Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009
Functionally graded cellular structures such as bio-inspired functionally graded materials for ma... more Functionally graded cellular structures such as bio-inspired functionally graded materials for manufacturing implants or bone replacement, are a class of materials with low densities and novel physical, mechanical, thermal, electrical and acoustic properties. A gradual increase in cell size distribution, can impart many improved properties which may not be achieved by having a uniform cellular structure.The material properties of functionally
This study uses a three dimensional model of the knee joint to determine which knee joint motion ... more This study uses a three dimensional model of the knee joint to determine which knee joint motion schemes lead to ACL injury, while exploring the possible types of concomitant injuries associated with each motion scheme. The physical elements of the knee joint including bones, articular cartilage, meniscus and ligaments were obtained by reconstructing magnetic resonance images. A failure locus representing the relationship between motion schemes and knee joint injury was created from finite element simulations considering knee flexion, femoral axial rotation and both valgus and varus motion. The relationships between knee joint orientation and various tissue failures were examined and susceptibility spectrums for knee injuries were obtained. The posterolateral bundle demonstrated higher rupture susceptibility than the anteromedial bundle. The average varus angular displacement for ACL failure was 46.6\% lower than the average valgus angular displacement. Femoral external rotation decreases overall ACL valgus/varus failure angle by 27.5\% compared to internal rotation. Articular cartilage injury was shown to occur prior to ACL failure in all valgus simulations. A simplified and computationally efficient version of the full 3D model showed close correlation to the complete model with respect to ligament failure and shows that if only ligament failure is of interest, a simple model can be used. The results of this study highlight several detrimental joint motions and can aid in improved clinical diagnoses and improved training programs for athletes.
Materials, Nondestructive Evaluation, and Pressure Vessels and Piping, 2006
This paper presents an efficient method for simulating the bone remodeling procedure. This method... more This paper presents an efficient method for simulating the bone remodeling procedure. This method is based on the trajectorial architecture theory of optimization and employs a truss-like model for bone. The truss was subjected to external loads including 5 point loads simulating the hip joint contact forces and 3 muscular forces at the attachment sites of the muscles to the bone. The strain in the links was calculated and the links with high strains were identified. The initial truss is modified by introducing new links wherever the strain exceeds a prescribed value; each link undergoing a high strain is replaced by several new links by adding new nodes around it using the Delaunay method. Introduction of these new links to the truss, which is conducted according to a weighted arithmetic mean formula, strengthens the structure and reduces the strain within the respective zone. This procedure was repeated for several steps. Convergence was achieved when there were no critical links ...
Background Strength imbalances and flexibility deficits of the hamstrings and hip flexors have be... more Background Strength imbalances and flexibility deficits of the hamstrings and hip flexors have been identified as potential risk factors for hamstring injuries, but research on athletes at the Division III level are limited, potentially due to a lack of resources and technology. Purpose The purpose of this study was to conduct isokinetic and flexibility assessments to screen male soccer athletes at risk of sustaining a hamstring injury. Study Design Observational cohort Methods Standardized isokinetic testing of concentric muscle performance, measured by peak torque of the quadriceps and hamstrings and hamstring-to-quadriceps ratios, was conducted using a Biodex isokinetic dynamometer at speeds of 60 and 180°/sec. Additionally, the Active Knee Extension (AKE) test and the Thomas test were performed bilaterally to objectively measure flexibility. Paired sample t-tests were used to compare left and right lower extremities for all outcomes, with the level of significance set at p<0....
Temporomandibular disorders (TMDs) are a group of problems characterized by a dull, deep orofacia... more Temporomandibular disorders (TMDs) are a group of problems characterized by a dull, deep orofacial pain typically in front of the ear, the muscles of mastication, the masseter in particular, or the temporomandibular joint (TMJ). People with a TMD might also
ASME 2011 Summer Bioengineering Conference, Parts A and B
A full or partial tear of the anterior cruciate ligament (ACL) is a common and painful injury tha... more A full or partial tear of the anterior cruciate ligament (ACL) is a common and painful injury that has been estimated to occur approximately 250,000 times annually in the U.S. [1]. Articular cartilage and meniscal injuries are also associated with ACL injuries [2]. ACL injuries can often lead to degenerative osteoarthritis of the articular cartilage [2]. An epidemiology study of athletic injuries by Majewski et al. [3] determined that out of 19,530 sports injuries, 20% were ACL injuries and 8% were medial collateral ligament (MCL) injuries.
Volume 2: Biomedical and Biotechnology Engineering; Nanoengineering for Medicine and Biology
This study investigated movement combinations which may cause injury to the anterior cruciate lig... more This study investigated movement combinations which may cause injury to the anterior cruciate ligament (ACL). A 3-Dimensional finite element knee joint model, including bones and ligament bundles, was developed. Bone was modeled as rigid, and a transversely isotropic material was applied to the ligament structures. This study incorporates a novel approach for developing bundle specific prestrain within the ligament structures. The bundles were stretched from their zero load lengths to their reference lengths, producing a strain field mimicking in vivo conditions at full knee extension. A failure locus was created by performing multiple knee joint motion combination simulations until ligament failure. The locus shows which movement combinations of internal/external femoral rotation and varus/valgus angle cause failure within the ACL bundles at 25° of knee flexion. The 3D model provided improved accuracy for locating bundle ruptures. By monitoring stresses and strains within the ligam...
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009
Functionally graded cellular structures such as bio-inspired functionally graded materials for ma... more Functionally graded cellular structures such as bio-inspired functionally graded materials for manufacturing implants or bone replacement, are a class of materials with low densities and novel physical, mechanical, thermal, electrical and acoustic properties. A gradual increase in cell size distribution, can impart many improved properties which may not be achieved by having a uniform cellular structure.The material properties of functionally
This study uses a three dimensional model of the knee joint to determine which knee joint motion ... more This study uses a three dimensional model of the knee joint to determine which knee joint motion schemes lead to ACL injury, while exploring the possible types of concomitant injuries associated with each motion scheme. The physical elements of the knee joint including bones, articular cartilage, meniscus and ligaments were obtained by reconstructing magnetic resonance images. A failure locus representing the relationship between motion schemes and knee joint injury was created from finite element simulations considering knee flexion, femoral axial rotation and both valgus and varus motion. The relationships between knee joint orientation and various tissue failures were examined and susceptibility spectrums for knee injuries were obtained. The posterolateral bundle demonstrated higher rupture susceptibility than the anteromedial bundle. The average varus angular displacement for ACL failure was 46.6\% lower than the average valgus angular displacement. Femoral external rotation decreases overall ACL valgus/varus failure angle by 27.5\% compared to internal rotation. Articular cartilage injury was shown to occur prior to ACL failure in all valgus simulations. A simplified and computationally efficient version of the full 3D model showed close correlation to the complete model with respect to ligament failure and shows that if only ligament failure is of interest, a simple model can be used. The results of this study highlight several detrimental joint motions and can aid in improved clinical diagnoses and improved training programs for athletes.
Materials, Nondestructive Evaluation, and Pressure Vessels and Piping, 2006
This paper presents an efficient method for simulating the bone remodeling procedure. This method... more This paper presents an efficient method for simulating the bone remodeling procedure. This method is based on the trajectorial architecture theory of optimization and employs a truss-like model for bone. The truss was subjected to external loads including 5 point loads simulating the hip joint contact forces and 3 muscular forces at the attachment sites of the muscles to the bone. The strain in the links was calculated and the links with high strains were identified. The initial truss is modified by introducing new links wherever the strain exceeds a prescribed value; each link undergoing a high strain is replaced by several new links by adding new nodes around it using the Delaunay method. Introduction of these new links to the truss, which is conducted according to a weighted arithmetic mean formula, strengthens the structure and reduces the strain within the respective zone. This procedure was repeated for several steps. Convergence was achieved when there were no critical links ...
Background Strength imbalances and flexibility deficits of the hamstrings and hip flexors have be... more Background Strength imbalances and flexibility deficits of the hamstrings and hip flexors have been identified as potential risk factors for hamstring injuries, but research on athletes at the Division III level are limited, potentially due to a lack of resources and technology. Purpose The purpose of this study was to conduct isokinetic and flexibility assessments to screen male soccer athletes at risk of sustaining a hamstring injury. Study Design Observational cohort Methods Standardized isokinetic testing of concentric muscle performance, measured by peak torque of the quadriceps and hamstrings and hamstring-to-quadriceps ratios, was conducted using a Biodex isokinetic dynamometer at speeds of 60 and 180°/sec. Additionally, the Active Knee Extension (AKE) test and the Thomas test were performed bilaterally to objectively measure flexibility. Paired sample t-tests were used to compare left and right lower extremities for all outcomes, with the level of significance set at p<0....
Temporomandibular disorders (TMDs) are a group of problems characterized by a dull, deep orofacia... more Temporomandibular disorders (TMDs) are a group of problems characterized by a dull, deep orofacial pain typically in front of the ear, the muscles of mastication, the masseter in particular, or the temporomandibular joint (TMJ). People with a TMD might also
ASME 2011 Summer Bioengineering Conference, Parts A and B
A full or partial tear of the anterior cruciate ligament (ACL) is a common and painful injury tha... more A full or partial tear of the anterior cruciate ligament (ACL) is a common and painful injury that has been estimated to occur approximately 250,000 times annually in the U.S. [1]. Articular cartilage and meniscal injuries are also associated with ACL injuries [2]. ACL injuries can often lead to degenerative osteoarthritis of the articular cartilage [2]. An epidemiology study of athletic injuries by Majewski et al. [3] determined that out of 19,530 sports injuries, 20% were ACL injuries and 8% were medial collateral ligament (MCL) injuries.
Volume 2: Biomedical and Biotechnology Engineering; Nanoengineering for Medicine and Biology
This study investigated movement combinations which may cause injury to the anterior cruciate lig... more This study investigated movement combinations which may cause injury to the anterior cruciate ligament (ACL). A 3-Dimensional finite element knee joint model, including bones and ligament bundles, was developed. Bone was modeled as rigid, and a transversely isotropic material was applied to the ligament structures. This study incorporates a novel approach for developing bundle specific prestrain within the ligament structures. The bundles were stretched from their zero load lengths to their reference lengths, producing a strain field mimicking in vivo conditions at full knee extension. A failure locus was created by performing multiple knee joint motion combination simulations until ligament failure. The locus shows which movement combinations of internal/external femoral rotation and varus/valgus angle cause failure within the ACL bundles at 25° of knee flexion. The 3D model provided improved accuracy for locating bundle ruptures. By monitoring stresses and strains within the ligam...
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