An Investigation into the Measurement and Prediction of Mechanical Stiffness of Lower-limb Prostheses used for Running

Two energy return prosthesis are subjected to three different statically applied loading methods. This initial study proposes that statically applied loading to a sport prosthesis using several controlled methods were statistically robust enough to derive a mechanical stiffness value. However, any predicted stiffness is drawn into question when allowing any movement of the distal end. This uncertainty will make any evaluation or prescription of lower-limb prosthesis technology based upon their stiffness incorrect. In addition, the peak calculated stiffness at the expected bodyweight induced ground impact load of a runner is judged the most representative assessment method. This study attempts to build on previous research advocating the need to monitor the performance of prosthesis lower-limb technology in disability sport. Practitioner Summary: This paper extends previous research regarding the fairness of prosthetics technology used in running with a lower-limb amputation. It pilots a quantitative assessment of high activity prosthetics technology and ultimately demonstrates how incorrect assessment can lead to incorrect specification of running prosthesis for elite level spor

Sprinting with an amputation: Some race-based lower-limb step observations.

BACKGROUND: T44 sprinting with an amputation is still in a state of relative infancy. Future scope for athletic training and prosthetic limb development may be assisted with a better understanding of information derived from T44 athletes when under race-based conditions. OBJECTIVES: To investigate the behaviour of step count and step frequency when under competitive conditions. STUDY DESIGN: The study comprises two elements: (1) a video-based analysis of race-based limb-to-limb symmetry and (2) a video-based analysis of race-based step count. METHODS: Video analysis of several major events from 1996-2012 are assessed for step count and step limb-to-limb symmetry characteristics. RESULTS: The video analysis highlights limb-to-limb imbalances greater than those indicated in the previous literature. A low step count is determined to be desirable for success in the 100-m event. CONCLUSION: Future analysis of athletes with a lower-limb amputation would be worthwhile when placed under race-based conditions as the limb-to-limb behaviour is more exaggerated than those seen in typical studies held within a laboratory setting. The within-event behaviour of step counts requires further investigation to establish where these take place or whether it is a cumulative step length issue. CLINICAL RELEVANCE: This article increases the understanding of the race-based behaviour of amputee athletes and provides more information to contribute to any discussions on the performance of lower-limb prostheses

Lower limb stiffness and maximal sprint speed in 11-16-year-old boys

The purpose of the study was to examine the relationship between vertical stiffness, leg stiffness and maximal sprint speed in a large cohort of 11-16-year-old boys. Three-hundred and thirty-six boys undertook a 30 m sprint test using a floor-level optical measurement system, positioned in the final 15 m section. Measures of speed, step length, step frequency, contact time and flight time were directly measured whilst force, displacement, vertical stiffness and leg stiffness, were modeled from contact and flight times, from the two fastest consecutive steps for each participant over two trials. All force, displacement and stiffness variables were significantly correlated with maximal sprint speed (p 0.7) relationship with sprint speed, while vertical center of mass displacement, absolute vertical stiffness, relative peak force, and maximal leg spring displacement had large (r > 0.5) relationships. Relative vertical stiffness and relative peak force did not significantly change with advancing age (p > 0.05), but together with maximal leg spring displacement accounted for 96% of the variance in maximal speed. It appears that relative vertical stiffness and relative peak force are important determinants of sprint speed in boys aged 11-16 years, but are qualities that may need to be trained due to no apparent increases from natural development. Practitioners may wish to utilize training modalities such as plyometrics and resistance training to enable adaptation to these qualities due to their importance as predictors of speed in youth

Immunopathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common inflammatory arthropathy. The majority of evidence, derived from genetics, tissue analyses, models, and clinical studies, points to an immune-mediated etiology associated with stromal tissue dysregulation that together propogate chronic inflammation and articular destruction. A pre-RA phase lasting months to years may be characterized by the presence of circulating autoantibodies, increasing concentration and range of inflammatory cytokines and chemokines, and altered metabolism. Clinical disease onset comprises synovitis and systemic comorbidities affecting the vasculature, metabolism, and bone. Targeted immune therapeutics and aggressive treatment strategies have substantially improved clinical outcomes and informed pathogenetic understanding, but no cure as yet exists. Herein we review recent data that support intriguing models of disease pathogenesis. They allude to the possibility of restoration of immunologic homeostasis and thus a state of tolerance associated with drug-free remission. This target represents a bold vision for the future of RA therapeutics

Reflexion von Eignung und Neigung für den Lehrberuf:Seminarkonzept zur Reflexion von Eignung und Neigung

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Early rheumatoid arthritis is characterized by a distinct and transient synovial fluid cytokine profile of T cell and stromal cell origin

Pathological processes involved in the initiation of rheumatoid synovitis remain unclear. We undertook the present study to identify immune and stromal processes that are present soon after the clinical onset of rheumatoid arthritis ( RA) by assessing a panel of T cell, macrophage, and stromal cell related cytokines and chemokines in the synovial fluid of patients with early synovitis. Synovial fluid was aspirated from inflamed joints of patients with inflammatory arthritis of duration 3 months or less, whose outcomes were subsequently determined by follow up. For comparison, synovial fluid was aspirated from patients with acute crystal arthritis, established RA and osteoarthritis. Rheumatoid factor activity was blocked in the synovial fluid samples, and a panel of 23 cytokines and chemokines measured using a multiplex based system. Patients with early inflammatory arthritis who subsequently developed RA had a distinct but transient synovial fluid cytokine profile. The levels of a range of T cell, macrophage and stromal cell related cytokines ( e. g. IL-2, IL-4, IL-13, IL-17, IL-15, basic fibroblast growth factor and epidermal growth factor) were significantly elevated in these patients within 3 months after symptom onset, as compared with early arthritis patients who did not develop RA. In addition, this profile was no longer present in established RA. In contrast, patients with non-rheumatoid persistent synovitis exhibited elevated levels of interferon-gamma at initiation. Early synovitis destined to develop into RA is thus characterized by a distinct and transient synovial fluid cytokine profile. The cytokines present in the early rheumatoid lesion suggest that this response is likely to influence the microenvironment required for persistent RA

Running impact forces: from half a leg to holistic understanding – comment on Nigg et al.

Running impact forces have immediate relevance for the muscle tuning paradigm proposed here and broader relevance for overuse injuries, shoe design and running performance. Here, we consider their mechanical basis. Several studies demonstrate that the vertical ground reaction force-time (vGRFT) impulse, from touchdown to toe-off, corresponds to the instantaneous accelerations of the body’s entire mass (Mb) divided into two or more portions. The simplest, a two-mass partitioning of the body (lower-limb, M1=0.08•Mb; remaining mass, M2=0.92•Mb) can account for the full vGRFT waveform under virtually all constant-speed, level-running conditions. Model validation data indicate that: 1) the non-contacting mass, M2, often accounts for one-third or more of the early “impact” portion of the vGRFT, and 2) extracting a valid impact impulse from measured force waveforms requires only lower-limb motion data and the fixed body mass fraction of 0.08 for M1

A New Direction to Athletic Performance: Understanding the Acute and Longitudinal Responses to Backward Running

Backward running (BR) is a form of locomotion that occurs in short bursts during many overground field and court sports. It has also traditionally been used in clinical settings as a method to rehabilitate lower body injuries. Comparisons between BR and forward running (FR) have led to the discovery that both may be generated by the same neural circuitry. Comparisons of the acute responses to FR reveal that BR is characterised by a smaller ratio of braking to propulsive forces, increased step frequency, decreased step length, increased muscle activity and reliance on isometric and concentric muscle actions. These biomechanical differences have been critical in informing recent scientific explorations which have discovered that BR can be used as a method for reducing injury and improving a variety of physical attributes deemed advantageous to sports performance. This includes improved lower body strength and power, decreased injury prevalence and improvements in change of direction performance following BR training. The current findings from research help improve our understanding of BR biomechanics and provide evidence which supports BR as a useful method to improve athlete performance. However, further acute and longitudinal research is needed to better understand the utility of BR in athletic performance programs

Right drug, right patient, right time: aspiration or future promise for biologics in rheumatoid arthritis?

Individualising biologic disease-modifying anti-rheumatic drugs (bDMARDs) to maximise outcomes and deliver safe and cost-effective care is a key goal in the management of rheumatoid arthritis (RA). Investigation to identify predictive tools of bDMARD response is a highly active and prolific area of research. In addition to clinical phenotyping, cellular and molecular characterisation of synovial tissue and blood in patients with RA, using different technologies, can facilitate predictive testing. This narrative review will summarise the literature for the available bDMARD classes and focus on where progress has been made. We will also look ahead and consider the increasing use of ‘omics’ technologies, the potential they hold as well as the challenges, and what is needed in the future to fully realise our ambition of personalised bDMARD treatment

Profilmerkmale von Zentren für Lehrerbildung

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