56 Clin. Biomech. 1986; 1: No 1

position change. This should be considered by practitioners who consider these measurements to be objective evidence for demonstrating the results of chiropractic adjustments.

Sigler DC, Howe JW. J Manip Physiol Ther 1985; 6: X-80

Pain due to nerve injury Some of the chronic pains that follow disc rupture, myelography, and discectomy may be due to injury to peripheral nerves or nerve roots. The neural mechanisms underlying these pain syndromes are discussed and possible etiologies examined. The roles of peripheral and central changes in neuronal activity and connectivity are explored: plasticity in the nervous system may either be the cause of pain in the 5% of people who develop chronic pain after nerve injury or what prevents pain in the 95% who do not become painful after nerve injury. More research on the behavior of damaged nerves and their central connections is essential.

Loeser JD. Spine 1985; 10: 232-5

A fibrinolytic defect in chronic back pain syndromes Blood fibrinolytic activity was measured in 18 subjects with severe chronic back pain and 18 age and sex matched controls. The patients showed evidence of defective fibrinolysis-namely, significant prolongation of the euglobulin clot-lysis time, reduction in fibrin-plate lysis-area and plasminogen levels, and increase in levels of the fibrinolytic inhibitors a2 antiplasmin and a2 macroglobulin. This defect could be associated with fibrin deposition and scar formation and be responsible for the development and/or perpetuation of chronic inflammation and scarring at sites of damage in the spine. Enhancement of fibrinolytic activity may offer a new approach to the management of these back problems, and a double-blind controlled trial is in progress.

Jayson MIV, Keegan A, Million R. Tomlinson I. Lancet 1984; ii: 11867

ERGONOMICS

Trunk posture and trapezius muscle load while working in standing, supported-standing, and sitting positions A study of standing, supported-standing (‘riding’ on a rounded seat), and sitting postures was carried out on persons simulating assembly work in places with poor leg space. These postures and the upper trapezius muscle load were examined using statometric and electromyographic methods, respectively. While supported-standing or sitting, the lumbar spine moved toward kyphosis, even where there was no backward rotation of the pelvis. In adopting the position for anteriorly placed work, the upper arms were raised 30” forward or more; then, if a greater reach was necessary, the trunk was flexed as well. It is concluded that if leg space is poor, variation between supported-standing and standing should be encouraged, and an ordinary oftice chair avoided. Working level should be arranged so that it is lower than 5 cm above elbow level if no arm/wrist support is possible.

Bendix T, Krohn L, Jessen F, Aards A. Spine 1985; 10: 433-9

Metabolic costs of stoopwalking and crawling This paper is a study of the metabolic costs of crawling and stoopwalking as performed by trained male and female

subjects. After training, male and female subjects crawled and stoopwalked at a range of task speeds and in task postures set at 100,90,80,70, and 60% of each subject’s erect stature. It was found that as the task posture became more stooped, or the task speed increased, there were marked increases in metabolic cost. Further analysis found these increases to be due to the task speed within a posture rather than from the task posture. It was also found that in some task postures, the combination of speed and posture resulted in metabolic costs of performance which would be limiting in terms of non-fatigued task performance time.

Morrissey SJ, George CE, Ayoub MM. Appl Erg 1985; 16: 99-102

The automated Hettinger test in the diagnosis and prevention of repetition strain injuries The Hettinger test measures changes in skin temperature following vibration of the hand. The test was evaluated on 67 people from light manufacturing and office jobs, and was found to separate the groups of known repetition injured and known repetition uninjured, with 90% accuracy. The high accuracy of the test in diagnosis suggests that physiological factors are very important in the development of these injuries. The test appears to measure a constitutional factor rather than or in addition to injury symptoms. as it identified healed as well as current injuries. The test score of individuals appears to identify their relative susceptibility to injury. Highly susceptible individuals are injured on jobs that are safe for most people. Such people need far more careful treatment than more robust individuals. and may require susceptibility reduction procedures in addition to job redesign. Attention given to susceptibility identification and reduction may yield substantial benefits in reducing injuries from repetitive work.

Brown DA. Coyle IR, Beamont PE. Appl Erg 1985; 16: 113-8

Electromyography as an aid in the prevention of excessive shoulder strain Disorders in the musculo-skeletal system constitute the most common reasons for lowered working capacity and sick-leave in the engineering industry. The symptoms are often located in the neck-shoulder-arm and are greatly influenced by unfavourable muscle loads. A method for the routine study 01 muscular activity has been developed and tested for the purpose of reducing the risk of such work-related disorders. This method is based on the application of an electromyographic (EMG) technique and is primarily intended to facilitate the ergonomic assessment and the selection of alternative work postures.

The tests performed confirm that EMG studies, in a simplified version for the shop-floor, may constitute a valuable aid for an objective analysis. They demonstrate that the EMG equipment used offers good possibilities to detect differences in muscle load in different work postures and that it meets the requirements for rapid presentation of the measured values. a simple analysis procedure, use on the shop-floor and simple handling.

GranstrGm B, Kvarnstrom S. Tiefenbacher F. Appl Erg 1985; 16: 49-54