A prospective study of factors affecting recovery from musculoskeletal injuries.

PURPOSE: Research suggests the importance of psychosocial factors in recovery from musculoskeletal injuries. The objective of this study was to identify predictors of recovery among U.S. Marines who had musculoskeletal injuries of the back, knee, or shoulder. METHODS: A sample of 134 participants was assessed at baseline and followed for 1 year to determine outcome information. RESULTS: The strongest predictor of injury recovery at the 1-year follow-up was recovery expectations. In a multivariate logistic model with key demographic and psychosocial factors controlled, individuals who had high recovery expectations at baseline were over five times as likely to be recovered at follow-up as individuals who had low expectations (OR = 5.18, p\.01). CONCLUSIONS: This finding is consistent with a large body of research that has linked recovery expectations with better recovery outcomes in patients with musculoskeletal injuries as well as with research linking recovery expectations with better outcomes across a wide range of medical conditions.Applied to military populations, interventions designed to modify recovery expectations may have the potential to improve rates of return to duty and to reduce rates of disability discharge.

Medical malpractice allegations of iatrogenic addiction in chronic opioid analgesic therapy: forensic case reports.

OBJECTIVES: The objectives for presenting these medico-legal forensic case reports are the following: 1) detail three cases where chronic opioid analgesic therapy (COAT) was alleged to cause iatrogenic addiction and/or re-addiction; 2) detail the plaintiff's and defendant's medical experts' opinions on these allegations; and 3) through analyzing these cases, develop some recommendations for future prevention of such allegations during COAT. METHODS: Case Reports. RESULTS: Medico-legal issues surrounding the allegation of iatrogenic addiction were identified in each case. CONCLUSIONS: Before starting COAT, physicians should obtain and document patient informed consent for the risk of addiction/re-addiction with COAT treatment. Patients with a history of addictions pre-COAT should be placed on adherence monitoring immediately on beginning COAT.

Course, diagnosis, and treatment of depressive symptomatology in workers following a workplace injury: a prospective cohort study.

OBJECTIVES: To estimate prevalence, incidence, and course of depressive symptoms and prevalence of mental health treatment following a workplace injury, and to estimate the association between depressive symptoms and return-to-work (RTW) trajectories. METHOD: In a prospective cohort study, workers filing a lost-time compensation claim for a work-related musculoskeletal disorder of the back or upper extremity were interviewed 1 month (n = 599) and 6 months (n = 430) postinjury. A high level of depressive symptoms was defined as 16 or more on the self-reported Center for Epidemiologic Studies-Depression (CES-D) Scale. The following estimates are reported: prevalence of high depressive symptom levels at 1 and 6 months postinjury; incidence, resolution, and persistence of high depressive symptom levels between 1 and 6 months; and prevalence of self-reported mental health treatment and depression diagnosis at 6 months postinjury. RESULTS: Prevalence of high depressive symptom levels at 1 month and 6 months postinjury were 42.9% (95% CI 38.9% to 46.9%) and 26.5% (95% CI 22.3% to 30.7%), respectively. Among participants reporting high depressive symptom levels at 1 month postinjury, 47.2% (95% CI 39.9% to 54.5%) experienced a persistence of symptoms 6 months postinjury. By 6 months, 38.6% of workers who never returned to work or had work disability recurrences had high depressive symptom levels, compared with 17.7% of those with a sustained RTW trajectory. At 6-month follow-up, 12.9% (95% CI 5.8% to 20.1%) of participants with persistently high depressive symptom levels self-reported a depression diagnosis since injury and 23.8% (95% CI 14.7% to 32.9%) were receiving depression treatment. CONCLUSIONS: Depressive symptoms are pervasive in workers with musculoskeletal injuries, but transient for some, and seldom diagnosed as depression or treated.

Physical and Psychosocial Work Environmental Risk Factors for Back Injury among Healthcare Workers: Prospective Cohort Study.

The incidence of occupational back injury in the healthcare sector remains high despite decades of efforts to reduce such injuries. This prospective cohort study investigated the risk factors for back injury during patient transfer. Healthcare workers (n = 2080) from 314 departments at 17 hospitals in Denmark replied to repeated questionnaires sent every 14 days for one year. Using repeated-measures binomial logistic regression, controlling for education, work, lifestyle, and health, the odds for back injury (i.e., sudden onset episodes) were modeled. On the basis of 482 back injury events, a higher number of patient transfers was an important risk factor, with odds ratio (OR) 3.58 (95% confidence interval (CI) 2.51-5.10) for 1-4 transfers per day, OR 7.60 (5.14-11.22) for 5-8 transfers per day, and OR 8.03 (5.26-12.27) for 9 or more transfers per day (reference: less than 1 per day). The lack of necessary assistive devices was a common phenomenon during back injury events, with the top four lacking devices being sliding sheets (30%), intelligent beds (19%), walking aids (18%), and ceiling lifts (13%). For the psychosocial factors, poor collaboration between and support from colleagues increased the risk for back injury, with OR 3.16 (1.85-5.39). In conclusion, reducing the physical burden in terms of number of daily patient transfers, providing the necessary assistive devices, and cultivating good collaboration between colleagues are important factors in preventing occupational back injuries among healthcare workers.

The influence of age on quality of life after upper body burn.

BACKGROUND: In Spain, the number of aged persons is increasing. By the year 2066, it is expected that 34.6% of the Spanish population will be over 65 years of age. Elderly people present a higher burning risk owing in part to impaired balance and decreased physical strength, lower cognitive abilities, or socioeconomic context. OBJECTIVE: Burns to the upper body body are common and affect both emotional state and physical function, thus leading to reduced quality of life (QoL). Our objective was to determine the influence of age on the QoL of patients who experienced burns to the upper body, with burns with 2 years. METHODS: This is an observational study with a sample of 58 patients with burns only on the upper body. Patients were divided into two groups: 29 patients of age over 65 years and 29 patients under 65 years; all of them attended the Vall d'Hebron Burn Center, Barcelona, between 2011 and 2014. From the original sample, 45 patients had survived by the time the information was gathered. The QoL of these individuals was evaluated with the Spanish version of the Burn Specific Health Scale. Demographic data (sex, age, total burn surface area [TBSA], burn mechanism, pathological history, length of hospital stay, and rehabilitation duration) were collected. Statistical analysis included parametric and nonparametric tests as appropriate with R3.3.3. RESULTS: There were no differences between groups regarding the mechanism of burn, TBSA, length of hospital stay, and the domains of QoL test. High blood pressure, diabetes, and other comorbidities were significantly more common in the elderly group than in the younger group. Eleven patients died in the elderly group and two in the younger group (p=0.012). CONCLUSION: As opposed to what could be expected, in this study, there were no significant differences between surviving patients in both age groups in terms of perceived QoL. Nevertheless, mortality after a burn in the upper side of the body was significantly higher in elderly people than in younger people. The present study results do not support the use of different rehabilitation approaches in elderly patients.

A comparison of health-related quality of life for individuals with mental health disorders and common chronic medical conditions.

OBJECTIVES: The purpose of this study was to compare the burden of disease experienced by people with mental health conditions with people who have common medical disorders. Three prevalent medical disorders--the burden of disease of back/neck problems, diabetes, and hypertension--were compared with the mental health category of depression, anxiety, or emotional problem. METHODS: This study used data from the nationally representative 2003-2004 National Health and Nutrition Examination Survey for respondents aged 18 or older (n = 4,833). The measurement of health-related quality of life (HRQOL) used was the Healthy Days Measures developed by the Centers for Disease Control and Prevention. Unadjusted and adjusted HRQOL were compared for individuals reporting each of the four conditions. Adjusted HRQOL was assessed using ordinary least squares regression, which controlled for gender, age, race/ethnicity, education, marital status, comorbidity, and income. RESULTS: Individuals with mental health conditions experienced 17.6 total unhealthy days per month, while those with back and neck problems and those with hypertension experienced 12.2 total unhealthy days per month, and those with diabetes experienced 12.3 total unhealthy days per month. After adjusting for socioeconomic and demographic characteristics as well as comorbid conditions, mental health conditions were responsible for a 6.8-day decrease in healthy days per month compared with average adults (p < 0.001). Mental health conditions resulted in significantly lower HRQOL than back or neck problems (p = 0.053), diabetes, (p = 0.002), and hypertension (p = 0.012). CONCLUSIONS: There were significant differences between the HRQOL found in mental and medical conditions, with mental health conditions being responsible for significantly greater impairment of HRQOL. An efficient health-care system should consider the relative disease burden of specific conditions when allocating public health resources.

Is a history of work-related low back injury associated with prevalent low back pain and depression in the general population?

BACKGROUND: Little is known about the role of prior occupational low back injury in future episodes of low back pain and disability in the general population. We conducted a study to determine if a lifetime history of work-related low back injury is associated with prevalent severity-graded low back pain, depressive symptoms, or both, in the general population. METHODS: We used data from the Saskatchewan Health and Back Pain Survey - a population-based cross-sectional survey mailed to a random, stratified sample of 2,184 Saskatchewan adults 20 to 69 years of age in 1995. Information on the main independent variable was gathered by asking respondents whether they had ever injured their low back at work. Our outcomes, the 6-month period prevalence of severity-graded low back pain and depressive symptoms during the past week, were measured with valid and reliable questionnaires. The associations between prior work-related low back injury and our outcomes were estimated through multinomial and binary multivariable logistic regression with adjustment for age, gender, and other important covariates. RESULTS: Fifty-five percent of the eligible population participated. Of the 1,086 participants who responded to the question about the main independent variable, 38.0% reported a history of work-related low back injury. A history of work-related low back injury was positively associated with low intensity/low disability low back pain (OR, 3.66; 95%CI, 2.48-5.42), with high intensity/low disability low back pain (OR, 4.03; 95%CI, 2.41-6.76), and with high disability low back pain (OR, 6.76; 95%CI, 3.80-12.01). No association was found between a history of work-related low back injury and depression (OR, 0.85; 95%CI, 0.55-1.30). CONCLUSION: Our analysis shows an association between past occupational low back injury and increasing severity of prevalent low back pain, but not depression. These results suggest that past work-related low back injury may be an important risk factor for future episodes of low back pain and disability in the general population.

Patient clusters in acute, work-related back pain based on patterns of disability risk factors.

OBJECTIVE: To identify subgroups of patients with work-related back pain based on disability risk factors. METHODS: Patients with work-related back pain (N = 528) completed a 16-item questionnaire of potential disability risk factors before their initial medical evaluation. Outcomes of pain, functional limitation, and work disability were assessed 1 and 3 months later. RESULTS: A K-Means cluster analysis of 5 disability risk factors (pain, depressed mood, fear avoidant beliefs, work inflexibility, and poor expectations for recovery) resulted in 4 sub-groups: low risk (n = 182); emotional distress (n = 103); severe pain/fear avoidant (n = 102); and concerns about job accommodation (n = 141). Pain and disability outcomes at follow-up were superior in the low-risk group and poorest in the severe pain/fear avoidant group. CONCLUSIONS: Patients with acute back pain can be discriminated into subgroups depending on whether disability is related to pain beliefs, emotional distress, or workplace concerns.

Investigating risk factors for chronicity: the importance of distinguishing between return-to-work status and self-report measures of disability.

OBJECTIVE: The objective of this study was to examine whether the outcome of psychosocial risk factor analyses varied as a function of whether the outcome variable was return-to-work status or self-reported functional disability. METHODS: Participants were 255 workers who sustained a soft tissue injury to the back and participated in a community-based secondary prevention program. Assessment of psychologic risk factors (pain severity, pain catastrophizing, fear of movement/reinjury, depression) was conducted at pretreatment. RESULTS: Logistic regression revealed that pain catastrophizing (odds ratio [OR], 0.53; 95% confidence interval [CI] = 0.32-0.88) and pain severity (OR, 0.65; 95% CI = 0.45-0.94) were significant predictors of return to work. However, when change in self-reported disability was used as the outcome variable, none of the psychosocial risk factors emerged as significant predictors. CONCLUSIONS: Given the important theoretical, clinical, and policy implications of the outcome of risk factor research, more research is needed to further clarify the respective advantages and limitations to using self-reported versus return to work-based measures of disability.

Changes in spine loading patterns throughout the workday as a function of experience, lift frequency, and personality.

BACKGROUND CONTEXT: Psychosocial stressors have been associated with low back pain reporting. However, response to psychosocial risk factors may be dependent on the individual's personality type that, in turn, can affect muscle recruitment and spine loading. This study explores how personality might be associated with spine loading during repetitive lifting performed throughout an entire work shift. PURPOSE: Assess spine loading as a function of an individual's personality type during repetitive, long-term exposure to a materials handling tasks. STUDY DESIGN: Laboratory experiment where experienced and inexperienced participants performed repetitive, asymmetric lifts at various load and lift frequency levels throughout a series of 8-hour exposure periods. Spine loads were monitored throughout the work period. PATIENT SAMPLE: Twelve novice and 12 experienced materials handlers who were asymptomatic for back pain. OUTCOME MEASURES: Spine compression, anterior-posterior (A/P) shear, and lateral shear at the L5-S1 level. METHODS: Participants were categorized into personality types based upon the Myers-Briggs personality type indicator. An electromyography-assisted biomechanical model was used to assess spine compression, A/P shear, and lateral shear throughout the exposure period. RESULTS: The results indicate that intuitors had higher shear spinal loading regardless of moment exposure, lift frequency, and time through the work period, compared with the sensor personality type. In addition, higher spine compressive and shear forces occurred in the perceiver personality compared with the judgers' personality trait, regardless of moment and, often, lift frequency. Novice lifters typically experienced greater spine loading. CONCLUSIONS: The results suggest that when there exists a personality-job environment mismatch, spinal loading increases via an increase in antagonistic co-contraction. The trends suggest that inherent personality characteristics may play a role in one's motor control strategies when performing a repetitive lifting task.

Catastrophizing, pain, and disability in patients with soft-tissue injuries.

The present study examined the role of catastrophizing in predicting levels of pain and disability in a sample of individuals who had sustained soft-tissue injuries to the neck, shoulders or back following work or motor vehicle accidents. Participants were 86 (27 men, 59 women) consecutive referrals to the Atlantic Pain Clinic, a multidisciplinary treatment centre for the management of persistent pain disorders. Findings revealed that catastrophizing, measured by the Pain Catastrophizing Scale (PCS; Sullivan, M.J.L. et al., Psychol. Assess., 7 (1995) 524-532) was significantly correlated with patients' reported pain intensity, perceived disability and employment status. The results of a regression analysis further showed that catastrophizing contributed to the prediction of disability over and above the variance accounted for by pain intensity. In addition, catastrophizing was associated with disability independent of the levels of depression and anxiety. The rumination subscale of the PCS was the strongest predictor of pain and disability. Theoretical and clinical implications of the findings are discussed.

Psychologically based occupational rehabilitation: the Pain-Disability Prevention Program.

OBJECTIVES: To describe the development, implementation, and preliminary outcome of the Pain-Disability Prevention (PDP) Program. The PDP Program is a 10-week cognitive-behavioral intervention program that aims to increase daily involvement in goal-directed activity and minimize psychological barriers to activity involvement after occupational injury. Workers' Compensation Board claimants with soft tissue injuries to the back, who were still off work 6 weeks after injury and showed evidence of at least one "yellow flag," were offered participation in the PDP Program. DESIGN: A single-group, prospective treatment outcome analysis. PARTICIPANTS: Data from the first 104 claimants who participated in the PDP Program are summarized. RESULTS: Participation in the PDP Program was associated with a 60% success rate, where success was defined as return to work (45%) or readiness to return to work (15%). Initial scores on measures of catastrophizing, fear of movement/reinjury, and depression afforded 92% correct classification of treatment outcome. Early treatment changes in catastrophizing and fear of movement/reinjury were also predictive of treatment outcome. CONCLUSIONS: The findings suggest that a psychologically based activity mobilization program can be an effective means of yielding reductions in psychological risk factors for occupational disability. Challenges to program implementation, fidelity to protocol, and issues related to cost efficacy are discussed.

A controlled trial of an educational pamphlet to prevent disability after occupational low back injury.

STUDY DESIGN: Randomized controlled trial. OBJECTIVE: To test the ability of an educational pamphlet to improve recovery in terms of pain, work status, and health care utilization after occupational low back injury. BACKGROUND: Low back pain and disability persist as occupational health problems of epidemic proportions. Because interventions based on biomechanical models have had limited impact, recent educational approaches to preventing back problems have stressed psychosocial recovery issues. METHODS: A pamphlet was developed by compiling activity resumption, self-care, and attitudinal advice from recent publications. The pamphlet was sent at random to half of all consenting workers reporting back pain within 11 days of occupational injury between 7/96 and 6/97. Three and 6 months later, back pain, work status, health care use, and pamphlet impact outcomes were assessed through structured telephone interviews. RESULTS: Of the 726 eligible workers, 486 consented to participate. Consenters and nonconsenters and intervention and control groups were similar in initial demographic variables. The pamphlet had no statistically significant impact at the 0.05 significance level on pain severity or reduction, health care visits, or work absence. Of the 229 pamphlet recipients, 129 thought it had provided useful information, but only 25 thought it had helped them return to work more quickly. CONCLUSIONS: In this trial, a pamphlet stressing psychosocial recovery issues did not prevent or reduce postinjury pain, health care use, or work absence.

Sensitivity and specificity of the indicators of sincere effort of the EPIC lift capacity test on a previously injured population.

STUDY DESIGN: Randomized control post-test only. OBJECTIVES: To investigate the reliability and validity of the EPIC Lift Capacity test's indicators of sincere effort. SUMMARY OF BACKGROUND DATA: The EPIC Lift Capacity test (ELC) (Employment Potential Improvement Corp., Santa Ana, CA) is a functional evaluation tool used to identify physical limitations involved in lifting and manual materials handling. Identification of insincere effort is an integral component of such functional testing because of the potential secondary gain issues surrounding the various populations typically involved in this form of testing. The purpose of this study was to determine the sensitivity and specificity of the "indicators of sincere effort" of the EPIC Lift Capacity test when used on a previously injured population typical of subjects for which the test is designed. METHODS: Subjects consisted of 41 volunteers (age 22 to 58 years) with a previously diagnosed musculoskeletal pathology of the spine or extremities. Volunteers were randomized into either the control group, instructed to give a sincere maximum effort, or the experimental group, instructed to give an insincere effort at 50% of their perceived maximum effort. All tests were administered by certified clinical evaluators according to the standardized EPIC Lift Capacity test protocol.- RESULTS: Overall accuracy in identifying participants' level of effort was 86.84%. The indicators of valid effort exhibited both high positive (94.44%) and negative (80.00%) predictive values. The indicators of valid effort accounted for 94.9% of the total variance in the determination of the subjects' overall effort level. Interrater reliability for agreement of subjects' overall effort was good (interclass correlation coefficient = 0.82). CONCLUSIONS: Through use of standardized indicators of sincere effort, certified EPIC Lift Capacity test evaluators were able to predict sincerity of effort with a high degree of reliability and validity. The rater's systematicobservational evaluation of effort was shown to be the single best indicator of sincere effort.

Back injury and work loss. Biomechanical and psychosocial influences.

The exponential increase in occupational low back pain disability is a problem that is not being addressed adequately in clinical practice. The notion of achieving primary control through ergonomic intervention, based on biomechanics principles, has so far been unhelpful. The traditional secondary prevention strategies of rest and return to restricted work duties are seemingly suboptimal. Biomechanics/ergonomic considerations may be related to the first onset of low back pain, but there is little evidence that secondary control based solely on these principles will influence the risk of recurrence or progression to chronic disability. More promising in this respect are programs that take account of the psychosocial influences surrounding disability. Work organizational issues are clearly important, but so also is the behavior of clinicians. The balance of the available evidence suggests that clinicians generally should adopt a proactive approach to rehabilitation by recommending, whenever possible, early return to normal rather than restricted duties as well as complementary psychosocial advice if the issue of chronic disability is to be successfully tackled.

Claim rates of compensable back injuries by age, gender, occupation, and industry. Do they relate to return-to-work experience?

STUDY DESIGN: A retrospective cohort study of Michigan workers' compensation cases involving back injuries in 1986 and 1987 with incidence and outcome data. OBJECTIVE: To determine claim rates by age, gender, and industry or occupation for compensable back injuries and to investigate the relation between occupation and return to work. SUMMARY OF BACKGROUND DATA: The cohort of 24,094 Michigan workers' compensation cases from 1986 and 1987 in which claimants were compensated for back injuries was reviewed. Compensation eligibility requires more than 7 days' disability after injury. METHODS: Claim rates for back injuries by age, gender, and industry or occupation using employment data interpolated from 1980 and 1990 Census 1% Public Use Microdata Samples. Cox proportional hazards analysis was performed for return to work in the first 8 weeks after injury, with occupation coded at the three-digit level. RESULTS: All-age claim rates for Michigan compensable back injuries by occupation ranged between 0.03% and 1.7% annually (0.39% for all cases) and were generally higher in women in white collar occupations and in men in blue collar occupations. The claim rate peaked in men in the 25-34 year range, with the highest rates in manual labor occupations. The peak claim rates by age were less marked in women, tending to occur broadly throughout the 25-44-year range. Similar all-age values were recorded by industry. The male-to-female risk ratio over all occupations does not vary by age and is approximately 1.4:1. As the classification of occupation became more detailed, large differences in risk were documented within major occupation groups. The highest risk in this study was approximately 6% annually for 25-44 year old men in driver-sales (beverage truck drivers and delivery workers). Only 7 of 40 occupation categories showed a significant relative hazard for return to work in the first 8 weeks after injury, and these were blue collar occupations with earlier return than the reference sales category. For Michigan compensable back injuries, a rough estimate of the true annual incidence of new claims is 94% of the reported claim rate. CONCLUSIONS: The relative risk of compensable back injury is generally higher for females in white collar occupations, higher for males in blue collar occupations and approximately equal in service occupations. Although the risk of back injury is related to occupation, the same occupational factors do not operate as a barrier to return to work.

A cross-sectional study correlating lumbar spine degeneration with disability and pain.

STUDY DESIGN: Cross-sectional design. OBJECTIVES: To investigate the correlation between degeneration in the lumbar spine and self-reported disability and pain levels in patients with and without a history of trauma. SUMMARY OF BACKGROUND DATA: The link between lumbar spine degeneration and low back pain remains controversial, as does the correlation between trauma and spinal degeneration. METHODS: Radiographic and questionnaire data were collected from 172 consecutive patients with low back pain. Back pain severity was measured using two scales: one for pain over the entire episode and one for pain during the previous week. All patients also completed the Revised Oswestry Disability Questionnaire before radiography was performed. Further questions concerning the chronicity of symptoms and trauma were included. RESULTS: Controlling for age, patients with low back pain with a history of trauma had a statistically significant increase in the severity of facet degeneration (P < 0.02) compared with nontrauma patients with low back pain. However, there was no difference in disability and pain scores between the trauma and nontrauma patients or between the genders. A weak correlation between pain severity ratings and the number of levels of degeneration and the severity of the degeneration at the disc and facets was noted. CONCLUSIONS: Patients with low back pain with a history of trauma had more severe facet arthrosis than do nontrauma patients with low back pain, but there were no differences in pain and disability. There was a weak correlation between the quantity and severity of lumbar degeneration with pain levels, but not with disability scores. These findings are discussed in the light of recent reports regarding the cervical spine.

Positive and negative evidence of risk factors for back disorders.

The scientific literature on work-related back disorders was reviewed to identify consistent risk factors and to determine the strength of the association between the two. Thirty-five publications were selected with quantitative information. Lifting or carrying loads, whole-body vibration, and frequent bending and twisting proved to be the physical load risk factors consistently associated with work-related back disorders. Job dissatisfaction and low job decision latitude proved to be important, but the evidence was not consistent across different studies and study designs. The epidemiologic studies illustrated the importance of several confounders, especially age, smoking habits, and education. In this review, gender, height, weight, exercise, and marital status were consistently not associated with back disorders in occupational populations.

Partitioning the contributing role of biomechanical, psychosocial, and individual risk factors in the development of spine loads.

BACKGROUND CONTEXT: The role of biomechanical workplace factors in spine loading has been well documented. However, our understanding of the role of psychosocial and individual factors in producing spine loads is poorly understood. Even less is understood about the relative contribution of these factors with respect to kinematic, kinetic and muscle activity responses, as well as spine loading. PURPOSE: To explore the relative contribution of biomechanical and psychosocial workplace factors and individual characteristics on the biomechanical responses and spine loading. STUDY DESIGN/SETTING: The contribution of various levels of workplace factors to spine loading was monitored under laboratory conditions. PATIENT SAMPLE: Sixty (30 male and 30 female) college-age individuals who were asymptomatic to low back pain. OUTCOME MEASURES: Trunk kinematics and kinetics, muscle activity and the three-dimensional spinal loads. METHODS: The subjects performed lifting tasks while being exposed to varying levels of biomechanical (lift rate, load weight and task asymmetry) and psychosocial (social support and mental concentration) workplace factors as well as an unexplored (load placement) workplace factor. RESULTS: The workplace job demands that had the largest contribution were load placement (4% to 30%) and load weight (15% to 55%). Mental concentration and social environment had a relatively small contribution to the spinal loads (up to 0.2%). Anthropometry played a large role in the shears (about 12% to 58%) but a relatively minor role in the compressive forces (about 3%). CONCLUSIONS: Under the given experimental conditions, load weight is the most important factor when controlling compression forces associated with lifting, but other factors, such as individual characteristics, significantly contribute to the shear loads. Thus, one must account for the weight lifted and the anthropometric dimensions when designing the workplace. For the first time, the relative contribution of workplace job demands and individual factors in the development of spine loading have been identified.