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 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 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 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 Predicting Risk Factors of Non Contact Anterior Cruciate Ligament Injuries During Single Leg Landing written by Ali Nicholas and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The literature suggests that body kinematics and musculoskeletal differences are major factors contributing to the high disparity in non-contact Anterior Cruciate Ligament (ACL) injury rate between genders. The literature also indicates that the incidence of non-contact ACL injury predominates during single-leg landing sports such as basketball, soccer, and handball. Despite this, there are few studies investigating kinematics or musculoskeletal differences between genders during single-leg landing from increasing vertical heights and horizontal distances. The objectives of this study are threefold: first, conduct a gap study identifying the barriers to predicting mechanisms and risk factors for non-contact ACL injury. Second, propose a new approach that can address some of the challenges encountered in some existing non-contact ACL injury study approaches. Finally, whilst determining whether or not gender differences explain the higher rate of ACL injuries among females, identify and correlate the biomechanical and musculoskeletal variables significantly impacted by gender, vertical landing height, and/or horizontal landing distance and their interactions to various ACL injury risk predictor variables during single-leg landing. Experiments using male and female subjects, inverse dynamics analysis using Visual3D, and musculoskeletal modeling simulation using AnyBody Modeling System were approaches used to explore these objectives. Salient findings from this dissertation includes but are not limited to, non-contact ACL injury that occurs during single-leg landing is mutifaceted entailing many factors that cannot be captured in any one existing ACL injury study approach. Non-contact ACL injury during single-leg landing may not be gender specific. Both vertical height and horizontal distance of landing increase the risk of non-contact ACL injury during single-leg landing. Body kinematics during single-leg landing may not be the sole determinant in attenuating ground reaction forces and consequently risk of ACL injury. The hamstring and gastrocnemius muscles were determined to strain shield the ACL while the quadriceps were found to have no significant effect on risk of ACL injury during single-leg landing. Within the findings and limitations of this study the knowledge garnered from this research may aid in tailoring future studies so as to enable more robust non-contact ACL injury prevention protocols.

Download or read book Return to Sport after ACL Reconstruction and Other Knee Operations written by Frank R. Noyes and published by Springer Nature. This book was released on 2019-11-05 with total page 709 pages. Available in PDF, EPUB and Kindle. Book excerpt: The wealth of information provided in this unique text will enable orthopedic surgeons, medical practitioners, physical therapists, and trainers to ensure that athletes who suffer anterior cruciate ligament (ACL) injuries, or who require major knee operations for other reasons, have the best possible chance of safely resuming sporting activity at their desired level without subsequent problems. Divided into seven thematic sections, the coverage is wide-ranging and encompasses common barriers to return to sport, return to sport decision-based models, and the complete spectrum of optimal treatment for ACL injuries, including preoperative and postoperative rehabilitation. Advanced training concepts are explained in detail, with description of sports-specific programs for soccer, basketball, and tennis. Readers will find detailed guidance on objective testing for muscle strength, neuromuscular function, neurocognitive function, and cardiovascular fitness, as well as validated assessments to identify and manage psychological issues. In addition, return to sport considerations after meniscus surgery, patellofemoral realignment, articular cartilage procedures, and knee arthroplasty are discussed. Generously illustrated and heavily referenced, Return to Sport after ACL Reconstruction and Other Knee Operations is a comprehensive resource for all medical professionals and support staff working with athletes and active patients looking to get back in the game with confidence.

Download or read book ACL Injuries in the Female Athlete written by Frank R. Noyes and published by Springer. This book was released on 2018-09-07 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: This successful book, now in a revised and updated second edition, reviews all aspects of anterior cruciate ligament (ACL) injuries in female athletes, with the focus on complete, noncontact ACL injuries. The opening section discusses anatomy and biomechanics and explains the short- and long-term impacts of complete ACL ruptures, including long-term muscle dysfunction and joint arthritis. Risk factors and possible causes of the higher noncontact ACL injury rates in female athletes compared with male athletes are then discussed in depth. Detailed attention is devoted to neuromuscular training programs and their effectiveness in reducing noncontact ACL injury rates in female athletes, as well as to sports-specific ACL injury prevention and conditioning programs of proven value. Rehabilitation programs after ACL injury and reconstruction that reduce the risk of a future injury are explored, and the concluding section looks at worldwide implementation of neuromuscular ACL injury prevention training and future research directions. The book will be of value to orthopedic surgeons, physical therapists, athletic trainers, sports medicine primary care physicians, and strength and conditioning specialists.

Download or read book Anticipatory and Reactionary EMG and Knee Joint Kinematics Between Male and Female Athletes During Single Leg Landing Tasks written by Hui Min Carolynn Tan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Background: Females are more likely to suffer anterior cruciate ligament (ACL) injuries. Muscle activity may be responsible in preventing ACL tears during jump-landings. Purpose: To determine a) whether sex differences exist in knee joint motion and muscle activity during preparatory and landing phases of single leg drop-jumps (SLJ) and b) whether an association between preparatory muscle activity and sex and landing knee joint motion exist. Methods: 33 male and 21 female athletes were recruited. Standardized biomechanical and electromyography procedures were used to record joint motion and muscle activity during the SLJ. Results: No sex differences in knee motion and muscle activity were found in preparatory and landing phases (p>0.05). Sex was not associated with knee motion in landing phases (p>0.05). Preparatory rectus femoris and medial hamstring muscle activity was associated with knee motion during landing phases (p

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 Influence of Residual Fatigue on Lower Limb Stiffness During Jump Landing written by Lindsay Victoria Slater and published by . This book was released on 2010 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Background: Anterior cruciate ligament (ACL) injuries have become commonplace among female athletes in today's society. With more than 70% of injuries resulting from noncontact mechanisms such as jump landing, the relationship between fatigue and altered movements patterns has become an important topic of research. Purpose: The main purpose of this study was to investigate the influence of residual fatigue on lower extremity kinematics and vertical leg stiffness at landing as experienced by female athletes. Method: The participants in this study were 12 NCAA female intercollegiate soccer players. Participants completed five single-leg drop jumps on their dominant leg every day for 4 days. The first day was completed without intervention to obtain pre-fatigue data and drop jumps on days two through four were completed after a fatigue protocol. Results: A repeated measures MANOVA did not reveal significant differences in post-fatigue peak knee flexion angle, vertical ground reaction forces, or vertical leg stiffness. Despite lack of statistical significance, vertical leg stiffness was increased during post-fatigue testing when compared to pre-fatigue values. Implications: The increased vertical leg stiffness may indicate altered landing techniques in post-fatigue states. If fatigue results in compromised movement patterns, it may explain the increased number of ACL injuries during the end of soccer matches. Suggestions for Future Research: Future research with a larger sample size should include post-fatigue dominant and nondominant leg comparison due to previous conflicting findings regarding which limb is most often injured. Future researchers should also quantify the magnitude of fatigue induced by the fatiguing protocol to document the strength of the independent variable.

Download or read book Comparisons of Pr landing and Early Landing Knee Flexion Angles Between Sexes and Landing Tasks written by Ling Li and published by . This book was released on 2021 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anterior cruciate ligament (ACL) injury is one of the most common and severe injuries to the lower extremity, commonly occurring when individuals land with a single leg. Compared with male athletes, females have a higher incidence of ACL injuries. Although there is a wealth of information regarding the difference in landing mechanisms between sexes and landing tasks, most biomechanical studies regarding the difference have focused on mechanisms of ACL injuries in the landing phase after ground contact. Importantly, none has focused specifically on the pre-landing biomechanics for ACL injury risk to assess the difference between sexes and landing tasks. The purpose of the current research was to compare pre-landing and early landing knee biomechanics between men and women and between double-leg and single-leg landings. Sixteen males and sixteen females participated in this study. The landing task required participants to jump forward from a 30 cm box placed half of the participant's body height from the force platform and land with either the testing leg or both legs. Kinematic variables included the minimal knee flexion angle in pre-landing, timing of minimal knee flexion angles in pre-landing, and average knee flexion angular velocity between the minimal knee flexion angle and initial ground contact. Knee flexion angles at initial contact and Knee flexion angles and average angular velocity 50 ms after initial contact were also extracted. Kinetic variables included peak vertical and posterior ground reaction forces within 50ms after landing. All dependent variables were significantly different between the two landing conditions (p

Download or read book ACL Injuries in the Female Athlete written by Frank R. Noyes and published by Springer Science & Business Media. This book was released on 2013-01-04 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nearly a million anterior cruciate ligament (ACL) injuries occur each year worldwide, causing long-term problems in the knee joint. This textbook examines the short- and long-term impacts of ACL injuries on the basis of hundreds of published studies. Risk factors for such injuries are explored using data from hypothesis-driven investigations, and possible causes of the higher risk of noncontact ACL injuries in female athletes are analyzed. Neuromuscular training programs shown to reduce the rate of these injuries in female athletes are described in step-by-step detail with the aid of numerous color photographs and video demonstrations. In addition, detailed descriptions are provided for rehabilitation programs to be used after ACL reconstruction in order to reduce the risk of a future injury. The book will be of value to orthopedic surgeons, physical therapists, athletic trainers, sports medicine primary care physicians, and strength and conditioning specialists.

Download or read book The Multiple Ligament Injured Knee written by Gregory C. Fanelli and published by Springer Science & Business Media. This book was released on 2012-08-16 with total page 469 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Multiple Ligament Injured Knee: A Practical Guide to Management includes the most developed knowledge needed to successfully diagnose and treat knee ligament injuries. This thorough work presents anterior and posterior cruciate and collateral ligament anatomy and biomechanics along with non-invasive methods for diagnosing the extent of injury, such as radiographic and arthroscopic evaluation. Various injuries are discussed in addition to useful treatment techniques, including arthroscopic reconstruction, posterolateral and posteromedial corner injury and treatment, assessment and treatment of vascular injuries, assessment and treatment of nerve injuries, rehabilitation, and post-operative results. Each of these clearly written chapters is accompanied by a wealth of line drawings and photographs that demonstrate both the surgical and non-surgical approaches to examination and treatment.

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 The Effect of Exercise on the Biomechanical Determinants of Knee Energy Absorption During Single leg Jump cuts written by Anne E. Pollard and published by . This book was released on 2015 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anterior cruciate ligament injuries are common in a wide variety of sports and most frequently occur during activities requiring rapid deceleration such as landing and cutting. Deceleration of the body's center of mass during movement results primarily from eccentric muscle contraction. This type of contraction serves to absorb energy from the whole-body system with the magnitude of energy absorbed directly related to the internal joint moment and the joint angular velocity. There is substantial evidence to demonstrate that following exercise females land with lesser knee flexion which may increase their risk for ACL injury. However, it is not known whether this change in knee position is a compensatory mechanism to overcome a reduction in quadriceps moment producing capacity that occurs during sustained exercise. It is possible that a more extended knee position is used after exercise in order to allow for greater knee flexion angular velocity so that the magnitude of knee energy absorption (EA) during landing can be maintained. Therefore, the purpose of this study was to: 1) evaluate the influence of exercise on the magnitude of knee EA during a single-leg jump-cut and, and 2) identify whether exercise influences the individual biomechanical determinants (internal knee moment and knee angular velocity) of knee EA. Forty recreationally active females performed single-leg jump-cuts before and after a standardized 30-minute exercise protocol. From recorded motion capture and ground reaction force data, the magnitude of knee EA, mean internal knee extension moment, and mean knee flexion angular velocity during the initial 100 milliseconds of landing were calculated. Despite no change in knee flexion angle at initial contact, females landed with 10% lesser knee EA following the exercise protocol. The lesser EA was the result of a 14% reduction in mean internal knee extension moment coupled with an 8% reduction in mean knee flexion angular velocity post-exercise. The results suggest that females utilized a stiffer landing strategy with lesser knee EA after sustained exercise. While the magnitude of the EA reduction observed during the single-leg jump-cut is probably not clinically meaningful, it is likely that the adoption of a stiffer landing strategy following exercise during more demanding movement tasks might result in increased loading of static structures and greater lower extremity injury risk.

Download or read book Prevention of Noncontact ACL Injuries written by Letha Y. Griffin and published by Academy. This book was released on 2001 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: This important work will help you understand: the epidemiology of noncontact ACL injuries; risk factors for injuries; the "at-risk" athlete; neuromuscular prevention programs; their influence on injury rates. Supported by the American Orthopaedic Society for Sports Medicine, the National Athletic Trainers Association Research and Education Foundation, the National Collegiate Athletic Association, and the Orthopaedic Research and Education Foundation.

Download or read book Influence of Thigh Muscle Forces on Anterior Cruciate Ligament Forces During Single leg Landing from Three Different Heights written by Jonathan M. Bulluck and published by . This book was released on 2010 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over 200,000 anterior cruciate ligament (ACL) injuries occur every year amounting to billions of dollars being spent on the ACL annually. While the quadriceps muscle produces an anterior shear force on the tibia that causes the ACL to strain, the hamstrings muscle can protect the ACL by producing a posterior shear force to the tibia reducing the strain. When the hamstrings contract simultaneously with the quadriceps, ACL strains are considerably less compared to isolated quadriceps forces, thus the balance of hamstring and quadriceps muscle forces play a critical role in determining the forces on the ACL. During dynamic landing tasks, quadriceps demands increase as the landing height increases, which may cause the ACL to be more susceptible to injury. The purpose of this study was to determine the relationship of the quadriceps and hamstring muscle forces on ACL forces during single-leg landing from three different heights. We hypothesized that the ratio between hamstrings and quadriceps muscle forces would be negatively correlated to peak ACL forces during landing from three different heights. We anticipated that the hamstring to quadriceps ratio would decrease as landing height increased primarily due to the increased quadriceps demands. Three males with an average height of [1].75"0.07m with an average mass of 74.08"8.66kg and three females with an average height of 1.70"0.04m and an average mass of 55.93"6.83kg landed on their right leg from three different heights, 15cm, 30cm, and 45cm. Musculoskeletal modeling was used to estimate muscle forces. Regression analyses predicted the ACL forces from all three heights, and the heights pooled together. The results showed that the quadriceps muscles forces were strongly positively correlated to the peak ACL force while the hamstrings muscle forces were not significantly correlated to peak ACL force. Linear analysis showed the hamstring to quadriceps ratio to be moderately negatively correlated with peak ACL force (r2 = 0.278), but nonlinear curve analysis showed a stronger relationship between these variables (r2 = 0.425). However, as the landing height increased, these linear and nonlinear relationships both decreased. This signifies that another factor was contributing to the peak ACL force especially at higher heights. The combined influence of ground reaction forces and the hamstring to quadriceps ratio revealed that as landing height increased the ground forces became more of a factor in predicting peak ACL forces compared to the hamstring to quadriceps ratio being the dominant predictor at the lowest heights. In conclusion, the data support our hypothesis the hamstring to quadriceps ratio was inversely related to the peak ACL force although the strength of this relationship was height dependent. Further, as landing height increases, the ground reaction forces become the stronger predictor of peak ACL forces compared to the hamstring to quadriceps force ratio.