重复性伸腕作业劳动负荷与前臂伸肌的表面肌电特征

目的用表面肌电描记术(surface electromyography,SEMG)评价低力量负荷下,频率、重量和运动角度3个负荷因素对重复性伸腕运动中前臂肌肉应激状态和疲劳的影响。方法16名男性志愿者在规定的重量(1．96、4．90 N)、频率(8．0、33．3次/min)和角度(45°、90°)下做8组伸腕动作各20 min,并在作业开始和结束后做20%最大随意收缩力(MVC)的静态伸腕动作2～3s,采集并分析其尺侧腕伸肌和指伸肌的表面肌电信号。结果伸腕力量负荷(1．96、4．90 N)分别约为伸肌MVC手收缩力的1．40%和3．50%。当3个负荷因素的水平升高时,肌电的平均功率频率(MPF)和中位频率(MF)均降低,其中指伸肌MPF降低的差异有统计学意义(P＜0．05或P＜0．01),其MF在角度和重量两因素中的改变差异有统计学意义(P＜0．05或P＜0．01)。随负荷水平的升高,伸肌波幅值可分3～4组,组间差异有统计学意义(P＜0．05)；逐步回归分析显示,3因素负荷水平均与肌电波幅值呈正相关．结论各作业中指伸肌均明显疲劳；伸肌疲劳的首要负荷因素是频率,其次是重量和角度；MF、MPF和波幅指标可以描述低力量负荷下前臂肌肉的应激和疲劳状况。     

Identification of motion from multi-channel EMG signals for control of prosthetic hand

The authors in this paper propose an effective and efficient pattern recognition technique from four channel electromyogram (EMG) signals for control of multifunction prosthetic hand. Time domain features such as mean absolute value, number of zero crossings, number of slope sign changes and waveform length are considered for pattern recognition. The patterns are classified using simple logistic regression (SLR) technique and decision tree (DT) using J48 algorithm. In this study six specific hand and wrist motions are identified from the EMG signals obtained from ten different able-bodied. By considering relevant dominant features for pattern recognition, the processing time as well as memory space of the SLR and DT classifiers is found to be less in comparison with neural network (NN), k-nearest neighbour model 1 (kNN-Model-1), k-nearest neighbour model 2 (kNN-Model-2) and linear discriminant analysis. The classification accuracy of SLR classifier is found to be 91 ± 1.9%.     

Hand movements classification for myoelectric control system using adaptive resonance theory

This research proposes an exploratory study of a simple, accurate, and computationally efficient movement classification technique for prosthetic hand application. Surface myoelectric signals were acquired from the four muscles, namely, flexor carpi ulnaris, extensor carpi radialis, biceps brachii, and triceps brachii, of four normal-limb subjects. The signals were segmented, and the features were extracted with a new combined time-domain feature extraction method. Fuzzy C-means clustering method and scatter plot were used to evaluate the performance of the proposed multi-feature versus Hudgins’ multi-feature. The movements were classified with a hybrid Adaptive Resonance Theory-based neural network. Comparative results indicate that the proposed hybrid classifier not only has good classification accuracy (89.09 %) but also a significantly improved computation time.     

静态负荷表面肌电信号功率谱的二维地形图分析

目的：研究在静态负荷条件下肱二头肌和腰部脊竖肌疲劳发生,发展过程中的表面肌电（SEMC）变化特征。方法：14名受试者分别参加肱二头肌和腰部脊竖肌等长运动负荷实验,取表面肌电信号进行FFT功率谱及其功率谱二维地形图分析。结果：2种负荷条件下,频域指标－平均功率频率（MPF）和中位频率（MF）的时间序列曲线均呈现直线递减变化;同时功率谱二维地形图分析呈现不同的变化规律。结论：不同类型的肌肉在疲劳过程中MPF和MF的下降所包含的信息不尽相同,并且主要表现为SEMG信号功率谱的带宽和分量值上的差异。     

Overuse injury syndromes of the hand, forearm and elbow

The basic role of the shoulder, upper arm, elbow, forearm, and wrist is to place the hand in the appropriate position, so that it can fulfill its function. The upper extremity, especially the wrist and the hand, has a very complex anatomy with a large number of bones, muscles, tendons and nerves. They are essential to work and sport activities and are subject to acute and/or chronic mechanical injuries. This is why overuse injuries are the most common in these regions. They are often characterised by tendinitis, tenosynovitis, tunnel syndromes, or stress fractures. This paper gives an overview of the most common overuse syndromes of the hand, wrist, forearm and elbow, describing their characteristic symptoms and methods of diagnosis and treatment. The syndromes are trigger finger, dorsal radiocarpal impingement syndrome (gymnast's wrist), DeQuervain's disease, tenosynovitis of other dorsal compartments, intersection syndrome (oarsman's wrist), flexor carpi ulnaris tendinitis, flexor carpi radialis tendonitis, humeral epicondylitis (tennis elbow), posterior impingement syndrome of the elbow, medial tension and lateral compression syndrome, stress fracture in the hand, wrist, forearm and elbow, and tunnel syndromes.     

Biomechanical analysis of upper extremity risk in Sign Langauge Interpreting

Upper extremity cumulative trauma distorders (UECTD) have been identified as an occupational health problem in professional Sign Language Interpreters (SLI). A previous study of UECTD in SLI has indicated significant differences between interpreters working with pain and those working without pain. This earlier research focused on gross measures of hand/wrist movement, work/rest cycles, and deviations from an optimal work envelope. The present paper describes a detailed biomechanical analysis of wrist and forearm activity associated with SLI. This assessment included forearm (flexion and extension) and wrist (flexion/extension and radial/ulnar deviation) measures of movement frequency, counts of individual motion, joint movement velocities and accelerations as well as range of motion. The analyses revealed that the postures required for interpreting result in the signing hand frequently held in a fully pronated position, with the palm facing out. The wrist was most frequently in an ulnar deviation and/or extension while the elbow was flexed more than 90° and held in close to the body with the fingers pointing up. The frequency of motions for the forearm and wrist were observed to be 270 per minute (4.5 Hz), which is equivalent to 13,600 per 50 minute lecture hour. The mean absolute joint movement velocity and acceleration values were relatively high in contrast to industrial jobs with wrist and forearm accelerations between 34,754 degreees/sec² and 36,046 degrees/sec², respectively. The findings from this biomechanical analysis indicates that SLI can involve highly repetitive, awkward movements with significant accelerations of the hand and wrist. Such job characteristics may predispose interpreters to upper extremity CTD-related disorders.     

基于BP神经网络的表面肌电信号模式分类的研究

将神经网络与AR模型相结合提出了一种表面肌电信号模式分类算法。该算法能成功地从腕伸肌和腕屈肌的两道表面肌电信号中识别脱伸、腕屈、腕内旋和腕外旋四种运动模式。实验结果表明：用AR模型参数作BP网输入的肌电模式分类器，运行速度快、识别率高、鲁棒性好，在假肢等人一机仿生系统的控制中具有很好的应用前景。     

Maximal acceptable torques of highly repetitive screw driving,ulnar deviation,and handgrip tasks for 7-hour workdays

This study represents a continuation of a series of psychophysical studies on repetitive motions of the wrist and hand conducted at the Liberty Mutual Research Center for Safety and Health. The purpose of the study was to quantify maximum acceptable torques of six motions performed on separate days but within the context of the same experiment. The six motions were screw-driving clockwise with a 31-mm handle, a 40-mm handle, and a 39-mm yoke handle; screw-driving counterclockwise with a 31-mm handle; ulnar deviation with a power grip (similar to knife cutting), and a handgrip task (similar to a pliers task). A psychophysical methodology was used in which the subject adjusted the resistance on the handle, and the experimenter manipulated or controlled all other variables. Ten subjects performed the six tasks at repetition rates of 15, 20, and 25 motions per minute. Subjects performed the tasks for 7 hours per day, 5 days per week, for 4 weeks. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work they performed. Symptoms were recorded by the subjects during the last 5 min of each hour. The results revealed that mean maximum acceptable torques ranged from 0.33 to 0.65 Nm for screw driving, 1.08 to 1.13 Nm for ulnar deviation, and 4.80 to 4.85 Nm for the handgrip task. These values represent 14 to 24% (median of 17%) of maximum isometric torque depending on the frequency and motion. A table of maximum acceptable torques and forces of the six motions is presented for application in the field.     

The impact of whole-hand vibration exposure on the sense of angular position about the wrist joint

Objectives: The purpose of this research is to determine the impact of whole-hand vibration on the capacity of subjects to identify previously presented positions of the hand in both wrist flexion and extension. Methods: In each movement direction, targets of 15 or 30° were presented with an imposed passive movement from the start position. During the second imposed movement, subjects were required to identify when the target position had been reached. For the vibration condition, 15 s of whole-hand vibration exposure was repeated immediately prior to each target position trial. Proprioceptive capacity was assessed by comparing the identified angular position with the reference position–angular distance expressed in terms of absolute error (AE), constant error (CE), and variable error (VE). Results: For three of the four target positions (15 and 30° flexion and 15° extension), the absolute, constant, and VEs of target identification were insensitive to vibration, whereas for the 30° extension target, both the absolute and CE were significantly different before and after the vibration application, showing the subjects overshooting previously presented target position. All three error measures were larger for the long targets than the short targets. Conclusions: Short-duration exposure to whole-hand vibration is insufficient to compromise post-vibration position sense in the wrist joint, except near the end range of joint movement in wrist extension. Complement contribution of different proprioceptive receptors (muscle, joint, and skin receptors) seems to be crucial for accuracy to reproduce passive movements, since the capacity of any individual class of receptor to deliver information about movement and position of the limbs is limited.     

高频超声检查在手腕部肿块中的应用

目的分析手腕部肿块的高频超声征象,探讨高频超声对手腕部肿块的诊断价值。方法回顾性分析32例手腕部肿块的二维及彩色多普勒超声表现,观察肿块的位置、大小、形态、边界、内部回声及彩色血流信号等,与手术病理结果对照。结果 32例手腕部肿块中病理证实腱鞘囊肿19例,腱鞘巨细胞瘤3例,腱鞘纤维瘤2例,血管瘤2例,脂肪瘤2例,表皮样囊肿2例,神经鞘瘤2例。高频超声共发现肿块32个,检出率100%,符合率81.3%。结论各类型手腕部肿块的超声征象具有其不同表现,高频彩色多普勒超声对手腕部肿块诊断准确性较高,可作为术前诊断的参考。     

Effect of Time Elapsed since Last Pruner Maintenance on Upper-Extremity Biomechanics during Manual Flower Cutting

Objective: Manual flower cutting imposes large biomechanical demands on workers’ upper extremities. Solutions are required to reduce these demands. This study investigated the effect of time elapsed since the last pruner maintenance on the biomechanical demands of the upper extremities during flower-cutting operations.

Methods: Sixteen experienced workers were recruited. All workers performed flower cutting 1, 15, and 30 days after standard pruner maintenance, including cleaning, adjustment, and sharpening. The outcomes included kinematics of the wrist, elbow, and forearm; muscular activity of the extensor carpi radialis, extensor carpi ulnaris, flexor carpi radialis, flexor carpi ulnaris, biceps and medium deltoids of the dominant arm; and self-reported effort.

Results: On average across muscles, a 15-day delay (from 1 to 15 and from 15 to 30 days) in the execution of pruner maintenance increased over 8% the median recorded muscular activity as measured by the percentage of the maximum voluntary contraction of the root mean square signal. An increase in time since last pruner maintenance resulted in an increase in the 90th percentile pronation–supination posture (larger excursion toward pronation); the median and the 90th percentile velocity of the wrist and elbow; and the 90th percentile acceleration in the pronation–supination direction. There was an increase in perceived effort as measured by a Borg scale as time since last maintenance increased from 1 to 15 days.

Conclusion: Increasing the frequency of pruner maintenance procedures can effectively reduce workers’ mechanical exposures during manual flower-cutting operations. Companies should implement daily maintenance programs considering their implementation capacity and expected benefits.     

Identification of a feature selection based pattern recognition scheme for finger movement recognition from multichannel EMG signals

This paper focuses on identification of an effective pattern recognition scheme with the least number of time domain features for dexterous control of prosthetic hand to recognize the various finger movements from surface electromyogram (EMG) signals. Eight channels EMG from 8 able-bodied subjects for 15 individuals and combined finger activities have been considered in this work. In this work, an attempt has been made to recognize a number of classes with the least number of features. Therefore, EMG signals are pre-processed using dual tree complex wavelet transform to improve the discriminating capability of features and time domain features such as zero crossing, slope sign change, mean absolute value, and waveform length is extracted from the pre-processed data. The performance of extracted features is studied with different classifiers such as linear discriminant analysis, naive Bayes classifier, quadratic support vector machine and cubic support vector machine with and without feature selection algorithms. The feature selection has been studied using particle swarm optimization (PSO) and ant colony optimization (ACO) with different number of features to identify the effect of features. The results demonstrated that naive Bayes classifier with ant colony optimization shows an average classification accuracy of 88.89% with a response time of 0.058025 ms for recognizing the 15 different finger movements with 16 features with significant difference in accuracy compared to SVM classifier with feature selection for a significance level of 0.05. There is no significant difference in the accuracy, specificity and sensitivity of an SVM classifier with and without feature selection. But the processing time is significantly more than the LDA and NB classifier. The PSO and ACO results revealed that slope sign changes contribute to recognizing the activity. In PSO, mean absolute value has been found to be effective compared to waveform length, contradictory with ACO. Further, the zero crossings have been found to be not effective in classification of finger movements in both the methods.     

A digestive tolerance study of maltitol after occasional and regular consumption in healthy humans

AIM: We aimed to evaluate the gastro-intestinal tolerance to an indigestible bulking sweetener containing sugar alcohol using a double-blind random cross-over study. METHOD: In order to simulate their usual pattern of consumption, 12 healthy volunteers ingested maltitol or sucrose throughout the day, either occasionally (once a week for each sugar, first period) or regularly (every day for two 9 day periods, second period). In both patterns of consumption, daily sugar doses were increased until diarrhea and/or a grade 3 (ie severe) digestive symptom occurred, at which the dose level was defined as the threshold dose (TD). RESULTS: In the first period (occasional consumption), the mean TD was 92+/-6 g with maltitol and 106+/-4 g with sucrose (P=0.059). The mean intensity of digestive symptoms was 1.1 and 1.3, respectively (P=NS). Diarrhea appeared in six and one subjects respectively (P=0.035). In the second period (regular consumption), the mean TD was 93+/-9 g with maltitol and 113+/-7 g with sucrose (P=0.008). The mean intensity of digestive symptoms was 1.7 and 1.2, respectively (P=NS). However, diarrhea appeared in eight and three subjects, respectively (P=0.04). Maltitol and sucrose TDs between the two periods were not different. CONCLUSIONS: Under our experimental conditions, in comparison to sucrose: (a) occasional or regular consumption of maltitol is not associated with severe digestive symptoms; (b) in both patterns of maltitol consumption, diarrhea frequency is higher, but it appeared only for very high doses of maltitol, much greater than those currently used; (c) maltitol does not lead to intestinal flora adaptation after a 9 day period of consumption.     

三种计算机工作台的工效学评价

为评价三种计算机操作的工效学特点，我们在实验室采用ＥＭＧ技术对使用三种操作台时腕部及肩部肌肉的负荷及疲劳的发生发展过程进行了研究。结果表明，使用新型台时桡侧腕屈肌的ＩＥＭＧ值比使用普通台和抽屈台时低，提示使用新型台时腕部负荷较小。随时间延长，使用普通台，抽屉台，新型台时桡侧腕屈肌的ＩＥＭＧ值分别在第１０分，３０分和６０分时达到最高值，提示使用新型台可延缓腕部肌肉疲劳的发生，而对肩部肌肉无明显影响。     

Biomechanical strains on the hand-wrist system during grapevine pruning

OBJECTIVES: In order to understand the high prevalence of musculoskeletal disorders of the hand among vineyard workers, we conducted a study to evaluate biomechanical strains on the hand-wrist system during grapevine pruning. METHODS: Surface electromyography (sEMG) activity of the right flexor digitorum muscle and wrist posture were analysed in six healthy vineyard workers using the same hand-powered pruning shears during grapevine pruning. RESULTS: The biomechanical strains on the hand-wrist system were high during grapevine pruning. Mean sEMG activity during pruning was high [23.5% (standard error of the mean (SEM): 0.4) in the maximal voluntary handgrip contraction (MVC)], as was the mean cutting frequency per minute (38; range=24-48). Approximately 14% of cuts were performed with the wrist in extreme flexion/extension (F/E) (>60% of the maximum range). Numerous cuts required moderate (20%-40% of the maximum range) or extreme (>50% of the maximum range) ulnar deviation (17% and 12% of cuts, respectively). Approximately 18% of cuts required both high muscular activity (sEMG >15% MVC) and extreme ulnar/radial (U/R) deviation of the wrist (>50% of the maximum range). CONCLUSION: Pruning imposes high biomechanical strains on the hand-wrist system in view of the repetitiveness of the task. The magnitude of physical exposure during pruning explains the high prevalence of hand disorders among vineyard workers. The use of ergonomic pruning shears is advised to lower force exertion and to reduce the frequency of awkward wrist postures during pruning.     

Mobile teledermatology: a feasibility study of 58 subjects using mobile phones

We investigated the diagnostic agreement between teledermatology based on images from a mobile phone camera and face-to-face (FTF) dermatology. Diagnostic agreement was assessed for two teledermatologists (TD) in comparison with FTF consultations in 58 subjects. In almost three-quarters of the cases (TD1: 71%; TD2: 76%), the telediagnosis was fully concordant with the FTF diagnosis. Furthermore, the diagnosed diseases were almost all in the same diagnostic category (TD1: 97%; TD2: 90%). If mobile teledermatology had been used for remote triage, TD1 could have treated 53% subjects remotely and 47% subjects would have had to consult a dermatologist FTF. TD2 could have treated 59% subjects remotely, whereas 41% subjects would have had to consult a dermatologist FTF. Forty-eight subjects responded to a questionnaire, of whom only 10 had any concerns regarding teledermatology. Thirty-one subjects stated that they would be willing to pay to use a similar service in future and suggested an amount ranging from euro5 to euro50 per consultation (mean euro22) (euro = pound0.7, US $1.4). These results are encouraging as patient acceptance and reimbursement represent potential obstacles to the implementation of telemedicine services.     

A Comparison of Wrist Posture and Forearm Muscle Activities While Using an Alternative Keyboard and a Standard Keyboard

The wrist posture associated with the use of the conventional QWERTY keyboard is a risk factor for work-related musculoskeletal disorders in the upper limbs. Newly designed keyboards have been produced with the aim to reduce the strain in the wrist and forearm region. The present study compared the effects of using a standard keyboard and a split/angled keyboard on the forearm muscle activities and wrist joint angles. Ten subjects (6 males and 4 females) performed a standard keyboard task for 30 min, using each of the two keyboards while wrist joint angles and electromyography (EMG) were recorded. Wrist extension and ulnar deviation angles were both significantly reduced with the split/angled keyboard (p = .030 and .010), and lower EMG activities were recorded in the extensor carpi radialis and ulnaris muscles. The present results implied that the split/angled keyboard may be a better instrument for prolonged keyboard operation, resulting in reduced strain in the wrist and forearm region.     

Nested case-control study of hand and wrist work-related musculoskeletal disorders in carpenters

Unionized carpenters (n = 522) participated in a telephone interview regarding their jobs and musculoskeletal symptoms. From this group, a nested case-control study was conducted on 25 symptomatic carpenters who met a hand or wrist work-related musculoskeletal disorder (WMD) case definition and on 35 asymptomatic carpenters who were of similar, age, sex, height, and weight. The purpose of the study was to determine if questionnaire symptom data could be used to estimate the prevalence of hand/wrist WMDs. To test this hypothesis, a subset of subjects underwent physical examination and electrodiagnostic testing to determine if these symptom-derived cases had findings of carpal tunnel syndrome or other hand or wrist musculoskeletal disorders. Standardized upper extremity physical examinations and unilateral ulnar and median nerve conduction studies were administered. Physical examination findings of CTS were significantly increased among WMD cases. Mean median sensory and motor distal latencies were significantly longer (P < 0.05) and median sensory amplitudes smaller in cases compared to controls. Median relative to ulnar sensory and motor latencies also were longer in cases. A median mononeuropathy at the wrist was found in 78% of the cases. These findings suggest that symptom-derived WMD data are useful in estimating the prevalence of CTS among carpenters. © 1996 Wiley-Liss, Inc.     

A study of factors influencing return to work after wrist or ankle fractures

BACKGROUND: Factors associated with time to return to work are poorly understood for occupational injuries, other than those to the back. METHODS: Anonymized data on claims for work-related wrist or ankle fracture between 1/1/1998 and 12/31/2002 were identified in administrative data held by the Workers Compensation Board in Alberta, Canada. Bivariate and Cox regression analyses were used to identify factors associated with return to work. RESULTS: Increased duration of temporary disability (TD) was associated with older age, female gender, work in construction and construction trade services, smaller company size, higher industry claim rates, a fall/jump from a height, ankle fracture, and greater medical aid costs in the 30 days following injury (used as a proxy for severity). CONCLUSIONS: Factors associated with longer time off work were largely consistent with those reported following back injury. Median time to return to work was longer following ankle than wrist fracture. Although Workers' Compensation Board (WCB) administrative data provided information that could be used to identify factors affecting return to work, better information on injury severity would considerably enhance their research potential.