Download or read book The Effects of Knee Joint Loading on Dynamic Tasks in Individuals Several Years Post ACL Reconstruction written by Meredith Nannette Decker and published by . This book was released on 2020 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Joint loading of the lower extremity is studied to identify risk factors for anterior cruciateligament (ACL) injuries and to determine limb asymmetries. Asymmetrical loading in the lower extremity during ACL reconstruction (ACLR) rehabilitation and at the time of return to sport or activity will cause compensations during functional movements, which can lead to unwanted joint re-injury or long-term joint damage. Re-injury and/or development and progression of knee osteoarthritis (OA) is prevalent after ACLR; therefore, joint loading measurements at extended time points from reconstruction and after return to play may help to identify how asymmetrical loading and compensatory movement strategies contribute to these occurrences. The joints of the lower extremity experience different stresses when ACLR individuals return to physical activity after clearance from rehabilitation because there are varying intensities and physical demands on individual athletes. Individuals also may actually avoid loading their ACLR knee because of persistent symptoms, poor perception, or limited knee extensor eccentric control . Therefore, our understanding of the impact of both excessive and limited knee joint loading on knee OA can be developed from an understanding of the normal and abnormal lower extremity movement patterns or strategies during various functional tasks in ACLR individuals. Study 1 (Chapter 2) takes a comprehensive approach to understand the difference in joint loading by way of energy absorption (EA) and energy absorption contribution (EAC) during three different functional tasks, single-leg squat (SLS), single-leg hop, and gait, in ACLR individuals 2-9 years removed from surgery and healthy, matched control participants. Advanced statistical analyses were used to identify interaction effects between each task within each group and between groups. There were differences between both groups in EA and EAC across all joints when comparing each physical performance task. Knee joint loading was greatest for both groups during the SLS task. ACLR participants utilized strategies with greater hip compensations during hop tasks and greater ankle contribution during gait tasks. These findings suggest the ability of ACLR participants to utilize altered loading strategies when performing different functional tasks and likely represent an avoidance of loading the knee of the surgical limb. The avoidance of knee joint loading in ACLR subjects are likely due to strength and range of motion asymmetries in the surgical limb compared to the non-surgical limb within ACLR subject as well as the matched limb within the healthy controls.Physical performance on different functional tasks is not only related to physical capacity but it is also related to a patient's self-efficacy related to the task, so it is important to measure a patient's perception of their capabilities as these cannot be objectively proven with lab tests.Self-reported function (SRF) has been utilized in conjunction with other biomechanical measures to explain kinetic and kinematic alterations; however, the comparison to EA and EAC has not been explored. Study 2 (Chapter 3) used performance on the previously mentioned physical performance tasks to identify an interaction effect with SRF, as measured by the Knee injury and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) forms. Overall, across functional tasks, ACLR subjects with lower SRF also used joint loading strategies that limited knee loading and emphasized hip and ankle compensations. These data support the notion that a lower perception of function will lead to changes in energy absorption. When compared to control subjects, ACLR subjects with SRF in either low or high sub-groups consistently demonstrated altered loading strategies with more ankle and/or hipcontribution in an effort to underload the knee. The findings of these investigations provide insightful information into energy absorption measures of joint loading within a variety of functional tasks in a previously unstudied time frame (2-9 years) following ACLR. Movement asymmetries and deficits in joint loading will impact knee joint health and the inclusion of measures of SRF are a necessary compliment to objective findings as understanding how ACLR individuals perceive their ability to load their surgical knee may help our understanding of asymmetrical loading patterns. Future work should identify EA and EAC across other performance tasks, in addition longitudinal investigations of joint loading and SRF in ACLR patients beyond the typical continuum of care from surgery through rehabilitation and return to activity should be pursued.

Download or read book The Effects of ACL Injury on Gait Mechanics and the Initiation of Osteoarthritis written by Michael Zabala and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rupture of the anterior cruciate ligament (ACL) is one of the most common injuries to the knee. Unfortunately, individuals who experience this injury are likely to develop osteoarthritis of the knee much earlier than would be expected due to the normal ageing process, and this remains true even after surgical reconstruction of the ligament. Research has suggested that a major contributing factor to the development of premature osteoarthritis is altered knee mechanics which change the loading conditions of the cartilage in the joint. Furthermore, it has been shown that altered knee mechanics are present following rupture of the ACL and persist after reconstruction surgery. Despite initial reports, there still remains a need for a comprehensive understanding of both altered knee mechanics in both ACL deficient and ACL reconstructed knees as well as changes in cartilage morphology following ACL injury. Therefore, the goal of this dissertation is to address the question of the relationship between certain changes in knee mechanics and cartilage morphology as they relate to the development of osteoarthritis following both ACL injury and reconstruction. The first study presented involves an analysis of the knee mechanics in individuals with unilateral ACL deficiencies. This group was important in that they were free of knee pain and had no sign of osteoarthritis on MRI over a time frame that ranged up to three decades from injury. This provided a unique opportunity to explore the potential for a protective functional adaption. The results of this study suggest that alteration in knee mechanics may act as a protective mechanism against osteoarthritis development since when subjects were separated into "Short Term" and "Long Term", based upon the time from injury, only those in the "Long Term" group demonstrated a relationship between the external knee flexion moment, which is representative of the interaction between quadriceps and hamstrings muscle to control rotation and translation during walking. This is indicative of an adaptive control mechanism present in some subjects who were able to last many years after the injury without reconstruction surgery. These results suggest the potential for new methods for rehabilitation following ACL injury. The second study presented involves an analysis of the knee mechanics of individuals with unilateral ACL reconstructions during gait, stair ascent, and stair descent at two years from surgery. The results demonstrate a reduction in the external joint moments of ACL reconstructed knees and an increase in the joint moments of uninjured contralateral knees during each activity compared to healthy controls. This suggests two things: 1.) compensation for residual muscle weakness in the affected limb is needed by the contralateral knee during ambulation and 2.) a decrease in daily joint loading in ACL reconstructed knees and an increase in joint loading in contralateral knees. Decreased loading of the ACL reconstructed knee may seem counterintuitive to what was expected in patients who will likely develop premature osteoarthritis in this knee. However, this finding is consistent with the suggestion that changes in joint kinematics and even decreased joint loading following the injury may contribute to the initial cartilage breakdown. Note: Taken together the results of study 1 and 2 suggest that the interaction between muscle function and kinematics should be further considered in the development of knee OA in this population. The third and final study involves articular cartilage morphology analysis of individuals with unilateral ACL reconstructions at two and four years from surgery. The results illustrate differences between cartilage thickness of ACL reconstructed and healthy contralateral knees at both times of testing. The findings show significantly thinner cartilage in the lateral tibial compartment of ACL reconstructed knees at two years from surgery. These differences became more pronounced at four years from surgery and include the addition of a significantly thicker medial region of the tibia of ACL reconstructed knees compared to healthy contralateral knees. The results indicate that patterns of cartilage thickness change are detectable as early two years following ACL reconstruction, and these patterns become more pronounced at 4 years which suggests cartilage begins a degenerative pathway substantially in advance of clinically detectable OA. This finding is important since it provides a basis for assessing early interventions to reduce the risk of knee OA following ACL injury. This dissertation helps to further the understanding of altered knee mechanics following both ACL rupture and reconstruction. In addition, a possible pattern of OA initiation has been reported. Each of these studies will benefit future studies with the ultimate goal of a complete understanding of OA initiation and development in ACL ruptured and reconstructed knees.

Download or read book Relating Subjective and Objective Knee Function After Anterior Cruciate Ligament Injury Through Biomechanical and Neuromusculoskeletal Modelling Approaches written by Kenneth Smale and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Background: Knee injuries have a considerable impact on both the person's psychological and physical health. We currently have tools to address each of these aspects but they are often considered independent of each other. Little work has been done to consolidate the subjective and objective functional ability of anterior cruciate ligament (ACL) injured individuals, which can be detrimental when implementing a return-to-play decision-making scheme. The lack of understanding concerning the relationship of these two measures may account for the high incidence of re-injury rates and lower quality of life exhibited by so many of these patients. Purpose: The purpose of this doctoral thesis is to investigate the relationship between subjective and objective measures of functional ability in ACL deficient and ACL reconstructed conditions through biomechanical and neuromusculoskeletal modelling approaches. Methods: This thesis is comprised of five studies based on a single in vivo data collection protocol, medical imaging and in silico data analyses. The in vivo data collection was of test-retest design where ACL deficient patients participated prior to their operation and approximately ten months post-reconstruction. This experimental group was matched to a healthy, uninjured control group, which was tested a single time. The first study of this thesis involved a descriptive analysis of spatiotemporal, neuromuscular, and biomechanical patterns during hopping and side cut tasks in addition to subjective functional ability questionnaires. Then, two novel measures of dynamic knee joint control were developed and applied along with a third measure to determine if changes in joint control exist between the three groups (Study 2). The relationships of these objective measures of functional ability to subjective measures were then examined through correlation and regression models (Study 3). Following this, a method of including magnetic resonance imaging to construct patient-specific models was developed and implemented to determine realistic kinematic and ligament lengthening profiles (Study 4). These patient-specific models were then applied to quantify knee joint loading in the form of contact and ligament forces, which were correlated to subjective measures of functional ability (Study 5). Results: Even though no major differences in neuromuscular patterns were observed between all three groups, it was found that subjective patient-reported outcome measures scores and biomechanical measures in the form of knee flexion angles and extensor moments were lower in the ACL deficient group compared to healthy controls. These differences continued to exist 10 months post-operation as the ACL reconstructed group had not fully recovered to patterns observed in the healthy controls. The current findings also suggest a possible hierarchy in the relationships between objective and subjective measures of functional ability. Basic kinematic objective measures such as knee flexion angle show small to moderate correlations, while more comprehensive measures such as stiffness and joint compressive force show moderate to strong correlations to subjective questionnaires. Finally, this thesis developed patient-specific OpenSim models that were used to produce appropriate kinematics and ligament lengthening with the reduction in soft tissue artefact. Conclusion: This thesis demonstrated that patients who are high-functioning in the ACL deficient state show greater improvements in subjective outcome scores after ACL reconstruction compared to objective measures. Biomechanical and neuromusculoskeletal modelling approaches identified important differences between the healthy and ACL deficient groups that were not resolved post-operatively. Our results also demonstrate that certain subjective and objective measures of functional ability are strongly correlated. The knowledge gained from this test-retest design and novel patient-specific in silico models aids clinicians in managing their expectations regarding the effectiveness of reconstruction and the respective long-term sequelae.

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 SHORT STEP KNEE OSTEOARTHRITIS A BEGINNERS GUIDE TO RUNNING POST ACLR written by Collin Douglas Bowersock and published by . This book was released on 2016 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: SHORT STEP KNEE OSTEOARTHRITIS: A BEGINNERS GUIDE TO RUNNING POST ACLR By Collin Douglas Bowersock April 29, 2016 Director of Thesis: John D. Willson, PT, PhD Major Department: Kinesiology Introduction: Post anterior cruciate ligament reconstruction (ACLR), individuals are 3-4x more likely to develop knee osteoarthritis (OA). Increased knee joint loads, and knee joint loading characteristics have been associated with knee OA. Specifically, peak loads, cumulative loads, and loading rate loads about the knee have been associated with the onset and progression of knee OA. Running increases the magnitude of these loads and an estimated 90% of individual's participant in lower levels of activity such as running post ACLR. Changes in cartilage morphology that are seen as early as 4 months post ACL injury may suggest the cartilages inability to manage high cyclical loads associated with running. Thus, promoting interventions to decrease joint loads during running post ACLR may prevent or impede degenerative joint changes. Decreasing step length has been shown to decrease knee forces within the healthy population but due to gait changes seen post ACLR, it is unclear if these reductions will be seen among the ACLR population. Between limb kinematic differences have also been seen, but no study has compared joint loads between limbs post ACLR. The further understanding of how the two limbs interact post ACLR may improve clinical recommendations. The first purpose of this study was to test for changes in tibiofemoral joint (TFJ) and patellofemoral (PFJ) loading parameters as individuals with a history of unilateral ACLR run with a shorter step length. The secondary purpose was to compare PFJ and TFJ loading parameters during running. Variables of interest include peak force, force*time impulse, impulse per km, and average loading rate. Methods: Eighteen individuals ( =22 years) with unilateral ACLR reconstruction 2 to 7 years prior were recruited for the study. Lower extremity gait analysis was conducted using a motion capture system and instrumented treadmill. Participants ran at their preferred speed ( =2.65 m/s) and preferred step length, followed by a 5% and 10% decreased step length condition. Two separate Two-Way analysis of variance were used to test for linear trends across step length conditions (3 factor) and between limb differences (2 factor). Least significant difference tests were used to analyze differences between step length conditions. Results: Linear trends were observed across step length conditions for PFJ, TFJ, and mTFJ peak force (all p [less than] 0.000), PFJ, TFJ, and mTFJ impulse (all p [less than] 0.000), and PFJ, TFJ, and mTFJ impulse per km (all p [less than] 0.012). A 5% and 10% decrease in step length were successful in reducing peak joint force, force*time impulse, and impulse per km by 4 to 12%. Between limb differences were observed. The experimental limb experienced a 7% decreased force*time impulse and impulse per km within the TFJ. Conclusion: Individuals with ACLR who ran with a shorter step length reduced peak force, force*time impulse, and cumulative impulse per km within the PFJ, TFJ, and mTFJ compartment, and these reductions had a linear trend from preferred step length, a 5% decrease, and a 10% decrease. Between limb loading differences were seen within the TFJ. Future longitudinal studies to examine this running modification's effect on knee joint cartilage thickness and health post ACLR appear justified.

Download or read book Muscle Force Contributions to Knee Joint Loading written by Nirav Maniar and published by . This book was released on 2017 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anterior cruciate ligament (ACL) injuries are one of the most common knee injuries suffered by athletic populations. ACL injuries are particularly burdensome due to potential surgical requirements, extensive rehabilitation time and associated financial costs for the individual and the community. Additionally, ACL injuries are associated with increased risk of early onset knee osteoarthritis. As such, ACL injury preventative and rehabilitative strategies are of paramount importance.ACL injuries typically occur during non-contact dynamic tasks, such as unanticipated sidestep cutting. At the time of injury, the knee joint experiences relatively large degrees of knee valgus and rotation (either internal or external) and high mechanical loads. These loading patterns, along with the anterior shear force, are known to increase loads on the ACL, especially in combination with each other. Muscles produce forces that can cause and oppose these knee joint loads, and therefore play a critical role in dictating the size and the nature of the loads experienced by the ACL. Prior research has investigated the role of muscle force in ACL load development, and has indicated that the hamstrings are most capable of reducing ACL loads. Subsequently, any pathology that may influence hamstring function may increase the risk of ACL injury. (...) The data from this program of research will inform ACL injury rehabilitation and injury prevention practices which should consider not only targeting the hamstrings but also other non-knee-spanning muscles for loading and unloading the knee during sidestep cutting. Additionally, this thesis provides data that may inform strategies aiming to modulate muscle forces to alter tibiofemoral compressive forces, which may be involved in ACL injury and concomitant meniscal and articular cartilage injury. Finally, this thesis provides further data informing how these muscles contribute to the performance of sidestep cut, in order to achieve optimal balance between performance and injury risk considerations. The findings from this thesis also dictates that future investigations that aim to examine the link between prior HSI and increased knee joint loading need to broaden the scope of such work to consider the influence of other lower-limb muscles as well as multi-planar movements.

Download or read book Sports Injuries written by Mahmut Nedim Doral and published by Springer Nature. This book was released on 2015-06-29 with total page 3295 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sports Injuries: Prevention, Diagnosis, Treatment and Rehabilitation covers the whole field of sports injuries and is an up-to-date guide for the diagnosis and treatment of the full range of sports injuries. The work pays detailed attention to biomechanics and injury prevention, examines the emerging treatment role of current strategies and evaluates sports injuries of each part of musculoskeletal system. In addition, pediatric sports injuries, extreme sports injuries, the role of physiotherapy, and future developments are extensively discussed. All those who are involved in the care of patients with sports injuries will find this textbook to be an invaluable, comprehensive, and up-to-date reference.

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 Revision ACL Reconstruction written by Robert G. Marx and published by Springer Science & Business Media. This book was released on 2013-09-05 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although anterior cruciate ligament (ACL) reconstruction has a high success rate, a substantial number of patients are left with unsatisfactory results. Revision ACL Reconstruction: Indications and Technique provides detailed strategies for planning and executing revision ACL reconstructions. Concise chapters by a leading group of international orthopedic surgeons cover the diagnosis of failed ACL reconstruction, patient evaluation, preoperative planning for revision ACL surgery and complex technical considerations.

Download or read book Current Concepts in ACL Reconstruction written by Freddie H. Fu and published by SLACK Incorporated. This book was released on 2008 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: From evaluation to outcome, Current Concepts in ACL Reconstruction will help you keep pace with the latest techniques for the treatment of anterior cruciate ligament injuries. This text provides the most complete and up-to-date information for the surgical reconstruction of a torn ACL including details about the newer double-bundle procedure. Both American and international perspectives on the treatment of ACL injuries are included to provide the most comprehensive review on the market today. Inside this richly illustrated text, Drs. Freddie H. Fu and Steven B. Cohen along with contributions from the world's most experienced knee surgeons review the basic science, kinematic, imaging, and injury patterns surrounding the ACL. Surgical concepts, various techniques for reconstruction, and diverse opinions on approaching the ACL are also included. Current Concepts in ACL Reconstruction explains the anatomical basis in order to provide the most current surgical principles to ensure the patient receives the best surgical outcomes. To reflect recent advancements in ACL treatment, the emerging double-bundle technique is comprehensively covered. The differences between the single- and double-bundle techniques are discussed with perspectives from leading international experts in double-bundle reconstruction. An accompanying video CD-ROM demonstrates the various procedures mentioned throughout the text. In addition, several of the world's most experienced surgeons provide their perspective from what they have learned by performing ACL surgery for over 25 years, along with their insight into the future treatment of ACL injuries. What you will want to learn more about: - Differences between single- and double-bundle reconstruction techniques - Outcomes of single- and double-bundle reconstruction - Pediatric ACL reconstruction - Gender differences in ACL injury - Radiographic imaging - Computer navigation assistance for ACL reconstruction - Injury patterns of the ACL - Graft choices in ACL surgery - Revision ACL surgery - Postoperative rehabilitation after ACL reconstruction - Outcome measures to assess success after surgery Current Concepts in ACL Reconstruction answers the need for a comprehensive information source on the treatment of ACL injuries. Orthopedic residents and surgeons will be prepared with this thorough review of ACL reconstruction by their side.

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 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 Physical Rehabilitation of the Injured Athlete written by Gary L. Harrelson and published by . This book was released on 2004 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt: Represents collaboration among orthopaedists, physical trainers, and athletic trainers. It reviews the rehabilitation needs for all types of sports injuries, stressing the treatment of the entire kinetic chain with various exercises. Chapters have been extensively revised, featuring new concepts and techniques. The 3rd edition includes four new chapters (Proprioception and Neuromuscular Control; Cervical Spine Rehabilitation; Functional Training and Advanced Rehabilitation; and Plyometrics), new contributors and new features, such as summary boxes and tables.

Download or read book Rotatory Knee Instability written by Volker Musahl and published by Springer. This book was released on 2016-09-27 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is designed to equip the reader with the knowledge and tools required for provision of individualized ACL treatment based on the best available evidence. All major aspects of the assessment of rotatory knee instability are addressed in depth. A historical overview of arthrometers, both invasive and non-invasive, is provided, and newly developed devices for the measurement of rotatory knee laxity are considered. Recent advances with respect to the pivot shift test are explained and evidence offered to support a standardized pivot shift test and non-invasive quantification of the pivot shift. Specific surgical techniques for rotatory laxity are described, with presentation of the experience from several world-renowned centers. In addition, functional rehabilitation and “return to play” are discussed. In keeping with the emphasis on an individualized approach, the book highlights individualization of surgical reconstruction techniques in accordance with the specific injury pattern and grade of rotatory knee laxity as well as the use of individualized rehabilitation techniques. Numerous high-quality images illustrate key points and clear take-home messages are provided.

Download or read book Simulating the Effects of Anterior Cruciate Ligament Injury and Treatment on Cartilage Loading During Walking written by Colin Robert Smith and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current treatments for anterior cruciate ligament injury are largely successful at restoring stability to the knee and enabling patients to return to functional activities. However, the long-term outcomes are suboptimal, with high percentages of patients showing signs of early onset osteoarthritis (OA) 10 years post-injury regardless of treatment. In vitro and animal studies indicate that alterations in cartilage loading patterns following injury disrupt tissue homeostasis and are likely a key factor in the initiation of OA. Dynamic imaging studies indicate altered kinematics, and thus loading patterns, are present in ACL deficient and reconstructed knees during functional movements. Thus, improvements in both conservative rehabilitation and surgical reconstruction treatments for ACL injury are necessary to restore cartilage loading and preserve the long-term health of the knee. Musculoskeletal computer simulation provides opportunity to gain insight into the how modification in treatments effect knee mechanics during movement. However, existing simulation frameworks either focus on resolving detailed knee mechanics with finite element models, or the muscle forces necessary to generate a measured movement using musculoskeletal models. Few simulation frameworks are capable of simultaneously resolving whole-body and joint scale dynamics. Traditionally, despite the substantial uncertainty in model parameters and the objective used to resolved muscle redundancy, musculoskeletal simulations have been performed in a deterministic manner. This dissertation introduces the Concurrent Optimization of Muscle Activations and Kinematics (COMAK) framework to predict muscle forces and knee joint mechanics during movement in a probabilistic manner. The COMAK framework was then applied to investigate conservative and surgical treatments for ACL injury. The framework predictions indicate that wear patterns in ACL and menisci deficient knees correspond with regions that experience increased contact pressure during walking. To better inform surgical practices, the framework was used to assess the influence of controllable factors (graft stiffness, reference strain, and tunnel locations) on predicted knee mechanics during walking. For conservative treatment, model predictions indicate that cartilage loading patterns during walking cannot be restored solely through altered muscle coordination strategies.

Download or read book A Forward Dynamics Simulation Study of Increasing Load on the Anterior Cruciate Ligament of the Knee for Young Women Performing Recreational Drop Jump Activities written by Julia Kar and published by . This book was released on 2011 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anterior Cruciate Ligament (ACL) injuries are among the most common injuries incurred by both recreational and professional athletes. ACL injuries often occur during popular contact sports like basketball, football, volleyball and baseball, and non-contact activities like aerobics, jogging and running. Non-contact actions like jumping, sprinting and sidecutting that involve sudden or rapid changes in motion may lead to ACL injuries. At the instance of an injury, the knee joint muscles and ligaments typically undergo extremely high loads. The ACL, which is an integral part of the knee joint undergo high strain rates and rapid energy absorption, and consequently get injured. As has been shown by others, ACL injury is related to a number of dynamic variables of the knee joint. An important observation made in recent years is that recreational (also professional) female athletes have higher incidences of noncontact ACL injuries than males 33, 35. The primary focus of this study was to determine effects of several dynamic variables, associated with both knee and ACL, during normal recreational drop-jump activities performed by young female athletes. Subjects recruited were eleven young adult female recreational athletes who felt comfortable participating in the drop-jump activities, from heights of 30, 40 and 50 cm. Using a simulation environment to recreate the trials, changes in ACL load and strain were observed along with several dynamic variables related to ACL load and strain, among which the three most important were, 1. knee flexion, 2. knee valgus (abduction) which may be accompanied by increased internal rotation, and, 3. flexor to extensor muscle recruitment ratios, i.e., the co-contraction of flexor and extensor muscles. Observations from the above simulations formed the basis of the final step involving forward dynamic simulation, where the knee joint was subject to higher valgus by decreasing the distance between the knees (medial translation). Significant changes to ACL load and strain were seen in the added medial translation simulations compared to the simulations from the original jumps. Mean fiber strain for the additional valgus simulation increased from 8.82 ± 0.08 % to 11.82 ± 0.04 % for the right ACL and from 8.18 ± 0.08 % to 11.34 ± 0.06 % for the left. Mean ACL tensile force increased from 1058.19 ± 2.04 N to 1102.19 ± 1.86 N for the right ACL and from 1056.77 ± 12.36 N to 1099.99 ± 2.02 N for the left. Average peak (from eleven subjects) ACL tensile force increased from 1165.36 ± 123.83 N to 1197.07 ± 129.11 N for the right ACL and from 1160.64 ± 121.32 N to 1193.11 ± 130.16 N for the left.

Download or read book Neuromuscular Strategies for Regulating Knee Joint Moments in Healthy and Injured Populations written by Teresa Flaxman and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Background: Joint stability has been experimentally and clinically linked to mechanisms of knee injury and joint degeneration. The only dynamic, and perhaps most important, regulators of knee joint stability are contributions from muscular contractions. In participants with unstable knees, such as anterior cruciate ligament (ACL) injured, a range of neuromuscular adaptations has been observed including quadriceps weakness and increased co-activation of adjacent musculature. This co-activation is seen as a compensation strategy to increase joint stability. In fact, despite increased co-activation, instability persists and it remains unknown whether observed adaptations are the result of injury induced quadriceps weakness or the mechanical instability itself. Furthermore, there exists conflicting evidence on how and which of the neuromuscular adaptations actually improve and/or reduce knee joint stability. Purpose: The overall aim of this thesis is therefore to elucidate the role of injury and muscle weakness on muscular contributions to knee joint stability by addressing two main objectives: (1) to further our understanding of individual muscle contribution to internal knee joint moments; and (2) to investigate neuromuscular adaptations, and their effects on knee joint moments, caused by either ACL injury and experimental voluntary quadriceps inhibition (induced by pain). Methods: The relationship between individual muscle activation and internal net joint moments was quantified using partial least squares regression models. To limit the biomechanical contributions to force production, surface electromyography (EMG) and kinetic data was elicited during a weight-bearing isometric force matching task. A cross-sectional study design determined differences in individual EMG-moment relationships between ACL deficient and healthy controls (CON) groups. A crossover placebo controlled study design determined these differences in healthy participants with and without induced quadriceps muscle pain. Injections of hypertonic saline (5.8%) to the vastus medialis induced muscle pain. Isotonic saline (0.9%) acted as control. Effect of muscle pain on muscle synergies recruited for the force matching task, lunging and squatting tasks was also evaluated. Synergies were extracted using a concatenated non-negative matrix factorization framework. Results/Discussion: In CON, significant relationships of the rectus femoris and tensor fascia latae to knee extension and hip flexion; hamstrings to hip extension and knee flexion; and gastrocnemius and hamstrings to knee rotation were identified. Vastii activation was independent of moment generation, suggesting mono-articular vastii activate to produce compressive forces, essentially bracing the knee, so that bi-articular muscles crossing the hip can generate moments for the purpose of sagittal plane movement. Hip ab/adductor muscles modulate frontal plane moments, while hamstrings and gastrocnemius support the knee against externally applied rotational moments. Compared to CON, ACL had 1) stronger relationships between rectus femoris and knee extension, semitendinosus and knee flexion, and gastrocnemius and knee flexion moments; and 2) weaker relationships between biceps femoris and knee flexion, gastrocnemius and external knee rotation, and gluteus medius and hip abduction moments. Since the knee injury mechanism, is associated with shallow knee flexion angles, valgus alignment and rotation, adaptations after ACL injury are suggested to improve sagittal plane stability, but reduce frontal and rotational plane stability. During muscle pain, EMG-moment relationships of 1) semitendinosus and knee flexor moments were stronger compared to no pain, while 2) rectus femoris and tensor fascia latae to knee extension moments and 3) semitendinosus and lateral gastrocnemius to knee internal rotation moments were reduced. Results support the theory that adaptations to quadriceps pain reduces knee extensor demand to protect the joint and prevent further pain; however, changes in non-painful muscles reduce rotational plane stability. Individual muscle synergies were identified for each moment type: flexion and extension moments were respectively accompanied by dominant hamstring and quadriceps muscle synergies while co-activation was observed in muscle synergies associated with abduction and rotational moments. Effect of muscle pain was not evident on muscle synergies recruited for the force matching task. This may be due to low loading demands and/or a subject-specific redistribution of muscle activation. Similarly, muscle pain did not affect synergy composition in lunging and squatting tasks. Rather, activation of the extensor dominant muscle synergy and knee joint dynamics were reduced, supporting the notion that adaptive response to pain is to reduce the load and risk of further pain and/or injury. Conclusion: This thesis evaluated the interrelationship between muscle activation and internal joint moments and the effect of ACL injury and muscle pain on this relationship. Findings indicate muscle activation is not always dependent on its anatomical orientation as previous works suggest, but rather on its role in maintaining knee joint stability especially in the frontal and transverse loading planes. In tasks that are dominated by sagittal plane loads, hamstring and quadriceps will differentially activate. However, when the knee is required to resist externally applied rotational and abduction loads, strategies of global co-activation were identified. Contributions from muscles crossing the knee for supporting against knee adduction loads were not apparent. Alternatively hip abductors were deemed more important regulators of knee abduction loads. Both muscle pain and ACL groups demonstrated changes in muscle activation that reduced rotational stability. Since frontal plane EMG-moment changes were not present during muscle pain, reduced relationships between hip muscles and abduction moments may be chronic adaptions by ACL that facilitate instability. Findings provide valuable insight into the roles muscles play in maintaining knee joint stability. Rehabilitative/ preventative exercise interventions should focus on neuromuscular training during tasks that elicit rotational and frontal loads (i.e. side cuts, pivoting maneuvers) as well as maintaining hamstring balance, hip abductor and plantarflexor muscle strength in populations with knee pathologies and quadriceps muscle weakness.