Abstracts
News:
Live Poster Showcase - CBJC 2022
The following abstract submissions have been chosen to present their research in one of the following Live Poster Showcase sessions at this year's conference.
| Thursday April 21st 5:40 - 6:45 pm |
Congratulations to all those that have been chosen.
| AUTHOR* PAPER ID |
TITLE ABSTRACT |
| Basice Science for MSK | |
| Choi, Cho-E* | 3D Printing Biomaterial-Nanoparticle Composite for Bone Healing |
| 44 | Background and Rationale. Hydrogels are three-dimensional water-swellable polymeric matrices that have found extensive use in tissue engineering and drug delivery. 3D printing is the construction of a three-dimensional object that is developed via the outline of a digital model and has a wide range of possible applications in the biomedical field. However, current hydrogels lack the biological and mechanical properties required to be a successful implant. To overcome these limitations, nanoparticles can be incorporated into hydrogels to improve their mechanical, biological, and drug delivery properties. Objective. Objective I: Optimization of printing parameters and the nanocomposite hydrogel composition by comparing the dimensions of the printed hydrogels. Objective II: Characterizing the optimized nanocomposite hydrogel formulation through chemical, physical, and biological analysis. Methodology. Nanocomposite hydrogels were prepared using 3D printing. Drug was loaded inside the nanocomposite hydrogel scaffold to further induce bone regeneration. Results. The nanocomposite hydrogel can be used to fabricate 3D printed structures with defined shapes and sizes. This nanocomposite hydrogel showed good cytocompatibility. However, a higher concentration of nanoparticles led to cell death. We also observed that nanoparticles help retain the release of the drug. Significance and future studies: This nanocomposite hydrogel can be used to print desired structures. 3D printed nanocomposite hydrogel scaffolds present themselves as a plausible mechanism for drug delivery in bone regeneration applications. |
| Ermina Hadzic | Examining Mig6/EGFR Signalling in PTOA |
| 15 | Background: Osteoarthritis (OA) is a degenerative whole-joint disorder with no current disease modifying treatment. The Epidermal Growth Factor Receptor (EGFR) signalling pathway plays an important role in cartilage/bone development & homeostasis, both attenuating and aggravating OA in a context-dependent manner. Mitogen inducible-6 (Mig6) is a scaffold protein that negatively regulates EGFR signalling and is important for joint homeostasis. Cartilage specific Mig6 deletion has anabolic effects on both the cartilage and bone. Further, mice overexpressing Mig6 are predisposed to age-related OA. Mig6 may be a viable drug target in OA, but a better understanding of its role is required. Rationale: Our present focus is to contextualize the role of the Mig6/EGFR pathway in OA, specifically post-traumatic OA (PTOA) both in vivo and in vitro. Methods: Human primary synoviocytes and chondrocytes will be used to quantify Mig6 levels. Both cell types will be stimulated with TGFa or lentiviral shRNA to suppress Mig6 expression. Following treatment, gene expression will be analyzed. We will also generate tamoxifen induced, cartilage specific Mig6 deficient mice using the Acan-CreER driver. Knockout will be induced before or after surgical induction of PTOA. Behavioural analysis, micro-CT scanning, and scoring joint damage will be completed. Results: Currently, it is too early to report results, but we expect that Mig6 expression in our cell work will be highly context-dependent, and the Mig6 deficient mice will have a slower progression of OA than the control mice. Significance and Impact: In Canada, OA is the second most prevalent chronic condition leading to disability with a rising economic cost. OA cases will continue to rise and create significant personal and economic burden on society until a successful treatment is established. I believe our work will increase our understanding of Mig6/EGFR signalling, providing the data required for future clinical drug trials. |
| Jeffrey L Hutchinson | Histopathological Analysis of Age-Associated Disc Degeneration in CD1 and C57BL6 Mice |
| 20 | BACKGROUND: The most recent Global Burden of Disease study reported low back pain as the leading cause of years lived with disability, with a lifetime prevalence of approximately 80%. Intervertebral disc degeneration (IVDD) is believed to be a major contributor to low back pain, associated with ~40% of cases, with no disease modifying treatments. It has been previously shown that aging, anatomical location, and sex all effect the progression of IVDD, but have not been characterized in common laboratory mouse strains. The current study was designed to compare age-associated IVDD across anatomical regions of the spine, in CD1 and C57BL6 mice based on histopathological evaluation. METHODS: We used histopathological analysis of cervical, thoracic, lumbar, and caudal IVDs of both male and female CD1 and C57BL6 mouse strains at 6, 12, 20 and 24 months-of-age (N=5-10 mice/group). Intact spinal segments were sectioned sagittally and stained with Safranin-O/ Fast Green. Sections were scored by two blinded observers using the scoring system developed by Tam et al (2017). RESULTS: Histopathological scores in C57BL6 and CD1 significantly increased in the lumbar region over time. Male C57BL6 mice showed significantly increased degeneration in lumbar IVDs compared to female mice. In addition, CD1 mice showed a significant increase in thoracic IVDD at 20 and 24 months-of-age. While both C57BL6 and CD1 mice experienced age-associated degeneration in the lumbar region, male CD1 mice additionally showed higher histopathological scores in IVDs of the cervical and thoracic spine at all time points examined. SIGNIFICANCE: IVDD does not progress at the same rate between and within anatomical regions. While lumbar degeneration was found to be increased in male compared to female C57BL6 mice, no sex-related differences were found in CD1 mice. Differences in strain presentation of IVDD are important considerations when designing experiments investigating IVDD in laboratory mouse strains. |
| Lawan, Aliyu Mr*; Faul, James; Leung, Andrew; Leung, Stephanie; Battie, Michele | Detection and Characterization of Vertebral Endplate Structural Defects on Clinical CT and Micro-CT: A Diagnostic Test Validity Study |
| 45 | Background: Studies of Endplate Structural Defects (EPSD) may further the understanding of pathoanatomical mechanisms underlying back pain. However, with CT, as with MRI, the common measurement methods used to document EPSD have not been validated, Rationale: There is uncertainty about what the observations on clinical imaging represent or how accurately they capture the presence or absence of EPSDs. Purpose: To determine the reliability and validity of two common endplate structural defects (EPSD) assessment methods. Methods: 418 endplates on clinical-CT sagittal slices obtained from 19 embalmed cadavers (aged 62-91 years) were independently assessed by three assessors using two methods. The corresponding micro-CT from the harvested T7-S1 spines were assessed by another independent rater with excellent intra-rater reliability (Kappa=0.96, 95%CI: 0.91–0.99). Results: The inter-rater reliability between each pair of raters was good for the presence (Kappa=0.60-0.69) and poor reliability for specific EPSD phenotypes (Kappa=0.43 - 0.58). Erosion, for which Brayda-Bruno lacked a category, was mainly (82.8%) classified as wavy/irregular. While most notched defects (n=15, 46.9%) and Schmorl’s nodes (n=45, 79%) using Brayda-Bruno’s classification were recorded as focal defects using Feng’s. When compared to micro-CT, fractures (n=53) and corner defects (n=28) were routinely missed on clinical-CT. Endplates classified as wavy/irregular on clinical CT corresponded to erosion (n=29, 21.2%), jagged defects (n=21, 15.3%) and calcification (n=19, 13.9%) on micro-CT. Overall, there was a sensitivity of 70.9% and specificity of 79.1% for Feng’s method, and 79.5% and 57.5%, respectively, using Brayda-Bruno’s. All EPSD clinical-CT and micro-CT dimensions significantly correlated (p<0.001), except with defect depth. Future Studies: Neither method contained sufficient EPSD phenotypes to provide the needed specificity. A study is needed to examine a combined assessment method. |
| Starlee Lively | Plasma MiRNAs predict Postsurgical Pain in Spine Osteoarthritis Patients |
| 3 | Background: Spine facet osteoarthritis-induced lumbar spinal stenosis (S-FOA+LSS) is the principal cause of chronic back (and leg/neurogenic claudication) pain for 1 in 5 adults over the age of 65, and is the primary reason for spinal surgery in this age group. While surgery is successful for many, 30% of S-FOA+LSS patients show little to no improvement in their post-surgical pain. Purpose: The objective of the present study was to determine whether a microRNA (miRNA) signature could be identified in presurgical blood plasma that corresponded with level of S-FOA+LSS patient post-surgical pain one year later. Methods: RNA was extracted from baseline plasma of S-FOA+LSS patients and prepared for miRNA sequencing (n=56). Statistical approaches were performed to identify differentially expressed miRNAs associated with reduced 1-year postsurgical pain. Computational analysis was used to assemble the networks of predicted gene targets and identify top signaling pathways of the associated miRNAs. Results: We identified a panel of 4 circulating candidate miRNAs (hsa-miR-155-5p, hsa-let-7e-5p, hsa-miR-125a-5p, hsa-miR-99b-5p) with higher levels at presurgical baseline that were associated with greater changes in the combined back and leg Numeric Pain Rating Scale (NPRS20Δ). We then identified putative gene targets and pathways associated with each of the 4 miRNAs. Most of the putative gene targets and enriched pathways were uniquely ascribed to each of the 4 miRNAs and no predicted pathways were shared by all 4 miRNAs. Instead, the largest cluster of intersecting enriched pathway terms was identified for hsa-miR-125a-5p, hsa-miR-155-5p, and hsa-let-7e-5p, which included transforming growth factor-β1 receptor, Wnt signaling, epithelial–mesenchymal transition regulators, and cholecystokinin signaling. Conclusions: The findings presented in this study are important as they represent the first steps in a pain biomarker discovery in this understudied group of OA patients. |
| Basic Science for MSK - Bone | |
| David E Cunningham | Evaluating the Efficacy of Measuring Implant-bone Fixation Methods in the Evaluation of Orthopaedic Implants |
| 49 | Background: Failure of orthopaedic implants due to loss of fixation remains a significant clinical concern. A number of studies have focused on evaluating the loosening of implants, and the ASTM has published evaluation methods in the quantification of implant fixation with focus on the micromotion occurring at the implant/bone interface. However, recent literature has suggested that these industry-accepted evaluation protocols may have some limitations. Context: The ASTM F2028 standard for the dynamic evaluation of glenoid loosening and disassociation suggests the usage of linear variable differential transducers (LVDTs) to quantify the relative motion of the implant to bone. However, recent studies using combined LVDT and digital tracking (DT) methods have noted that using LVDTs can overreport bone-implant relative motion. The purpose of this work is to compare results obtained using DT and LVDT micromotion measurements. Methods: A stainless-steel implant surrogate was used with a custom loading apparatus to stimulate bone-implant micromotion on a bovine tibial bone bed (n=5). An incrementally increasing eccentric load of 10-160 [N] was applied at one end of the implant surrogate, causing lift-off on the opposite side. Micromotion was quantified synchronously using a LDVT and a previously validated DT technique. Differences in micromotion were recorded and evaluated over five trials at different locations on the bony surface. Results: Average measurements for LDVT and DT methods were computed at all loading increments (Fig. 1). Over the entire dataset, average micromotion via LVDT was 158% ± 65% higher than average micromotion via DT. Conclusion: The use of LVDTs is of value when determining the effect of various implant designs and fixation techniques in parametric studies. However, they would appear to not accurately quantify absolute micromotion at the interface. An absolute measurement at the interface is better served using the OT system employed herein. |
| Cole T Fleet | Analysis of Bone Loss Depth in Favard Type E3 Glenoid Erosions |
| 33 | Background: Incorrect glenoid component positioning in the presence of superior glenoid bone loss can lead to baseplate loosening and subsequent implant failure. Previous studies have examined morphological characteristics of superior glenoid erosion to improve glenoid component positioning in reverse shoulder arthroplasty. These studies, however, did not consider the depth of bone loss across the glenoid which is important in determining the thickness of bone graft or metal augmentation required to restore the joint line. Therefore, the purpose of this study was to investigate the distribution of bone loss depth across Favard type E3 glenoid erosions (Sirveaux et al., 2004). Methods: A total of 35 (27 female and 8 male; 21 right and 14 left) computer tomography (CT) scans were obtained from scapulae exhibiting type E3 glenoid wear. All scans were segmented and converted into solid three-dimensional (3D) models. A scapular statistical shape model (SSM) was then generated to predict the premorbid anatomy of each eroded scapula. A custom MATLAB (MathWorks, U.S.) code was used to calculate the average depth of glenoid bone loss across four glenoid quadrants, in addition to the value and location of the maximum erosion depth. Scapular and glenoid coordinate systems were created for each scapula model to describe the location of maximum bone loss depth. Results: The average maximum depth of glenoid bone loss was 13±7mm with no significance found between genders (p=0.47). The average location of maximum depth corresponded to 9:40 on a right glenoid clock face. No significant difference was observed between average bone loss depth in the four quadrants of the glenoid (p=0.128). Conclusion: The results from this study can be used to better understand the distribution of glenoid bone loss in shoulders exhibiting type E3 glenoid wear. These results can be further used to improve glenoid component positioning and joint line reconstruction in reverse shoulder arthroplasty. |
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Human & Technology Interaction for Health |
| Kamiar Ghoseiri | The perils of long-term locked knee ankle foot orthosis: narrative biomechanical and physiological insights |
| 39 | Background: The locked knee ankle foot orthosis (L-KAFO) maintains the knee in extension through the gait cycle to promote walking stability in patients with severe lower extremity motor impairment. The stance control KAFO (SC-KAFO) is a new technology that allows knee flexion during swing while maintaining stability in stance. Uptake of the SC-KAFO is limited in practice due to cost, need for training, and a narrow clinical application. Further, rejection is reported due to inability to master device use. Therefore, the L-KAFO, and the perils of long-term use, remains the standard of care. Purpose: To provide a deeper insight into the biomechanical and physiological impacts of L-KAFO and possible impact of SC-KAFO on balance, gait, joint and soft tissue health. Discussion: KAFO use improves postural stability by providing mechanical support, sensory input, increased base of support, and reduced sway of the body’s center of pressure. However, the L-KAFO leads to arthrogenic (i.e. bone, cartilage, joint capsule, and ligament), myogenic (i.e. muscle, tendon), skin changes, gait asymmetry with increased energy expenditure, and reduced shock absorption. Consequently, the risk of developing low back pain, osteoarthritis of the lower limbs and spinal joints, skin dermatitis and ulceration increases. There is evidence that using an SC-KAFO improves gait symmetry and decreases energy expenditure however, the physiologic effects are not well understood. Significance & Impact: More evidence is needed to identify the appropriate patient population and determine if the SC-KAFO diminishes arthrogenic and myogenic complications associated with L-KAFO use. Additionally, quantifying the type of exercise and training needed to master use of the SC-KAFO is warranted to justify the increased cost. Future Work: To design a study that compares gait symmetry, balance, energy expenditure, and training required to master use of L-KAFO versus SC-KAFO for people who require a KAFO to walk. |
| Bernadette A McCann | SEX DIFFERENCES IN MUSCLE FUNCTION ACROSS KNEE OSTEOARTHRITIS SEVERITY |
| 21 | Background: Females have a higher prevalence and burden of osteoarthritis (OA) than males. Low knee extensor strength in females has been linked to knee OA initiation. Less clear, is whether other muscle function measures differ between sexes as markers of clinical severity progression. Purpose: To determine if differences in knee extensor (KE), flexor (KF) and plantar flexor (PF) muscle strength and activation patterns during walking previously linked to OA severity and progression were modified by sex. Methods: Participants 40-65 yrs categorized into asymptomatic (ASYM), moderate (MOA) and severe (SOA) based on clinical OA severity completed self-selected speed walks while electromyographic (EMG) data were recorded from lateral and medial vasti (VL/VM), hamstrings (LH/MH) and gastrocnemius (LG/MG) muscles. KE, KF, and PF strength was measured from maximal effort contractions (MVIC) on a dynamometer. EMG waveforms were analyzed using principal component analyses (PCA) to capture overall activation (PCmag) and prolonged activation (PCdiff) features. Two-factor (sex, severity) ANOVAs tested for significant interactions/main effects for strength and PC scores (α=0.05). Results: 324 participants included 118 ASYM, 141 MOA, and 65 SOA. LH PCmag, LH and VL PCdiff had significant severity main effects only. Significant interactions were found for muscle strength and remaining PC scores. Post hoc results showed higher strength in males than females for KF and KE at all severity levels, but for PF only in the two OA groups. KE and PF strength differed across all severity levels for females only. Higher and more prolonged activity was found in OA females compared to males for most muscles. Conclusion: Muscle strength and activation differences between sexes support a more generalized co-activation pattern in females, consistent with greater clinical severity and systemic pathogenesis in females. Sex differences aid our understanding of accelerated progression in females. |
| Milani Zadeh, Sohrob*; MacDermid, Joy; Johnson, Jim; Birmingham, Trevor | Wearable sensors in upper extremity MSK conditions: a scoping review |
| 36 | Wearable sensors are critical elements in developing next-generation health care technologies regarding assessment and treatment. In this regard, the present scoping review aims to describe the state of the literature concerning the applications of wearable sensors in patients with upper extremity musculoskeletal disorders (UE-MSK) or individuals at risk of developing a musculoskeletal (MSK) condition. A systematic search of PubMed, Embase, Scopus, and IEEEXplore databases was conducted, and the studies focused on the populations with MSK conditions or the at-risk of developing an MSK condition that used wearable sensors on upper body regions since 2010 were included. The extracted data includes the study designs, aims, sensor types and numbers, and outcomes of interest. Specific features such as home-based applicability, wireless data transmission ability, and the system’s comfortability assessment were also investigated. We synthesized the extracted information thematically and sorted them into related categories. Seventy-six studies were extracted and categorized based on the aim of the study as evaluation in patients (27 studies), work-related risk factors in musculoskeletal conditions (31 studies), and evaluation of healthy people (18 studies). Most of the included studies were descriptive (50%), 29% (22) were case series, and 16% (12) case-control. IMU sensors were primarily included in wearable systems (84%) or EMG sensors (14%). In fifteen studies (20%), wearable sensors were used for treatment and motion assessment (80%). Sixteen studies (21%) used them as a home-based application, 37 studies (49%) as wireless wearable systems and five studies (7%) investigated the comfortability level of the wearable system. According to the results, focusing on home-based applicability, comfortability, using other types of sensors (EMG), and inclusion of wearable systems in treatment are recommended for future studies in this field. |
| Inflammation & Autoimmune Diseaese | |
| Garth Blackler | HLA-DR4 and its Affect on Atherosclerosis in an Animal Model |
| 11 | Background: Rheumatoid arthritis (RA) patients are 1.5 times more likely to develop cardiovascular disease (CVD) compared to the general population and the risk is higher for patients expressing the HLA-DR4 gene. The mechanisms by which HLA-DR4 contributes to CVD risk in RA is unknown. Purpose: To characterize western diet mediated CVD in a novel mouse model that expresses the HLA-DR4 gene and is susceptible to atherosclerosis. Methods: Mice transgenic for the human HLA-DR4 gene (DR4tg), were cross-bred with an established model for atherosclerosis, low density lipoprotein receptor knock-out (LDLR-/-) mice. The DR4tgLDLR-/- (N=24) and LDLR-/- (N=12) control mice were fed a high fat, high cholesterol (HFHC) diet or regular diet (RD) for 12 weeks. Serum was analyzed for lipoproteins using a colorimetric assay or ELISA. Tissue sections from liver were stained with hematoxylin and eosin to assess clinical features of non-alcoholic fatty liver disease. En face preparation of isolated aortas were stained for lipids with SUDAN IV. Results: We found that DR4tgLDLR-/- and LDLR-/- mice fed a HFHC diet vs. RD had higher serum levels of LDL, aortic plaque surface area and clinical signs of non-alcoholic fatty liver disease. Serum LDL levels were significantly higher in HFHC-fed LDLR-/- vs. DR4tgLDLR-/- (1602mg/dL vs. 905.3mg/dL, respectively; p=0.0056), whereas the proportion of oxLDL was higher in HFHC fed DR4tgLDLR-/- vs. LDLR-/- mice (53.31 nmole oxLDL/mg LDL vs. 12.71 nmole oxLDL/mg respectively; p=0.0017). Aortic plaque burden was similar between HFHC-fed LDLR-/- and DR4tgLDLR-/- mice. Conclusion: In a mouse model of atherosclerosis, expression of HLA-DR4 led to lower levels of circulating LDL but increased levels of oxLDL while maintaining similar plaque burden. Further investigation is needed to understand the underlying mechanisms contributing to the increased prevalence of oxLDL in HLA-DR4 associated CVD and highlights the importance of this non-classical risk factor. |
| Injury Prevention & Rehabilitation | |
| Victor A Carranza | Selecting the Proper Osteotomy Modeling Method for a High Tibial Osteotomy |
| 38 | Background: Medial opening wedge high tibial osteotomy (HTO) is a surgical procedure intended to relieve the symptoms of osteoarthritis in the medial compartment of the knee by altering the coronal and sagittal plane alignment of the knee. In previous studies, the osteotomy cut and wedge opening in a HTO finite element (FE) model has been performed in one of two ways: i) clinically relevant method (CRM) or ii) simplified method (SM). Purpose: The purpose of this study is to determine whether the simplified method is an acceptable assumption for a HTO FE modelling study when analyzing the stresses and strains in the plate, screw, and throughout the proximal tibia. Methods: Seven tibia models were reconstructed from CT scans of seven cadaveric specimen. Two sets of models were created from the same set of specimens to create the CRM (n=7) and SM (n=7) dataset. The osteotomy in the CRM was simulated by virtually creating an osteotomy and simulating the opening to a correction of 10mm. In the SM, the osteotomy was simulated by simply removing a wedge from the proximal tibia where the size of which would match the void normally created by a 10mm opening height, without changing the tibial geometry. Results: A statistically significant difference in the mean plate stresses were found with the SM experiencing 36% greater stresses through the plate construct. A statistically significant difference in mean screw stresses were found between the CRM and SM with the SM experiencing 6%-43% more stress. Additionally, the SM experienced 24% greater stresses at the apex of the osteotomy near the hinge when compared to the CRM. Impact: Selecting the appropriate modelling method that best represents the clinical scenario is the first crucial step in creating a representative FE model. To account for the mechanical change in a HTO, it is recommended to perform the opening (CRM) of a HTO FE modeling study when analyzing the stresses and strains in the plate or screws. |
| Dominique Cava | Comparing Control Modes for Patient-Specific Neuromusculoskeletal Models |
| 27 | Aberrant mechanical loading is a risk factor for knee osteoarthritis, but cannot be directly measured in the intact knee. Patient-specific computational neuromusculoskeletal (nMSK) models offer a means to estimate the magnitude and distribution of knee loads. The purpose of this study was to compare results from patient-specific computational nMSK models using two simulated neuromuscular control modes. Kinematic and kinetic gait data from five patients were used to create patient-specific models in OpenSim. These data were provided as inputs to an inverse dynamics analysis. A computational nMSK model was then executed in CEINMS, providing the ability to process data using two simulated neuromuscular control modes. The electromyography (EMG)-prioritized mode emphasized minimization of error between computed and experimental muscle activations while accepting greater error in computed internal joint torques. The torque-prioritized mode emphasized minimization of error between internal and external joint torques while accepting greater error in computed muscle activations. Outputs from each mode were compared to corresponding experimental muscle activations and external torques. The root mean square error (RMSE) and standard error (SE) between the computed and experimental muscle activations (%MVIC) for all muscles using the EMG-prioritized mode were 0.7% and 1.9%, respectively, and much higher (15.5% and 44.7%, respectively) for the torqueprioritized mode. The RMSE and SE between internal and external knee flexion torques (Nm) using the EMG-prioritized mode were 991.7% and 84%, respectively and substantially lower (58.4% and 5.5%, respectively) for the torque-prioritized mode. The EMG-prioritized mode provided better agreement between computed and experimental muscle activations, but produced substantial torque errors 1600% higher than the torque-prioritized mode. Results suggest greater utility of the torque-prioritized mode for these data. |
| Callahan Doughty | The biomechanical evaluation of partial injuries to the superficial medial collateral ligament |
| 25 | Purpose: In 95% of cases, injury to the anterior cruciate ligament (ACL) occurs in combination with a partial injury to the superficial medial collateral ligament (sMCL) [2]. Injury to the sMCL is often healed without surgical intervention [1,3]. Although, it is known that complete rupture of the MCL results in load transfer onto the ACL, making ligament grafts susceptible to failure [3], the effect of partial injuries of the sMCL have been largely ignored, despite being more common. Thus, the objective is to evaluate changes in knee kinematics and in situ ligament forces during simulated laxity tests following partial-, and complete-sMCL injuries. Methods: Twelve cadaver knees were mounted onto 6 degrees of freedom joint motion simulator (AMTI VIVO). An 8 Nm valgus moment, 4 Nm external-, 4 Nm internal- rotatory torque, and an anteromedial rotatory laxity load (89 N anterior translation + 4 Nm ER), were applied, at 0°, 30°, 60° and 90° of flexion. Intact joint behavior was recorded, followed by either: Sequence 1 (n = 8) cutting the ACL, dMCL, partial sMCL and then full sMCL; or Sequence 2 (n=4) cutting the dMCL, partial sMCL, full sMCL and ACL. Partial sMCL injury was created applying a 10 Nm valgus torque at 30° of flexion, and pie-crusting the sMCL to create a 2.0mm medial opening. Results: Partial injury to the sMCL transferred 1.7 ± 0.6 Nm (p=0.331) to the ACL during valgus rotation (n=4), complete injury resulted in transfer of 4.9 ± 0.6 Nm (p=0.024) to the ACL. During ER partial injury resulted in the transfer of 0.6 ± 0.2 Nm (p=0.313) to the ACL. Conclusion: Partial injury to the sMCL resulted in a significant transfer of load onto the ACL during clinical tests of valgus-, external-rotation, and AMR. Surgical repair of partial sMCL injuries should be further investigated. References: [1] LaPrade 2009 [2] Miyasaka 1991 [3] Robinson 2006 |
| New Ideas and Emerging Trends for MSK Health | |
| Emily Bangsboll | Mechanics of Porous Tibial Implant Components |
| 43 | Background: Porous orthopaedic implants may be embedded with antibiotics to reduce the necessity and burden of two-staged revision surgeries for treating infected prostheses. Gyroid lattice structure may be advantageous over the previously explored strut-based designs for such high-fatigue applications, since gyroids have shown improved fatigue performance and reduced stress shielding. Objective: This study involves finite element models and cyclic fatigue simulation to assess the stress distribution and fatigue life of total knee replacement tibial components with gyroid structure of various porosities. Methods: Three implants were modelled with material properties of Ti-6Al-4V and varying gyroid lattice porosity (60, 70, or 80%) to compare against a solid control implant. Each implant underwent cyclic axial loading in a standardized cantilever fatigue test, which replicated the worst-case scenario of medial loading without bone support, in addition to simulations within two proximal tibia models. Results: Although the worst-case simulations indicated finite fatigue lives and stresses exceeding the yield strength of Ti-6Al-4V (880 MPa) for all porosities, fatigue failure was not definitive as the elements yielded because of stress singularities. Observations found that the implant-in-bone models had infinite life at the lowest loading condition, apart from the 70% porous design. A negligible volume percentage of elements yielded, suggesting that fatigue failure was unlikely for all porous implant specimens with applied loads up to 1000 N (inclusive). Significance: Validation involving physical testing will allow us to optimize the implant design to further reduce stress concentrations. These preliminary findings suggest that tibial components with gyroid structure may be a mechanically viable solution to two-stage revision surgeries, but additional work to optimize the shape and the antibiotic elution dynamics is required. |
| Rémy P Benais | Comparison of numerical methods for modeling trabecular bone indentation |
| 28 | Computational modeling of trabecular bone indentation during implant subsidence has been extensively studied using the finite element (FE) method. Previous studies have only inferred subsidence risk based on local stress and strain concentrations, lacking inclusion of appropriate failure behaviour to accurately predict damage and deformation. The smoothed particle hydrodynamics (SPH) method has only recently been studied in orthopedic applications [1]. This novel FE strategy has shown promise in representing high strain, crushing, and localized densification and damage. However, no comparison of different material models for trabecular bone behaviour has yet been performed. The goal of this study was to implement a meshless SPH approach to compare different material models for the elastic-viscoplastic material behaviour of trabecular bone compaction. Confined trabecular bone indentation was modelled in the commercial FE solver LS-Dyna. Gathered literature data for time-dependent behaviour of bone tissues was used to identify appropriate constitutive material models for trabecular bone available in LS-Dyna: one exhibiting pressure-dependent yielding (PDY) and one independent of pressure (PIY). Trabecular bone response for each were compared based on the effective plastic strain fields at during indentation to examine the material model’s ability to capture the crushing and densification phenomena. Bone densification occurs predominantly below the indenter in the PDY model, and it is apparent all around the indenter with the PIY model. With experimental evidence showing that trabecular bone whitening occurs directly under the indenter [2], the PDY model performs favorably. The presented work shows the ability of the SPH method to qualitatively demonstrate trabecular bone crushing and densification behaviour, as well as the apparent benefit of pressure-dependent yielding in reproducing trabecular bone response. [1] Kulper SA et al. 2018. [2] Kelly N et al. 2013. |
| Matthew S Chapelski | Bone Microstructure in Children with Congenital Heart Defects: A Pilot Study |
| 7 | Purpose: Little is known about the bone microstructure of children with congenital heart disease (CHD). Therefore, the purpose of this study was to evaluate the bone microstructure of children with CHD compared to a previously published reference standard of typically developing peers. Methodology: Twelve children with CHD (7 female) participated in the study. High resolution peripheral quantitative computed tomography (HRpQCT) measured bone microarchitecture of the non-dominant tibia and radius were obtained from all participations. Z-scores were calculated using sex-, ethnic-, and age-specific healthy reference values (Gabel at a., 2018). Results: Comparing height and weight to CDC growth curves there were no differences in the height or weight of children with CHD (Z-score<2.0). When compared to bone microstructure reference standards, male children with CHD had significantly lower cortical thickness at the radius and tibia (Z-score>2.0). Females with CHD also had lower cortical thickness at the radius (Z-score>2.0), but not the tibia (Z-score=1.5). Impact: This pilot study provides insight into potential impairment in bone microstructure. Regardless of sex children with CHD may have impaired cortical thickness at the radius. While males with CHD may also have impaired cortical thickness at the tibia. Future Studies: Future research needs to examine the bone microstructure of children with CHD to determine if deficits exist since bone development during the growing years impacts lifetime skeletal health and fracture risk. |
| Chaudhry, Daniyya N* | Determining the Duration of Hypercoagulability Following Elective Total Hip and Total Knee Arthroplasty using Thrombelastography |
| 50 | Background:Osteoarthritis (OA) is a leading cause of disability worldwide. Joint replacement surgery (arthroplasty) is an effective treatment for managing OA. Post-operatively, patients are at a high risk of developing life-threatening blood clots, knows as venous thromboembolisms (VTE). For VTE prevention, patients are prescribed blood thinners (thromboprophylaxis) for 10-35 days, yet the duration of increased VTE risk is unknown. Thrombelastography (TEG) is a point-of-care tool that can provide an accurate assessment of a patient’s clotting profile. TEG can identify increased clotting risk (hypercoagulability). An elevated maximal amplitude (MA, a measure of clot strength) from TEG analysis has been shown to be predictive of VTE. Therefore, TEG is ideal for quantifying the duration of hypercoagulability and post-operative VTE risk. Objectives:This study aims to utilize serial TEG analysis to identify patients at increased VTE risk and to define the duration of hypercoagulability, following arthroplasty. Methods: This study is a prospective cohort of patients over the age of 50, who are scheduled for an elective hip or knee arthroplasty at the Foothills Medical Centre. Following informed consent, blood specimen draws will be analyzed using TEG until 6-weeks post-operatively. MA values ³ 65 mm will indicate a hypercoagulable state. Thromboprophylaxis will be standardized to aspirin, for 4 weeks for hip and 2 weeks for knee arthroplasty. One-sample t-tests will be used to compare mean MA to the ³ 65 mm threshold. Anticipated Results:We hypothesize that some patients will demonstrate hypercoagulability beyond routine thromboprophylaxis and that those who suffer a VTE will have an elevated MA. Significance:Serial TEG analysis following hip and knee arthroplasty has been limited to nine days post-operatively. We will determine post-operative hypercoagulability duration for the first time to inform thromboprophylaxis clinical practice guidelines for VTE prevention. |
| Iryna Liubchak | Conducting polymer hydrogels for drug delivery and tissue engineering |
| 46 | Articular cartilage tissue doesn`t have direct blood supply and innervation, which significantly limits its self-repair ability. Unfortunately, pathologies that involve the degradation of articular cartilage, such as osteoarthritis (OA), remain hard to treat and progress over time leading to a significant destruction of the hyaline cartilage layer in the large weight-bearing joints. Our primary research objective is to develop a biomaterial for use in the local drug delivery system and stimulate cartilage regeneration. We propose to use biocompatible conducting polymer polypyrrole (PPy) as a drug carrier and synthetic hydrogel as a matrix to improve the mechanical properties of the composite material. Hydrogels were polymerized via photo-crosslinking from the aqueous solution of a synthetic polymer Poly(ethylene) glycol diacrylate (PEGDA). PPy was deposited within the structure of PEGDA hydrogels via the interfacial chemical polymerization method. This study aimed to investigate the efficiency of incorporating anionic compounds into PPy by doping the model drug fluorescein (Fl) with PPy during the oxidative chemical polymerization and initiating its release in alkaline media through deprotonation of the polymer backbone. The biocompatibility of the composite PPy hydrogels was studied using the cartilage cell line ATDC5 according to the ISO 10993-12. The two-step fabrication process used in this study included the preparation of the hydrogel followed by the deposition of PPy allowing to tune the physical properties of the matrix and ensure the mechanical stability of the composite. The photopolymerizable nature of PEGDA also allows for the stereolithography 3D printing of complex shapes and structures of the matrix. The release of Fl from the material in alkaline solution has confirmed the successful incorporation of the dopant into PPy and the possibility for the ‘on-demand’ release. Conducting hydrogels demonstrated no cytotoxic effect over the 14d period. |
| Brandyn Powelske | The Alberta Back Care Pathway – protocol for a hybrid effectiveness-implementation study |
| 40 | Introduction: In Canada, individuals experiencing low back pain (LBP) will often seek treatment from their family doctor largely because primary care is provided at no-cost. Unfortunately, numerous barriers, especially cost, prevent access to first-line, evidence-based interventions resulting in inappropriate use of opioids, imaging and specialist referrals. To overcome this problem, the Alberta Back Care Pathway (ABCp) was developed by stakeholders to provide physicians and their patients with at least one first-line, no-cost intervention for presentations of acute, sub-acute, chronic, chronic non-responsive and radiculopathy LBP. Objective: To evaluate the implementation and effectiveness of the ABCp in primary care settings. Methods: Pre-implementation and concurrent controls (patient and physician) will include participating and non-participating PCNs respectively. Physicians who choose to participate will refer patients presenting with LBP to the pathway, if appropriate, and offer first-line interventions based on duration and presenting symptoms. This could incorporate pharmacological and/or non-pharmacological interventions, including education and exercise via the GLA:D Back program (Good Life with Osteoarthritis: Denmark). Program implementation and effectiveness outcomes will be evaluated within the RE-AIM framework. For example, implementation adoption at the individual level will be evaluated by the number of physicians utilizing the program and system-level effectiveness measurement will be evaluated by determining health resource utilization changes (measured by patient visits, specialist referrals, and imaging). Results: Our expected results are that 1) ABCp will be adopted by 50% or more of eligible PCN physicians 2) 50% of eligible LBP patients will enroll in the program, and 3) there will be a significant difference (p<0.05) with patient outcomes and system-level measures related to cost and healthcare utilization compared to control groups. |
