Journal of Back and Musculoskeletal Rehabilitation
ELSEVIER
Journal of Back and Musculoskeletal Rehabilitation 9 (1997) 11-14
Occupational back pain: then and now l.A.D. Anderson The Lanterns, II Dettrick Road, Edinburgh, Scotland EHIO 5BJ, UK
1. Historical background
2. SBPR influences
Before the Society for Back Pain Research was founded, studies in Scandinavia [1], Manchester [2] and Edinburgh [3] had reported that the prevalence of back pain in male workers was approximately 30%. More detailed studies indicated that the ratio of low back pain (LBP) to scapulohumeral pain (SlIP) was of the order of 3:1. It was also well established that the prevalence increased with age, was higher among those engaged in heavy tasks than light work, and also among those who had to adopt awkward postures for long periods. At that time the distribution of back pain syndromes throughout almost every section of the International Classification of Diseases (ICD) made consistency difficult and encouraged specialists from a wide range of clinical disciplines to classify back disorders according to their own nomenclatures and thus justify their numerous therapies - some of which were quite bizarre. Finally the attitude of the General Medical Council (GMC) to liaison between Registered Medical Practitioners and therapists who were not on their register meant that joint studies were difficult.
It would be wrong to suggest that the establishment of the SBPR corrected all these defects at a stroke. However, the society encouraged multidisciplinary discussion and research among all interested parties. Concurrently, there was a general arousing of interest in the problem both internationally and nationally. Thus the ninth revision of the ICD [4] improved on its predecessors in that conditions such as 'sciatica' and 'lumbar neuralgia', which had been classified with neurological diseases, were transferred with others to the general heading of 'dorsopathies' among the rubrics relating to rheumatic diseases (codes 720-724). Perhaps the most important groups excluded from the revision were those relating to congenital defects such as curvature of the spine. Also classified elsewhere were acute injuries; thus, unless a clear indication was given by certifying physicians that the condition was chronic, such diagnoses as sacro-iliac strain would be coded separately in any routinely presented data. The British Minister of Health contributed to the kindled interest by setting up the Cochrane Working Party. The first recommendation of its Report [5] was that 'further improvements in ser-
1053·8127/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reselVed. PH S 1053·8127(97)00040-7
12
J.A.D. Anderson / Journal of Back and Musculoskeletal Rehabilitation 9 (1997) 11-]4
vices can be planned rationally only when there is better understanding of the nature, occurrence and causes of back pain and of effective ways of modifying it. The Working Group recommends that sustained and increased support for research relevant to these areas is not only essential, but should command higher priority'. It is perhaps regrettable that, in view of such a clear recommendation and the jncreased funding which was available at the time, so many of the epidemiological studies published since the foundation of SBPR have done little more than reaffirm the previously well-known high prevalence rates of sickness absence in working populations. One nettle which SBPR might have grasped was to try and reach. agreement on definitions, not only in anatomical terms but also in relation to chronicity, having regard to the fact that many cases of back pain are self limiting and do not recur. On the more positive side, there is little doubt that the SBPR encouraged the studies of ergonomics and job analysis in relation to back pain in work forces. This was against a background of some 30 years ago when a meeting sponsored by the International Labour Organization [6] agreed that maximum weights to be lifted single handed should be 50 kg (25 kg for youths); this figure was suggested for straight lifts up to waist level with the load held close to the body. Later Chaffin and his colleagues developed the concept of Lift Strength Ratio, defined as the maximum load to be lifted, divided by the predicted strength of a large strong male in the same position [7]. They also postulated that compensation must be applied for weights held at a distance from the body axis or lifted above the horizontal. Although some might challenge the exact figures suggested by Chaffin as the lines of equivalent weight, few would argue with the underlying principle, which also has implications for the dimensions of the load to be lifted. Bulky packages are likely to have centres of gravity further removed from the body axis so that, weight for weight, bulky packages will impose greater demands on the supporting spine. These hypotheses can be sustained under
laboratory conditions. Indeed, Andersson [8], using manometers attached to needles lodged in the centres of intervertebral discs has shown that intra-abdominal pressure varies with intra-discal pressure and that both vary with the weights being lifted. He also demonstrated that posture affects these pressures. Clearly, observations using these laboratory techniques are not feasible at the workbench. Also, continuous visual observation is not only expensive but is likely to lead to changes in working habits of those being observed. Accordingly, continuous observation using less direct methods and suitable for most working situations were developed [9]. Paired surface electrodes were placed over the two lumbar muscle masses and inclinometers measuring antero-posterior and lateral flexion were fixed to the sacrum and upper lumbar spine. Simultaneous recordings of intra-abdominal pressure were obtained from a swallowed radio pressure pill. The apparatus could be worn continuously for work shifts of 8 h with data being fed to slow-running tape recorders carried on a belt, which also acted as a receiving aerial for the radio pills. The device had the advantage that an inexpensive mock up of the recorder and dummy radio pills could be used for several days before the definitive measurements were made so that workers got used to them and so were unaware of the exact day on which the active devices were being used. It was possible to identify jobs (or even tasks within jobs) which could prove hazardous in terms of LBP and recommend appropriate action. Thus the suggestion was made that a heavy lifting task should either be done by two men or a mechanical device be used. In a different setting, a checkout girl who was required to sit with a rotated spine for unduly long periods was asked to intersperse her time at the till with spells of tidying shelves. Such suggestions were made with 'evidence' to which both management and ·representatives of the workforce had equal access. Likewise both sides of industry could be satisfied that checks had been made on these particular hazards under the requirements of the Health and
J.A.D. Anderson / Journal of Back and Musculoskeletal Rehabilitation 9 (1997) 11-]4
Safety at Work Act (HSWA). Indeed, in one series of observations the recordings were at such variance with the job description, it was possible to identify an undesirable practice in relation to LBP [10]. 3. The future As stated above, numerical counts and sickness absence rates in different work forces are unlikely to advance knowledge significantly - particularly without agreement about definitions or the inclusion of those forced to leave jobs on health grounds. Accordingly, the SBPR should discourage such unproductive research. However, the report by Kaligh and Wood [11] into regional differences in Britain could well be worth further consideration. Future studies of job analysis may well be useful in persuading both sides of industry that checks have been made in relation to the HSWA and possibly reduce frivolous litigation. It would appear that further research based on environmental aspects of occupational back pain are likely to be limited in their usefulness. Accordingly, other aspects need to be explored, including the personal side, by seeking to identify those at high risk of developing back pain and steering them away from heavy jobs with awkward postures. However, this also is a potential disaster area in real terms. Thus Kosiak [12], nearly 30 years ago, claimed apparent success by recommending the exclusion of those with suspicious X-rays from heavy employment. The reduction in back pain days saved the employers money but this was at a cost in human terms of denying employment to 1181 out of 4103 applicants (an exclusion rate of 29%). The use of other screening tests such as spinal stenosis [13], capillary fragility [14], spinal curvature [15] or spondylolisthesis [16] to determine risk are unlikely to be specific enough for practical application for some years yet. Deyo [17] has thrown down the gauntlet by enquiring about the need for a new research paradigm and the recent supplement to Spine, introduced by Andersson and Weinstein [18], has several challenging papers including the need for properly controlled clinical trials. Perhaps this
13
should be the way forward. However, it must be conceded that prolonged intervention studies of the kind outlined would be expensive to launch and difficult to sustain. Even the HSWA and the increased tendency to litigation are unlikely to justify the costs of such clinical trials in the workplace for what is, after all, a non-fatal syndrome. It may be that the debate this afternoon will explore some of these issues. However, if nothing new transpires then the recent comment by Larsson [19], that back pain disorders are the nemesis of medicine and the albatross of industry, will continue to be justified. References [1] Kellgren JH, Lawrence JS, Aitken-Swann J. Rheumatic complaints in an urban population. Ann Rheum Dis 1969;28:121-138. [2] Magora A. Investigation of the relationship between low back pain and occupation I. Ind Med Surg 1970;39:465-47l. [3] Anderson JAD. Rheumatism in industry: a review. Br J Ind Med 1971;28:103-12l. [4] World Health Organization. International classification of diseases, 9th revision. London: HMSO, 1977. [5] Dept. of Health and Social Security. Working Group on Back Pain (Chairman: A. Cochrane). London: DHSS, 1979. [6] International Labour Organisation. Maximum weight regulations. Geneva: ILO, 1967. [7] Chaffin DB. Manual materials handling. J Environ Pathol ToxicoI1979;2:31-66. [8] Andersson CBJ, Ortengen R, Nachemson A. Intradiskal pressure, intraabdominal pressure and myoelectric back muscle activity related to posture and loading. Clin Orthop 1989;129:156-164. [9] Otun EO, Anderson JAD, Heinrich I, O'Hare H. Back pain: aspects of measurement. In: Brothwood J, editor. Proceedings of the Society for Occupational Medicine. London: SOM 1984;40-44. [10] Anderson JAD. Dorsopathies. Bailliere's Clin RheumatoI1987;1:561-582. [11] Kaligh PJ, Wood PHN. Arthritis and Rheumatism in the Eighties. London: Arthritis and Rheumatism Council, 1986. [12] Kosiak M, Aurelius JR, Hartfiel WF. The low back problem. J Occup Med 1969;10:588-593. [13] Porter R, Wicks M, Ottewell D. Measurement of the spinal canal by diagnostic ultrasound. J Bone Jnt Surg (Br) 1978;60:481-484. [14] Sweetman BJ, Anderson JAD. Capillary resistance and back pain. Rheumatol Rehabil 1975;14:1-6.
14
!A.D. Anderson / Journal of Back and Musculoskeletal Rehabilitation 9 (J997) ]]-14
Dickson R, Coates R, Duthie R. Report on School Screening for Scoliosis. Oxford: Department of Orthopedics, University Oxford, 1980. [16] Wiltse JJ. Surgery for intervertebral disk disease. Clin Orthop 1977;129:22-45. [t 7] Deyo RA. Practice variations, treatment fads, rising disability. Spine 1993;18:2153-2162. [15]
Andersson OBJ, Weinstein IN. Introduction, health outcomes related to low back pain. Spine 1994;18:2026-2027 (Suppi). [19] Larsson L-O, Mudhockar OS, Baurn J, Srivastava DK. Benefits and liabilities of hyperrnobility in the back pain disorders of industrial workers. J Int Med [18]
1995;238:461-467.
ELSEVIER
Journal of Back and Musculoskeletal Rehabilitation 9 (1997) 11-14
Occupational back pain: then and now l.A.D. Anderson The Lanterns, II Dettrick Road, Edinburgh, Scotland EHIO 5BJ, UK
1. Historical background
2. SBPR influences
Before the Society for Back Pain Research was founded, studies in Scandinavia [1], Manchester [2] and Edinburgh [3] had reported that the prevalence of back pain in male workers was approximately 30%. More detailed studies indicated that the ratio of low back pain (LBP) to scapulohumeral pain (SlIP) was of the order of 3:1. It was also well established that the prevalence increased with age, was higher among those engaged in heavy tasks than light work, and also among those who had to adopt awkward postures for long periods. At that time the distribution of back pain syndromes throughout almost every section of the International Classification of Diseases (ICD) made consistency difficult and encouraged specialists from a wide range of clinical disciplines to classify back disorders according to their own nomenclatures and thus justify their numerous therapies - some of which were quite bizarre. Finally the attitude of the General Medical Council (GMC) to liaison between Registered Medical Practitioners and therapists who were not on their register meant that joint studies were difficult.
It would be wrong to suggest that the establishment of the SBPR corrected all these defects at a stroke. However, the society encouraged multidisciplinary discussion and research among all interested parties. Concurrently, there was a general arousing of interest in the problem both internationally and nationally. Thus the ninth revision of the ICD [4] improved on its predecessors in that conditions such as 'sciatica' and 'lumbar neuralgia', which had been classified with neurological diseases, were transferred with others to the general heading of 'dorsopathies' among the rubrics relating to rheumatic diseases (codes 720-724). Perhaps the most important groups excluded from the revision were those relating to congenital defects such as curvature of the spine. Also classified elsewhere were acute injuries; thus, unless a clear indication was given by certifying physicians that the condition was chronic, such diagnoses as sacro-iliac strain would be coded separately in any routinely presented data. The British Minister of Health contributed to the kindled interest by setting up the Cochrane Working Party. The first recommendation of its Report [5] was that 'further improvements in ser-
1053·8127/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reselVed. PH S 1053·8127(97)00040-7
12
J.A.D. Anderson / Journal of Back and Musculoskeletal Rehabilitation 9 (1997) 11-]4
vices can be planned rationally only when there is better understanding of the nature, occurrence and causes of back pain and of effective ways of modifying it. The Working Group recommends that sustained and increased support for research relevant to these areas is not only essential, but should command higher priority'. It is perhaps regrettable that, in view of such a clear recommendation and the jncreased funding which was available at the time, so many of the epidemiological studies published since the foundation of SBPR have done little more than reaffirm the previously well-known high prevalence rates of sickness absence in working populations. One nettle which SBPR might have grasped was to try and reach. agreement on definitions, not only in anatomical terms but also in relation to chronicity, having regard to the fact that many cases of back pain are self limiting and do not recur. On the more positive side, there is little doubt that the SBPR encouraged the studies of ergonomics and job analysis in relation to back pain in work forces. This was against a background of some 30 years ago when a meeting sponsored by the International Labour Organization [6] agreed that maximum weights to be lifted single handed should be 50 kg (25 kg for youths); this figure was suggested for straight lifts up to waist level with the load held close to the body. Later Chaffin and his colleagues developed the concept of Lift Strength Ratio, defined as the maximum load to be lifted, divided by the predicted strength of a large strong male in the same position [7]. They also postulated that compensation must be applied for weights held at a distance from the body axis or lifted above the horizontal. Although some might challenge the exact figures suggested by Chaffin as the lines of equivalent weight, few would argue with the underlying principle, which also has implications for the dimensions of the load to be lifted. Bulky packages are likely to have centres of gravity further removed from the body axis so that, weight for weight, bulky packages will impose greater demands on the supporting spine. These hypotheses can be sustained under
laboratory conditions. Indeed, Andersson [8], using manometers attached to needles lodged in the centres of intervertebral discs has shown that intra-abdominal pressure varies with intra-discal pressure and that both vary with the weights being lifted. He also demonstrated that posture affects these pressures. Clearly, observations using these laboratory techniques are not feasible at the workbench. Also, continuous visual observation is not only expensive but is likely to lead to changes in working habits of those being observed. Accordingly, continuous observation using less direct methods and suitable for most working situations were developed [9]. Paired surface electrodes were placed over the two lumbar muscle masses and inclinometers measuring antero-posterior and lateral flexion were fixed to the sacrum and upper lumbar spine. Simultaneous recordings of intra-abdominal pressure were obtained from a swallowed radio pressure pill. The apparatus could be worn continuously for work shifts of 8 h with data being fed to slow-running tape recorders carried on a belt, which also acted as a receiving aerial for the radio pills. The device had the advantage that an inexpensive mock up of the recorder and dummy radio pills could be used for several days before the definitive measurements were made so that workers got used to them and so were unaware of the exact day on which the active devices were being used. It was possible to identify jobs (or even tasks within jobs) which could prove hazardous in terms of LBP and recommend appropriate action. Thus the suggestion was made that a heavy lifting task should either be done by two men or a mechanical device be used. In a different setting, a checkout girl who was required to sit with a rotated spine for unduly long periods was asked to intersperse her time at the till with spells of tidying shelves. Such suggestions were made with 'evidence' to which both management and ·representatives of the workforce had equal access. Likewise both sides of industry could be satisfied that checks had been made on these particular hazards under the requirements of the Health and
J.A.D. Anderson / Journal of Back and Musculoskeletal Rehabilitation 9 (1997) 11-]4
Safety at Work Act (HSWA). Indeed, in one series of observations the recordings were at such variance with the job description, it was possible to identify an undesirable practice in relation to LBP [10]. 3. The future As stated above, numerical counts and sickness absence rates in different work forces are unlikely to advance knowledge significantly - particularly without agreement about definitions or the inclusion of those forced to leave jobs on health grounds. Accordingly, the SBPR should discourage such unproductive research. However, the report by Kaligh and Wood [11] into regional differences in Britain could well be worth further consideration. Future studies of job analysis may well be useful in persuading both sides of industry that checks have been made in relation to the HSWA and possibly reduce frivolous litigation. It would appear that further research based on environmental aspects of occupational back pain are likely to be limited in their usefulness. Accordingly, other aspects need to be explored, including the personal side, by seeking to identify those at high risk of developing back pain and steering them away from heavy jobs with awkward postures. However, this also is a potential disaster area in real terms. Thus Kosiak [12], nearly 30 years ago, claimed apparent success by recommending the exclusion of those with suspicious X-rays from heavy employment. The reduction in back pain days saved the employers money but this was at a cost in human terms of denying employment to 1181 out of 4103 applicants (an exclusion rate of 29%). The use of other screening tests such as spinal stenosis [13], capillary fragility [14], spinal curvature [15] or spondylolisthesis [16] to determine risk are unlikely to be specific enough for practical application for some years yet. Deyo [17] has thrown down the gauntlet by enquiring about the need for a new research paradigm and the recent supplement to Spine, introduced by Andersson and Weinstein [18], has several challenging papers including the need for properly controlled clinical trials. Perhaps this
13
should be the way forward. However, it must be conceded that prolonged intervention studies of the kind outlined would be expensive to launch and difficult to sustain. Even the HSWA and the increased tendency to litigation are unlikely to justify the costs of such clinical trials in the workplace for what is, after all, a non-fatal syndrome. It may be that the debate this afternoon will explore some of these issues. However, if nothing new transpires then the recent comment by Larsson [19], that back pain disorders are the nemesis of medicine and the albatross of industry, will continue to be justified. References [1] Kellgren JH, Lawrence JS, Aitken-Swann J. Rheumatic complaints in an urban population. Ann Rheum Dis 1969;28:121-138. [2] Magora A. Investigation of the relationship between low back pain and occupation I. Ind Med Surg 1970;39:465-47l. [3] Anderson JAD. Rheumatism in industry: a review. Br J Ind Med 1971;28:103-12l. [4] World Health Organization. International classification of diseases, 9th revision. London: HMSO, 1977. [5] Dept. of Health and Social Security. Working Group on Back Pain (Chairman: A. Cochrane). London: DHSS, 1979. [6] International Labour Organisation. Maximum weight regulations. Geneva: ILO, 1967. [7] Chaffin DB. Manual materials handling. J Environ Pathol ToxicoI1979;2:31-66. [8] Andersson CBJ, Ortengen R, Nachemson A. Intradiskal pressure, intraabdominal pressure and myoelectric back muscle activity related to posture and loading. Clin Orthop 1989;129:156-164. [9] Otun EO, Anderson JAD, Heinrich I, O'Hare H. Back pain: aspects of measurement. In: Brothwood J, editor. Proceedings of the Society for Occupational Medicine. London: SOM 1984;40-44. [10] Anderson JAD. Dorsopathies. Bailliere's Clin RheumatoI1987;1:561-582. [11] Kaligh PJ, Wood PHN. Arthritis and Rheumatism in the Eighties. London: Arthritis and Rheumatism Council, 1986. [12] Kosiak M, Aurelius JR, Hartfiel WF. The low back problem. J Occup Med 1969;10:588-593. [13] Porter R, Wicks M, Ottewell D. Measurement of the spinal canal by diagnostic ultrasound. J Bone Jnt Surg (Br) 1978;60:481-484. [14] Sweetman BJ, Anderson JAD. Capillary resistance and back pain. Rheumatol Rehabil 1975;14:1-6.
14
!A.D. Anderson / Journal of Back and Musculoskeletal Rehabilitation 9 (J997) ]]-14
Dickson R, Coates R, Duthie R. Report on School Screening for Scoliosis. Oxford: Department of Orthopedics, University Oxford, 1980. [16] Wiltse JJ. Surgery for intervertebral disk disease. Clin Orthop 1977;129:22-45. [t 7] Deyo RA. Practice variations, treatment fads, rising disability. Spine 1993;18:2153-2162. [15]
Andersson OBJ, Weinstein IN. Introduction, health outcomes related to low back pain. Spine 1994;18:2026-2027 (Suppi). [19] Larsson L-O, Mudhockar OS, Baurn J, Srivastava DK. Benefits and liabilities of hyperrnobility in the back pain disorders of industrial workers. J Int Med [18]
1995;238:461-467.
