Download or read book The Effect of Sagittal Plane Mechanics on Anterior Cruciate Ligament Strain During Jump Landing written by Ryan Bakker and published by . This book was released on 2014 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Anterior cruciate ligament (ACL) is an important ligament in the knee. Non-contact ACL injuries are a common occurrence among athletes, leading to large financial burdens and long term physical concerns. The underlying biomechanics leading to these non-contact ACL injuries are unknown, in part due to limited experimental studies investigating the mechanics of dynamic activities. Understanding these mechanics is critical for injury prevention and risk analysis. The primary objective of this study was to investigate the underlying sagittal plane mechanics leading to increasing ACL strain during jump landing. A hybrid in-vivo/computational/in-vitro approach was used to measure ACL strain in relation to these mechanics. Motion capture was performed on ten subjects performing a single leg jump landing and both whole-body kinematics and ground reaction forces were collected. Musculoskeletal models were driven using this data to estimate the lower limb muscle forces from the jump landing. Five cadaver knee specimens were instrumented to measure ACL strain and mounted on a dynamic knee simulator. Muscle forces and sagittal plane kinematics were then applied on the cadaver specimens, dynamically recreating the activity. Strain in the anterior cruciate ligament was measured for each simulation. Bivariate correlation and multivariate linear regression analyses were performed with both maximum ACL strain and time to maximum ACL strain with the sagittal plane mechanics measured during the motion capture. Correlation analysis found increasing ACL strain was correlated with increasing ground reaction forces, increasing body weight, decreasing hip flexion angles, increasing hip extension moments, and increasing trunk extension moments, among others. Time to max ACL strain was correlated with increasing knee flexion angles and increasing knee angle velocities. The multivariate linear regression revealed anatomical factors account for most of the variance in maximum ACL strain, but suggests landing softly by increasing joint angles and absorbing impact, are important strategies for reducing ACL strain. Time to max ACL strain regression was influenced by anatomic factors and knee velocities. An athlete may have little or no control over the anatomic factors contributing to ACL strain, but altering their landing strategy to reduce the chance of injury. The empirical relationship developed between increasing joint angles, energy absorption and ACL strain in this study could be used to estimate the relative strain between jumps and to develop training programs designed to reduce an athlete's risk of injury.

Download or read book A Combined In vivo in vitro Approach to Study Knee Injury Mechanism written by Preet Sabharwal and published by . This book was released on 2011 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anterior cruciate ligament (ACL) stabilizes the knee during various sporting activities and has great importance as the knee relies entirely on the ligaments and muscles for stabilization. The ACL commonly gets injured during sports activities such as basketball, soccer, and football. In the United States over 80,000 ACL injuries occur every year. There has been decades of research performed on ACL injuries regarding the injury mechanisms of non-contact ACL injuries, but yet they are still not well understood. This is mainly because trials and tests cannot be conducted on live subjects to understand the injury mechanisms. Existing in-vivo and in-vitro studies in the literature do not relate the effects of dynamic knee muscle forces and kinematics of sports activities with the strain in the ACL. In this thesis, in-vivo and in-vitro approaches are combined to quantify the effects of muscle group forces on ACL strain during jump landing. This is done by first obtaining muscle force profiles of the knee by performing motion capture and inputting the ground reaction forces and kinematics into a musculoskeletal model. Using the muscle forces and a six axis sagittal plane dynamic knee injury simulator the jump landing simulation can be performed. Six electromechanical actuators controlled by a multi-axis control system apply dynamic muscle forces at the insertion sites of the hamstrings, quadriceps, gastrocnemius, and a hip moment to simulate the hip flexors. The ACL strain is measured using a differential variable reluctance transducer mounted on the ACL. Our results show that the simulator is able to successfully perform jump landing. The muscle force-time profiles tracked the input very well. The ACL strain from our studies fell within a reasonable level compared to data from other studies of jump landing. This simulator has proven to be successful in simulating high-risk motions.

Download or read book ACL Strain During Single leg Jump Landing written by Anna Maria Polak and published by . This book was released on 2018 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anterior cruciate ligament (ACL) is a commonly-injured ligament in the human knee joint. ACL injury repair is a costly procedure; however, left unrepaired, ACL injuries can lead to complications later in life. In order to understand ACL injury, metrics such as strain in the ACL are measured under various loading conditions. A motion which has potential to cause ACL injury, a single leg jump landing, was replicated and ACL strain was recorded. Two common approaches for this purpose are in-vitro studies involving cadavers, and finite element (FE) modelling of the knee joint. Once ACL strain during the potentially injurious motion is evaluated, it is easier to work towards potential improvements to protective or rehabilitative equipment, such as knee braces. The objective of the current study was to measure ACL strain during a single leg jump landing using two different methods: 1. In-vitro experiments involving cadavers: - ACL strain vs. time was measured with unbraced and braced cadaver knees. 2. Finite element modelling of the human knee: - The finite element model was assessed using the in-vitro experiments, and can potentially be used to evaluate braced knee conditions in the future. The inputs for the experiments and finite element model were taken from motion capture, which was done in-vivo on two participants in a previous study. The two participants provided input kinetics and kinematics of a single-leg jump landing. The kinematic and kinetic inputs were then applied to three cadaveric specimens using the dynamic knee simulator (DKS) at the University of Waterloo, and ACL strain relative to the beginning of the trial was measured. The cadaver knees were also tested wearing an Össur CTi Custom knee brace, and the effect of the knee brace on relative ACL strain was measured. A finite element model of the human knee joint was also investigated by extracting the right leg of an existing full human body model, the Global Human Body Model Consortium (GHBMC) average-sized male (M50) model, and updating some of the tissue mechanical properties. The same boundary conditions from the experimental iv study were applied to the GHBMC right leg model, and relative ACL strain was calculated and compared against the experimental data. The experimental maximum relative ACL strain for an unbraced full jump landing was 0.032 and 0.057 for participant #1 input and 0.062 for participant #2 input. The computational maximum relative ACL strain was 0.042 for participant #1 input and 0.139 for participant #2 input. The finite element model was able to replicate the experimental ACL strain vs. time curves reasonably well, with a mean squared error of less than 0.01 for all loading scenarios. The results of the unbraced vs. braced jump landing experiments showed that the knee brace had no effect on ACL strain. The mean squared error between unbraced and braced ACL strain vs. time curves was less than 0.0011 for all loading cases, which is a low error value when compared to strains in the range of 0.015- 0.089. The jump landing finite element model is an important first step in using finite elements to predict relative ACL strain during jump landing. Future research directions include study of factors affecting ACL strain, incorporating the knee brace into the finite element model to investigate possible improvements to the brace, and investigating the benefits of adopting a subject-specific geometry for the model.

Download or read book The Effect of Mid flight Trunk Motion on Landing Mechanics written by Taylour J. Hinshaw and published by . This book was released on 2017 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anterior cruciate ligament (ACL) is a commonly experienced injury that can cause long-term negative health consequences. Previous research has observed increased trunk motion when ACL injuries occur during jump-landing tasks and suggest that trunk perturbation experienced while in the air may be a contributing factor to ACL injuries, however, the cause-effect relationship between trunk motion and ACL loading has not been established. The current researcher quantified the influences that both medial and lateral mid-flight trunk motions on landing biomechanics through center of mass analysis. Results from the current study showed that at initial contact, the upper body moved towards the reaching direction while the pelvis, ipsilateral leg, and contralateral leg moved in the opposite direction for the left and right reaching conditions when compared to the up condition. The ipsilateral leg moved closer to the overall COM and the contralateral leg moved further away, resulting in an asymmetric landing posture. The ipsilateral leg landed earlier for the left and right reaching conditions when compared to the up condition and also experienced a greater amount of vertical ground reaction force putting it at a higher risk for injury. Injury prevention programs should incorporate effective strategies to compensate for trunk motion experienced during the mid-flight of a jump.

Download or read book Comparing Knee Joint Mechanics Across Phases of the Menstrual Cycle written by Bethany Kilpatrick and published by . This book was released on 2020 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anterior cruciate ligament (ACL) injuries are among the most commonly occurring knee injury. Compared to men in the same sports, females are two to eight times at higher risk for ACL injury. Research suggests that hormone fluctuations across the menstrual cycle (MC) play a crucial role in ACL injuries due to their effect on tendons and ligament's mechanical properties. PURPOSE: To examine knee joint laxity during dynamic movements across three-time points of the MC. METHODS: Seven young, healthy females with regular MCs performed three jump-landing tasks (double leg depth jump, single-leg lateral jump, and single-leg forward jump) across the early-follicular, ovulatory, and mid-luteal phases of the MC. Peak frontal and sagittal plane knee joint angles and moments were measured to assess joint stability during dynamic movements in each jump trial were analyzed. The researchers used an analysis of variance (ANOVA) to determine the effects of the menstrual cycle's phases on joint mechanics during each jump task. RESULTS: No significant change occurred in knee joint frontal or sagittal plane angles or moments across MC time points. CONCLUSION: In support of finding from prior studies, the researchers did not observe any changes in knee joint mechanics across the menstrual cycle phases, suggesting that MC hormonal fluctuations do not affect the knee joint's mechanical properties tendons and ligaments enough to cause changes in joint laxity. Future research should examine the specific relationships between measured hormone levels and knee joint mechanics during dynamic movements across the MC phases to assess these relations more accurately.

Download or read book The Effect of Mid flight Whole body and Trunk Rotation on Landing Mechanics written by Meghan Critchley and published by . This book was released on 2018 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Altered trunk positions have been observed when anterior cruciate ligament (ACL) injuries occur. The purpose of the current study was to quantify the effect of whole body and trunk rotation on the biomechanics of jump-landings associated with ACL loading. Forty (20 male, 20 female) participants performed three jump-landing-jump trials in 5 separate conditions with or without whole-body and trunk rotation. Compared with most other conditions, the trunk rotated ipsilateral (TRI) condition resulted in increased stance time, increased peak GRF, decreased knee flexion angles, increased knee valgus and internal rotation angles at initial contact and during the first 100 ms of landing. Increased GRF and decreased knee flexion angles were also found in the whole-body contralateral (WBC) condition. The TRI condition resulted in landing biomechanics associated with increased ACL loading and injury risk. The findings may provide information for understanding ACL injury mechanism and developing injury risk screening and prevention strategies.

Download or read book Biomechanical Alterations in Athletes with Anterior Cruciate Ligament Reconstruction and the Implications for Osteoarthritis written by Albert J. Chen and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An anterior cruciate ligament (ACL) injury is a traumatic event that can lead to long term disability and greater risk of radiographically diagnosed osteoarthritis (OA). While ACL reconstruction (ACLR) can restore anterior laxity to acceptable levels, dynamic instability can persist. Analysis of gait and other sport specific tasks show persistent changes in lower limb mechanics that not only affect second injury risk, but may be a primary factor in early onset OA. A definitive mechanistic link has yet to be established between ACL injury, ACLR and OA, but current evidence strongly indicates that OA development is related to the changes in tibiofemoral kinematics that are present after injury and ACLR. Therefore, the aims of this dissertation were to: 1) Determine the effects of ACL injury and ACLR on lower limb biomechanics during sport specific tasks, and 2) Determine the effects of ACL injury and ACLR on subject specific model predicted ACL strain and cartilage contact patterns. The hypothesis tested was that lower limb biomechanics in those with ACLR would be significantly altered compared to their uninvolved limb and to uninjured controls. In addition, it was hypothesized that the models of ACLR subjects would predict larger ligament strains compared to the uninjured controls, and demonstrate altered cartilage contact patterns. To test these hypotheses, patients with ACLR were recruited for these studies. First, lower limb biomechanics during a single leg hop were examined to determine correlations with patient reported function at the return to sport (RTS) time point. In addition, patients with ACLR were also examined at longer follow-up times to determine how their peak kinetics and kinematics differed from their uninvolved limbs and uninjured controls during gait and a drop vertical jump (DVJ). The latter cohort of subjects underwent identical protocols to generate subject specific finite element (FE) models. These models were based on their magnetic resonance imaging (MRI) scans and utilized their own biomechanical variables as inputs. The outputs of these FE models were compared to those from an in vitro pneumatic impactor study. The results of the studies indicate that lower limb biomechanics after ACLR are significantly altered at short- and long-term follow-ups. Patients with ACLR at the return to sport time point had lower limb biomechanics that were significantly correlated with patient reported outcome scores. The uninjured control displayed frontal plane mechanics that have been shown to increase risk for an ACL tear. The injured group also displayed altered biomechanics in the frontal and sagittal plane during gait and DVJ. The FE models of the injured group produced lower ACL strains compared to the uninjured group, but did not show any significant differences in cartilage contact. In comparison to the cadaveric tests, the ACL strain from the FE models did not differ significantly from the cadaveric specimens.

Download or read book Computational Modelling of Knee Tissue Mechanics During Single Leg Jump Landing written by Harish Rao and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The anterior cruciate ligament (ACL) plays a crucial role in stabilising the knee joint in anterior tibial translation and internal tibial rotation. Non-contact ACL injuries are a major concern in sport-related activities due to sudden dynamic manoeuvres involved. Concomitant injuries to other tissues of the knee joint such as meniscal tears are common with ACL injuries. Treatment of ACL injuries through surgical reconstructions and rehabilitation imposes a large socioeconomic burden on healthcare systems. Researchers have extensively used a combination of in-vitro experiments on cadaveric specimens and computational modelling to explore the biomechanical factors surrounding ACL injury in dynamic knee movements. The primary objective of this study was to develop a subject-specific knee finite element (FE) model to simulate an injury-causing motion - single-leg jump landing and validate ACL strain based on previous in-vitro experiments. Medical images of a cadaver specimen were segmented to generate three-dimensional (3D) models of the anatomic structures of the knee joint. High-quality meshes of the segmented 3D models were produced. Digitization technique was used to replicate the knee ligament insertion sites of the cadaver specimen in the model accurately. The kinematic response of the model under basic knee motions was validated with published experimental data. Muscle forces and kinematic inputs from a previous study involving the motion capture of ten participants were used as the boundary conditions to simulate a jump landing motion. Explicit FE analyses were performed on the model under half, and full muscle force conditions and the ACL and meniscal strain outputs were compared with experimental results. Results showed that the ACL strain trends in the half muscle force jump simulations of two participant profiles (P5, P6) agreed well with the in-vitro experimental results from the cadaver knee. However, the computational peak ACL strain values of the two profiles (5.5 % at 228 ms and 4.9 % at 177 ms) did not agree well with the experimental results (2.8 % at 151 ms and 3.5 % at 164 ms). The ACL strain trends during the full muscle force jump simulations of ten participant profiles (P1 - P10) showed better agreement with the experimental results from different cadaver knees of a previous study. In addition, in the half muscle force jump simulations of two participant profiles (P5, P6), the peak values of posterior medial meniscal strain from the FE model (0.7 % and 1.4 %) agreed well with the experimental results (0.75 % and 1.3 %) from different cadaver knees. This study demonstrated a methodology to develop a subject-specific FE model of the knee joint that could be used to recreate in-vitro dynamic experimental conditions to make predictions of ACL and medial meniscal strains, providing an effective approach to overcome the limitations of experimental testing. Future work will use the established model to predict the risk of injury and design injury prevention strategies in dynamic knee loading scenarios.

Download or read book The Effects of a Soccer specific Vertical Jump on Landing Mechanics written by Sophia Mancini and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Background: Anterior cruciate ligament (ACL) injury frequently occurs in female soccer athletes during deceleration movements such as landings. In soccer, landings mostly occur following jumping headers. Little research has been done to determine the mechanics that follow and how they compare to standard drop vertical jumps (DVJ). The purpose of this study was to analyze differences between jumps and landings in kinematics, kinetics, and muscle activation patterns in female soccer athletes to better assess the sport-specific risk for ACL injury. It was hypothesized that more biomechanical tendencies associated with ACL risk factors would emerge from soccer-specific vertical jumps (SSVJ) compared to DVJs and second landings (L2) compared to first landings (L1). Methods: 8 female participants (20.88 ± 1.17 years; 1.68 ± 0.06 m; 58.77 ± 7.65 kg) performed DVJs and SSVJs. Motion capture, force, and electromyography (EMG) data were collected to calculate joint motion, loading, and muscle activation throughout landing phases. Data were analyzed using RM-ANOVA, collapsed across jump (DVJ vs. SSVJ) and landing (L1 vs. L2). Results: Significant findings were revealed in all categories, however, kinematic variables were the most profound results. Significantly higher jump height was achieved in DVJs (p=0.008). SSVJs and L2s produced less peak hip (p=0.03; d=0.817) (p=0.007; d=1.566) and knee 2 (p=0.002; d=0.732) (p=0.002; d=1.476) flexion during landing, respectively. A significant interaction was present for trunk flexion at initial contact (p=0.034). Follow-up tests revealed no significant differences following headers. Discussion: SSVJ-L2s displayed a more erect landing at the hip and knee, a known ACL risk factor, however, it is unclear whether these results are due to trunk movement during heading. Limited results in kinetic and EMG variables may be explained by the difference in jump height achieved, therefore further investigation in a more elite population is required. Additionally, SSVJs may be a good sport-specific screening tool.

Download or read book Examination of Lower Extremity Mechanics During Three Landing Tasks and Injury Prediction Ability of Those Models as Compared to a Functional Test written by Timothy George Coffey and published by . This book was released on 2015 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anterior cruciate ligament (ACL) ruptures are one of the most common knee ligament injuries suffered by both male and female athletes. These injuries are severe in nature and also have long-term impacts on activities of daily living. Significant research has been conducted utilizing a drop landing task to attempt to better understand the mechanics behind the injury and to help identify at-risk athletes for targeted intervention. However, there have not been any published standards for the height of the drop landing activity, and previous researchers have also raised some concerns about the ability of a drop landing task to replicate the landing mechanics of a sport-specific task. To examine possible differences in performance based on specific landing tasks, the first study compared the landing mechanics of male and female high school athletes in three different landing conditions (drop landing, DL; adjusted height drop landing, AHDL; and a vertical jump task, VJL) (Chapter 3). Thirty-seven (37) athletes completed bilateral landings in the three conditions, and their kinetic and kinematic landing mechanics were compared across conditions. For the male participants, maximum knee flexion during landing was greater in AHDL condition as compared to the DL and VJL conditions. Both male and female participants demonstrated greater hip adduction at impact and overall maximum value in the VJL condition as compared to the two drop landings. As drop landing tasks have been used to identify at-risk athletes, it was important to examine the three different tasks' ability to predict lower extremity ligamentous injuries, and whether those 3D motion analysis predictors were more precise than a quick clinical symmetry screening tool (Chapter 4). One-hundred-and-sixty-five (165) athletes completed the clinical symmetry screen, and a subgroup of thirty-seven (37) athletes completed the 3D motion analysis. All of these participants were surveyed for lower extremity ligamentous injuries over the course of a season. Due to a small number of reported injuries, none of the injury predictor models based on 3D motion analysis landing mechanics or the clinical symmetry screening tool were able to produce accurate predictor models of injury. Knee abduction moment has been shown to be one of the strongest predictors of ACL injuries, and due to the collection of bilateral kinetics for a previous study (Chapter 3), there was a need to examine differences in KAM between the three different landing tasks (Chapter 5). Ten (10) recreational athletes completed bilateral landings in the three conditions, with foot placement relative to force plates to enable KAM calculation. The participants did not demonstrate any difference in KAM between the three landing conditions; however, a test for constant variance showed that the AHDL resulted in significantly less variance in KAM than DL or VJL. The results of these studies suggest that while easy to standardize, a set height drop landing task does not produce identical landing mechanics to those from an adjusted height drop landing task or a vertical jump task. Further research is needed to create or justify standardized landing tasks for researchers to utilize that produce consistent results that best duplicate the landing mechanics athletes performed during sporting activities. While the landing mechanics demonstrated in the three tasks and the results from the clinical screening were not able to predict injuries, future studies should examine quick clinical screening tools to identify athletes at a high risk of injury.

Download or read book Multi plane Multi joint Analysis of Limb Support Moments with Gender Comparison and Analysis of Sagittal Plane Tibiofemoral Shear During a Rapid Deceleration Task written by Jeffery T. Podraza and published by . This book was released on 2014 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Injury of the anterior cruciate ligament (ACL) within the knee joint is a common occurrence among all age groups. Females have a 2-10 times greater rate of ACL injury versus males. Non-contact rapid deceleration movements are considered the most common source of injury which occurs most often with the knee near full extension. ACL strain is thought to result from excessive anterior tibial translation and or a valgus collapse. There is a dearth of literature that investigates the non-contact mechanism of ACL injury from the perspective of it being a multi-planar, multi-joint occurrence. The three analyses presented utilized kinematic and kinetic measures of a lunge deceleration movement to identify the effect of the hip knee and ankle moments of force on the overall limb support moment (LSM) and to determine the presence of gender differences within this LSM model. Additionally, the tibiofemoral shear load generated by the deceleration maneuver was calculated via a sagittal plane knee model. Twenty subjects, (10 male, 10 female), performed deceleration trials landing within the ranges of 0 - 25, 25 - 50 and 50 - 75 degrees of knee flexion. Repeated measures ANOVA was used to compare LSMs and the contribution of individual joint moments at initial contact (IC) and IC through 50 ms after. Tibiofemoral shear loads based on a sagittal plane knee model where compared across the three landing conditions at IC and at their peak. A multivariate ANOVA was used to assess for gender differences within the limb support and individual moment data across conditions and assessed time frames. Significant limb support moment differences were noted in all three planes. Sagittal plane support increased while frontal plane support decreased with increased knee flexion at landing. Transverse plane support was considered unsupportive. Sagittal plane limb support was generated predominately by the knee while the hip is responsible for the majority of frontal plane and transverse plane limb support. Gender differences were noted predominantly at IC. Female frontal plane limb support was less than males due to an unsupportive net hip adductor moment when landing initially. In the sagittal plane female limb support was greater than males at IC due to a greater magnitude hip extensor contribution as well as a larger ankle extensor moment. In the transverse plane female support was greater than males only at IC in the 0-25 degree condition. Although females generated greater resistance to lower limb collapse in the sagittal plane, the differences in hip and ankle moments suggested they landed with less shock absorption initially. This lack of shock absorption and the presence of a net hip adductor moment, which implies a greater potential for frontal plane limb collapse, may be an explanation as to why females injure their ACL more often than males. Overall shear load was found to increase as knee flexion increased. This is contrary to the understanding that ACL injury occurs with the knee near full extension. The contribution to the overall shear in the 0-25 degree condition is dominated by the patellar tendon contribution. However, a small joint reaction force shear contribution mitigates the dominant patellar tendon contribution thereby lowering the overall shear with the knee near full extension. Overall the present data brings into question the applicability of a strict sagittal plane mechanism of injury while implicating a diminished capacity for shock absorption and a large frontal plane hip adductor moment as possible reasons for injury gender disparity.

Download or read book Task Sex and Age Effect on Sagittal Plane Biomechanics During Single Leg and Double Leg Jump landings written by Hui Min Carolynn Tan and published by . This book was released on 2019 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ACL Injuries in Female Athletes written by Robin West and published by Elsevier Health Sciences. This book was released on 2018-12-07 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: This easy-to-read reference presents a succinct overview of clinically-focused topics covering the prevention, treatment, and rehabilitation of ACL injuries in the female athlete. Written by two professional team physicians, it provides practical, focused information for orthopaedic and sports medicine surgeons and physicians. Covers ACL injury risk factors and prevention, including biomechanics, biology, and anatomy of the female athlete. Discusses graft choices, the biology of healing, rehabilitation and return to play, future options for treatment, and more. Addresses special considerations such as pediatric ACL and revision ACL. Consolidates today’s available information and experience in this timely area into one convenient resource.

Download or read book Dynamic Simulations and Data Mining of Single leg Jump Landing written by Kristin Denise Morgan and published by . This book was released on 2014 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is estimated that 400,000 anterior cruciate ligament (ACL) injuries occur in the United States each year with the cost of ACL reconstruction surgery and rehabilitation exceeding $1 billion annually. The majority of ACL injuries are non-contact injuries occurring during cutting and jump landing movements. Because the majority of the injuries are non-contact injuries there is the potential to develop programs to reduce the risk of injury. Given our understanding of the joint kinematics and kinetics that place an individual at high risk for ACL, researchers have developed neuromuscular training programs that focus on improving muscle function in order to help the muscles support and stabilize the knee during the dynamic movements that increase the strain on the ACL. Yet, despite the implementation of these neuromuscular-based ACL injury training intervention programs ACL rates continue to rise. Thus the objective of this dissertation is to determine the cause and effect relationship between joint biomechanics and muscle function with respect ACL injury. There are four studies in this dissertation. The first two studies rely heavily on the development of subject-specific musculoskeletal models to analyze muscle contribution during single-leg jump landing. These studies will generate forward dynamic simulations to estimate muscle force production and contribution to movement. The results of these studies will aid in the development of muscle-targeted ACL injury training intervention programs. The last two studies will employ data mining techniques; such as, principal component analysis (PCA) and wavelet analysis along with stability methods from control theory, to evaluate an individual’s risk of ACL injury and determine how muscle function differs for individuals at varying levels of injury risk. The goal will be to use this information to develop a more robust ACL injury prescreening tool. The use of both dynamic simulations and data mining techniques provides a unique approach to investigating the relationship between joint biomechanics and muscle function with respect to ACL injury. And this approach has the potential to gain much needed insight about the underlying mechanism of ACL injury and help progress ACL research forward.

Download or read book Understanding and Preventing Anterior Cruciate Ligament Injuries Using Novel Motion Analysis Systems written by Ariel Veronica Dowling and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall goal of this dissertation is to use novel motion analysis systems to investigate the underlying mechanisms that cause an anterior cruciate ligament (ACL) injury and then to explore movement modification methods that might prevent ACL injuries from occurring. Additionally, novel motion analysis systems can provide new information about ACL injuries and therefore should be used to help analyze these injuries from a different perspective. This thesis provides the results from multiple experimental studies that used two novel motion analysis systems to investigate the underlying causes of ACL injury and potential injury prevention methods. Using a markerless motion capture system, the first investigation determined that increasing the coefficient of friction of the shoe-surface condition will change a subject's movement strategies during a sidestep cutting task in specific ways that may increase the risk of ACL injury. This investigation provides a biomechanical basis for the increased incidence of ACL injuries on high friction surfaces, and suggests that females are more at risk for ACL injury when cutting on high friction surfaces. In terms of novel motion analysis systems, there is a need for simple, cost effective methods to identify athletes at a higher risk for ACL injury during jumping tasks. As such, the second study assessed the capacity of a wearable inertial-based system to evaluate ACL injury risk during jumping tasks. The proposed system measured the knee flexion angle and the trunk lean, and demonstrated good concurrent validity and discriminative performance in terms of the known risk factors for ACL injury. This study also reported the angular velocity of the thigh and shank segments during bilateral and unilateral drop jumps for the first time. Furthermore, this study illustrated that there is an association between the coronal segment angular velocity and knee abduction moment, and that the coronal segment angular velocity can differentiate between subjects at higher risk for ACL injury. Recent studies have shown that the incidence of ACL injury can be decreased through the use of intervention programs. Therefore, the objective for the final study was to determine if an independent inertial-based system can be used to modify jump landing mechanics in order to decrease the risk for ACL injury by providing real-time feedback based on known kinematic and kinetic injury risk factors. This study found that the subjects reduced their risk for ACL injury after training with the system because there were significant increases in the maximum knee flexion angle and the maximum trunk lean. The subjects also reduced their risk for injury by decreasing their thigh coronal angular velocity, which was correlated with a decrease in their knee abduction moment. This study suggests that an inertial-based system could be used for interventional training aimed at reducing the risk for ACL injury.

Download or read book Non contact ACL Injuries During Landing written by Ata Kiapour and published by . This book was released on 2013 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anterior cruciate ligament (ACL) is one of the most common sites of the injury in the knee joint. Over 120,000 ACL injuries occur annually in the United States, mainly affecting the young athletic population with females at a reported 2-8 fold greater risk than males. Non-contact injuries constitute the predominant mechanism of ACL injury (in over 70% of ACL injuries) occur mainly during landing following a jump and lateral cutting maneuvers. Due to long term disabilities associated with ACL injury (i.e. joint instability, pain and early development of osteoarthritis), potential loss of sports participation and high costs associated with surgical reconstruction, prevention is an appealing option to avoid the complications associated with ACL injury. While many advances have been made in terms of surgical and rehabilitation interventions, patients who have suffered ACL injury face long-term consequences that include lowered activity levels, 10-25 % incidence of re-injury 5 years after return to sport and 50-100 % incidence of osteoarthritis within 10-15 years of injury, regardless of the treatment. Despite the substantial effort conducted on investigation of the non-contact ACL injuries, the mechanism of these injuries is not well understood. Many proposed risk factors can be categorized as anatomic, neuromuscular or biomechanical. However, just biomechanical and neuromuscular risk factors can be defined as modifiable factors, which can be modified through targeted intervention strategies in an effort to reduce the risk of injury. Identification of modifiable risk factors for ACL injury represents a major step in the reduction of the incidence of injury. A better understanding of the mechanisms underlying non-contact ACL injuries and associated risk factors, might serve to improve current prevention strategies and decrease the risk of early-onset knee osteoarthritis. This proposal aims to employ a unique combination of established ex vivo and in silico methods in order to gain an in depth understanding of knee joint biomechanics during dynamic landing (as an identified high-risk task) with a specific focus on ACL injury. The objectives of this dissertation were to investigate the non-contact ACL injury during landing in an effort to identify the potential biomechanical and neuromuscular risk factors and determine the mechanisms that lead to these injuries. Cadaveric experiments were conducted on 20 normal, relatively young instrumented lower extremities. Following knee arthrometry, specimens were tested under a wide range of quasi-static single- and multi-axial loading conditions in order to quantify the global the biomechanical response of the tibiofemoral joint with regards to joint kinematics, ACL and MCL strains, and intra-articular cartilage pressure distribution. Subsequently, multiple bi-pedal and uni-pedal landing scenarios were simulated using a custom designed novel drop-stand. An extensive physiologic loading protocol was designed based on the identified high-risk loading factors from quasi-static characterization to simulated a wide range of landing scenarios. The findings of these cadaveric experiments were suggested the anterior tibial shear force, knee abduction moment and internal tibial rotation moment as the most critical biomechanical risk factors for the non-contact ACL injury during landing. Results further suggested the multi-planar loading condition consists of all three identified biomechanical risk factors as the most probable mechanism for non-contact ACL injuries. Findings finally highlighted the importance of dynamic knee valgus collapse as a primary factor contributing to these injuries (Specific Aim I). In addition to cadaveric experiments, a detailed anatomic non-linear finite element (FE) model of the lower extremity was developed from imaging data of a healthy, young female athlete. The developed model includes bony and soft tissue structures of the knee joint such as major ligaments, trans-knee muscles, articular cartilage and menisci. The model was then extensively validated against cadaveric measurements of joint kinematics, ligament strains and cartilage pressure distribution under a wide range of static, quasi-static and dynamic loading conditions. A comprehensive FE parametric study was conducted in order to investigate the effect of trans-knee muscle loads on knee joint biomechanics and risk of ACL injury. The findings in combination with ex vivo data resulted in identification of the anterior-posterior and medial-lateral muscle force imbalances as the potential neuromuscular risk factors lead to high ACL strains and high risk of ACL injury (Specific Aim II). The developed FE model was further used to help better interpret the experimental findings in an effort to identify ACL injury biomechanical risk factors and associated mechanism (Specific Aim I). Finally a novel framework was developed in order to customize the validated generalized FE model based on the structural properties of ACL and critical tibiofermoral anatomic factors. The customized models were then validated based subject-specific ACL strain data obtained ex vivo. It was shown that the customized models using the proposed approach lead to more realistic FE-predicted ACL strain compared to the generalized FE model. Findings suggested that this novel, validated framework can be used as a critical risk-screening tool in the large-scale clinical assessment of ACL injury risk among individuals (Specific Aim III).

Download or read book The Effect of Distraction on Female Lower Limb Biomechanics During a Drop Jump Landing Relevance to Preventing Anterior Cruciate Ligament ACL Injuries written by Hannah L. Price and published by . This book was released on 2015 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: