Work-related posttraumatic upper limb disorder. A case report

In this paper we describe a patient with mor-sensory loss in the right forearm and hand, which persisted more than 2 years after work-related crush trauma of the left hand. Radiographic and electromyographic investigations, somatosensory evoked potentials, CT scans of the encephalus as well as the Minnesota Multiphasic Personality Inventory and the Roarschach test have been performed. On the basis of these investigations, we think this represents a case of conversion disorder with somatic features. Included is a brief overview of other psychological illness with physical findings involving the upper limb.

[Ergonomic evaluation of the physical tasks in "precision fusion" operations]

In the present paper we performed an "on-site" ergonomic analysis of the work tasks in in-plant industrial workers. Specific work cycles have been identified and analysed. We measured spatial and temporal parameters of the different actions performed by the workers, and we then defined the related risk levels according to the internationally accepted guide-lines. The results obtained indicate the need of an ergonomic intervention with the aim of providing structural changes in the work station.

[An ergonomic study of postures of toll collectors]

The working activities of operators in the workstations along the italian motor ways involve repetitive movements of upper limbs and neck with asymmetric postures of the trunk. The tasks examined are characterized by factors potentially dangerous for developing musculo-skeletal disorders, such as repetitivity, and prolonged constrained postures. It is therefore crucial that dimensional and structural characteristics of the workplace are adequately designed, with regard to the anthropometric parameters and the type of activity performed. The results of our "on-site" investigation, using an observational method (OCRA), dedicated computerized modules for postural analysis (software "Vision 3000", Promatek, Ltd.), and recordings of myoelectrical activity (surface EMG) in the muscles of the shoulder girdle, have shown the need of a partial re-designing of the man-workstation system under investigation.

[Evaluation of the capacity of work using upper limbs after radical latero-cervical surgery]

Evaluation of arm work capacity after radical neck surgery. The aim of this paper is to describe an approach for the assessment of work capacity in patients who underwent radical neck surgery, including those treated with radiation therapy. Nine male patients, who underwent radical neck surgery 2 months before being referred to our Unit, participated in the study. In addition to manual muscle strength test, we performed the following functional evaluations: 0-100 Constant scale for shoulder function; maximal shoulder strength in adduction/abduction and intrarotation/extrarotation; instrumental. We measured maximal isokinetic strength (10 repetitions) with a computerized dynamometer (Lido WorkSET) set at 100 degrees/sec. During the rehabilitation phase, the patients' mechanical parameters, the perception of effort, pain or discomfort, and the range of movement were monitored while performing daily/occupational task individually chosen on the simulator (Lido WorkSET) under isotonic conditions. On this basis, patients were encouraged to return to levels of daily physical activities compatible with the individual tolerable work load. The second evaluation at 2 month confirmed that the integrated rehabilitation protocol successfully increased patients' capacities and "trust" in their physical capacity. According to the literature, the use of isokinetic and isotonic exercise programs appears to decrease shoulder rehabilitation time. In our experience an excellent compliance has been noted. One of the advantages of the method proposed is to provide quantitative reports of the functional capacity and therefore to facilitate return-to-work of patients who underwent radical neck surgery.

Work capacity of the upper limbs after mastectomy

Cancer patients are now more often long-term survivors and their needs for returning to social and productive activities have become a primary focus of intervention. The purpose of the present study was to propose an objective evaluation test for predicting endurance capacity in breast cancer patients after surgery, in order to optimize return to work or previous daily activities, and for monitoring changes during rehabilitation. Twenty female patients (mean age: 44 +/- 5), who underwent radical breast surgery 2 months before being referred to our Unit, participated in the study. In addition to the measures of the circumferences in the arm-forearm and manual muscle strength test, we performed the following functional evaluations: 0-100 Constant scale for shoulder function; instrumental evaluation of daily/occupational upper limb activities (Lido WorkSET). We monitored the mechanical parameters, the perception of effort, pain or discomfort, and the range of movement while performing a 3-minute steady daily/occupational task chosen by the subject. Patients were asked to perform the 3-minute test at three different intensities ("moderate", "somewhat hard", "hard") until the perception of fatigue, pain or discomfort was rated > 3 on the 10 point Borg's scale. The 'power-duration' product (Watt x min) defined by the three tests (see Fig. 1) represented the individual tolerable work load, since subjective indicators of pain/discomfort remained within tolerable limits during the exertion. On this basis, patients were encouraged to return to levels of daily physical activities compatible with the individual tolerable work load. The second evaluation, although no statistical analysis was performed, confirmed that the "guided" daily activity in a 2-month period increased patients' capacities and "trust" in their physical capacity.

Tolerability to prolonged lifting tasks. A validation of the recommended limits

Prolonged physical exertion is subjectively regulated by the perception of effort. This preliminary study was conducted to validate the use of subjective perceptions of effort in assessing objectively tolerable workloads for prolonged lifting tasks. Ten healthy male subjects tested their maximal lifting capacity (MLC) on a lift dynamometer (LidoLift, Loredan Biomed., West Sacramento, CA) and underwent incremental and 30-minute endurance lifting tests. Cardiorespiratory parameters were monitored with an oxygen uptake analyzer, mechanical parameters were calculated using a computerized dynamometer. Ratings of perceived exertion were given on Borg's 10-point scale. Physiological responses to repetitive lifting were matched with subjective perceptions. A single-variable statistical regression for power functions was performed to obtain the individual "iso-perception" curves as functions of the mechanical work exerted. We found that the "iso-perception" curve corresponding to a "moderate" perception of effort may represent the individual "tolerance threshold" for prolonged lifting tasks, since physiological responses at this level of intensity did not change significantly and the respiratory exchange ratio was less than one. The individually tolerable weight for lifting tasks lasting 30 min has been expressed as a percentage of the isoinertial MLC value and compared with the currently recommended limits for prolonged lifting tasks (Italian legislation D.L. 626/94). On the basis of our preliminary results a "tolerance threshold" of 20% MLC has been proposed for prolonged lifting tasks.

A field methodology for ergonomic analysis in occupational manual materials handling

A methodology is presented for the 'on-site' evaluation of work-related physical activities. In a first session, video recordings were made of six industrial plant workers during their routine occupational tasks. Heart rate (HR) and subjective perception of effort were monitored. The video recordings were then analysed with appropriate software to determine the musculo-skeletal load ('Vision 3000', Promatek, Montreal) and to evaluate energy expenditure ('Energy', University of Michigan). The indirect estimates of energy expenditure were validated in a second session by monitoring the six subjects' oxygen consumption (VO2) during the same activities with a portable telemetric oxygen uptake analyser (Cosmed 'K2', Rome). No statistically significant differences were found between direct measurements of VO2 and the computerised estimates of energy expenditure. Biomechanical parameters obtained in the two sessions did not differ. Therefore, we conclude that the 'Energy' programme and the 'Vision 3000' program provide a fast and reliable profile of job requirements.

Reliability of a hand gripping endurance test

The aim of this study was to assess the reproducibility of a new endurance test for hand grip movements. On six occasions separated by at least 3 days, 30 healthy subjects performed six maximal endurance tests in two different positions with a hand grip tool attached to an isokinetic dynamometer. The test consisted of repeated maximal grip movements (1-min bouts for men and 30-s bouts for women subjects) at an angular velocity of 45 degrees/s. A custom-made PC programme was used to collect data on peak torque and mechanical work, and to provide the following parameters: basal torque, basal work, time until basal values fell to 20, 30 and 50% of the initial peak values, slopes of decay of torque and work over time. The intraclass correlation coefficient (ICCC) was then computed to assess the reproducibility of the parameters obtained during the tests. An 'almost perfect' (0.8 < ICCC = 1) reproducibility of the basal torque values in both positions and a 'substantial' (0.6 < ICCC = 0.8) or 'almost perfect' reproducibility of the slope values referred to the torque decay over time was observed. Feasible applications of this new endurance test in ergonomics and vocational rehabilitation are discussed.

[The assessment of functional capacity in workers with the thoracic outlet syndrome. A pilot study]

Occupational specialists are well aware of the lack of objective measurements for the diagnosis and the functional evaluation of workers affected by thoracic outlet syndrome (TOS). Subjects affected by TOS refer pain, sensation of fatigue in the arm frequently aggravated by overhead work. A "stick-up" position tends to close the costoclavicular space and tense the neck and shoulder muscles to bring into play the abnormal compression mechanism that may affect the brachial plexus nerves and the subclavian vessels. In a previous study, we demonstrated the reliability of an isokinetic hand grip endurance test. In this pilot study we asked 7 industrial workers affected by TOS to perform a 30-second isokinetic endurance test for hand gripping with a Lido WorkSET dynamometer. Tests were performed in two positions (resting and "stick-up" position) before and after a 3-week intensive rehabilitation program. In addition, the subjects performed daily aerobic exercise with an arm crank ergometer. Objective indexes of posttreatment improvement were found. Subjects were able to generate higher grip forces during the isokinetic hand grip endurance test and to sustain higher mechanical workload with the arm ergometer at the same intensity level for longer duration after completion of the rehabilitation program.

[Indicators of dynamic work tolerability in healthy subjects]

This paper reports a study on the dynamics of tolerability in performing dynamic cycling in healthy subjects. Data on individually tolerable levels (power x duration) was obtained from 9 subjects by means of three submaximal tests on an ergometric bicycle lasting < or = 40 minutes, with constant load (50%, 65% and 80% of maximum VO2 reached during a previous test of increasing difficulty within the limits of the symptoms). During performance of the test we monitored heart rate and subjective perception of fatigue (Borg's 10-point scale). We then defined the individual functions of "isoperception", which expressed the individual trend of the product "power x duration" at identical subjective perception score. On the basis of the metabolic parameters monitored, the individual isoperceptive functions at a "moderate" level of fatigue (3 on the Borg scale) were defined as "tolerability) threshold" for prolonged dynamic cycling. The product "power x duration" defined by the isoperceptive curves at a "moderate" level of fatigue does in fact reflect the individual aerobic capacity that can be sustained for prolonged dynamic activity (under 60 minutes). In order to validate the hypothesis of tolerability of the functions identified, three further short tests were performed (duration < or = 8.5 minutes) on an ergometric bicycle, with measurement of ventilatory and metabolic parameters.

Tolerable exercise intensity in the early rehabilitation of paraplegic patients. A preliminary study

Accessible indicators for setting exertion levels in newly injured paraplegias could be useful to improve their daily and occupational performances in less time than is presently required. Eight male newly injured paraplegic subjects performed progressive resisted and endurance exercise tests on an arm cranking ergometer. Cardiorespiratory parameters during exercise were monitored with an oxygen uptake analyzer and perceived exertion was rated on Borg's 10-point scale. Four subjects (Group A) underwent an 'enhanced' rehabilitation protocol which included aerobic arm training sessions. The prescription of exercise intensity was tailored to each subject's tolerable power output for prolonged exertion. The remaining four (Group B) followed a 'conventional' rehabilitation program. Tests were repeated in both groups after 6 weeks. We observed a greater improvement in endurance capacity in Group A than in Group B after completion of the rehabilitation program. A 6-week 'enhanced' rehabilitation program based on a 'moderate' intensity of exercise was well tolerated and effective in improving the fitness levels of newly injured paraplegic subjects. Subjective perception has been shown to be a simple and accessible indicator for setting exertion levels.

Individual profiles of dyspnoea and fatigue in chronic bronchitic patients, defined by intensity and duration of submaximal workloads performed

The subjective perception of fatigue and dyspnoea during submaximal exercise was studied in 10 chronic bronchitic patients using Borg's CR10 scale, with the aim of developing a model for the assessment of sustainable workloads (through the definition of individual perceptual profiles). Each subject performed five trials, consisting of steptests at constant submaximal workloads. Fatigue (CRf) and dyspnoea (CRd) perceptions, heart rate (HR) and duration times were measured. Maximal duration was set at 30 min. The trial was stopped if a fatigue/dyspnoea score of 7 ("very strong") or 85% of the maximum HR was reached. The growth of fatigue and dyspnoea perceptions (R) as functions of time (S) were expressed by the formula: R = a + c (S-b)n. Parameters a, b, c and n calculated for each subject and trial were (mean and SD): a = 0.49 (0.31); b = 2 (0); c = 1.3 (0.61); and n = 0.55 (0.2) for dyspnoea; a = 0.51 (0.27); b = 2 (0); c = 1.4 (0.75); and n = 0.55 (0.2) for fatigue. Individual CR3 "iso-perception" curves (W = k t alpha) for fatigue and dyspnoea in a workload/duration reference system were computed from the experimental data obtained during the five trials. Mean values of the exponent alpha were (.0.5) +/- (-0.23) for dyspnoea, and (-0.41) +/- (-0.22) for fatigue. The CR3 "iso-perception" curves represented the subjectively acceptable level of exertion (defined for load and duration). By doubling the duration and workload, CRd score increments of 1.55 (SD 0.46) and 4.9 (SD 0.42), respectively, were computed. Subjective perceptions are correlated to the intensity and duration of submaximal workload performed, and can be used in conjunction with physiological parameters to predict acceptable workloads in chronic bronchitic patients.

Quantification of muscular activity in the shoulder region during monotonous repetitive work

The purpose of this preliminary study was to evaluate the degree of myoelectric activity (EMG) in the shoulder muscles during repetitive monotonous work cycles in order to assess the load on the shoulder muscles. The tasks were video recorded and the movements performed were analyzed with a direct computer-based observational method (OS-WALD). The amplitude distribution probability function (ADPF) of the surface EMG from the deltoideus lateralis and trapezius pars descendens muscles was analyzed in 6 persons working on assembly lines. For each subject, "on-site" EMG and video recordings were performed over 10-minute periods at four different workstations on the same day. Force/EMG amplitude calibration curves had been previously calculated for the same subjects using a strain-gauge dynamometer. The results obtained during the working periods were the following: the mean static contraction level, as defined by Jonsson (13), was 1.3% MVC in the trapezius muscle and 0.5% MVC in the deltoid muscle; the medium contraction level was 5.2% MVC in the trapezius and 1.7% MVC in the deltoid; the peak contraction level was 17% MVC in the trapezius and 6.2% MVC in the deltoid. When compared to previously suggested upper limits of ADPF levels, all the contraction levels monitored were below the recommended limits. The assessment of musculoskeletal load in the shoulder region via EMG and video recordings led us to conclude that the work cycles examined were characterized by low-repetitive monotonous work and were well organized in order to avoid the occurrence of musculoskeletal injuries.

Predicting endurance limits in arm cranking exercise with a subjectively based method

The purpose of this study was to compare a method for predicting endurance capacity at different workloads based on subjective perception of effort with the technique for determining 'critical power' (CP) proposed by Moritani et al. (1981). Three trained paraplegic subjects performed two protocols during separate sessions. The 'subjective' protocol consisted of graded and continuous tests on an arm crank ergometer, during which cardiorespiratory (heart rate, oxygen consumption, ventilation and respiratory exchange ratio) and subjective (Borg's 10-point scale) parameters were monitored continuously. A statistical regression analysis for power functions was performed to obtain the individual ¿iso-perception' curves in a power/duration reference system. The other protocol consisted of the determination of the CP of the muscle groups involved in arm cranking exercises according to the protocol proposed by Moritani et al. (1981). Subjects performed three tests in which the power output remained constant (50, 37.5 and 25 W) and led to the onset of muscular fatigue. The results of the two protocols were compared. The validity of the subjective perception of effort as a predictor of individual endurance capacity was confirmed by the relationship between time to exhaustion and work performed during constant-power tests as proposed by Moritani et al. (1981).

[Rheumatism caused by anticonvulsants: presentation of 2 clinical cases with work reintegration]

We present two cases of rheumatism induced by phenobarbital therapy. The duration of treatment before the onset of this condition was 12 months and 20 years, respectively. In both cases, a therapeutic exercise program and drug therapy provided lasting resolution of symptoms.

[Use of subjective perception of exertion in the evaluation of the tolerance to repetitive lifting: a pilot study]

This preliminary study was conducted to validate subjective perception of effort as indicator of the tolerable workload for prolonged lifting tasks. Three healthy male subjects underwent endurance and incremental lifting tests. Cardiorespiratory parameters (HR, VO2) were monitored with a portable telemetric oxygen uptake analyzer, mechanical parameters were calculated from a lift dynamometer. Rating of perceived exertion was given on Borg's CR-10 scale. Individual fitness profiles for lifting tasks were obtained from the individual relationships between oxygen consumption and heart rate at different lifting frequencies. Physiological responses to repetitive lifting were matched with subjective perceptions. The relationship between perception of exertion and time was described by power functions, Y = a.Xn, in which 0 < n < 1. A single-variable statistical regression for power functions was performed to obtain the individual "iso-perception" curves. The iso-perception curve corresponding to a "moderate effort" (CR3) identified the individual tolerable threshold for prolonged lifting tasks. The individually tolerable power output over time for lifting tasks was calculated.

Functional correlates in the rehabilitation of occupational low back pain

The aim of this preliminary report was to identify physiological parameters related to functional improvement in industrial workers with occupational low back pain (LBP) undergoing an intensive rehabilitation program. Four able-bodied and four LBP industrial workers were evaluated before and after a 4-week rehabilitation program. Dynamic and static strength tests, namely sustained isometric contractions, were performed in conjunction with surface electromyographic (EMG) measurements. Significant pre-rehabilitation differences were found between the two groups. Measured forces changed significantly in LBP subjects immediately after rehabilitation. No significative changes were found in the control subjects after the rehabilitation program. After rehabilitation, the slope of decay of the median frequency of the EMG power spectrum at L4 level, during a 60-sec isometric submaximal (60% MVC) contraction, decreased significantly (p < 0.02) indicating a lower fatigue level.

[Physical workload demands: the combined use of 2 evaluation programs]

A computerized methodology is presented for the "on-site" evaluation of work-related physical activities in industrial plant workers. Subjects were videotaped during the activities while heart rate and subjective perception of effort were monitored. The videorecordings were then analyzed with two appropriate software, in order to identify activities at high risk for musculoskeletal injuries ("Vision 3000" program, Promatek Ltd., Montreal) and to evaluate energy expenditure ("Energy" program, University of Michigan). Validation of the energy expenditure indirect analysis system was done by monitoring oxygen consumption (VO2) with a portable telemetric oxygen uptake analyzer ("K2", Cosmed, Rome). No statistically significant differences were found between direct measurements of VO2 and laboratory-derived estimates of energy consumption. The utilization of these two software provides a fast and reliable profile of job requirements and associated risks of musculoskeletal injury.