362 research outputs found

    Plasticity of morphological and mechanical properties of muscles and tendons: Effects of maturation and athletic training

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    In den letzten Jahrzehnten ist die Zahl der Erwachsenen und Jugendlichen, die an nicht organisierten oder wettbewerbsorientierten Sportarten teilnehmen, gestiegen. In der Pubertät beeinflussen sowohl hormonelle Veränderungen als auch mechanische Belastungen die Entwicklung von Muskeln und Sehnen. Derzeit gibt es keine Informationen über die Interaktion dieser beiden Stimuli, aber es besteht die Vermutung, dass im Zuge der Pubertät bei Athleten und Nicht-Athleten im Vergleich zu Muskelkraft und Sehnensteifigkeit ungleiche Verhältnisse auftreten können. Die Folge dieses Ungleichgewichts könnte eine höhere mechanische Belastung für die Sehnen sein, was weiter zu Verletzungen führen kann. Angesichts der unzureichenden Beweise für die Entwicklung des muskulotendinösen Gewebes während der Pubertät und des Mangels an Kenntnissen darüber, wie die Reifung die Muskel-Sehnen-Einheit, insbesondere die Interaktion mit überlagerten mechanischen Belastungen, beeinflusst, untersucht diese Arbeit die morphologische und mechanische Entwicklung von Knieextensoren und Patellasehne, indem Nicht-Athleten und Athleten aus drei Altersgruppen verglichen werden (frühe Pubertät: 12–14 Jahre, engl.:EA; späte Pubertät: 16–18 Jahre, engl.: LA; Erwachsene: 20–35 Jahre, engl.: YA). Athleten erreichten häufiger Dehnungsgrößen von mehr als 9% Dehnung im Vergleich zu Nicht-Athleten, was auf einen erhöhten mechanischen Bedarf an der Sehne hinweist. Obwohl das Training die Eigenschaften der M. quadriceps femoris-Sehnen-Einheit verbessert, bleibt ihre Entwicklung von früher Pubertät bis zum Erwachsenenalter bei Athleten und Nicht-Athleten ähnlich, mit dem Hauptunterschied zwischen früher Pubertät und später Pubertät. Alter und sportliches Training waren jedoch mit einer höheren Prävalenz von Ungleichgewichten innerhalb der Muskel-Sehnen-Einheit und einer damit einhergehenden erhöhten mechanischen Belastung oder Beanspruchung für die Patellasehne verbunden.In recent decades, the number of adults and especially adolescents who participate in some kind of non-organized or competitive sports has been increasing. During adolescence, the development of muscle and tendons is affected both by maturation, due to hormonal changes, and by mechanical loading. However, there is no information currently on the interaction of this double fold stimulus although there is reason to believe that during adolescence in athletes and non-athletes there may be imbalances developing between muscle strength capacity and tendon stiffness. The result of this imbalance could be the tendon exposure to high mechanical demand by the associated working muscles, which might further lead to tendon injury. Considering the not satisfactory evidence of the musculotendinous tissue development during adolescence, and the lack of knowledge about how maturation affects the muscle-tendon unity, especially in interaction with superimposed mechanical loading, this thesis investigates the morphological and mechanical development of the knee extensors and patellar tendon, by comparing non-athletes and athletes in three different age groups (i.e., early adolescents: EA 12–14 years; late adolescents: LA 16–18 years, and young adults: YA 20–35 years). Athletes were more likely to reach strain magnitudes higher than 9% strain compared to non-athlete controls indicating an increased mechanical demand for the tendon. Although athletic training enhances the properties of the quadriceps femoris muscle-tendon unit, their development from early-adolescence to adulthood remains similar in athletes and non-athletes with the major alterations between early and LA. However, both age and athletic training were associated with a higher prevalence of imbalances within the muscle-tendon unit and a resultant increased mechanical demand for the patellar tendon

    Making Bipedal Robot Experiments Reproducible and Comparable: The Eurobench Software Approach

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    This study describes the software methodology designed for systematic benchmarking of bipedal systems through the computation of performance indicators from data collected during an experimentation stage. Under the umbrella of the European project Eurobench, we collected approximately 30 protocols with related testbeds and scoring algorithms, aiming at characterizing the performances of humanoids, exoskeletons, and/or prosthesis under different conditions. The main challenge addressed in this study concerns the standardization of the scoring process to permit a systematic benchmark of the experiments. The complexity of this process is mainly due to the lack of consistency in how to store and organize experimental data, how to define the input and output of benchmarking algorithms, and how to implement these algorithms. We propose a simple but efficient methodology for preparing scoring algorithms, to ensure reproducibility and replicability of results. This methodology mainly constrains the interface of the software and enables the engineer to develop his/her metric in his/her favorite language. Continuous integration and deployment tools are then used to verify the replicability of the software and to generate an executable instance independent of the language through dockerization. This article presents this methodology and points at all the metrics and documentation repositories designed with this policy in Eurobench. Applying this approach to other protocols and metrics would ease the reproduction, replication, and comparison of experiments.This study is supported by the European Union’s Horizon 2020 research and innovation program under Grant Agreement no 779963, project Eurobench

    Evaluating footwear “in the wild”: Examining wrap and lace trail shoe closures during trail running

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    Trail running participation has grown over the last two decades. As a result, there have been an increasing number of studies examining the sport. Despite these increases, there is a lack of understanding regarding the effects of footwear on trail running biomechanics in ecologically valid conditions. The purpose of our study was to evaluate how a Wrap vs. Lace closure (on the same shoe) impacts running biomechanics on a trail. Thirty subjects ran a trail loop in each shoe while wearing a global positioning system (GPS) watch, heart rate monitor, inertial measurement units (IMUs), and plantar pressure insoles. The Wrap closure reduced peak foot eversion velocity (measured via IMU), which has been associated with fit. The Wrap closure also increased heel contact area, which is also associated with fit. This increase may be associated with the subjective preference for the Wrap. Lastly, runners had a small but significant increase in running speed in the Wrap shoe with no differences in heart rate nor subjective exertion. In total, the Wrap closure fit better than the Lace closure on a variety of terrain. This study demonstrates the feasibility of detecting meaningful biomechanical differences between footwear features in the wild using statistical tools and study design. Evaluating footwear in ecologically valid environments often creates additional variance in the data. This variance should not be treated as noise; instead, it is critical to capture this additional variance and challenges of ecologically valid terrain if we hope to use biomechanics to impact the development of new products

    Occupational Therapy Strategies for Postural Orthostatic Tachycardia Syndrome

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    Effectiveness of occupational therapy strategies with adults with postural orthostatic tachycardia syndrome

    Lower limb strength and biomechanics after anterior cruciate ligament reconstruction

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    Rupture of the anterior cruciate ligament (ACL) is one of the most significant injuries to the knee joint, with the frequency of injury increasing over the last 10 years. Of these injuries, the increase in incidence among young female athletes (<18 years) has been especially significant. Direct and indirect management of ACL injuries range from 100millionincountrieslikeAustralia,toasmuchas100 million in countries like Australia, to as much as 2 billion in the United States. The increasing rates of ALC injury and significant associated costs places significant pressure on the healthcare system. The high economic cost of ACL injuries is typically associated with ACL reconstruction (ACLR) and the subsequent rehabilitation period. Restoration of lower limb muscle strength, function, and coordination, as well as a gradual return to activities like running, jumping, landing, and agility tasks are all components of a structured rehabilitation program and criteria for return to sports (RTS). Following the completion of rehabilitation, up to 80% of people are able to RTS of some level. Despite the high rate of RTS, a significant number of ACLR individuals will report poor subjective knee function (e.g., knee pain during activity), be subjected to a high risk of reinjury and be prone to early onset of knee osteoarthritis. There is evidence that these poor outcomes are worse in females than in males. Lower limb strength (e.g., hamstrings and quadriceps) and biomechanical asymmetries are common after ACLR. These asymmetries have been associated with the poor outcomes previously mentioned. As a result, restoration of maximal hamstrings and quadriceps strength symmetry is a focus of rehabilitation and criteria for RTS clearance following ACLR. However, there is evidence that explosive quadriceps strength does not recover at the same rate as maximal quadriceps strength during the first year following ACLR. Whether this is also true in the hamstrings is still unknown and previous studies have only explored concurrent recovery of explosive and maximal strength in males. Given their function in providing dynamic stability and loading on the knee joint, the hamstrings and quadriceps have received much attention during assessment, rehabilitation, and criteria for RTS following ACLR. However, dynamic tasks (e.g., sidestep cutting) commonly performed in team sports require complex activity and coordination of the different lower limb muscles. This has been previously investigated in healthy individuals but to date, it is still unknown how ACLR affects the function of the different lower limb muscles during sidestep cutting. Additionally, reductions in knee joint loading (e.g., contact force) have been reported from 3-9 months and up to 2 years following ACLR. Quadriceps strength deficits have been proposed to be a major factor influencing the reduced knee joint contact forces after ACLR. However, it is still unknown whether knee joint contact forces are reduced after the restoration of quadriceps strength at RTS. The purpose of this doctoral thesis was two-part. Firstly, to investigate restoration of both explosive and maximal hamstrings and quadriceps strength during early and late rehabilitation following ACLR in males and females. Second, to explore lower limb biomechanics following the restoration of strength following rehabilitation. The knowledge derived from this program of research is aimed at identifying factors that are modifiable during the rehabilitation period after ACLR, information that should help to guide future clinical and research effort. The first study of this program of research (Chapter 2) was a systematic review and meta-analysis that explored the time-course of hamstrings and quadriceps strength asymmetries during the preoperative period up to six and 12 months following ACLR between males and females. Initial database search retrieved 6,046 articles. After screening for eligibility, 31 studies were included in the systematic review while 13 articles had enough data for meta-analysis. The findings showed that limb symmetry in maximal hamstrings and quadriceps strength are the most commonly used measure of strength following ACLR. Strength asymmetries in the hamstrings and quadriceps were present from preoperative to six and 12 months after ACLR. Despite the proposed importance of explosive strength following ACLR, studies looking at its time-course of recovery are limited. Furthermore, while sex differences in patient outcomes have been previously reported, majority of the data collected were either not stratified and/or dominated by male participants (males = 62%; females = 30%, sex not reported = 8%). To address gaps in the literature identified in Chapter 2, an observational cohort study was conducted for the second study of this thesis (Chapter 4). This study investigated the maximal and explosive strength recovery of the quadriceps and hamstrings following ACLR. In this study, participants were assessed during the early (3-6 months) and late (7-12 months) stage of rehabilitation following an ACLR with hamstring tendon (HT) autografts. There was a significant influence of time after ACLR on the limb-symmetry index (LSI) for maximal hamstrings (Early: 86 ± 14; Late 92 ± 13; p = 0.005) and quadriceps (Early, 73 ± 15; Late 91 ± 12; p <0.001) strength. Additionally, explosive quadriceps strength LSI showed significant improvements over time (Early: 82 ± 30; Late: 92 ± 25; p = 0.03). However, despite the recovery of maximal hamstring strength there were still significant deficits in explosive hamstring measures later in rehabilitation (Early: 86 ± 46; Late: 83 ± 22; p = 0.75). Additionally, Chapter 4 also investigated whether there were differences in strength recovery between males and females following ACLR. While no differences were found in the rate of explosive and maximal strength recovery between sexes, females had greater quadriceps strength asymmetries (maximal and explosive) compared to males across ACLR rehabilitation. The ability to perform dynamic tasks (e.g., sidestep cutting) is one of the major determinants of an ACLR individual’s readiness to RTS. Sidestep cutting tasks, in particular, are common in change-of-direction sports. It is also during these tasks that ACL injuries frequently occur. Previous studies found kinematic and kinetic impairments during sidestep cutting performance in ACLR individuals. However, these studies have been joint level analysis of lower limb biomechanics. Given the complex coordination of the different lower limb muscles during the performance of a sidestep cut, the third study of this thesis (Chapter 5) explored the lower limb muscle contributions to ground reaction forces during vertical support, deceleration, propulsion, and redirection of forces during a sidestep cut in ACLR limbs (who had a quadriceps strength LSI ≥ 90%) and compared them to healthy limbs. Chapter 5 found that muscle function during a sidestep cut is significantly different in the ACLR limb when compared to the contralateral and control limbs. There were less contributions to vertical support (contralateral mean difference = -0.040 BW.s, 95%CI = -0.049 to -0.031, p < 0.001; control mean difference = -0.042 BW.s, 95%CI = -0.061 to -0.022, p < 0.001), braking (contralateral mean difference = 0.020 BW.s, 95%CI = 0.014 to 0.027, p < 0.001; control mean difference = 0.029 BW.s, 95%CI = 0.017 to 0.041), and medial redirection (contralateral mean difference = -0.006 BW.s, 95%CI = -0.01 to -0.001, p = 0.011) GRFs from the quadriceps of the ACLR limb when compared to the contralateral uninjured limb. Alterations in gluteus maximus, gastrocnemius, soleus, hamstrings, and dorsiflexors muscle function were also found when comparing the ACLR and contralateral uninjured limbs. Despite resolution of quadriceps strength asymmetry following ACLR rehabilitation, the quadriceps’ role in contributing forces for the execution of a sidestep cut is significantly impaired. Furthermore, muscle contributions from other major lower limb muscles are also altered following RTS. Given the alterations in the ability of the quadriceps to modulate GRFs despite restoration of isokinetic strength symmetry, the final study of this thesis (Chapter 6) was conducted with the aims of investigating patellofemoral (PFJ) contact forces in the ACLR limb when compared to healthy limbs at time of RTS. Chapter 6 demonstrated that ACLR limbs have lower PFJ contact forces compared to the contralateral (mean difference = 5.89 BW, 95%CI = 4.7 to 7.1, p < 0.001) and control limbs (mean difference = 4.44 BW, SE = 2.1 to 6.8, p = < 0.001). Additionally, the ACLR limb possessed smaller knee flexion angles (contralateral mean difference = 4.88°, 95%CI = 3.0 to 6.7, p < 0.001; control mean difference = 6.01°, 95%CI = 2.0 to 10.0, p < 0.002) as well as lower knee extension moment and quadriceps force (contralateral mean difference = 4.14 BW, 95%CI = 3.4 to 4.9, p < 0.001; control mean difference = 2.83 BW, 95%CI = 1.4 to 4.3, p < 0.001). These findings suggest that PFJ loading can still be impaired despite the restoration of quadriceps strength symmetry which could have potential implications for PFJ osteoarthritis. In conclusion, this program of research showed that explosive and maximal quadriceps strength asymmetries resolve during ACLR rehabilitation. Hamstrings maximal strength also restores during the same time; however, explosive hamstrings strength did not. While it was also found that sex does not influence strength recovery, females did have larger maximal and explosive quadriceps strength asymmetries compared to males following ACLR. Finally, impairments in lower limb biomechanics (less quadriceps muscle contributions to vertical support, deceleration, and medial redirection, lower PFJ contact force and quadriceps force, and smaller knee flexion angle) are still present in the ACLR limb compared to the healthy limbs during the performance of a sidestep cut. These deficits still exist, despite the recovery of maximal quadriceps strength following ACLR and provides evidence for the assessment of lower limb muscle function during dynamic movements as part of the RTS criteria

    Individuality in balance control: Using conventional analytical & machine learning approaches to reveal person-specific differences in standing balance control.

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    The balance control system ensures that humans can perform tasks in a variety of postures despite bipedal stance being inherently unstable. It manages this instability by producing motor outputs that are appropriate to sensory input given the objective of maintaining balance. An inability to maintain this balance may result in a fall which can have both short and long-term physical, psychological, and social effects. The ability to maintain balance is a strong predictor of fall-risk and mobility limitations. Falling has been associated with specific populations such as older adults and those with neurological and neuromuscular pathologies. However, it is possible that some younger individuals may have poor balance control which places them at a greater fall-risk in the face of age and pathology-related influences. The potential importance of revealing person-specific differences in balance control in healthy, young adults has led to the focus of this thesis. This thesis was designed to determine whether a healthy, young adult’s balance control system, as measured by their balance performance, is specific to the individual and could be distinguished from any other individual. The thesis explores the use of different methods of measuring of body movement (kinetic or kinematic), and the analytical techniques which, when collectively applied, may more sensitively reveal these individual differences. General methodology consisted of sixty-one healthy, young adults (ages 18-35), free of any neurological or neuromuscular disorders, performing a series of static standing balance trials. Four task conditions, Base of Support (standard and narrow) and Vision (open and closed), were performed five times, each for thirty seconds. Balance performance was measured kinetically using two floor-mounted force plates, and kinematically using three inertial measurement units placed on the head, sternum, and lumbar region of the back. The resulting data became the substrate for the analyses used in the three studies. Study 1 quantified the consistency of an individual’s balance performance across task conditions relative to the other individuals. Centre-of-pressure data collected from force plates was analyzed using established linear and non-linear analytical methods within the time- and frequency-domains and then input into a linear mixed-effects model. Subject-specific factors, such as anthropometrics and vision quality, were controlled to reduce the number of confounding variables. Correlational analysis of the random-effect, participant, revealed moderate to strong correlations of individual balance performances across task conditions with the strength of these correlations dependent on the analytical technique used. Study 1 confirmed that (1) task-related differences in balance performance could be detected by a variety of analytical techniques, and that (2) the correlations found in relative balance performance across task conditions suggest that an individuals’ balance control system may be specific to the individual. Study 2 expanded on Study 1 by representing body movement kinematically using body-worn inertial measurement units. Similar analytical approaches were used and moderate to excellent correlations in relative balance performance across task conditions were observed. The use of kinematic data in this study also revealed kinematic strategies that could only be obtained by modelling a person as a multi-link, rigid body and not as a single-link, inverted pendulum; an assumption commonly made when using kinetic data. Like Study 1, this work demonstrated that relative balance performance within persons were comparable across tasks of varying difficulty and, as such, indirectly supports the idea that balance control that may be specific to the individual. Study 3 focused on analytical approaches that could more directly reveal the unique features of balance control within individuals. This study employed a machine-learning, classification algorithm in an attempt to identify individuals by their balance performance using kinetic or kinematic measures. Once provided with the prototypical balance performances of a discrete number of individuals, the algorithm was able to correctly attribute the balance performance of a mystery person to one of those individuals with an accuracy greater that what could be achieved by random chance. Representing body movement with kinetic, time-series data yielded the highest accuracies (Accuracy (nway = 5) = 92.08%; Accuracy (nway = 20) = 74.69%). However, it is believed that if kinematic data was recorded with more fidelity, then even greater accuracies could be possible. Study 3 demonstrated that (1) balance performance data contains features specific to the individual which may quantitatively indicate individuality in the balance control system, and (2) that the ability to reveal this individuality is dependent on how the balance performance is represented. This thesis provided two main contributions, (1) support for the idea that balance control during quiet standing, as revealed through balance performance, contains features that are specific to the individual, and (2) an, outline, albeit preliminary, of the task conditions, methods of measurement, and analytical techniques best suited to reveal this individuality

    1st EFORT European Consensus: Medical & Scientific Research Requirements for the Clinical Introduction of Artificial Joint Arthroplasty Devices

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    Innovations in Orthopaedics and Traumatology have contributed to the achievement of a high-quality level of care in musculoskeletal disorders and injuries over the past decades. The applications of new implants as well as diagnostic and therapeutic techniques in addition to implementation of clinical research, have significantly improved patient outcomes, reduced complication rates and length of hospital stay in many areas. However, the regulatory framework is extensive, and there is a lack of understanding and clarity in daily practice what the meaning of clinical &amp; pre‐clinical evidence as required by the MDR is. Thus, understanding and clarity are of utmost importance for introduction of new implants and implant-related instrumentation in combination with surgical technique to ensure a safe use of implants and treatment of patients. Therefore EFORT launched IPSI, The Implant and Patient Safety Initiative, which starting from an inaugural workshop in 2021 issued a set of recommendations, notably through a subsequent Delphi Process involving the National Member Societies of EFORT, European Specialty Societies as well as International Experts. These recommendations provide surgeons, researchers, implant manufacturers as well as patients and health authorities with a consensus of the development, implementation, and dissemination of innovation in the field of arthroplasty. The intended key outcomes of this 1st EFORT European Consensus on “Medical &amp; Scientific Research Requirements for the Clinical Introduction of Artificial Joint Arthroplasty Devices”are consented, practical pathways to maintain innovation and optimisation of orthopaedic products and workflows within the boundaries of MDR 2017/745. Open Access practical guidelines based on adequate, state of the art pre-clinical and clinical evaluation methodologies for the introduction of joint replacements and implant-related instrumentation shall provide hands-on orientation for orthopaedic surgeons, research institutes and laboratories, orthopaedic device manufacturers, Notified Bodies but also for National Institutes and authorities, patient representatives and further stakeholders. We would like to acknowledge and thank the Scientific Committee members, all International Expert Delegates, the Delegates from European National &amp; Specialty Societies and the Editorial Team for their outstanding contributions and support during this EFORT European Consensus
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