Biomechanical analysis of loading/unloading a ladder on a truck

Loading/unloading a ladder on vehicles are frequent tasks and involve overhead handling that may expose workers to risk factors of shoulder musculoskeletal disorders. The objective of the present study was to evaluate posture, forces required and perceived exertion when loading and unloading the ladder on a utility truck. Thirteen male overhead line workers from an electric utility in Brazil participated in this study. Shoulder elevation angle was measured using inclinometers. The required force to load/unload the ladder was measured by dynamometer. Subjective assessment of the perceived exertion was recorded to compare the exertion reported during the test conditions to the field conditions. The task of loading/unloading the ladder presented risks of shoulder musculoskeletal disorders (MSDs) to workers because it requires high levels of force (approximately 60% of the maximal force) combined with overhead posture of the shoulders (more than 100 from the neutral posture). Age and height presented to interfere in biomechanical risks presented in load/unload task. There was no significant difference between the subjective exertion during the test conditions and handling the ladder in the field. Ergonomic intervention is recommended to reduce these risks for shoulder MSDs.4112492249

Are posture data from simulated tasks representative of field conditions? Case study for overhead electric utility workers

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Many ergonomics studies are conducted in laboratory-simulated work environments to assess risks for the development of musculoskeletal disorders under more controlled conditions. However, the simulated conditions could be of questionable validity with respect to reproduction of field conditions involving risk factors. The objective of this study was to verify whether the postures recorded for neck extension/flexion and upper arm elevation of overhead electric utility workers in a simulated environment were similar to those recorded in a field environment. Of the three frequently performed tasks analysed, two presented similar exposure in both conditions. However, differences were identified for a more complex task (relay replacement). These results suggest that simulated tasks may be more representative for more standardised tasks. This may indicate that researchers investigating risks should avoid simplifying complex tasks when reproducing field posture exposure in laboratories, since omitting extra subtasks may lead to an inaccurate reproduction of field exposure.551113821394Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CAPES [23038.006938/2011-72]FAPESP [2008/10372-4, 2008/10399-0]CNPq [301772/2010-0

Effects of sensor, trials and knee joint variables on electrogoniometric gait recordings

INTRODUCTION: Different sources of variations, such as electrogoniometer characteristics and procedures, may affect the accuracy and precision of movement measurements during gait. OBJECTIVE: To quantify the variations and compare the effects produced by different sources of variation in electrogoniometric gait recordings: the sensors, procedures (trials) and the knee joint. METHODS: Knee flexion/extension and valgus/varus movements were recorded during gait on the treadmill. The recordings were partitioned into strides and normalized in time using a routine developed in MatLab. Mean curves for the knee during gait were derived from 50 strides, and seven conditions were evaluated: one comparing pairs of sensors; two comparing pairs of different trials (including variations due to sensors); and four comparing the right and left knees (including variations due to sensors and trials). Mean standard deviations of the differences were calculated. To estimate the variations relating to the trial and the knee joint, the compound standard deviations were transformed into variances and split into their components. RESULTS: The variation introduced by pairs of sensors in the same model applied in one trial was smaller than the variation introduced by the same sensor used in two consecutive trials. Furthermore, the variation introduced by the difference between the right and left knees was greater than the variation introduced by the difference between sensors (A and B) and trials (1 and 2). CONCLUSIONS: It is, therefore, preferable to use different sensors in the same data recording (simultaneous) than use the same sensor in two different recordings (consecutive)

Postures and Movements in the Most Common Tasks of Power Line Workers

The repair and maintenance of electrical power lines involves awkward postures, which are known risk factors for developing musculoskeletal disorders. The aim of the present study was to quantify postures and movements of upper arm, head, upper back and neck in the main tasks performed by line workers. Posture of twelve right-handed line workers was recorded by inclinometry and presented as percentiles of angular and angular velocity distributions. All tasks involved considerable upper-arm elevation, ranging from 73 degrees to 115 degrees for the 90th percentile. Upper-arm elevation showed significant differences between tasks, but no consistent differences between right and left sides. Regarding velocity, the right arm presented higher levels than the left arm. All tasks required significant extension of head, upper back and neck, ranging from 7 degrees to 67 degrees for head (10th percentile). All tasks, except the one performed with a continuous extension, also involved pronounced flexion, ranging from 33 degrees to 60 degrees for the head (90th percentile). Work which required highly elevated arms also required significant head extension (r(2)=0.56). Awkward postures of upper arms, head, upper back and neck were identified by inclinometry, demonstrating the need for preventative interventions to reduce musculoskeletal disorders among line workers.49448249

Effects of sensor, trials and knee joint variables on electrogoniometric gait recordings

Introduction: Different sources of variations, such as electrogoniometer characteristics and procedures, may affect the accuracy and precision of movement measurements during gait. Objective: To quantify the variations and compare the effects produced by different sources of variation in electrogoniometric gait recordings: the sensors, procedures (trials) and the knee joint. Methods: Knee flexion/extension and valgus/varus movements were recorded during gait on the treadmill. The recordings were partitioned into strides and normalized in time using a routine developed in MatLab. Mean curves for the knee during gait were derived from 50 strides, and seven conditions were evaluated: one comparing pairs of sensors; two comparing pairs of different trials (including variations due to sensors); and four comparing the right and left knees (including variations due to sensors and trials). Mean standard deviations of the differences were calculated. To estimate the variations relating to the trial and the knee joint, the compound standard deviations were transformed into variances and split into their components. Results: The variation introduced by pairs of sensors in the same model applied in one trial was smaller than the variation introduced by the same sensor used in two consecutive trials. Furthermore, the variation introduced by the difference between the right and left knees was greater than the variation introduced by the difference between sensors (A and B) and trials (1 and 2). Conclusions: It is, therefore, preferable to use different sensors in the same data recording (simultaneous) than use the same sensor in two different recordings (consecutive)

Change in knee kinematics during gait after eccentric isokinetic training for quadriceps in subjects submitted to anterior cruciate ligament reconstruction

Knee kinematics after anterior cruciate ligament (ACL) reconstruction is of interest in studies evaluating the effect of training programs. Many studies have addressed knee flexion/extension but not valgus/varus movements. Considering that joint stability is a major concern in ACL reconstruction surgery, movements occurring in the frontal plane of the knee also deserve attention. Knee extensor torque was analyzed by an isokinetic dynamometer and the angular amplitudes and velocities of flexion/extension and valgus/varus movements were analyzed by goniometry during gait 9 months after ACL reconstruction. The analysis was repeated after 3 months of eccentric isokinefic training of the quadriceps in five patients. The gait pattern was also recorded for 10 healthy controls. The knee extensor torque and flexion/extension range of movement during gait increased significantly after training. However, an unexpectedly increased valgus, most pronounced during the swing phase, which may imply adverse effects on the knee, was also observed in the ACL reconstructed knee. The recorded valgus angles may however be overestimated due to crosstalk. Thus, the extent of the increased valgus, as well as the mechanisms involved and the functional and clinical implications, need clarification before eccentric training after ACL reconstruction can be generally recommended. (C) 2005 Elsevier B.V. All rights reserved

T antigen–specific CD8⁺ T cells associate with PD-1 blockade response in virus-positive Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a highly immunogenic skin cancer primarily induced by Merkel cell polyomavirus, which is driven by the expression of the oncogenic T antigens (T-Ags). Blockade of the programmed cell death protein-1 (PD-1) pathway has shown remarkable response rates, but evidence for therapy-associated T-Ag–specific immune response and therapeutic strategies for the nonresponding fraction are both limited. We tracked T-Ag–reactive CD8+ T cells in peripheral blood of 26 MCC patients under anti-PD1 therapy, using DNA-barcoded pMHC multimers, displaying all peptides from the predicted HLA ligandome of the oncoproteins, covering 33 class I haplotypes. We observed a broad T cell recognition of T-Ags, including identification of 20 T-Ag–derived epitopes we believe to be novel. Broadening of the T-Ag recognition profile and increased T cell frequencies during therapy were strongly associated with clinical response and prolonged progression-free survival. T-Ag–specific T cells could be further boosted and expanded directly from peripheral blood using artificial antigen-presenting scaffolds, even in patients with no detectable T-Ag–specific T cells. These T cells provided strong tumor-rejection capacity while retaining a favorable phenotype for adoptive cell transfer. These findings demonstrate that T-Ag–specific T cells are associated with the clinical outcome to PD-1 blockade and that Ag-presenting scaffolds can be used to boost such responses.</p