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Objectives: The aims of the study were to analyze muscular strain and fatigue of urologists during the performance of transurethral resections using direct and video endoscopy and to reduce the muscular effort by an ergonomic arrangement of the operation equipment., Methods: The study was performed before, during and after the introduction of a video-guided resection method. Muscular strain and fatigue were studied by means of surface electromyograms derived from various shoulder and back muscles of surgeons., Results: During direct endoscopy, muscular strain was found to be significantly higher for the shoulder muscles than during monitor endoscopy. The occurrence of muscular fatigue was established for at least one of the muscles under test in all operations during the application of direct endoscopy. A routine use of the video method was facilitated by arranging the operation equipment according to ergonomic principles. This results in a reduction in muscular fatigue, in particular for the trapezius muscle. For this muscle the number of operations accompanied with fatigue was lowered from about 80% before redesign to about 42% after redesign., Conclusion: Muscular strain and fatigue of urologists occurring during transurethral resections is reduced by applying video endoscopy instead of using direct endoscopy. The routine use of the video method requires an ergonomic arrangement of the operation equipment.

An electromyographical fatigue analysis was performed in the operating theatre on four surgeons during 14 urological operations in which 'direct endoscopy' (cf. Luttmann et al. 1996, Part I) was applied. Surface electromyograms (EMG) were derived from the m. trapezius on both sides of the body, the right m. deltoideus, and the left m. erector spinae. The surgeons' activities were documented by simultaneously recording an electrical activity code signal parallel to the EMGs. The electrical activity (EA) was formed from the raw EMG by rectification and continuous averaging. For purposes of spectral analysis, the EMGs were digitized and converted to the frequency domain by Fast Fourier Transformation. During the performance of endoscopic surgery, an increase in EA, as well as a spectral shift towards lower frequencies, are observed for at least one of the muscles under test in all of the operations. This indicates the development of muscular fatigue in the course of the operations. The finding is confirmed by applying a newly developed method for the joint analysis of the spectrum and the amplitude of EMGs (JASA) which permits discrimination between fatigue-induced and force-related changes in the EMG. Utilizing this method, the development of fatigue was confirmed for 11 of the 14 operations in the case of the right m. trapezius. The right trapezius muscle therefore constitutes a bottleneck for the performance of the operations. The endurance time was estimated from the increase in EA and compared with the actual duration of the operations. Since both are of the same order of magnitude, it is concluded that the final part of an operation has to be performed when the muscles are already fatigued. Application of the newly available method known as 'monitor endoscopy' (cf. Part I) can lead to a reduction in muscular strain and fatigue. This, in turn, will enable operations to be performed at less risk to the patient.

An electromyographical field study was performed in the operating theatre on four surgeons during 15 urological operations. In the course of the operations two endoscopic techniques were applied alternately: (1) direct endoscopy, and (2) monitor endoscopy. During direct endoscopy the surgeon looks into the urethra and the bladder via an endoscope. In monitor endoscopy, by contrast, the operating area is observed via a video system consisting of a camera mounted on top of the endoscope and a monitor. During the operations surface electromyograms were derived from both trapezius muscles, the right deltoideus muscle and the left erector spinae muscle. An activity code describing the surgeons' activity was additionally recorded. Analysis of the activity recording reveals that the monitor endoscopic method is preferred in the first third of the operations, whereas preference is given to the direct method in the last third. The electromyographical measurements indicate that during monitor endoscopy the myoelectrical activity of both trapezius muscles and of the right deltoideus muscle is significantly reduced in comparison with the activity for the direct endoscopic technique. A significant influence of the surgical technique on the myoelectrical activity could not be established for the erector spinae muscle. The electromyographical findings reveal that the activity of the shoulder musculature required for the maintenance of the posture and the performance of the operation is significantly lower in monitor endoscopy than in direct endoscopy. Consequently, a clear reduction in muscular strain can be achieved during the performance of endoscopic operations in urology if a video system is employed.

In the terminology of occupational hygiene and the WAO no distinction has been made to date between "load" and "strain". Occupational medicine and ergonomics by contrast, in addition to differentiating between the terms, have been developing the "load-strain approach" since about 1970. After outlining the historical development of the terms and explaining them, the approach is derived and presented in a simple and extended form. Starting from demands made by the WAO, the significance of the approach for the planning and execution of ergonomic investigations is explained. In the approach differentiation between the "description", "assessment" and "judgement" of working conditions is recommended. Possible approaches and criteria for forming a judgment are presented and discussed, with special attention being paid to models for the operationalization of strain. A concept for pragmatic judgment is presented after discussion about the necessity, frequently encountered in practice, of balancing the demands of providing scientific proof and of arriving at decisions relevant to practical problems.

Material handling tasks result in high load on the skeletal system. Long-term employment in transportation jobs may therefore cause a high frequency of orthopaedic diseases, particularly in the spinal region. An epidemiological study was performed on employees from a large company in order to test this hypothesis. The medical history of 249 male transport workers was examined by means of statistical analysis of the orthopaedic diseases documented in the record file of their company's health service. For purposes of comparison, the same data evaluation was performed for an age-matched reference group consisting of 267 persons chosen randomly from among the male employees in the same company. The proportion of persons with orthopaedic diseases amounts to 77.1% among the transport workers and 62.9% among the reference persons. It is consequently 1.22 times higher for the transport workers than for the reference persons ("rate ratio RR" = 1.22). The greatest part of all orthopaedic diseases affects the spine. Within the spine, the lumbar region is the most frequently damaged. Both for the totality of all spinal sections as well as for diseases of particular spinal sections (cervical, thoracic, lumbar spine), the proportion of the transport workers with diseases is higher than that of the reference persons (RR between 1.20 and 1.36). The proportion of persons with spinal diseases increases with age in both groups. There is no observable difference between the groups with regard to the frequency of persons with degenerative diseases.(ABSTRACT TRUNCATED AT 250 WORDS)