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In this thesis, adaptations were made on the Hybrid Cadaveric System to accommodate new testing ramifications. The tests simulated dynamic loading (jump landings) from a 1ft. height with various degrees of valgus (fixed hamstring and quadricep forces) and various Quadricep (Q) and Hamstring (H) forces (fixed degrees of valgus) to determine how the Anterior Cruciate Ligament (ACL) and Medial Collateral Ligament (MCL) behave. The tests performed included 0Q 0H, 100Q 0H, 300Q 0H, 300Q 100H, and 5°, 15°, 25° of valgus. To determine the strain behavior of the ACL and MCL a variety of equipment was used, including electromagnetic force plate to take impact reading, cables used to create loading on the quadriceps and hamstrings, and two Differential Variance Resistance Transducers (DVRTs). These ultimately generated ACL and MCL strain allowing for a variety of strain comparisons under various circumstances. It was concluded that in a few cases there were statistically significant differences in strain for the ACL and MCL when applying various quadricep and hamstring forces (fixed valgus). It was also found that only statistical significance was present in ACL strain when comparing degrees of valgus (fixed quadricep and hamstring forces). The research concluded that muscle activation reduces strain on the ACL and MCL in these testing scenarios. It was also established that degrees of valgus effects the ACL but is negligible for the MCL. However, due to complications and variables, further testing is needed to increase accuracy and supply more definitive results. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Mathematical musculoskeletal modeling and simulation provide a means for proactive injury prevention. To be effective, these models must physiologically replicate shoulder function. Although several muscle force prediction (MFP) shoulder models exist, few have attempted to integrate the force contributions of ligaments, especially the glenohumeral ligaments. The purpose of the current study was to integrate seven shoulder ligaments into an existing computational shoulder model, and analyze both individual ligament characteristics and the influence on the model outputs. Using data from the literature, seven shoulder ligaments were integrated into the model: the costoclavicular, conoid, trapezoid, coracohumeral, superior glenohumeral, middle glenohumeral, and inferior glenohumeral. 10 subjects performed isometric exertions in 56 posture-force combinations. Upper body posture and hand force collected were used as inputs for three different model versions; No-Ligaments (NL) included, Glenohumeral-Ligaments (GH) included, and All-Ligaments (AL) included. Electromyographic (EMG) signals from 11 muscle sites were used for comparison with model MFPs. The primary analysis focused on the differences between the GH and NL versions. Normalized EMG amplitudes were plotted against normalized MFPs from both models. Ligament effects on model outputs were measured by comparing changes in correlation between EMG and MFP, changes in slopes regression lines relating EMG to MFP, and the frequency of zero-force prediction by the model. Paired Student’s t-tests were used to measure significant differences. Results showed significant correlations (Pearson product) between EMG amplitude and MFP in the lower trapezius and infraspinatus muscles (p<0.01). No significant differences were found in r-values for these muscles between the NL and GH model. Slopes of regression lines decreased when GH ligaments were added, while the change in zero-force predictions varied by muscle. This study highlights the sensitivity of musculoskeletal models to the inclusion of ligament forces. Though correlations did not change, decreases in slope indicate increased force prediction by the GH model. Though zero-force predictions for some muscles increased, the results from those that decreased suggest muscles are active in postures where they were originally believed to be inactive. This finding suggests that inclusion of GH ligaments into our model may help predict antagonist muscle activity. However, further research is required.

Mathematical musculoskeletal modeling and simulation provide a means for proactive injury prevention. To be effective, these models must physiologically replicate shoulder function. Although several muscle force prediction (MFP) shoulder models exist, few have attempted to integrate the force contributions of ligaments, especially the glenohumeral ligaments. The purpose of the current study was to integrate seven shoulder ligaments into an existing computational shoulder model, and analyze both individual ligament characteristics and the influence on the model outputs. Using data from the literature, seven shoulder ligaments were integrated into the model: the costoclavicular, conoid, trapezoid, coracohumeral, superior glenohumeral, middle glenohumeral, and inferior glenohumeral. 10 subjects performed isometric exertions in 56 posture-force combinations. Upper body posture and hand force collected were used as inputs for three different model versions; No-Ligaments (NL) included, Glenohumeral-Ligaments (GH) included, and All-Ligaments (AL) included. Electromyographic (EMG) signals from 11 muscle sites were used for comparison with model MFPs. The primary analysis focused on the differences between the GH and NL versions. Normalized EMG amplitudes were plotted against normalized MFPs from both models. Ligament effects on model outputs were measured by comparing changes in correlation between EMG and MFP, changes in slopes regression lines relating EMG to MFP, and the frequency of zero-force prediction by the model. Paired Student’s t-tests were used to measure significant differences. Results showed significant correlations (Pearson product) between EMG amplitude and MFP in the lower trapezius and infraspinatus muscles (p<0.01). No significant differences were found in r-values for these muscles between the NL and GH model. Slopes of regression lines decreased when GH ligaments were added, while the change in zero-force predictions varied by muscle. This study highlights the sensitivity of musculoskeletal models to the inclusion of ligament forces. Though correlations did not change, decreases in slope indicate increased force prediction by the GH model. Though zero-force predictions for some muscles increased, the results from those that decreased suggest muscles are active in postures where they were originally believed to be inactive. This finding suggests that inclusion of GH ligaments into our model may help predict antagonist muscle activity. However, further research is required.

The purpose of this study is to quantify the dynamic mechanical properties of human cervical ligaments following whiplash. Cervical ligaments function to provide spinal stability, propioception, and protection during traumatic events to the spine. The function of cervical ligaments is largely dependant on their dynamic biomechanical properties, which include force and energy resistance, elongation capability, and stiffness. Whiplash has been shown to injure human cervical spine ligaments, and ligamental injury has been shown to alter their dynamic properties, with potential clinical consequences such as joint degeneration and pain. In this study we quantified the dynamic properties of human lower cervical ligaments following whiplash and compared their properties to those of intact ligaments. Whiplash simulation was performed using biofidelic whole cervical spine with muscle force replication (WCS-MFR) models. Next, ligaments were elongated to failure at a fast elongation rate and peak force, peak elongation, peak energy, and stiffness values were calculated from non-linear force-elongation curves. Peak force was highest in the ligamentum flavum (LF) and lowest in the intraspinous and supraspinous ligaments (ISL+SSL). Elongation was smallest in middle-third disc (MTD) and greatest in ISL+SSL. Highest peak energy was found in capsular ligament (CL) and lowest in MTD. LF was the stiffest ligament and ISL+SSL least stiff. These findings were similar to those found in intact ligaments. When directly comparing ligaments following whiplash to intact ligaments in a prior study it was found that the anterior longitudinal ligament (ALL) and CL had altered dynamic properties that were statistically significant, suggesting that whiplash may alter the dynamic properties of cervical ligaments. These findings may contribute to the understanding of whiplash injuries and the development of mathematical models simulating spinal injury.

Thèse de doctorat : Bioingénierie : Vandoeuvre-les-Nancy, INPL : 2006. / Titre provenant de l'écran-titre. Bibliogr.

Thesis (Ph.D.)--Virginia Commonwealth University, 2009. / Prepared for: Dept. of Biomedical Engineering. Title from resource description page. Includes bibliographical references.

Knee injuries are a major cause of orthopedic disabilities in the United States. Current reconstruction techniques for torn anterior cruciate ligaments (ACL) require extensive surgery and long physical rehabilitation times since the tissue does not heal upon injury. A common ACL injury occurs where the gap at the rupture site remains open after injury and fails to heal, which can lead to premature osteoarthritis and disability. Hydrogels are a popular material used for tissue engineering applications due to their ability to retain water and good biocompatibility. Previous work has shown that hydrogels can be made through the mixed-mode reaction of radically crosslinked thiol groups and acrylate end groups. This project explores mixed-mode oligo[poly(ethylene glycol) fumarate] (OPF)-based hydrogels as alternate carriers for regeneration of partial tear ligament defects. The main purpose of this project was to determine the degradative properties of and cell response to thiol-PEG-thiol (PEG-diSH), a novel hydrogel material. The swelling and degradative properties of hydrogels containing three components OPF, PEG-diacrylate (PEG-DA), and PEG-diSH were characterized by their fold swelling. In addition, cell viability, morphology changes, proliferation and collagen production were analyzed in tri-ratio hydrogels with and without the presence of RGD over three weeks. Results showed that the hydrogels containing PEG-diSH demonstrated significantly larger fold swelling and promoted cell clustering (as shown by increased area of clusters), probably due to the larger mesh size and possibly due to the presence of free thiol functional groups present in the network from the mixed-mode reaction. However, an increase in cell number was not found in these gels up to eight days, suggesting that cell migration may play a role in the appearance of clusters. Additionally, increased cell spreading in response to RGD was observed inside gels containing PEG-diSH; no spreading was seen in the non PEG-diSH gels (± RGD), possibly because the mesh size was too small to allow for clustering or spreading within the matrix. Results from this work suggest that the presence of PEG-diSH could promote cell-cell contact within the clusters which could be useful in systems where direct contact promotes tissue formation or cell differentiation.

Thesis (MAppSc in Physiotherapy)--University of South Australia, 1995

Thesis (Ph.D.)--Tufts University, 2002. / Adviser: David L. Kaplan. Submitted to the Dept. of Biotechnology Engineering. Includes bibliographical references (leaves 207-221). Access restricted to members of the Tufts University community. Also available via the World Wide Web;