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Papers by Janet Ronsky

Research paper thumbnail of Concurrent validity and reliability of a semi-automated approach to measuring the magnetic resonance imaging morphology of the knee joint in active youth

Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine

Post-traumatic knee osteoarthritis is attributed to alterations in joint morphology, alignment, a... more Post-traumatic knee osteoarthritis is attributed to alterations in joint morphology, alignment, and biomechanics triggered by injury. While magnetic resonance (MR) imaging-based measures of joint morphology and alignment are relevant to understanding osteoarthritis risk, time consuming manual data extraction and measurement limit the number of outcomes that can be considered and deter widespread use. This paper describes the development and evaluation of a semi-automated software for measuring tibiofemoral and patellofemoral joint architecture using MR images from youth with and without a previous sport-related knee injury. After prompting users to identify and select key anatomical landmarks, the software can calculate 37 (14 tibiofemoral, 23 patellofemoral) relevant geometric features (morphology and alignment) based on established methods. To assess validity and reliability, 11 common geometric features were calculated from the knee MR images (proton density and proton density fa...

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Research paper thumbnail of Vertical Drop Jump Biomechanics of Patients With a 3- to 10-Year History of Youth Sport–Related Anterior Cruciate Ligament Reconstruction

Orthopaedic Journal of Sports Medicine, 2021

Background: A better understanding of movement biomechanics after anterior cruciate ligament reco... more Background: A better understanding of movement biomechanics after anterior cruciate ligament reconstruction (ACLR) could inform injury prevention, knee injury rehabilitation, and osteoarthritis prevention strategies. Purpose: To investigate differences in vertical drop jump (VDJ) biomechanics between patients with a 3- to 10-year history of youth sport–related ACLR and uninjured peers of a similar age, sex, and sport. Study Design: Cross-sectional study. Level of evidence III. Methods: Lower limb kinematics and bilateral ground-reaction forces (GRFs) were recorded for participants performing 10 VDJs. Joint angles and GRF data were analyzed, and statistical analysis was performed using 2 multivariate models. Dependent variables included sagittal (ankle, knee, and hip) and coronal (knee and hip) angles at initial contact and maximum knee flexion, the rate of change of coronal knee angles (35%-90% of the support phase; ie, slopes of linear regression lines), and vertical and mediolater...

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Research paper thumbnail of Development of a calibration procedure for integration of dual fluoroscopy and motion analysis

Journal of Undergraduate Research in Alberta, 2013

INTRODUCTION Accurate quantification of in vivo effects of injury on joint mechanics is essential... more INTRODUCTION Accurate quantification of in vivo effects of injury on joint mechanics is essential to identify movement abnormality and related joint pathologies such as osteoarthritis. Typically used Motion Analysis (MA) technologies for studying human gait and injury suffer from soft tissue movement artifact, which may prohibit identification of small but significant changes of joint motion. High-speed dual fluoroscopy (DF) systems such as the one at the Clinical Movement Assessment Laboratory, University of Calgary, provide movement-artifact-free, high-resolution (0.30-0.44°, 0.25-0.33mm) [1], in vivo bone kinematics during dynamic activities. Such systems however, represent a trade-off between high system accuracy and limited field of view (FOV~10 inch) [2] compared to MA systems. DF systems therefore typically provide information only for a single joint while MA systems may capture the whole body. This project worked toward the integration of traditional MA and state-of-the-art ...

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Research paper thumbnail of Characterizing Healthy Knee Symmetry using the Finite Helical Axis and Muscle Power During Open and Closed Chain Tasks

Journal of Biomechanics, 2019

Understanding healthy joint movement and muscle control, and injurious alterations, is important ... more Understanding healthy joint movement and muscle control, and injurious alterations, is important to determine musculoskeletal contributions to post-injury joint instabilities or altered dynamic joint function. The contralateral limb is often used as a point of reference to determine the effects of knee joint injury. However, it is currently difficult to interpret within subject variability between limbs as this is not well established in the healthy population. There is a continuing need to characterize healthy knee joint mechanics and neuromuscular control to determine the degree of symmetry within healthy individuals. The current study quantified limb symmetry in healthy individuals using the finite helical axis with a unique reference position (rFHA) and electromyography (EMG) approaches, for a closed-chain single leg squat (SLS) and an open-chain seated leg swing. Muscle power and FHA translation, orientation and dispersion were similar between limbs. However, the FHA was located significantly more anterior in the dominant limb relative to the contralateral during both tasks. These between-limb differences in FHA location could be attributed to differences in joint geometry and strength between limbs. This finding provides evidence that healthy knees have asymmetries which have implications for selection of control limbs in studies comparing conditions within and between individuals. Differences identified in dynamic joint function between tasks suggest that the SLS is useful for revealing joint asymmetries due to altered muscular control strategies, while the swing task is expected to highlight asymmetries in joint motion due to altered knee structures following injury.

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Research paper thumbnail of 536 The influence of a novel mechanical loading regimen on the molecular response of human facial skin cells

Journal of Investigative Dermatology, 2017

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Research paper thumbnail of Toward an Automatic Calibration of Dual Fluoroscopy Imaging Systems

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2016

High-speed dual fluoroscopy (DF) imaging provides a novel, in-vivo solution to quantify the six-d... more High-speed dual fluoroscopy (DF) imaging provides a novel, in-vivo solution to quantify the six-degree-of-freedom skeletal kinematics of humans and animals with sub-millimetre accuracy and high temporal resolution. A rigorous geometric calibration of DF system parameters is essential to ensure precise bony rotation and translation measurements. One way to achieve the system calibration is by performing a bundle adjustment with self-calibration. A first-time bundle adjustment-based system calibration was recently achieved. The system calibration through the bundle adjustment has been shown to be robust, precise, and straightforward. Nevertheless, due to the inherent absence of colour/semantic information in DF images, a significant amount of user input is needed to prepare the image observations for the bundle adjustment. This paper introduces a semi-automated methodology to minimise the amount of user input required to process calibration images and henceforth to facilitate the cali...

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Research paper thumbnail of Lateral Meniscectomy Affects In Vivo Stifle Joint Biomechanics

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Research paper thumbnail of Relationship Between Torso Surface Asymmetry and Spinal Deformity During Treatment of Scoliosis with Rigid Brace

Spine and torso models were generated concurrently with x-rays for twenty-three patients undergoi... more Spine and torso models were generated concurrently with x-rays for twenty-three patients undergoing scoliosis brace treatment. Clinical indices of spinal deformity and torso surface asymmetry indices were computed from models obtained when patient was first recruited and at approximately one year’s follow-up. Significant correction changes of the torso shape were detected in indices including orientation of cross-sectional principal axes of inertia (p=0.048) and Back Surface Rotation (p=0.08) though spinal corrections were from not significant to subtle (0.20_p_0.88). Trunk asymmetry should be assessed for an objective evaluation and understanding of the effect produced by a specific treatment. To assess changes in torso geometry and spinal deformity during treatment of idiopathic scoliosis with rigid brace. Relationship between torso surface geometry and spinal deformity when a rigid brace is applied is essential for better understanding of brace treatment mechanism and optimal application of external forces. Three-dimensional torso surface models were generated concurrently with postero-anterior x-rays for twenty-three patients undergoing scoliosis brace treatment, when first recruited and at approximately one year’s follow-up. Torso asymmetry indices describing principal axis orientation, back surface rotation, and asymmetry of the centroid line, left and right half-areas and the spinous process line were computed. The statistical paired t-Test (95% CI) was performed to test the probability that no difference exist after one year of treatment in both spinal and torso asymmetry indices. After one year follow-up patients showed a mean increase of only 2° for the major Cobb angle. This was consistent with not significant to subtle corrections found in clinical (p=0.88) and computed (p=0.75) Cobb angle, lateral deviation (p=0.20), orientation of plane of maximum deformity (p= 0.58) and maximum vertebral axial rotation (p=0.83). Furthermore, significant correction changes of the torso shape were detected in the orientation of cross-sectional principal axes (PAX) of inertia (p=0.048) and Back Surface Rotation (p=0.08). Here we have shown that we can acquire 3D torso surface and reliably measured a set of indices of transverse torso asymmetry. Future work will look at indication of predictive potential of torso surface indices. Funding: AHFMR, CIHR, Fraternal Order of Eagles, NSERC, GEOIDE.

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Research paper thumbnail of Precise Measurement of Cat Patellofemoral Joint Surface Geometry With Multistation Digital Photogrammetry

Journal of Biomechanical Engineering, 1999

Three-dimensional joint models are important tools for investigating mechanisms related to normal... more Three-dimensional joint models are important tools for investigating mechanisms related to normal and pathological joints. Often these models necessitate accurate three-dimensional joint surface geometric data so that reliable model results can be obtained; however, in models based on small joints, this is often problematic due to limitations of the present techniques. These limitations include insufficient measurement precision, the requirement of contact for the measurement process, and lack of entire joint description. This study presents a new non-contact method for precise determination of entire joint surfaces using multistation digital photogrammetry (MDPG) and is demonstrated by determining the cartilage and subchondral bone surfaces of the cat patellofemoral (PF) joint. The digital camera–lens setup was precisely calibrated using 16 photographs arranged to achieve highly convergent geometry to estimate interior and distortion parameters of the camera–lens setup. Subsequentl...

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Research paper thumbnail of Correlation between physical activity and the gait characteristics and ankle joint flexibility of the elderly

Clinical Biomechanics, 1995

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Research paper thumbnail of In vivo quantification of human patellofemoral joint contact

Proc Can Soc Biomech, 1994

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Research paper thumbnail of In-vivo force-displacement characteristics of the cat patellar tendon complex

Journal of Biomechanics, 1994

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Research paper thumbnail of Dynamic in vivo three-dimensional (3D) kinematics of the anterior cruciate ligament/medial collateral ligament transected ovine stifle joint

Journal of Orthopaedic Research, 2008

The objective of this study was to use an ovine stifle joint model to assess the impact of combin... more The objective of this study was to use an ovine stifle joint model to assess the impact of combined transection of the anterior cruciate and medial collateral ligaments on three-dimensional (3D) joint motion serially over 20 weeks after transection. In vivo 3D kinematics were measured in the right hind limb of eight sheep while walking on a treadmill (accuracy, 0.4 mm +/- 0.4 mm, 0.4 degrees +/- 0.4 degrees ). Five sheep received surgical ligament transection and three sheep received sham surgery without transection. At 2 weeks after transection, average joint flexion at hoof strike was significantly increased (8.9 degrees +/- 3.0 degrees ), and the tibial position was significantly shifted in the anterior direction relative to the femur during midstance (4.9 mm +/- 0.9 mm). By 20 weeks after transection, joint flexion had normalized, but the tibial position was significantly adducted (0.5 degrees +/- 0.7 degrees ) and shifted in the medial (2.5 mm +/- 1.2 mm), anterior (5.8 mm +/- 1.9 mm), and superior directions (1.6 mm +/- 0.4 mm). At 2 and 20 weeks after surgical intervention, the maximal anterior tibial position was significantly increased during mid-stance in the transected group (4.9 mm +/- 0. 9 mm and 5.8 mm +/- 1.9 mm) compared to the sham operated group (0.2 mm +/- 0.2 mm and -0.1 +/- 0.1 mm). Although the anterior tibial shift was observed in all transected sheep, a high degree of variability existed between sheep, in the initial joint position, the magnitude of the early change, the change over time, and the change at 20 weeks. In this situation statistics must be interpreted carefully, and in future studies, individual changes should be assessed in the context of individual pathological changes in order to investigate potential clinical significance.

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Research paper thumbnail of Comparison of Two Optical Imaging Systems to Reduce Radiation in Adolescents with Scoliosis

INTRODUCTION Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional (3D) deformity of the s... more INTRODUCTION Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional (3D) deformity of the spine characterized by abnormal lateral curvature and vertebral rotation affecting 2-3% of adolescents [1]. The current clinical diagnostic and monitoring method consists of full torso X-rays where the Cobb angle, a measure of spinal deviation from the vertical, is used to determine the magnitude of the deformity. Two major limitations are associated with this approach. First, the routine exposure to radiation has been linked to an increased risk of cancer in scoliotic patients [2]. Second, the Cobb angle is inadequate to fully define the deformity because it is a two-dimensional measure. A holistic approach to define the deformity and reduce radiation exposure is needed. Changes in spinal curvature alter torsal shape making the use of surface topography (ST) a potential alternative to detect and monitor AIS progression in 3D [3] as well as reduce periodic radiation exposure. The majorit...

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Research paper thumbnail of Fluoroscopy Validation of Noninvasive 3D Bone-Pose Tracking via External Pressure-Foils

Precise noninvasive bone motion tracking is a topic of increasing interest, as it provides medica... more Precise noninvasive bone motion tracking is a topic of increasing interest, as it provides medical practitioners with important information about musculoskeletal disorders and/or their treatment. Currently, the only non-invasive method that achieves 3D tracking precision below 1 mm is Dual Fluoroscopy (DF). However, this technique is expensive, restricted to only small measuring volumes and time periods, and can only be applied sporadically due to X-ray radiation limits. In a series of previous papers, the authors presented a new concept for bone motion tracking based on external virtual palpation of typical bone protuberances via motion-tracked pressure foils. This paper presents a DF validation of the method for three basic movements of the shank: flexion/extension, abduction/adduction and internal rotation. It is shown that by simple pressure-foil palpation, bone-tracking precisions of 0.5 to 1.0 mm and 0.3\(^{\circ }\) to 0.6\(^{\circ }\) can be attained with respect to manually...

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Research paper thumbnail of Vertical Drop Jump Performance in Youth With Juvenile Idiopathic Arthritis

Arthritis Care & Research, 2020

Juvenile idiopathic arthritis (JIA) is associated with altered body structure and function outcom... more Juvenile idiopathic arthritis (JIA) is associated with altered body structure and function outcomes that may expose youth with JIA to a greater risk of secondary joint injury. This study aimed to examine differences in vertical drop jump (VDJ) biomechanics for youth with JIA and healthy youth (control group).

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Research paper thumbnail of Natural History and Progression of Adolescent Idiopathic Scoliosis by Consecutive Spinal Radiographs

Purpose: The purpose of this study was to detect any possible prognostic factors which may affect... more Purpose: The purpose of this study was to detect any possible prognostic factors which may affect the spinal deformity progression and their relationships in idiopathic scoliosis. Methods: The stereo-radiograph of whole spine at each visit was reconstructed with two spinal x-ray images in PA 0° and 20° using DLT techniques. Sequential data sets with 3, 4 or 5 successive values of prognostic factors were extracted from 111 consecutive patients (12.3±2.3 yrs, Cobb angle 30.2±12.4°) and separated into the stable and the progressed groups, based on a progression threshold of Cobb angle 5° and 10°. The prognostic factors included gender, curve pattern, age, curve magnitude, apex location, lateral deviation and spinal growth. Effects of those factors were conducted by comparing them between two groups (statistical significances p Results: The progressed subjects were predominantly females (50–79%) with double curves. Double curves progressed on both curves RT and LL at the same times and ...

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Research paper thumbnail of Consequences of Juvenile Idiopathic Arthritis on Single Leg Squat Performance in Youth

Arthritis Care & Research

Juvenile idiopathic arthritis (JIA) affects body structure and function outcomes that may increas... more Juvenile idiopathic arthritis (JIA) affects body structure and function outcomes that may increase the risk of acute joint injury. The purpose of this study was to examine single leg squat (SLS) biomechanics for youth with JIA and their healthy peers. The study design was a matched pair cohort study.

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Research paper thumbnail of Bundle Adjustment-Based Stability Analysis Method with a Case Study of a Dual Fluoroscopy Imaging System

ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences, May 28, 2018

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Research paper thumbnail of Robust Self-Supervised Learning of Deterministic Errors in Single-Plane (Monoplanar) and Dual-Plane (Biplanar) X-ray Fluoroscopy

IEEE Transactions on Medical Imaging

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Research paper thumbnail of Concurrent validity and reliability of a semi-automated approach to measuring the magnetic resonance imaging morphology of the knee joint in active youth

Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine

Post-traumatic knee osteoarthritis is attributed to alterations in joint morphology, alignment, a... more Post-traumatic knee osteoarthritis is attributed to alterations in joint morphology, alignment, and biomechanics triggered by injury. While magnetic resonance (MR) imaging-based measures of joint morphology and alignment are relevant to understanding osteoarthritis risk, time consuming manual data extraction and measurement limit the number of outcomes that can be considered and deter widespread use. This paper describes the development and evaluation of a semi-automated software for measuring tibiofemoral and patellofemoral joint architecture using MR images from youth with and without a previous sport-related knee injury. After prompting users to identify and select key anatomical landmarks, the software can calculate 37 (14 tibiofemoral, 23 patellofemoral) relevant geometric features (morphology and alignment) based on established methods. To assess validity and reliability, 11 common geometric features were calculated from the knee MR images (proton density and proton density fa...

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Research paper thumbnail of Vertical Drop Jump Biomechanics of Patients With a 3- to 10-Year History of Youth Sport–Related Anterior Cruciate Ligament Reconstruction

Orthopaedic Journal of Sports Medicine, 2021

Background: A better understanding of movement biomechanics after anterior cruciate ligament reco... more Background: A better understanding of movement biomechanics after anterior cruciate ligament reconstruction (ACLR) could inform injury prevention, knee injury rehabilitation, and osteoarthritis prevention strategies. Purpose: To investigate differences in vertical drop jump (VDJ) biomechanics between patients with a 3- to 10-year history of youth sport–related ACLR and uninjured peers of a similar age, sex, and sport. Study Design: Cross-sectional study. Level of evidence III. Methods: Lower limb kinematics and bilateral ground-reaction forces (GRFs) were recorded for participants performing 10 VDJs. Joint angles and GRF data were analyzed, and statistical analysis was performed using 2 multivariate models. Dependent variables included sagittal (ankle, knee, and hip) and coronal (knee and hip) angles at initial contact and maximum knee flexion, the rate of change of coronal knee angles (35%-90% of the support phase; ie, slopes of linear regression lines), and vertical and mediolater...

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Research paper thumbnail of Development of a calibration procedure for integration of dual fluoroscopy and motion analysis

Journal of Undergraduate Research in Alberta, 2013

INTRODUCTION Accurate quantification of in vivo effects of injury on joint mechanics is essential... more INTRODUCTION Accurate quantification of in vivo effects of injury on joint mechanics is essential to identify movement abnormality and related joint pathologies such as osteoarthritis. Typically used Motion Analysis (MA) technologies for studying human gait and injury suffer from soft tissue movement artifact, which may prohibit identification of small but significant changes of joint motion. High-speed dual fluoroscopy (DF) systems such as the one at the Clinical Movement Assessment Laboratory, University of Calgary, provide movement-artifact-free, high-resolution (0.30-0.44°, 0.25-0.33mm) [1], in vivo bone kinematics during dynamic activities. Such systems however, represent a trade-off between high system accuracy and limited field of view (FOV~10 inch) [2] compared to MA systems. DF systems therefore typically provide information only for a single joint while MA systems may capture the whole body. This project worked toward the integration of traditional MA and state-of-the-art ...

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Research paper thumbnail of Characterizing Healthy Knee Symmetry using the Finite Helical Axis and Muscle Power During Open and Closed Chain Tasks

Journal of Biomechanics, 2019

Understanding healthy joint movement and muscle control, and injurious alterations, is important ... more Understanding healthy joint movement and muscle control, and injurious alterations, is important to determine musculoskeletal contributions to post-injury joint instabilities or altered dynamic joint function. The contralateral limb is often used as a point of reference to determine the effects of knee joint injury. However, it is currently difficult to interpret within subject variability between limbs as this is not well established in the healthy population. There is a continuing need to characterize healthy knee joint mechanics and neuromuscular control to determine the degree of symmetry within healthy individuals. The current study quantified limb symmetry in healthy individuals using the finite helical axis with a unique reference position (rFHA) and electromyography (EMG) approaches, for a closed-chain single leg squat (SLS) and an open-chain seated leg swing. Muscle power and FHA translation, orientation and dispersion were similar between limbs. However, the FHA was located significantly more anterior in the dominant limb relative to the contralateral during both tasks. These between-limb differences in FHA location could be attributed to differences in joint geometry and strength between limbs. This finding provides evidence that healthy knees have asymmetries which have implications for selection of control limbs in studies comparing conditions within and between individuals. Differences identified in dynamic joint function between tasks suggest that the SLS is useful for revealing joint asymmetries due to altered muscular control strategies, while the swing task is expected to highlight asymmetries in joint motion due to altered knee structures following injury.

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Research paper thumbnail of 536 The influence of a novel mechanical loading regimen on the molecular response of human facial skin cells

Journal of Investigative Dermatology, 2017

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Research paper thumbnail of Toward an Automatic Calibration of Dual Fluoroscopy Imaging Systems

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2016

High-speed dual fluoroscopy (DF) imaging provides a novel, in-vivo solution to quantify the six-d... more High-speed dual fluoroscopy (DF) imaging provides a novel, in-vivo solution to quantify the six-degree-of-freedom skeletal kinematics of humans and animals with sub-millimetre accuracy and high temporal resolution. A rigorous geometric calibration of DF system parameters is essential to ensure precise bony rotation and translation measurements. One way to achieve the system calibration is by performing a bundle adjustment with self-calibration. A first-time bundle adjustment-based system calibration was recently achieved. The system calibration through the bundle adjustment has been shown to be robust, precise, and straightforward. Nevertheless, due to the inherent absence of colour/semantic information in DF images, a significant amount of user input is needed to prepare the image observations for the bundle adjustment. This paper introduces a semi-automated methodology to minimise the amount of user input required to process calibration images and henceforth to facilitate the cali...

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Research paper thumbnail of Lateral Meniscectomy Affects In Vivo Stifle Joint Biomechanics

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Relationship Between Torso Surface Asymmetry and Spinal Deformity During Treatment of Scoliosis with Rigid Brace

Spine and torso models were generated concurrently with x-rays for twenty-three patients undergoi... more Spine and torso models were generated concurrently with x-rays for twenty-three patients undergoing scoliosis brace treatment. Clinical indices of spinal deformity and torso surface asymmetry indices were computed from models obtained when patient was first recruited and at approximately one year’s follow-up. Significant correction changes of the torso shape were detected in indices including orientation of cross-sectional principal axes of inertia (p=0.048) and Back Surface Rotation (p=0.08) though spinal corrections were from not significant to subtle (0.20_p_0.88). Trunk asymmetry should be assessed for an objective evaluation and understanding of the effect produced by a specific treatment. To assess changes in torso geometry and spinal deformity during treatment of idiopathic scoliosis with rigid brace. Relationship between torso surface geometry and spinal deformity when a rigid brace is applied is essential for better understanding of brace treatment mechanism and optimal application of external forces. Three-dimensional torso surface models were generated concurrently with postero-anterior x-rays for twenty-three patients undergoing scoliosis brace treatment, when first recruited and at approximately one year’s follow-up. Torso asymmetry indices describing principal axis orientation, back surface rotation, and asymmetry of the centroid line, left and right half-areas and the spinous process line were computed. The statistical paired t-Test (95% CI) was performed to test the probability that no difference exist after one year of treatment in both spinal and torso asymmetry indices. After one year follow-up patients showed a mean increase of only 2° for the major Cobb angle. This was consistent with not significant to subtle corrections found in clinical (p=0.88) and computed (p=0.75) Cobb angle, lateral deviation (p=0.20), orientation of plane of maximum deformity (p= 0.58) and maximum vertebral axial rotation (p=0.83). Furthermore, significant correction changes of the torso shape were detected in the orientation of cross-sectional principal axes (PAX) of inertia (p=0.048) and Back Surface Rotation (p=0.08). Here we have shown that we can acquire 3D torso surface and reliably measured a set of indices of transverse torso asymmetry. Future work will look at indication of predictive potential of torso surface indices. Funding: AHFMR, CIHR, Fraternal Order of Eagles, NSERC, GEOIDE.

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Research paper thumbnail of Precise Measurement of Cat Patellofemoral Joint Surface Geometry With Multistation Digital Photogrammetry

Journal of Biomechanical Engineering, 1999

Three-dimensional joint models are important tools for investigating mechanisms related to normal... more Three-dimensional joint models are important tools for investigating mechanisms related to normal and pathological joints. Often these models necessitate accurate three-dimensional joint surface geometric data so that reliable model results can be obtained; however, in models based on small joints, this is often problematic due to limitations of the present techniques. These limitations include insufficient measurement precision, the requirement of contact for the measurement process, and lack of entire joint description. This study presents a new non-contact method for precise determination of entire joint surfaces using multistation digital photogrammetry (MDPG) and is demonstrated by determining the cartilage and subchondral bone surfaces of the cat patellofemoral (PF) joint. The digital camera–lens setup was precisely calibrated using 16 photographs arranged to achieve highly convergent geometry to estimate interior and distortion parameters of the camera–lens setup. Subsequentl...

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Research paper thumbnail of Correlation between physical activity and the gait characteristics and ankle joint flexibility of the elderly

Clinical Biomechanics, 1995

Bookmarks Related papers MentionsView impact

Research paper thumbnail of In vivo quantification of human patellofemoral joint contact

Proc Can Soc Biomech, 1994

Bookmarks Related papers MentionsView impact

Research paper thumbnail of In-vivo force-displacement characteristics of the cat patellar tendon complex

Journal of Biomechanics, 1994

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Research paper thumbnail of Dynamic in vivo three-dimensional (3D) kinematics of the anterior cruciate ligament/medial collateral ligament transected ovine stifle joint

Journal of Orthopaedic Research, 2008

The objective of this study was to use an ovine stifle joint model to assess the impact of combin... more The objective of this study was to use an ovine stifle joint model to assess the impact of combined transection of the anterior cruciate and medial collateral ligaments on three-dimensional (3D) joint motion serially over 20 weeks after transection. In vivo 3D kinematics were measured in the right hind limb of eight sheep while walking on a treadmill (accuracy, 0.4 mm +/- 0.4 mm, 0.4 degrees +/- 0.4 degrees ). Five sheep received surgical ligament transection and three sheep received sham surgery without transection. At 2 weeks after transection, average joint flexion at hoof strike was significantly increased (8.9 degrees +/- 3.0 degrees ), and the tibial position was significantly shifted in the anterior direction relative to the femur during midstance (4.9 mm +/- 0.9 mm). By 20 weeks after transection, joint flexion had normalized, but the tibial position was significantly adducted (0.5 degrees +/- 0.7 degrees ) and shifted in the medial (2.5 mm +/- 1.2 mm), anterior (5.8 mm +/- 1.9 mm), and superior directions (1.6 mm +/- 0.4 mm). At 2 and 20 weeks after surgical intervention, the maximal anterior tibial position was significantly increased during mid-stance in the transected group (4.9 mm +/- 0. 9 mm and 5.8 mm +/- 1.9 mm) compared to the sham operated group (0.2 mm +/- 0.2 mm and -0.1 +/- 0.1 mm). Although the anterior tibial shift was observed in all transected sheep, a high degree of variability existed between sheep, in the initial joint position, the magnitude of the early change, the change over time, and the change at 20 weeks. In this situation statistics must be interpreted carefully, and in future studies, individual changes should be assessed in the context of individual pathological changes in order to investigate potential clinical significance.

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Research paper thumbnail of Comparison of Two Optical Imaging Systems to Reduce Radiation in Adolescents with Scoliosis

INTRODUCTION Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional (3D) deformity of the s... more INTRODUCTION Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional (3D) deformity of the spine characterized by abnormal lateral curvature and vertebral rotation affecting 2-3% of adolescents [1]. The current clinical diagnostic and monitoring method consists of full torso X-rays where the Cobb angle, a measure of spinal deviation from the vertical, is used to determine the magnitude of the deformity. Two major limitations are associated with this approach. First, the routine exposure to radiation has been linked to an increased risk of cancer in scoliotic patients [2]. Second, the Cobb angle is inadequate to fully define the deformity because it is a two-dimensional measure. A holistic approach to define the deformity and reduce radiation exposure is needed. Changes in spinal curvature alter torsal shape making the use of surface topography (ST) a potential alternative to detect and monitor AIS progression in 3D [3] as well as reduce periodic radiation exposure. The majorit...

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Research paper thumbnail of Fluoroscopy Validation of Noninvasive 3D Bone-Pose Tracking via External Pressure-Foils

Precise noninvasive bone motion tracking is a topic of increasing interest, as it provides medica... more Precise noninvasive bone motion tracking is a topic of increasing interest, as it provides medical practitioners with important information about musculoskeletal disorders and/or their treatment. Currently, the only non-invasive method that achieves 3D tracking precision below 1 mm is Dual Fluoroscopy (DF). However, this technique is expensive, restricted to only small measuring volumes and time periods, and can only be applied sporadically due to X-ray radiation limits. In a series of previous papers, the authors presented a new concept for bone motion tracking based on external virtual palpation of typical bone protuberances via motion-tracked pressure foils. This paper presents a DF validation of the method for three basic movements of the shank: flexion/extension, abduction/adduction and internal rotation. It is shown that by simple pressure-foil palpation, bone-tracking precisions of 0.5 to 1.0 mm and 0.3\(^{\circ }\) to 0.6\(^{\circ }\) can be attained with respect to manually...

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Research paper thumbnail of Vertical Drop Jump Performance in Youth With Juvenile Idiopathic Arthritis

Arthritis Care & Research, 2020

Juvenile idiopathic arthritis (JIA) is associated with altered body structure and function outcom... more Juvenile idiopathic arthritis (JIA) is associated with altered body structure and function outcomes that may expose youth with JIA to a greater risk of secondary joint injury. This study aimed to examine differences in vertical drop jump (VDJ) biomechanics for youth with JIA and healthy youth (control group).

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Research paper thumbnail of Natural History and Progression of Adolescent Idiopathic Scoliosis by Consecutive Spinal Radiographs

Purpose: The purpose of this study was to detect any possible prognostic factors which may affect... more Purpose: The purpose of this study was to detect any possible prognostic factors which may affect the spinal deformity progression and their relationships in idiopathic scoliosis. Methods: The stereo-radiograph of whole spine at each visit was reconstructed with two spinal x-ray images in PA 0° and 20° using DLT techniques. Sequential data sets with 3, 4 or 5 successive values of prognostic factors were extracted from 111 consecutive patients (12.3±2.3 yrs, Cobb angle 30.2±12.4°) and separated into the stable and the progressed groups, based on a progression threshold of Cobb angle 5° and 10°. The prognostic factors included gender, curve pattern, age, curve magnitude, apex location, lateral deviation and spinal growth. Effects of those factors were conducted by comparing them between two groups (statistical significances p Results: The progressed subjects were predominantly females (50–79%) with double curves. Double curves progressed on both curves RT and LL at the same times and ...

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Research paper thumbnail of Consequences of Juvenile Idiopathic Arthritis on Single Leg Squat Performance in Youth

Arthritis Care & Research

Juvenile idiopathic arthritis (JIA) affects body structure and function outcomes that may increas... more Juvenile idiopathic arthritis (JIA) affects body structure and function outcomes that may increase the risk of acute joint injury. The purpose of this study was to examine single leg squat (SLS) biomechanics for youth with JIA and their healthy peers. The study design was a matched pair cohort study.

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Research paper thumbnail of Bundle Adjustment-Based Stability Analysis Method with a Case Study of a Dual Fluoroscopy Imaging System

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