The purpose of this study was to compare the performance of a 2D video-based markerless motion ca... more The purpose of this study was to compare the performance of a 2D video-based markerless motion capture system to a conventional marker-based approach during a counter movement jump (CMJ). Twenty-three healthy participants performed CMJ while data were collected simultaneously via a marker-based (Oqus) and a 2D video-based motion capture system (Miqus, both: Qualisys AB, Gothenburg, Sweden). The 2D video data was further processed using Theia3D (Theia Markerless Inc.), both sets of data were analysed concurrently in Visual3D (C-motion, Inc). Excellent agreement between systems with ICCs >0.988 exists for Jump height (mean average error of 0.35 cm) and ankle and knee sagittal plane angles (RMS differences < 5°). The hip joint showed higher differences with an average RMSD of 16.9° but maintained a strong correlation of 0.885.
Arthroscopy, Sports Medicine, and Rehabilitation, 2020
The purpose of this study was to determine whether ankle brace use in university-level varsity vo... more The purpose of this study was to determine whether ankle brace use in university-level varsity volleyball athletes affected their 3-step spike jump height and whether certain types of ankle braces have a greater effect on jump height. Methods: Nine male university-level varsity volleyball athletes participated in a repeated-measures design study in which each athlete performed three 3-step volleyball spike jumps in 3 ankle brace conditions (soft, rigid, and no brace). Vertical jump height was measured by the Vertec device and video motion analysis at a university biomechanics research laboratory. Results: Vertical jump heights were significantly lower in both brace conditions (soft, 2.3 cm, standard deviation [SD] 1.2 cm, P < .001; rigid, 1.7 cm, SD 0.9 cm, P < .003) compared with the no-brace condition, and no differences in vertical jump height were observed between the brace conditions (0.6 cm, SD 0.3, P ¼ .3). There was a negative correlation between body fat percentage and vertical jump height (r ¼ e0.075, P ¼ .02). The Vertec device reliably measured vertical jump in all 3 conditions. The no-brace vertical ground reaction forces during the loading phase were significantly greater than brace conditions. Ankle range of motion was greatest in the no-brace condition. Conclusions: Results from this study suggests that high-performance athletes wearing ankle braces experience a significant decrease in vertical jump height independent of the type of ankle brace worn. Clinical Relevance: Sports physicians and health care providers caring for high-level athletes should counsel athletes on the trade-offs of wearing protective equipment in sport, as potential decreases in sports performance can lead to increased injury prevention. Level of Evidence: III.
International Journal of Statistics in Medical Research, 2013
Principal component analysis (PCA) has been successfully applied to gait data; however, interpret... more Principal component analysis (PCA) has been successfully applied to gait data; however, interpretation of the components is challenging. An alternative is to use a graphical display called biplot that gives insights into relationships and trends of data sets. Our goal was to demonstrate the sensitivity of gait variables to aging in elderly women with PCA-biplot. One hundred fifty-one elderly females (71.6±5.0 yrs), 152 adults (44.7±5.4 yrs) and 150 young (21.7±4.1 yrs) participated in the study. Gait spatial and temporal parameters were collected using a computerized carpet. PCA-biplot, discriminant analysis and MANOVA were used in the analysis. PCA-biplot revealed that elderly females walked with lower velocity, shorter step length, reduced swing time, higher cadence, and increased double support time compared to the other two groups. The greatest distances between the groups were along the variable step length with the elderly group showing a decrease of 8.4 cm in relation to the younger group. The discriminant function confirmed the importance of principal component 2 for group separation. Because principal component 2 was heavily weighted by step length and swing time, it represents a measure of stability. As women age they seek a more stable gait by decreasing step length, swing time, and velocity. PCA-biplot highlighted the importance of the variable step length in distinguishing between women of different age groups. It is well-known that as we age we seek a more stable gait. The PCA-biplot emphasized that premise and gave further important insights into relationships and trends of this complex data set.
Valgus unloader braces are a conservative treatment option for medial compartment knee osteoarthr... more Valgus unloader braces are a conservative treatment option for medial compartment knee osteoarthritis that aim to unload the damaged medial compartment through application of an external abduction moment. Patient response to bracing is highly variable, however. While some experience improvements in pain, function, and joint loading, others receive little to no benefit. The objective of this work was to analyze clinical measures and biomechanical characteristics of unbraced walking to identify variables that are associated with the mechanical effectiveness of valgus unloader bracing. Seventeen patients with medial knee osteoarthritis walked overground with and without a valgus unloader brace. A musculoskeletal model was used to estimate the contact forces in the medial compartment of the tibiofemoral joint and brace effectiveness was defined as the decrease in peak medial contact force between unbraced and braced conditions. Stepwise linear regression was used to identify clinical and biomechanical measures that predicted brace effectiveness. The final regression model explained 77% of the variance in brace effectiveness using two variables. Bracing was more effective for those with greater peak external hip adduction moments and for those with higher Kellgren-Lawrence grades, indicating more severe radiographic osteoarthritis. The hip adduction moment was the best predictor of brace effectiveness and was well correlated with several other measures indicating that it may be functioning as a "biomarker" for good bracing candidates. Clinical Significance: The ability to predict good candidates for valgus bracing may improve issues of patient compliance and could enable the ability to train patients to respond better to bracing.
A prospective study was conducted on a group of patients with unilateral nonspecific low back pai... more A prospective study was conducted on a group of patients with unilateral nonspecific low back pain (LBP) and healthy controls. To answer 3 questions: (1) Does pelvic asymmetry measured in standing affect the dynamics of motion performed in sitting? (2) Do patients with LBP perform trunk motions differently from non-LBP participants in sitting position? and (3) Do the kinematics of lateral flexion and axial rotation differ between sitting and standing positions? The effect of pelvic asymmetry on trunk motion while sitting remains unclear. LBP has been associated with altered trunk kinematics in standing; however, there is limited information available describing trunk kinematics in sitting position in comparison to standing. Pelvic asymmetry was measured in 54 patients with unilateral nonspecific LBP and 59 control subjects. A motion-analysis system was used to test the range and symmetry of lateral flexion and axial rotation in sitting and standing positions. Bivariate correlations,...
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2004
Modern gait analysis is a powerful non-invasive tool for calculating the mechanical factors invol... more Modern gait analysis is a powerful non-invasive tool for calculating the mechanical factors involved in pathological processes such as knee osteoarthritis (OA). Although very accurate measurements can be made, the clinical applicability and widespread use of gait analysis have been hindered by a lack of appropriate data analysis techniques for reducing and analysing the resulting large volumes of highly correlated gait data. This paper introduces a multidimensional galt data analysis technique that simultaneously considers multiple time-varying and discrete measures, exploiting the correlation structure between and within the measures. The multidimensional analysis technique was used to detect discriminatory mechanical features of knee OA gait patterns that involved interacting changes in several gait measures, at specific time portions of the gait cycle. The two most discriminatory features described a dynamic alignment difference and a loading response difference with knee OA.
Objective: To test the hypothesis that an association exists between the characteristics of the k... more Objective: To test the hypothesis that an association exists between the characteristics of the knee adduction moment and foot progression angle (FPA) in asymptomatic individuals and those with mild to moderate and severe knee osteoarthritis (OA). Design: Fifty asymptomatic individuals, 46 patients with mild to moderate and 44 patients with severe knee OA were recruited. Maximum knee adduction moment during late stance and principal component analysis (PCA) were used to describe the knee adduction moment captured during gait. Multiple regression models were used for each of the three group assignments to analyze the association between the independent variables and the knee adduction moment. Results: FPA explained a significant amount of the variability associated with the shape of the knee adduction moment waveform for the asymptomatic and mild to moderate groups (P < 0.05), but not for the severe group (P > 0.05). Walking velocity alone explained significant variance associated with the shape of the knee adduction moment in the severe OA group (P < 0.05). Conclusion: A toe out FPA was associated with altered knee adduction moment waveform characteristics, extracted using PCA, in asymptomatic individuals and those with mild to moderate knee OA only. These findings are directly implicated in medial knee compartment loading. This relationship was not evident in those with severe knee OA.
Objective: The objective of this study was to determine the association between biomechanical and... more Objective: The objective of this study was to determine the association between biomechanical and neuromuscular factors of clinically diagnosed mild to moderate knee osteoarthritis (OA) with radiographic severity and pain severity separately. Method: Three-dimensional gait analysis and electromyography were performed on a group of 40 participants with clinically diagnosed mild to moderate medial knee OA. Associations between radiographic severity, defined using a visual analog radiographic score, and pain severity, defined with the pain subscale of the WOMAC osteoarthritis index, with knee joint kinematics and kinetics, electromyography patterns of periarticular knee muscles, BMI and gait speed were determined with correlation analyses. Multiple linear regression analyses of radiographic and pain severity were also explored. Results: Statistically significant correlations between radiographic severity and the overall magnitude of the knee adduction moment during stance (r 2 ¼ 21.4%, P ¼ 0.003) and the magnitude of the knee flexion angle during the gait cycle (r 2 ¼ 11.4%, P ¼ 0.03) were found. Significant correlations between pain and gait speed (r 2 ¼ 28.2%, P < 0.0001), the activation patterns of the lateral gastrocnemius (r 2 ¼ 16.6%, P ¼ 0.009) and the medial hamstring (r 2 ¼ 10.3%, P ¼ 0.04) during gait were found. The combination of the magnitude of the knee adduction moment during stance and BMI explained a significant portion of the variability in radiographic severity (R 2 ¼ 27.1%, P < 0.0001). No multivariate model explained pain severity better than gait speed alone. Conclusions: This study suggests that some knee joint biomechanical variables are associated with structural knee OA severity measured from radiographs in clinically diagnosed mild to moderate levels of disease, but that pain severity is only reflected in gait speed and neuromuscular activation patterns. A combination of the knee adduction moment and BMI better explained structural knee OA severity than any individual factor alone.
Reverse shoulder arthroplasty is a relatively new procedure that is used to treat shoulders with ... more Reverse shoulder arthroplasty is a relatively new procedure that is used to treat shoulders with massive rotator cuff tears combined with arthritis, a condition that is not well managed using conventional shoulder arthroplasty. By reversing the 'ball-and-socket' anatomy of the shoulder, the constraint of the joint can be increased. Despite the success of this prosthesis in improving pain and function, complication rates remain high and instability is often reported as the most commonly occurring complication. The mechanism of dislocation as well as factors that can be modified to decrease the risk of dislocation are not well understood for reverse shoulder arthroplasty. Therefore, the purpose of this study was to create a platform for examining the stability of reverse shoulder arthroplasty and use this to investigate factors affecting stability, including shoulder orientation (abduction and abduction plane angles), loading direction, glenosphere eccentricity and diameter, and humeral socket constraint. An anatomical shoulder simulator was developed using a synthetic bone model and pneumatically actuated cables to represent the three heads of the deltoid. A displacing force was applied to the humeral head by a material testing machine in an anterior, posterior, superior, or inferior direction. The force required to dislocate the joint was used as a measure of stability and the identified factors and the interactions between factors were examined using a half-fraction factorial design experiment. Increases in glenohumeral abduction or inferior-offset of the glenosphere were found to improve the stability of the prosthesis. Additionally, increased humeral socket depth resulted in greater stability for all loading directions, with the exception of inferior loading. Abduction plane angle and glenosphere diameter had no effect on the stability of reverse shoulder arthroplasty. iii Co-Authorship This thesis contains the original work of Allison Clouthier, completed under the co-supervision of
Objectives: To compare the compressive strength of a bone substitute material (a-BSM TM) to cance... more Objectives: To compare the compressive strength of a bone substitute material (a-BSM TM) to cancellous bone when used to fill a defect void in a cadaver model of a Schatzker II split depression fracture of the lateral tibial plateau.
The accuracy of estimating the relative pose between knee replacement components, in terms of cli... more The accuracy of estimating the relative pose between knee replacement components, in terms of clinical motion, is important in the study of knee joint kinematics. The objective of this study was to determine the accuracy of the single-plane fluoroscopy method in calculating the relative pose between the femoral component and the tibial component, along knee motion axes, while the components were in motion relative to one another. The kinematics of total knee replacement components were determined in vitro using two simultaneous methods: single-plane fluoroscopic shape matching and an optoelectronic motion tracking system. The largest mean differences in relative pose between the two methods for any testing condition were 2.11, 0.31, and 1.11 in extension, abduction, and internal rotation respectively, and 1.3, 0.9, and 1.9 mm in anterior, distal, and lateral translations, respectively. For the optimized position of the components during dynamic trials, the limits of agreement, between which 95% of differences can be expected to fall, were À 2.9 to 4.51 in flexion, À 0.9 to 1.51 in abduction, À 2.4 to 2.11 in external rotation, À 2.0 to 3.9 mm in anterior-posterior translation, À 2.2 to 0.4 mm in distal-proximal translation and À 7.2 to 8.6 mm in medial-lateral translation. These mean accuracy values and limits of agreement can be used to determine whether the shape-matching approach using single-plane fluoroscopic images is sufficiently accurate for an intended motion tracking application.
This article was originally published in a journal published by Elsevier, and the attached copy i... more This article was originally published in a journal published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for non-commercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues that you know, and providing a copy to your institution's administrator.
Knee osteoarthritis (OA) is a multifactoral, progressive disease process of the musculoskeletal s... more Knee osteoarthritis (OA) is a multifactoral, progressive disease process of the musculoskeletal system. Mechanical factors have been implicated in the progression of knee OA, but the role of altered joint mechanics and neuromuscular control strategies in progressive mechanisms of the disease have not been fully explored. Previous biomechanical studies of knee OA have characterized changes in joint kinematics and kinetics with the disease, but it has been difficult to determine if these biomechanical changes are involved in the development of disease, are in response to degenerative changes in the joint, or are compensatory mechanisms in response to these degenerative changes or other related factors as joint pain. The goal of this study was to explore the association between biomechanical changes and knee OA severity in an effort to understand the changing role of biomechanical factors in the progression of knee OA. A three-group cross-sectional model was used that included asymptomatic subjects, subjects clinically diagnosed with moderate knee OA and severe knee OA subjects just prior to total joint replacement surgery. Principal component analysis and discriminant analysis were used to determine the combinations of electromyography, kinematic and kinetic waveform pattern changes at the knee, hip and ankle joints during gait that optimally separated the three levels of severity. Different biomechanical mechanisms were important in discriminating between severity levels. Changes in knee and hip kinetic patterns and rectus femoris activation were important in separating the asymptomatic and moderate OA gait patterns. In contrast, changes in knee kinematics, hip and ankle kinetics and medial gastrocnemius activity were important in discriminating between the moderate and severe OA gait patterns.
An in vitro radiostereometric analysis (RSA) phantom study of a total knee replacement was carrie... more An in vitro radiostereometric analysis (RSA) phantom study of a total knee replacement was carried out to evaluate the effect of implementing two new modifications to the conventional RSA procedure: (i) adding a landmark of the tibial component as an implant marker and (ii) defining an implant-based coordinate system constructed from implant landmarks for the calculation of migration results. The motivation for these two modifications were (i) to improve the representation of the implant by the markers by including the stem tip marker which increases the marker distribution (ii) to recover clinical RSA study cases with insufficient numbers of markers visible in the implant polyethylene and (iii) to eliminate errors in migration calculations due to misalignment of the anatomical axes with the RSA global coordinate system. The translational and rotational phantom studies showed no loss of accuracy with the two new measurement methods. The RSA system employing these methods has a precision of better than 0.05 mm for translations and 0.031 for rotations, and an accuracy of 0.05 mm for translations and 0.151 for rotations. These results indicate that the new methods to improve the interpretability, relevance, and standardization of the results do not compromise precision and accuracy, and are suitable for application to clinical data.
Ahstrnct-The automation provided by computer-assisted motion-tracking systems allows for threedim... more Ahstrnct-The automation provided by computer-assisted motion-tracking systems allows for threedimensional motion and force analysis. These systems combined with mathematical modelling are able to analyse quickly the intricate dynamics of human movement. Understanding the limitations of human motion analysis as performed by the present measurement techniques is essential for proper application of the results. It is necessary to validate the analysis system prior to subject testing. This paper provides a validation of an optoelectric motion-tracking system used in a dynamic knee assessment study. While the validation is shown with one particular system only, it is suggested that all systems used in two-or threedimensional motion analysis should be tested similarly in the actual configuration used. Three simple mechanical representations of the human knee have been used in this validation. The first model provided an understanding of the source and behaviour of the error introduced to the accuracy of defining a vector between the recorded coordinates of two markers. The other two models investigated the effect of processing methods specific to the knee analysis project. Separating the markers by at least 180 mm is recommended to produce stable vectors. Relative joint angles could be calculated in all three planes of rotation. The error in calculating flexion and longitudinal rotation was less than 2.0", while calculating adduction introduced errors of 4.0". Force calculations were found to be within 8%. The system behaviour was found to be consistent within the calibrated volume about the force platform. Simple mechanical models combined with straightforward procedures can provide validation in terms of clinically relevant parameters.
The reduction and analysis of gait waveform data is a signi®cant barrier to the clinical applicat... more The reduction and analysis of gait waveform data is a signi®cant barrier to the clinical application of gait analysis. Principal component modelling of gait waveform data reduced the waveform data to measures of distance from normal and these distance measures were shown to be sensitive to changes in gait pattern associated with knee osteoarthritis and its treatment by unicompartmental arthroplasty. Principal component models were developed for eight knee kinematic and kinetic gait waveforms of a group of 30 normal elderly subjects. Each model consisted of a set of loading vectors, principal component scores and residuals. The loading vectors revealed the structure of the model and the scores and residuals were used as the distance measures about which con®dence intervals were developed. Pre-operative and post-operative gait data from 13 unicompartmental arthroplasty (UCA) patients were used to demonstrate the application of the principal component models to pathological gait data. A gait score was developed to indicate the overall assessment of the kinematic and kinetic gait measures by the principal component models. This gait score was shown to agree with the
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
The purpose of this study was to compare the performance of a 2D video-based markerless motion ca... more The purpose of this study was to compare the performance of a 2D video-based markerless motion capture system to a conventional marker-based approach during a counter movement jump (CMJ). Twenty-three healthy participants performed CMJ while data were collected simultaneously via a marker-based (Oqus) and a 2D video-based motion capture system (Miqus, both: Qualisys AB, Gothenburg, Sweden). The 2D video data was further processed using Theia3D (Theia Markerless Inc.), both sets of data were analysed concurrently in Visual3D (C-motion, Inc). Excellent agreement between systems with ICCs >0.988 exists for Jump height (mean average error of 0.35 cm) and ankle and knee sagittal plane angles (RMS differences < 5°). The hip joint showed higher differences with an average RMSD of 16.9° but maintained a strong correlation of 0.885.
Arthroscopy, Sports Medicine, and Rehabilitation, 2020
The purpose of this study was to determine whether ankle brace use in university-level varsity vo... more The purpose of this study was to determine whether ankle brace use in university-level varsity volleyball athletes affected their 3-step spike jump height and whether certain types of ankle braces have a greater effect on jump height. Methods: Nine male university-level varsity volleyball athletes participated in a repeated-measures design study in which each athlete performed three 3-step volleyball spike jumps in 3 ankle brace conditions (soft, rigid, and no brace). Vertical jump height was measured by the Vertec device and video motion analysis at a university biomechanics research laboratory. Results: Vertical jump heights were significantly lower in both brace conditions (soft, 2.3 cm, standard deviation [SD] 1.2 cm, P < .001; rigid, 1.7 cm, SD 0.9 cm, P < .003) compared with the no-brace condition, and no differences in vertical jump height were observed between the brace conditions (0.6 cm, SD 0.3, P ¼ .3). There was a negative correlation between body fat percentage and vertical jump height (r ¼ e0.075, P ¼ .02). The Vertec device reliably measured vertical jump in all 3 conditions. The no-brace vertical ground reaction forces during the loading phase were significantly greater than brace conditions. Ankle range of motion was greatest in the no-brace condition. Conclusions: Results from this study suggests that high-performance athletes wearing ankle braces experience a significant decrease in vertical jump height independent of the type of ankle brace worn. Clinical Relevance: Sports physicians and health care providers caring for high-level athletes should counsel athletes on the trade-offs of wearing protective equipment in sport, as potential decreases in sports performance can lead to increased injury prevention. Level of Evidence: III.
International Journal of Statistics in Medical Research, 2013
Principal component analysis (PCA) has been successfully applied to gait data; however, interpret... more Principal component analysis (PCA) has been successfully applied to gait data; however, interpretation of the components is challenging. An alternative is to use a graphical display called biplot that gives insights into relationships and trends of data sets. Our goal was to demonstrate the sensitivity of gait variables to aging in elderly women with PCA-biplot. One hundred fifty-one elderly females (71.6±5.0 yrs), 152 adults (44.7±5.4 yrs) and 150 young (21.7±4.1 yrs) participated in the study. Gait spatial and temporal parameters were collected using a computerized carpet. PCA-biplot, discriminant analysis and MANOVA were used in the analysis. PCA-biplot revealed that elderly females walked with lower velocity, shorter step length, reduced swing time, higher cadence, and increased double support time compared to the other two groups. The greatest distances between the groups were along the variable step length with the elderly group showing a decrease of 8.4 cm in relation to the younger group. The discriminant function confirmed the importance of principal component 2 for group separation. Because principal component 2 was heavily weighted by step length and swing time, it represents a measure of stability. As women age they seek a more stable gait by decreasing step length, swing time, and velocity. PCA-biplot highlighted the importance of the variable step length in distinguishing between women of different age groups. It is well-known that as we age we seek a more stable gait. The PCA-biplot emphasized that premise and gave further important insights into relationships and trends of this complex data set.
Valgus unloader braces are a conservative treatment option for medial compartment knee osteoarthr... more Valgus unloader braces are a conservative treatment option for medial compartment knee osteoarthritis that aim to unload the damaged medial compartment through application of an external abduction moment. Patient response to bracing is highly variable, however. While some experience improvements in pain, function, and joint loading, others receive little to no benefit. The objective of this work was to analyze clinical measures and biomechanical characteristics of unbraced walking to identify variables that are associated with the mechanical effectiveness of valgus unloader bracing. Seventeen patients with medial knee osteoarthritis walked overground with and without a valgus unloader brace. A musculoskeletal model was used to estimate the contact forces in the medial compartment of the tibiofemoral joint and brace effectiveness was defined as the decrease in peak medial contact force between unbraced and braced conditions. Stepwise linear regression was used to identify clinical and biomechanical measures that predicted brace effectiveness. The final regression model explained 77% of the variance in brace effectiveness using two variables. Bracing was more effective for those with greater peak external hip adduction moments and for those with higher Kellgren-Lawrence grades, indicating more severe radiographic osteoarthritis. The hip adduction moment was the best predictor of brace effectiveness and was well correlated with several other measures indicating that it may be functioning as a "biomarker" for good bracing candidates. Clinical Significance: The ability to predict good candidates for valgus bracing may improve issues of patient compliance and could enable the ability to train patients to respond better to bracing.
A prospective study was conducted on a group of patients with unilateral nonspecific low back pai... more A prospective study was conducted on a group of patients with unilateral nonspecific low back pain (LBP) and healthy controls. To answer 3 questions: (1) Does pelvic asymmetry measured in standing affect the dynamics of motion performed in sitting? (2) Do patients with LBP perform trunk motions differently from non-LBP participants in sitting position? and (3) Do the kinematics of lateral flexion and axial rotation differ between sitting and standing positions? The effect of pelvic asymmetry on trunk motion while sitting remains unclear. LBP has been associated with altered trunk kinematics in standing; however, there is limited information available describing trunk kinematics in sitting position in comparison to standing. Pelvic asymmetry was measured in 54 patients with unilateral nonspecific LBP and 59 control subjects. A motion-analysis system was used to test the range and symmetry of lateral flexion and axial rotation in sitting and standing positions. Bivariate correlations,...
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2004
Modern gait analysis is a powerful non-invasive tool for calculating the mechanical factors invol... more Modern gait analysis is a powerful non-invasive tool for calculating the mechanical factors involved in pathological processes such as knee osteoarthritis (OA). Although very accurate measurements can be made, the clinical applicability and widespread use of gait analysis have been hindered by a lack of appropriate data analysis techniques for reducing and analysing the resulting large volumes of highly correlated gait data. This paper introduces a multidimensional galt data analysis technique that simultaneously considers multiple time-varying and discrete measures, exploiting the correlation structure between and within the measures. The multidimensional analysis technique was used to detect discriminatory mechanical features of knee OA gait patterns that involved interacting changes in several gait measures, at specific time portions of the gait cycle. The two most discriminatory features described a dynamic alignment difference and a loading response difference with knee OA.
Objective: To test the hypothesis that an association exists between the characteristics of the k... more Objective: To test the hypothesis that an association exists between the characteristics of the knee adduction moment and foot progression angle (FPA) in asymptomatic individuals and those with mild to moderate and severe knee osteoarthritis (OA). Design: Fifty asymptomatic individuals, 46 patients with mild to moderate and 44 patients with severe knee OA were recruited. Maximum knee adduction moment during late stance and principal component analysis (PCA) were used to describe the knee adduction moment captured during gait. Multiple regression models were used for each of the three group assignments to analyze the association between the independent variables and the knee adduction moment. Results: FPA explained a significant amount of the variability associated with the shape of the knee adduction moment waveform for the asymptomatic and mild to moderate groups (P < 0.05), but not for the severe group (P > 0.05). Walking velocity alone explained significant variance associated with the shape of the knee adduction moment in the severe OA group (P < 0.05). Conclusion: A toe out FPA was associated with altered knee adduction moment waveform characteristics, extracted using PCA, in asymptomatic individuals and those with mild to moderate knee OA only. These findings are directly implicated in medial knee compartment loading. This relationship was not evident in those with severe knee OA.
Objective: The objective of this study was to determine the association between biomechanical and... more Objective: The objective of this study was to determine the association between biomechanical and neuromuscular factors of clinically diagnosed mild to moderate knee osteoarthritis (OA) with radiographic severity and pain severity separately. Method: Three-dimensional gait analysis and electromyography were performed on a group of 40 participants with clinically diagnosed mild to moderate medial knee OA. Associations between radiographic severity, defined using a visual analog radiographic score, and pain severity, defined with the pain subscale of the WOMAC osteoarthritis index, with knee joint kinematics and kinetics, electromyography patterns of periarticular knee muscles, BMI and gait speed were determined with correlation analyses. Multiple linear regression analyses of radiographic and pain severity were also explored. Results: Statistically significant correlations between radiographic severity and the overall magnitude of the knee adduction moment during stance (r 2 ¼ 21.4%, P ¼ 0.003) and the magnitude of the knee flexion angle during the gait cycle (r 2 ¼ 11.4%, P ¼ 0.03) were found. Significant correlations between pain and gait speed (r 2 ¼ 28.2%, P < 0.0001), the activation patterns of the lateral gastrocnemius (r 2 ¼ 16.6%, P ¼ 0.009) and the medial hamstring (r 2 ¼ 10.3%, P ¼ 0.04) during gait were found. The combination of the magnitude of the knee adduction moment during stance and BMI explained a significant portion of the variability in radiographic severity (R 2 ¼ 27.1%, P < 0.0001). No multivariate model explained pain severity better than gait speed alone. Conclusions: This study suggests that some knee joint biomechanical variables are associated with structural knee OA severity measured from radiographs in clinically diagnosed mild to moderate levels of disease, but that pain severity is only reflected in gait speed and neuromuscular activation patterns. A combination of the knee adduction moment and BMI better explained structural knee OA severity than any individual factor alone.
Reverse shoulder arthroplasty is a relatively new procedure that is used to treat shoulders with ... more Reverse shoulder arthroplasty is a relatively new procedure that is used to treat shoulders with massive rotator cuff tears combined with arthritis, a condition that is not well managed using conventional shoulder arthroplasty. By reversing the 'ball-and-socket' anatomy of the shoulder, the constraint of the joint can be increased. Despite the success of this prosthesis in improving pain and function, complication rates remain high and instability is often reported as the most commonly occurring complication. The mechanism of dislocation as well as factors that can be modified to decrease the risk of dislocation are not well understood for reverse shoulder arthroplasty. Therefore, the purpose of this study was to create a platform for examining the stability of reverse shoulder arthroplasty and use this to investigate factors affecting stability, including shoulder orientation (abduction and abduction plane angles), loading direction, glenosphere eccentricity and diameter, and humeral socket constraint. An anatomical shoulder simulator was developed using a synthetic bone model and pneumatically actuated cables to represent the three heads of the deltoid. A displacing force was applied to the humeral head by a material testing machine in an anterior, posterior, superior, or inferior direction. The force required to dislocate the joint was used as a measure of stability and the identified factors and the interactions between factors were examined using a half-fraction factorial design experiment. Increases in glenohumeral abduction or inferior-offset of the glenosphere were found to improve the stability of the prosthesis. Additionally, increased humeral socket depth resulted in greater stability for all loading directions, with the exception of inferior loading. Abduction plane angle and glenosphere diameter had no effect on the stability of reverse shoulder arthroplasty. iii Co-Authorship This thesis contains the original work of Allison Clouthier, completed under the co-supervision of
Objectives: To compare the compressive strength of a bone substitute material (a-BSM TM) to cance... more Objectives: To compare the compressive strength of a bone substitute material (a-BSM TM) to cancellous bone when used to fill a defect void in a cadaver model of a Schatzker II split depression fracture of the lateral tibial plateau.
The accuracy of estimating the relative pose between knee replacement components, in terms of cli... more The accuracy of estimating the relative pose between knee replacement components, in terms of clinical motion, is important in the study of knee joint kinematics. The objective of this study was to determine the accuracy of the single-plane fluoroscopy method in calculating the relative pose between the femoral component and the tibial component, along knee motion axes, while the components were in motion relative to one another. The kinematics of total knee replacement components were determined in vitro using two simultaneous methods: single-plane fluoroscopic shape matching and an optoelectronic motion tracking system. The largest mean differences in relative pose between the two methods for any testing condition were 2.11, 0.31, and 1.11 in extension, abduction, and internal rotation respectively, and 1.3, 0.9, and 1.9 mm in anterior, distal, and lateral translations, respectively. For the optimized position of the components during dynamic trials, the limits of agreement, between which 95% of differences can be expected to fall, were À 2.9 to 4.51 in flexion, À 0.9 to 1.51 in abduction, À 2.4 to 2.11 in external rotation, À 2.0 to 3.9 mm in anterior-posterior translation, À 2.2 to 0.4 mm in distal-proximal translation and À 7.2 to 8.6 mm in medial-lateral translation. These mean accuracy values and limits of agreement can be used to determine whether the shape-matching approach using single-plane fluoroscopic images is sufficiently accurate for an intended motion tracking application.
This article was originally published in a journal published by Elsevier, and the attached copy i... more This article was originally published in a journal published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for non-commercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues that you know, and providing a copy to your institution's administrator.
Knee osteoarthritis (OA) is a multifactoral, progressive disease process of the musculoskeletal s... more Knee osteoarthritis (OA) is a multifactoral, progressive disease process of the musculoskeletal system. Mechanical factors have been implicated in the progression of knee OA, but the role of altered joint mechanics and neuromuscular control strategies in progressive mechanisms of the disease have not been fully explored. Previous biomechanical studies of knee OA have characterized changes in joint kinematics and kinetics with the disease, but it has been difficult to determine if these biomechanical changes are involved in the development of disease, are in response to degenerative changes in the joint, or are compensatory mechanisms in response to these degenerative changes or other related factors as joint pain. The goal of this study was to explore the association between biomechanical changes and knee OA severity in an effort to understand the changing role of biomechanical factors in the progression of knee OA. A three-group cross-sectional model was used that included asymptomatic subjects, subjects clinically diagnosed with moderate knee OA and severe knee OA subjects just prior to total joint replacement surgery. Principal component analysis and discriminant analysis were used to determine the combinations of electromyography, kinematic and kinetic waveform pattern changes at the knee, hip and ankle joints during gait that optimally separated the three levels of severity. Different biomechanical mechanisms were important in discriminating between severity levels. Changes in knee and hip kinetic patterns and rectus femoris activation were important in separating the asymptomatic and moderate OA gait patterns. In contrast, changes in knee kinematics, hip and ankle kinetics and medial gastrocnemius activity were important in discriminating between the moderate and severe OA gait patterns.
An in vitro radiostereometric analysis (RSA) phantom study of a total knee replacement was carrie... more An in vitro radiostereometric analysis (RSA) phantom study of a total knee replacement was carried out to evaluate the effect of implementing two new modifications to the conventional RSA procedure: (i) adding a landmark of the tibial component as an implant marker and (ii) defining an implant-based coordinate system constructed from implant landmarks for the calculation of migration results. The motivation for these two modifications were (i) to improve the representation of the implant by the markers by including the stem tip marker which increases the marker distribution (ii) to recover clinical RSA study cases with insufficient numbers of markers visible in the implant polyethylene and (iii) to eliminate errors in migration calculations due to misalignment of the anatomical axes with the RSA global coordinate system. The translational and rotational phantom studies showed no loss of accuracy with the two new measurement methods. The RSA system employing these methods has a precision of better than 0.05 mm for translations and 0.031 for rotations, and an accuracy of 0.05 mm for translations and 0.151 for rotations. These results indicate that the new methods to improve the interpretability, relevance, and standardization of the results do not compromise precision and accuracy, and are suitable for application to clinical data.
Ahstrnct-The automation provided by computer-assisted motion-tracking systems allows for threedim... more Ahstrnct-The automation provided by computer-assisted motion-tracking systems allows for threedimensional motion and force analysis. These systems combined with mathematical modelling are able to analyse quickly the intricate dynamics of human movement. Understanding the limitations of human motion analysis as performed by the present measurement techniques is essential for proper application of the results. It is necessary to validate the analysis system prior to subject testing. This paper provides a validation of an optoelectric motion-tracking system used in a dynamic knee assessment study. While the validation is shown with one particular system only, it is suggested that all systems used in two-or threedimensional motion analysis should be tested similarly in the actual configuration used. Three simple mechanical representations of the human knee have been used in this validation. The first model provided an understanding of the source and behaviour of the error introduced to the accuracy of defining a vector between the recorded coordinates of two markers. The other two models investigated the effect of processing methods specific to the knee analysis project. Separating the markers by at least 180 mm is recommended to produce stable vectors. Relative joint angles could be calculated in all three planes of rotation. The error in calculating flexion and longitudinal rotation was less than 2.0", while calculating adduction introduced errors of 4.0". Force calculations were found to be within 8%. The system behaviour was found to be consistent within the calibrated volume about the force platform. Simple mechanical models combined with straightforward procedures can provide validation in terms of clinically relevant parameters.
The reduction and analysis of gait waveform data is a signi®cant barrier to the clinical applicat... more The reduction and analysis of gait waveform data is a signi®cant barrier to the clinical application of gait analysis. Principal component modelling of gait waveform data reduced the waveform data to measures of distance from normal and these distance measures were shown to be sensitive to changes in gait pattern associated with knee osteoarthritis and its treatment by unicompartmental arthroplasty. Principal component models were developed for eight knee kinematic and kinetic gait waveforms of a group of 30 normal elderly subjects. Each model consisted of a set of loading vectors, principal component scores and residuals. The loading vectors revealed the structure of the model and the scores and residuals were used as the distance measures about which con®dence intervals were developed. Pre-operative and post-operative gait data from 13 unicompartmental arthroplasty (UCA) patients were used to demonstrate the application of the principal component models to pathological gait data. A gait score was developed to indicate the overall assessment of the kinematic and kinetic gait measures by the principal component models. This gait score was shown to agree with the
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
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Papers by Kevin Deluzio