Showing papers in "Spine in 1984"
TL;DR: The main findings were that good isometric endurance of the back muscles may prevent first-time occurrence of LBT in men and that men with hypermobile backs are more liable to contract LBT.
Abstract: Of all 30-, 40-, 50-, and 60-year-old inhabitants of Glostrup, a suburb of Copenhagen, 82% (449 men and 479 women) participated in a general health survey, which included a thorough physical examination relating to the lower back. The examination was constituted of anthropometric measurements, flexi
1,345 citations
TL;DR: To study the type and number of CAT scan abnormalities of the lumbar spine that occur in asymptomatic people, 52 studies from a control population with no history of back trouble were mixed randomly with six scans from patients with surgically proven spinal disease, and all were interpreted by three neuroradiologists in a blinded fashion.
Abstract: In order to study the type and number of CAT scan abnormalities of the lumbar spine that occur in asymptomatic people, 52 studies from a control population with no history of back trouble were mixed randomly with six scans from patients with surgically proven spinal disease, and all were interpreted
710 citations
TL;DR: This biomechanical study investigates the altered kinematics and biomechanics of the three different types of spinal fusion (posterior, bilateral-lateral, and anterior) on the adjacent, unfused segment as well as within the fused segment and to investigate their clinical implications.
Abstract: The effects of spinal fusion on fused segment and the adjacent, unfused segments play a significant role in the clinical effectiveness of spinal fusion for low-back pain with or without sciatica. Much of the information on this important subject is derived from clinical impressions. The purpose of this biomechanical study is to investigate the altered kinematics and biomechanics of the three different types of spinal fusion (posterior, bilateral-lateral, and anterior) on the adjacent, unfused segment as well as within the fused segment and to investigate their clinical implications. Sixteen fresh human cadaver lumbosacral spines were tested under a simulated physiologic loading condition. The test specimens included three motion segments, L3-4, L4-5, and L5-S1. To study the mechanics of the lumbar spine under combined compression and bending loads, a special apparatus was designed. These loads were applied by an MTS machine through two sets of pulley systems. The loads, as well as displacement data from both actuators, were recorded. A video camera system was utilized to record the kinematics of the spinal motion segment. The unfused specimen was tested first, and the fused specimen then was retested under the identical loading conditions. A total of 16 spine specimens were tested and evaluated--five posterior, four bilateral-lateral, and seven anterior fusions. All types of fusion resulted in increased bending and axial stiffnesses. Overall, anterior fusion provided the largest increase in stiffness, followed by bilateral-lateral fusion and posterior fusion.(ABSTRACT TRUNCATED AT 250 WORDS)
496 citations
TL;DR: The mechanism for the transmission of axial load across a facet joint is established and a facet-related hypothesis for low-back pain is proposed, which is a stiffening spring in compression and weak in tension.
Abstract: Low-back pain has a complex and multi-faceted etiology. The articular facets have been shown to be load-bearing structures and may be a site for low-back pain. The aim of this paper is to establish the mechanism for the transmission of axial load across a facet joint and to propose a facet-related h
484 citations
TL;DR: The anatomy and physiology of the nerve root complex in the lumbar spine are reviewed, with special reference to the effects of mechanical deformation of nerve roots in association with intervertebral disc herniation and spinal stenosis.
Abstract: The anatomy and physiology of the nerve root complex in the lumbar spine are reviewed, with special reference to the effects of mechanical deformation of nerve roots in association with intervertebral disc herniation and spinal stenosis. Biomechanical aspects of nerve root deformation induced by compression are discussed. The functional changes induced by compression can be caused by mechanical nerve fiber deformation but also may be a consequence of changes in nerve root microcirculation, leading to ischemia and formation of intraneural edema. Nerve root compression can, by different neurophysiologic mechanisms, induce motor weakness and altered sensibility or pain. Intraneural edema and demyelination seem to be critical factors for the production of pain in association with nerve root compression.
464 citations
TL;DR: A general three-dimensional finite element program has been developed and applied for the analysis of the lumbar L2-3 disc-body unit and results indicate that for a normal disc with an incompressible nucleus, the most vulnerable elements under compressive load are the cancellous bone and the end-plate adjacent to the nucleus space.
Abstract: It has been argued that a clarification of the mechanical causes of low-back pain requires a knowledge of the states of stress and strain throughout the lumbo-sacral spine. Since a purely experimental approach cannot provide this information, analytical model studies, to supplement measurements, are called for. In the present study, a general three-dimensional finite element program has been developed and applied for the analysis of the lumbar L2-3 disc-body unit. The analysis accounts for both the material and the geometric nonlinearities and is based on a representation of the annulus as a composite of collagenous fibers embedded in a matrix of ground substance. The geometry of the model analyzed is based on in vitro measurements. The validity of the model and the analysis procedure has been established by a comparison of those predictions that are also amenable to direct measurements, eg, the response of the disc-body unit to compressive load in terms of axial displacement, disc bulge, end-plate bulge, and intradiscal pressure. The states of stress and strain have then been computed in the cancellous bone, cortical shell, and the subchondral endplate of the intervertebral body and in the annulus fibers and ground substance of the disc when the unit is subjected to a compressive load. The results indicate that for a normal disc with an incompressible nucleus, the most vulnerable elements under compressive load are the cancellous bone and the end-plate adjacent to the nucleus space. On the other hand, for a degenerated disc, simulated in an extreme fashion by assuming it to be void of the nucleus, the analysis predicts the annulus bulk material to be also susceptible to failure. The annulus fibers do not appear to be vulnerable to rupture when the disc-body unit is subjected to pure compressive force.
458 citations
TL;DR: The results of 146 patients with anterior cervical intervertebral disc removal and fusions are reviewed and it is found that none of the patients thought they were made worse by surgery.
Abstract: The results of 146 patients with anterior cervical intervertebral disc removal and fusions are reviewed. The diagnosis was cervical spondylosis in 75%, disc protrusion in 16%, and spondylosis at one level with disc protrusions at another in 9%. There were 81 women and 65 men with an average age of 48 +/- 9 years. The average follow-up was 5 +/- 3.3 years. The rate of fusion was 97%. Complete pain relief occurred in 78%, partial in 18% and little or no pain relief in 4%. There were no serious complications, and none of the patients thought they were made worse by surgery.
433 citations
TL;DR: A new classification of lumbosacral transitional vertebra is presented based upon the morphologic and clinical characteristics with respect to herniated nucleus pulposus based on patients with positive myelographic findings of herniate lumbar disc.
Abstract: The relationship between herniated lumbar disc and abnormalities of the transverse process of the lumbosacral junction was investigated. Two hundred consecutive patients with positive myelographic findings of herniated lumbar disc were reviewed. Sixty patients presented abnormalities of the transverse process to satisfy the criteria for lumbosacral transitional vertebra. A new classification of lumbosacral transitional vertebra is presented based upon the morphologic and clinical characteristics with respect to herniated nucleus pulposus. Type I represents a "forme fruste" of lumbosacral transitional vertebra and shows no difference in the incidence of the location of herniations. In types III and IV, there are no herniations at the level of the lumbosacral transitional vertebra and no increase in the incidence of herniations just proximal to the lumbosacral transitional vertebra. The Type II lumbosacral transitional vertebra presents herniated lumbar disc at the level of transition. It also presents a greater than normal incidence of herniations at the level just above the lumbosacral transitional vertebra.
431 citations
TL;DR: Biplanar radiography was used to assess the normal three-dimensional movements of the lumbar spine in the erect posture in a group of asymptomatic volunteers, showing all the intervertebral joints had more movement in flexion than extension from the upright position.
Abstract: Biplanar radiography was used to assess the normal three-dimensional movements of the lumbar spine in the erect posture in a group of asymptomatic volunteers. The primary movements investigated were flexion and extension, while the three-dimensional analysis also measured any associated coupled lateral bends and axial rotations. The results showed that each intervertebral joint had a total range of flexion and extension of approximately 14 degrees, the lower levels moving slightly more than the upper levels. All the intervertebral joints had more movement in flexion than extension from the upright position, except for the L5/S1 joint, which showed no consistent pattern, some subjects extending more than flexing. Coupled movements of 4 degrees or more in flexion and 3 degrees or more in extension were shown to be abnormal.
388 citations
TL;DR: Measurements in vivo demonstrated that there was no simple mechanical coupling of the rotations, and that the lordotic shape of the lumbar spine together with muscular control are probably the two principal factors determining the relation between the primary and accompanying rotations.
Abstract: A three-dimensional radiographic technique was used to investigate the ranges of active axial rotation and lateral bending plus the accompanying rotations in the planes other than that of the primary voluntary movements in two groups of normal male volunteers. There was approximately 2 degrees of axial rotation at each intervertebral joint with L3-4 and L4-5 being slightly more mobile. Lateral bending of approximately 10 degrees occurred at the upper three levels, while there was significantly less movement of 6 degrees and 3 degrees at L4-5 and L5-S1, respectively. In the upper lumbar spine, axial rotation to the right was accompanied by lateral bending to the left and vice versa. At L5-S1, axial rotation and lateral bending generally accompanied each other in the same direction, while L4-5 was a transitional level. These measurements in vivo demonstrated that there was no simple mechanical coupling of the rotations, and that the lordotic shape of the lumbar spine together with muscular control are probably the two principal factors determining the relation between the primary and accompanying rotations.
372 citations
TL;DR: The authors have calculated the mathematic relationship between measured elements of illness behavior in chronic low-back pain and the most important psychologic disturbance in low- back pain is emotional distress.
Abstract: The authors have calculated the mathematic relationship between measured elements of illness behavior in chronic low-back pain. Objective physical impairment accounts for about one-half the total disability that also is affected by psychologic reactions. The most important psychologic disturbance in
TL;DR: Physical Impairment and disability are defined, simple clinical methods of assessing them in low-back disorders are described, and the relationship between them analyzed.
Abstract: Physical impairment and disability are defined, simple clinical methods of assessing them in low-back disorders are described, and the relationship between them analyzed.
TL;DR: A simple, single inclinometer modification of the method of Loebl is presented, which offers the opportunity to separate the components of the compound motion of hip and spine.
Abstract: Quantitative measures of physical function (range of motion, strength, stability) are critical to musculoskeletal care of the extremities, yet such objective measures in the spine are currently unavailable. In this paper, the authors present a simple, single inclinometer modification of the method of Loebl, which offers the opportunity to separate the components of the compound motion of hip and spine. Analysis of the motion in normal and chronic low-back pain patients allows differentiation of the groups, demonstration of progress in rehabilitation programs, determination of impairment, and provides tests of patient compliance and level of motivation.
TL;DR: All 26 patients with incomplete lesions improved postoperatively, with 19 of them entering the next Frankel subgroup, and the newly designed anterior instrumentation afforded enough stability to enable early ambulation with alignment and solid fusion.
Abstract: Twenty-seven burst fractures with neurologic deficits of the thoracolumbar-lumbar spine were treated with an one-stage anterior operation consisting of anterior decompression through vertebrectomy, realignment and stabilization with Zielke instrumentation (12 patients), and our new anterior instrumentation (15 patients). Only two disc spaces directly related to the injury were fused. No patient showed neurologic deterioration after surgery. All 26 patients with incomplete lesions improved postoperatively, with 19 of them entering the next Frankel subgroup. The newly designed anterior instrumentation afforded enough stability to enable early ambulation with alignment and solid fusion.
TL;DR: In this article, the authors conducted interviews with 303 men to determine aspects of work history and working environment that are related to low-back pain, including task frequencies, weights lifted, lifting postures, type of floor surface and chair support.
Abstract: Interviews were conducted with 303 men to determine aspects of work history and working environment that are related to low-back pain. Respondents included no pain, moderate pain, and severe pain samples. Data were obtained for 150 variables including task frequencies, weights lifted, lifting postures, type of floor surface, type of chair support, pushing, pulling, and carrying activities, driving vehicles, and attributions of pain occurrence to particular situations. Univariate analyses showed difference among the three pain groups for lifting method, having had lifting instruction, stretching and reaching activities, amount of sitting and twisting in seat, pushing materials of varied weights, and contributions of pain onset. Multivariate regression analyses selected activities from (1) standing and lifting, (2) carrying, pushing, and pulling, (3) sitting, (4) driving vehicles, and (5) using vibrating equipment that jointly explained pain group variance. The significant variables from each domain were used in second-level multiple regressions to explain differences between no pain and pain, and between moderate and severe pain. Computed weights for pulling, lifting method, weight carried, reaching and stretching, chair support, number of times/day in-out of chair, and heavy vibration exposure explained 27% of variance between moderate and severe pain groups. Weights for automobile driving, number of times/day in-out of vehicle, number of lifts/day, maximum weight pulled, sitting with feet on floor, and exposure to heavy vibration explained 23% of the variance between no pain and pain groups.
TL;DR: It was concluded that prevention should be directed to improvements in the occupational work load, particularly for younger nurses.
Abstract: Questionnaires were sent to qualified nurses (QNs) and nursing aides (NAs) to study the prevalence of low-back pain (LBP) and sciatica in relation to age, work-load, free time activities, menstruation, pregnancies and number of children. LBP and sciatica severe enough to make them unfit for daily tasks were significantly more common in NAs. Back injury and disability pension due to sciatic symptoms were also more common in NAs. Occupationally, NAs had twice the amount of lifting, bending, and rotation, while QNs reported more sitting and standing at work. Under the age of 30, the heaviness of the work was related to LBP in both NAs and QNs. It was concluded that prevention should be directed to improvements in the occupational work load, particularly for younger nurses.
TL;DR: Pupils found to have a history of back pain tended to have decreased lower limb joint mobility and increased trunk length compared with pupils without back pain, and back pain was more common in those who avoided sports.
Abstract: Out of 446 pupils aged 13-17 years, 115 were found to have a history of back pain. These pupils tended to have decreased lower limb joint mobility and increased trunk length compared with pupils without back pain. In 77 pupils whose site of back pain was identified, 38 had pain associated with the lumbar spine. These pupils had an increased trunk length while those with thoracolumbar or thoracic pain did not. Back pain was more common in those who avoided sports.
TL;DR: An epidemiologic case-control study to identify risk factors for acute prolapsed lumbar intervertebral disc was undertaken in Connecticut during 1979-1981 and found cigarettes smoking in the past year and use of Swedish and Japanese cars were associated with a lower-than-average risk.
Abstract: An epidemiologic case-control study to identify risk factors for acute prolapsed lumbar intervertebral disc was undertaken in Connecticut during 1979-1981 This paper focuses on nonoccupational factors of possible etiologic significance Persons in their 30s were affected most frequently Among surgical cases, the ratio of men to women was 15 to 1, while among probable and possible cases not undergoing surgery, the male to female ratio was about 1 to 1 Cigarette smoking in the past year was associated with an increased risk for prolapsed disc The greater the number of hours spent in a motor vehicle, the higher the risk Use of Swedish and Japanese cars was associated with a lower-than-average risk, while use of other cars was associated with a higher-than-average risk For each type of car, older cars were associated with higher risks than newer cars Variables that did not affect the risk for prolapsed lumbar disc in this study included height, weight, number of pregnancies, number of children, frequency of wearing shoes with high heels, smoking cigars or pipes, and participation in baseball or softball, golf, bowling, swimming, diving from a board, tennis, bicycling or jogging
TL;DR: The effects of injury to the intervertebral disc were investigated using three-dimensional flexibility and creep measurements of functional spinal units from fresh cadaver lumbar spines to observe changes in mechanical properties.
Abstract: The effects of injury to the intervertebral disc were investigated using three-dimensional flexibility and creep measurements of functional spinal units from fresh cadaver lumbar spines. The techniques utilized were accurate and the data had a high degree of reproducibility. An injury to the annulus and a removal of the nucleus significantly altered the mechanical properties of the spinal unit. Not only were the main motions affected but also the coupled motions. Sagittal plane symmetry was disturbed, resulting in asymmetric facet joint movements. These effects of injury could be measured because of the three-dimensionality of the experiments. Previous studies, utilizing only axial compression loading, claimed to observe no changes due to the disc injuries and are, therefore, in conflict with the present findings.
TL;DR: From April 1978 to October 1982, the authors performed 44 pelvic fixations as part of L-rod Instrumentation of a spinal deformity, and a pelvic fixation technique in which the pelvic segments of the rods were longer than 6 cm, completely intraosseous through their iliac course, and within 1.5 cm of the sciatic notch yielded the best results.
Abstract: From April 1978 to October 1982, the authors performed 44 pelvic fixations as part of L-rod instrumentation of a spinal deformity. Thirty scoliosis and revision scoliosis cases with a minimum of 1 year follow-up were analyzed for changes of the instrumentation with respect to the pelvis, angular changes at the lumbosacral junction, radiolucency about the portions of the rods providing pelvic fixation, and success of lumbosacral fusion. The technique for fixation was different among three groups of patients. A pelvic fixation technique in which the pelvic segments of the rods were longer than 6 cm, completely intraosseous through their iliac course, and within 1.5 cm of the sciatic notch, yielded the best results.
TL;DR: A new method for measuring spinal load is proposed, whereby changes in body height are used as a measure of disc compression, and examples are given of how the method can be used in ergonomic evaluations.
Abstract: A new method for measuring spinal load is proposed, whereby changes in body height are used as a measure of disc compression. The rate and magnitude of disc compression are caused by the loading and its temporal pattern. A device is reported for measuring body height (SD < 1 mm). Experiments showed
TL;DR: The thoracolumbar fascia was studied by dissection in ten adult human cadavers and was found to consist of two laminae, which form a retinaculum over the back muscles and constitute a series of accessory posterior ligaments that anchor the L2 to L5 spinous processes to the ilium and resist flexion of the lumbar spine.
Abstract: The thoracolumbar fascia was studied by dissection in ten adult human cadavers. The posterior layer of this fascia was found to consist of two laminae. The superficial lamina is formed by the aponeurosis of latissimus dorsi. The deep lamina consists of bands of fibers passing caudolaterally from the midline. Both laminae form a retinaculum over the back muscles, and the deep lamina constitutes a series of accessory posterior ligaments that anchor the L2 to L5 spinous processes to the ilium and resist flexion of the lumbar spine. The function of these ligaments is enhanced by the contraction of the back muscles and the action of certain, restricted portions of the abdominal muscles.
TL;DR: The author suggests that facet joint injections offer a simple, safe, and often dramatically effective means for managing mechanical derangements of the lumbar spine with the absence of nerve root irritation or compromise.
Abstract: Mechanical derangements of the lumbar spine, causing predominantly back pain with the absence of nerve root irritation or compromise, present a difficult treatment challenge to the average physician. The author suggests that facet joint injections offer a simple, safe, and often dramatically effective means for managing these problems. The historic background and technique are described in detail. The author presents his personal experience with 99 patients receiving a total of 117 facet joint injections in this retrospective, uncontrolled review. Results were classified as excellent in 17%, good in 25%, fair in 9%, mediocre in 4%, and no change in symptoms occurred in 44%. The procedure is recommended for diagnostic and conservative therapy.
TL;DR: This study investigated the relationship between cervical spine sagittal canal diameter and neurologic injury in cases of spinal fracture-dislocation, and found small diameter canals were correlated significantly with Neurologic injury, while large diameterCanals allowed protection from neurologic injuries in cervical fracture dislocation.
Abstract: This study investigated the relationship between cervical spine sagittal canal diameter and neurologic injury in cases of spinal fracture-dislocation. A group of 98 patients with such injuries was reviewed; 45 had no neurologic deficits, 39 had incomplete quadriplegia, and 14 had complete quadripleg
TL;DR: While the complications of sterility and impotence following anterior fusion have been over-exaggerated, caution and informed consent from adult males and parents of prepubertal male children is advisable.
Abstract: Recently, there is renewed interest in anterior fusion for spondylolisthesis and congenital and paralytic scoliosis with pelvic obliquity Some of the candidates are prepubertal boys Sterility after surgery in urogenitally normal prepubertal boys will not be determined until these patients mature A worldwide survey of 20 surgeons with 15-20 years of experience (4,500 cases) reports the frequency of sterility (retrograde ejaculation) to be 19 cases (042%) and impotence 20 cases (044%) One-fourth of the retrograde ejaculation cases resolved and became normal Impotence is non-organic The complication of retrograde ejaculation does not appear to be related to approach, though it was related to technique While the complications of sterility and impotence following anterior fusion have been over-exaggerated, caution and informed consent from adult males and parents of prepubertal male children is advisable
TL;DR: This syndrome occurs in two types of patients: the elderly person with degenerative scoliosis and a somewhat younger adult population with isthmic spondylolisthesis and at least 20% slip.
Abstract: This syndrome occurs in two types of patients: (1) the elderly person with degenerative scoliosis and (2) a somewhat younger adult population with isthmic spondylolisthesis and at least 20% slip. On plain radiograph, the Ferguson view (25 degrees caudocephalic) is best for visualizing the condition, however, CT is by far the best diagnostic tool. To show this far laterally, the "window" on the CT scanner must be opened wider than usual. Both coronal and parasagittal views will demonstrate the condition, but the coronal is the most valuable. Symptoms are classical spinal nerve compression. Usually it is the L5/S1 level that is involved, but other levels can be. At surgery, it is most important that nerve decompression be carried far enough laterally. This can mean sacrificing the lower half of the pedicle and the entire transverse process. Part of the body of S1 and of the sacral ala can be removed if the surgeon prefers. Because so much bone is removed, instability is a factor to be seriously considered. How to decompress adequately and still maintain stability often poses a most difficult problem.
TL;DR: The effect of this was to produce inhibition and reactivation of erectores spinae at a greater degree of vertebral flexion.
Abstract: Electromyographic activity of erectores spinae exhibits points of abrupt change during trunk flexion from the erect position and return extension. This study examined the positions at which the myoelectric activity suddenly disappeared and later reappeared. Forty adults were investigated to define accurately the inclinations of the trunk, pelvis, and vertebral column at these positions. The positions at the commencement and cessation of the period of electrical silence both occurred at two-thirds of maximum trunk flexion (mean = 80 degrees +/- 13 degrees SD). At these positions, all flexion measurements were significantly less than their maxima (P less than 0.001). Hip flexion at the commencement of electrical silence was slightly above one-half its maximum range, and similar to the position at the recommencement of electrical activity (mean = 40 degrees +/- 12 degrees SD). The most reproducible measurement (r = 0.88) in both positions was vertebral flexion (89% Max.; mean = 48 degrees +/- 6 degrees SD). Eleven of the male subjects repeated the experimental task holding 10.1 kg in their hands. The effect of this was to produce inhibition and reactivation of erectores spinae at a greater degree of vertebral flexion.
TL;DR: The analysis of radicular symptoms with nerve root Infiltration showed that radicular pain and/or claudication are caused mainly by single nerve root involvement, irrespective of the findings obtained by contrast studies.
Abstract: Anatomic studies using cadavers showed that three factors are responsible for radicular symptoms. The first is congenital or acquired abnormalities of nerves and nerve roots--the intradural segmental arrangement of rootlets, congenital anomalies of the nerve roots, and the furcal nerve. Another factor is changes of bone and soft tissue around nerves and nerve roots--indentation of nerve roots and extremely transverse courses of nerve roots. The third factor is a correlation of two other factors--spatial relationship of the nervous tissue to osseous and nonosseous elements of the spinal canal and the intervertebral foramen. In the intervertebral foramen, the nerve root is surrounded by a rather thick membranous structure, an epiradicular sheath, which is responsible for a tubular form obtained in nerve root infiltration. Anatomic abnormalities can be observed in contrast studies, but the defects revealed do not correspond necessarily with neurologic symptoms. In such cases, nerve root infiltration is very useful for a functional diagnosis. The analysis of radicular symptoms with nerve root infiltration showed that radicular pain and/or claudication are caused mainly by single nerve root involvement, irrespective of the findings obtained by contrast studies. Furthermore, therapeutic effect of nerve root infiltration can be expected in any disease and it can be applied as a final trial of conservative treatment.
TL;DR: While handling of loads is important, attention should be directed to other contributory factors such as unsafe floor surfaces and bending and twisting movements--not only at work but also in and around the home.
Abstract: During 1980, 1153 employees attended the Occupational Health Department with back pain out of a working population of 13,958 in a car factory. Four hundred one were absent from work and a further 64 patients were restricted by back pain and unable to perform their normal work. One hundred forty-seven cases of back pain arose at work, and 71 in and around the home. All those who were absent or restricted were questioned about the onset of back pain in order to distinguish between accidental and nonaccidental injuries (NAI), and an accident model was used to structure the information. There were 122 accidents, 114 NAI, and 165 patients who could not attribute a cause to their back pain. A significantly higher proportion of the NAI arose at home and, conversely, a higher proportion of accidents occurred at work. Eighty (66%) of the accidents were underfoot accidents, including 57 slips. There were highly significant differences between the body movements contributing to accidents and NAI. Significantly more of the NAI than the accidents involved load handling, but 52% of the patients able to attribute a cause to their back pain were not moving loads. While handling of loads is important, attention should be directed to other contributory factors such as unsafe floor surfaces and bending and twisting movements--not only at work but also in and around the home. Language: en