at a speed of 0.1μm/s·sarcomere and repeated after a ten minute rest at zero force. These tests were performed in a relaxation solution (passive) and an activation solution (active) where cross-bridge attachment was inhibited with 2,3 butanedionemonoxime. Myofibrils behaved viscoelastically producing an increased efficiency with repeat stretch-shortening cycles, but a decreased efficiency with increasing stretch magnitudes. Furthermore, we observed a first distinct inflection point in the force-elongation curve at an average sarcomere length of 3.5μm that was associated with an average force of 68±5nN/mm. This inflection point was thought to reflect the onset of Ig domain unfolding and was missing after a ten minute rest at zero force, suggesting a lack of spontaneous Ig domain refolding. These passive myofibrillar properties observed here are consistent with those observed in isolated titin molecules, suggesting that the mechanics of titin are well preserved in isolated myofibrils, and thus, can be studied readily in myofibrils, rather than in the extremely difficult and labile single titin preparations.Item Open Access Assignment of adverse event indexing terms in randomized clinical trials involving spinal manipulative therapy: an audit of records in MEDLINE and EMBASE databases.(BMC Medical Research Methodology, 2017-03-14) Gorrell, Lindsay M.; Engel, Roger Mark; Lystad, R. P.; Brown, Benjamin T.Background: Reporting of adverse events in randomized clinical trials (RCTs) is encouraged by the authors of The Consolidated Standards of Reporting Trials (CONSORT) statement. With robust methodological design and adequate reporting, RCTs have the potential to provide useful evidence on the incidence of adverse events associated with spinal manipulative therapy (SMT). During a previous investigation, it became apparent that comprehensive search strategies combining text words with indexing terms was not sufficiently sensitive for retrieving records that were known to contain reports on adverse events. The aim of this analysis was to compare the proportion of articles containing data on adverse events associated with SMT that were indexed in MEDLINE and/or EMBASE and the proportion of those that included adverse event-related words in their title or abstract. Methods: A sample of 140 RCT articles previously identified as containing data on adverse events associated with SMT was used. Articles were checked to determine if: (1) they had been indexed with relevant terms describing adverse events in the MEDLINE and EMBASE databases; and (2) they mentioned adverse events (or any related terms) in the title or abstract. Results: Of the 140 papers, 91% were MEDLINE records, 85% were EMBASE records, 81% were found in both MEDLINE and EMBASE records, and 4% were not in either database. Only 19% mentioned adverse event-related text words in the title or abstract. There was no significant difference between MEDLINE and EMBASE records in the proportion of available papers (p=0.078). Of the 113 papers that were found in both MEDLINE and EMBASE records, only 3% had adverse event-related indexing terms assigned to them in both databases, while 81% were not assigned an adverse event-related indexing term in either database. Conclusions: While there was effective indexing of RCTs involving SMT in the MEDLINE and EMBASE databases, there was a failure of allocation of adverse event indexing terms in both databases. We recommend the development of standardized definitions and standardized adverse events reporting tools for adverse events associated with SMT. Adequate reporting of adverse events associated with SMT will facilitate accurate indexing of these types of manuscripts in the databases.Item Open Access Bull Riding Injuries in Professional Rodeo(Vendome Group, LLC, 2003-06) Butterwick, Dale J.; Meeuwisse, Willem H.Item Open Access Bull Riding: Analysis and Application of a Specific Strength and Conditioning Program(National Strength and Conditioning Association, 2006-06) Barrett, Mark R.; Butterwick, Dale J.Item Open Access Calcium sensitivity of residual force enhancement in rabbit skinned fibers(American Journal of Physiology, 2014-08-15) Joumaa, Venus; Herzog, WalterIsometric force after active stretch of muscles is higher than the purely isometric force at the corresponding length. This property is termed residual force enhancement. Active force in skeletal muscle depends on calcium attachment characteristics to the regulatory proteins. Passive force has been shown to influence calcium attachment characteristics, specifically the sarcomere length dependence of calcium sensitivity. Since one of the mechanisms proposed to explain residual force enhancement is the increase in passive force that results from engagement of titin upon activation and stretch, our aim was to test if calcium sensitivity of residual force enhancement was different from that of its corresponding purely isometric contraction and if such a difference was related to the molecular spring titin. Force-pCa curves were established in rabbit psoas skinned fibers for reference and residual force-enhanced states at a sarcomere length of 3.0 μm 1) in a titin-intact condition, 2) after treatment with trypsin to partially eliminate titin, and 3) after treatment with trypsin and osmotic compression with dextran T-500 to decrease the lattice spacing in the absence of titin. The force-pCa curves of residual force enhancement were shifted to the left compared with their corresponding controls in titin-intact fibers, indicating increased calcium sensitivity. No difference in calcium sensitivity was observed between reference and residual force-enhanced contractions in trypsin-treated and osmotically compressed trypsin-treated fibers. Furthermore, calcium sensitivity after osmotic compression was lower than that observed for residual force enhancement in titin-intact skinned fibers. These results suggest that titin-based passive force regulates the increase in calcium sensitivity of residual force enhancement by a mechanism other than reduction of the myofilament lattice spacing.Item Open Access Cartilage and chondrocyte response to extreme muscular loading and impact loading: Can in vivo pre-load decrease impact-induced cell death?(Elsevier, 2015-07) Bourne, Douglas A.; Moo, Engkuan; Herzog, WalterImpact loading causes cartilage damage and cell death. Pre-loading prior to impact loading may protect cartilage and chondrocytes. However, there is no systematic evidence and understanding of the effects of pre-load strategies on cartilage damage and chondrocyte death. This study aimed at determining the effects of the pre-load history on impact-induced chondrocyte death in an intact joint.Item Open Access Cartilage boundary lubrication synergism is mediated by hyaluronan concentration and PRG4 concentration and structure(BioMed Central Musculoskeletal Disorders, 2015-12) Ludwig, Taryn E.; Hunter, Miles M.; Schmidt, Tannin A.Background Proteoglycan 4 (PRG4) and hyaluronan (HA) are key synovial fluid constituents that contribute synergistically to cartilage boundary lubrication; however, the effects of their concentrations as well as their structure, both of which can be altered in osteoarthritis, on this functional synergism are unknown. The objectives of this study were to evaluate cartilage boundary lubricating ability of 1) PRG4 + HA in solution at constant HA concentration in a range of PRG4 concentrations, 2) constant PRG4 concentration in a range of HA concentrations, 3) HA + reduced/alkylated (R/A) PRG4, and 4) hylan G-F 20 + PRG4. Methods Static and kinetic friction coefficients (μstatic,Neq, <μkinetic,Neq>) were measured using a previously characterized cartilage-cartilage boundary mode friction test for the following concentrations of purified PRG4 and HA: Test 1: HA (1.5 MDa, 3.3 mg/mL) + PRG4 from 4.5 – 1500 μg/mL; Test 2: PRG4 (450, 150, 45 μg/mL) + HA (1.5 MDa) from 0.3 – 3.3 mg/mL. Test 3: hylan G-F 20 (3. 3 mg/mL) + PRG4 (450 μg/mL). Test 4: HA (3.3 mg/mL) + R/A PRG4 (450 μg/mL). ANOVA was used to compare lubricants within (comparing 6 lubricants of interest) and between (comparing 3 lubricants of interest) test sequences, with Tukey and Fishers post-hoc testing respectively. Results This study demonstrates that both PRG4 and HA concentration, as well as PRG4 disulfide-bonded structure, can alter the cartilage boundary lubricating ability of PRG4 + HA solutions. The boundary lubricating ability of high MW HA + PRG4 solutions was limited by very low concentrations of PRG4. Decreased concentrations of high MW HA also limited the cartilage boundary lubricating ability of HA + PRG4 solutions, with the effect exacerbated by low PRG4 concentrations. The reduction of friction by addition of PRG4 to a cross-linked HA viscosupplement product, but not with addition of R/A PRG4 to HA, is consistent with a non-covalent mechanism of interaction where tertiary and quaternary PRG4 structure are important. Conclusions Collectively, these results demonstrate that deficiency of either or both PRG4 and HA, or alterations in PRG4 structure, may be detrimental to SF cartilage boundary lubricating function. This study provides further insight into the nature of cartilage boundary lubrication and advancement towards potential formulation of new intra-articular biotherapeutic treatments for osteoarthritis using PRG4 ± HA.Item Open Access Changes in joint coupling and variability during walking following tibialis posterior muscle fatigue(BioMed Central, 2011-02-04) Ferber, Reed; Pohl, Michael B.Item Open Access Changes in multi-segment foot biomechanics with a heat-mouldable semi-custom foot orthotic device(BioMed Central, 2011-06-21) Ferber, Reed; Benson, BrittanyItem Open Access Chronic uphill and downhill exercise protocols do not lead to sarcomerogenesis in mouse skeletal muscle(Journal of Biomechanics, 2019-11-05) Morais, Gustavo Paroschi; da Rocha, Alisson Luiz; Neave, Louise M.; de Araújo Lucas, Guilherme; Leonard, Timothy R.; Carvalho, Andrea; Silva, Adelino S. R.; Herzog, WalterIt has been suggested that eccentric contraction (EC) is associated with increases in serially-arranged sarcomeres (sarcomerogenesis), while concentric contraction (CC) has been associated with serial sarcomeres decrease. Sarcomerogenesis following EC is thought to be a protective muscle adaptation, preventing muscle injury in future eccentric exercise bouts (repeated bout effect). However, the mechanisms underlying sarcomerogenesis in EC remain unknown, and the sarcomerogenic responses observed in response to EC and CC are contradictory. We measured sarcomere length, sarcomere length uniformity, serial sarcomere number, and fascicle length in gastrocnemius medialis, tibialis anterior, vastus medialis and vastus lateralis in sedentary (SED) mice, and in mice following protocols of moderate uphill (TRU) and downhill (TRD) training and uphill (OTU) and downhill (OTD) overtraining. We found pain sensitivity after the first bout of EC exercise on TRD and OTD followed by a normalized sensory response after four weeks of training, indicating a repeated bout effect. However, these findings were not associated with sarcomerogenesis, as serial sarcomere numbers did not increase in TRD and OTD skeletal muscle samples compared to controls (SED). However, we found a decrease in serial sarcomere number in VL and TA in OTU group mice, which was associated with a decrease in fascicle length and no change of sarcomere length at the tested joint configuration. We conclude that excessive concentric muscle contraction (OTU group mice), leads to a decrease in serial sarcomere number, while moderate or excessive eccentric training, did not result in sarcomerogenesis, as reported in the literature.