Alf Nachemson

A prospective study of work perceptions and psychosocial factors affecting the report of back injury

A longitudinal, prospective study was conducted on 3,020 aircraft employees to identify risk factors for reporting acute back pain at work. The premorbid data included individual physical, psychosocial, and workplace factors. During slightly more than 4 years of follow-up, 279 subjects reported back problems. Other than a history of current or recent back problems, the factors found to be most predictive of subsequent reports in a multivariate model were work perceptions and certain psychosocial responses identified on the Minnesota Multiphasic Personality Inventory (MMPI). Subjects who stated that they “hardly ever” enjoyed their job tasks were 2.5 times more likely to report a back injury (P = 0.0001) than subjects who “almost always” enjoyed their job tasks. The quintile of subjects scoring highest on Scale-3 (Hy) of the MMPI were 2.0 times more likely to report a back injury (P = 0.0001) than subjects with the lowest scores. The multivariate model, including job task enjoyment, MMPI Scale-3, and history of back treatment, revealed that subjects in the highest risk group had 3.3 times the number of reports in the lowest risk group. These findings emphasize the importance of adopting a broader approach to the multifaceted problem of back complaints in industry and help explain why past prevention efforts focusing on purely physical factors have been unsuccessful.

Disc pressure measurements.

By measurements of intradiscal pressure in vitro, the hydrostatic properties of the nucleus pulposus of normal lumbar intervertebral disc were proven. The hydrodynamic properties seem to exist also in the somewhat degenerated disc, but not in the more severely deranged ones. Intravitally-performed measurements of disc pressure over the last 20 years in more than 100 individuals have demonstrated how the load on the lumbar disc varies with the position of the subjects body and during the performance of various tasks, both in standing and in sitting. Compared with the pressure or load in the upright standing position, reclining reduces the pressure by 50–80%, while unsupported sitting increases the load by 40%, forward leaning and weight lifting by more than 100%, and the position of forward flexion and rotation by 400%. Large augmentations in pressure were also observed in subjects performing various commonly prescribed strengthening exercises.

Effectiveness of treatment with a brace in girls who have adolescent idiopathic scoliosis. A prospective, controlled study based on data from the Brace Study of the Scoliosis Research Society.

In a prospective study by the Scoliosis Research Society, 286 girls who had adolescent idiopathic scoliosis, a thoracic or thoracolumbar curve of 25 to 35 degrees, and a mean age of twelve years and seven months (range, ten to fifteen years) were followed to determine the effect of treatment with observation only (129 patients), an underarm plastic brace (111 patients), and nighttime surface electrical stimulation (forty-six patients). Thirty-nine patients were lost to follow-up, leaving 247 (86 per cent) who were followed until maturity or who were dropped from the study because of failure of the assigned treatment. The end point of failure of treatment was defined as an increase in the curve of at least 6 degrees, from the time of the first roentgenogram, on two consecutive roentgenograms. As determined with use of this end point, treatment with a brace failed in seventeen of the 111 patients; observation only, in fifty-eight of the 129 patients; and electrical stimulation, in twenty-two of the forty-six patients. According to survivorship analysis, treatment with a brace was associated with a success rate of 74 per cent (95 per cent confidence interval, 52 to 84) at four years; observation only, with a success rate of 34 per cent (95 per cent confidence interval, 16 to 49); and electrical stimulation, with a success rate of 33 per cent (95 per cent confidence interval, 12 to 60).(ABSTRACT TRUNCATED AT 250 WORDS)

The Lumbar Spine An Orthopaedic Challenge

The low-back pain problem reviewed in this paper represents a great challenge to orthopaedic surgeons around the world. Although in most instances a rather undramatic problem, low-back pain is, in patients aged 30 to 60 years, the most expensive ailment from a socio-economic viewpoint. The intervertebral disc is most likely the cause of the pain, but at present the etiology is unknown, and hence, for the majority of patients, only symptomatic treatment is available. So far no convincing evidence exists that any type of conservative treatment for the patient with low-back pain is superior to natures own course. The paramount importance of a correct preoperative diagnosis for those with sciatica due to disc herniation is reiterated. For 98% of patients, the present knowledge of the psychologic, social, and mechanical stress factors, which are described in this paper, should be utilized for proper counseling, together with attempts at correction with any type of noninvasive modality according to the preference of the individual physician.

A Consensus Approach Toward the Standardization of Back Pain Definitions for Use in Prevalence Studies

Study Design. A modified Delphi study conducted with 28 experts in back pain research from 12 countries. Objective. To identify standardized definitions of low back pain that could be consistently used by investigators in prevalence studies to provide comparable data. Summary of Background Data. Differences in the definition of back pain prevalence in population studies lead to heterogeneity in study findings, and limitations or impossibilities in comparing or summarizing prevalence figures from different studies. Methods. Back pain definitions were identified from 51 articles reporting population-based prevalence studies, and dissected into 77 items documenting 7 elements. These items were submitted to a panel of experts for rating and reduction, in 3 rounds (participation: 76%). Preliminary results were presented and discussed during the Amsterdam Forum VIII for Primary Care Research on Low Back Pain, compared with scientific evidence and confirmed and fine-tuned by the panel in a fourth round and the preparation of the current article. Results. Two definitions were agreed on a minimal definition (with 1 question covering site of low back pain, symptoms observed, and time frame of the measure, and a second question on severity of low back pain) and an optimal definition that is made from the minimal definition and add-ons (covering frequency and duration of symptoms, an additional measure of severity, sciatica, and exclusions) that can be adapted to different needs. Conclusion. These definitions provide standards that may improve future comparisons of low back pain prevalence figures by person, place and time characteristics, and offer opportunities for statistical summaries.

Loads on the lumbar spine. Validation of a biomechanical analysis by measurements of intradiscal pressures and myoelectric signals.

UNLABELLED We studied the validity of predictions of compressive loads on the lumbar spine and contraction forces in lumbar trunk muscles based on a biomechanical model. The predictions were validated by quantitative measurements of myoelectric activities at twelve locations on the trunk and of the pressure in the third lumbar disc. Twenty-five tasks were performed isometrically by four healthy volunteers. The model predicted that the tasks imposed mean compressive loads on the spine of as much as 2400 newtons and required contraction forces of the posterior muscles of the back of as much as 1800 newtons. Intradiscal pressures of as much as 1600 kilopascals were measured. The predicted and measured quantities were well correlated. It appears that the model adequately predicted the compressive loads on the lumbar spine and the tensions in the back muscles. CLINICAL RELEVANCE Patients with low-back disorders limit their physical activities, which indicates that loading on the spine must be a factor in those disorders. This study shows that the loads imposed on the spine by physical activities need not be measured. They can easily be calculated. This will significantly accelerate biomechanics research on low-back disorders. The calculation techniques that we validated for predicting loads on the spine can be used to calculate the loads on any skeletal structure. Those loads are largely determined not by the externally applied loads, but by the moments of those applied loads and by the moments of the weights of the body segments that the structure must support.

Newest knowledge of low back pain. A critical look.

Scientific scrutiny of the low back problem demonstrates its socioeconomic importance in most industrialized societies. Natural history studies reveal that the prognosis for the low back pain patient is excellent; for those with sciatica and painful spondylolisthesis it is good. It is even relatively good for those older patients with symptoms of spinal stenosis. Although today there is a better understanding of pain, the pathomechanism of low back pain is unknown. However, for patients with sciatica, spondylolisthesis, and spinal stenosis, physicians are beginning to get a better perception of what causes the pain. Psychosocial factors, including insurance benefits, have been demonstrated to be more important than biomechanical workload not only for acute but also for chronic low back pain patients who are unable to work. Orthopedic surgeons must recognize this fact when contemplating operations for patients with ill-defined back syndromes. Rarely are diagnoses scientifically valid, nor is the effectiveness of surgery proven by acceptable clinical trials.

Long-term anatomic and functional changes in patients with adolescent idiopathic scoliosis treated by Harrington rod fusion.

One hundred patients from the Gothenburg Scoliosis Data Base were studied. They met the following criteria: (1) adolescent idiopathic scoliosis (2) completion of treatment before age 20, (3) a minimum follow-up of five years thereafter, (4) a minimum age of 22 years at final follow-up, and (5) operation performed by the senior author. Of these, 95 were personally examined. The surgical technique from 1968 to 1973 included a two-stage Harrington distraction, with fusion added at the second operation (52 patients). From 1973 to 1975, 48 patients were treated with a one-stage distraction and fusion after a week of preoperative Cotrel traction. Postoperatively, all patients were treated with a Milwaukee brace. A spinal examination and functional assessment, including a questionnaire and pain drawing, full standing anterior–posterior (AP), and lateral roentgenograms of the spine, was performed by independent observers. Eighty-five subjects without scoliosis served as a control group. The radiographic evaluation showed the usual nearly 50% permanent correction at the follow-up examination averaging nine years postoperatively. Lateral roentgenograms, however, demonstrated in 52% flattened or kyphotic cervical spines producing no significant complaints, non-significant flattening of the thoracic kyphosis, but significant lowering of the lumbar lordosis. Fifteen of the 24 patients with distal hook insertion and fusion including L4 or L5 demonstrated retrolisthesis. All had significant low-back pain. Degenerative facet joint changes and disc space narrowing was noted in 11 patients, again with a distal hook purchase in L4 or L5. Compared to the controls, the operated patients, as a group, revealed no lessened activity or back pain at any location. The operated patients, the majority (76%) cosmetically pleased, functioned at the same level as age-matched controls in regard to marriage, child-bearing, sports activities, and job performance. Although, as a group, the operated patients were functionally and socially very well indeed, low-back pain was found statistically significantly more often in patients in whom fusion was carried down to L4 or L5, compared to the control subjects.

The bone mineral content and ultimate compressive strength of lumbar vertebrae.

The bone mineral content of 109 lumbar vertebrae from 36 different subjects was determined by dual photon absorptiometry. The mean age of the subjects was 58.5 years (range, 31 to 79 years). The ultimate strength of the vertebral bodies was determined during axial compression. Bone mineral content and ultimate compressive strength were correlated (r = 0.86) and the strength was found to increase linearly with increasing amounts of bone mineral content. No differences in this correlation were found in the four vertebral levels (L1–4) included in the study, but a difference in this correlation was found between specimens taken from male and female subjects. The results make it possible to estimate the strength of a vertebral body from the knowledge of its bone mineral content as determined by dual photon absorptiometry and provide a basis for estimations of normal and abnormal amounts of bone mineral content in the vertebrae of the lumbar spine.

Long-term follow-up of patients with untreated scoliosis. A study of mortality, causes of death, and symptoms.

The mortality and causes of death in 115 patients (80 women), born 1902–1937, with untreated scoliosis were compared to the expected according to official Swedish statistics. Subgrouping for cause and onset of scoliosis was done. Fifty-five patients had died; 21 of respiratory failure and 17 of cardiovascular diseases. The mortality was significantly (P < 0.001) increased. The increased risk was apparent at 40–50 years of age. The mortality was significantly increased in infantile (P < 0.001) and juvenile (P < 0.01) scoliosis but not in adolescent scoliosis. The mortality was also increased in post-polio scoliosis, scoliosis combined with rickets and scoliosis of unknown etiology indicating an increased mortality in idiopathic scoliosis. Among the surviving patients anti-hypertunsive treatment was frequent (23 of 50).