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A laboratory study was conducted to evaluate the effects of handles, shape of the container, and dimensions of the container on maximum acceptable weight of lift using a psychophysical methodology. Ten male college students were required to lift six different boxes with handles, six without handles, and three different mailbags from the floor to a bench height (76 cm), using a free-style lifting technique. The six boxes varied in length and width, and the three mailbags varied in diameter and length. Statistical analysis showed that the maximum acceptable weights for mailbags and boxes without handles were lower than those for boxes with handles. The maximum acceptable weight significantly increased with an increase in dimensions of the mailbag. Among all the container characteristics studied, handles were found to have the most profound effect on maximum acceptable weight. It is concluded that the recommendations for maximum acceptable weight of the load based on boxes with handles need to be adjusted when applied to boxes without handles or to some other types of containers.

Objective: The objectives were to: (a) develop a continuous frequency multiplier (FM) for the Revised NIOSH Lifting Equation (RNLE) as a function of lifting frequency and duration of a lifting task, and (b) describe the Cumulative Lifting Index (CULI), a methodology for estimating physical exposure to workers with job rotation. Background: The existing FM for the RNLE (FME) does not differentiate between task duration >2 hr and <8 hr, which makes quantifying physical exposure to workers with job rotation difficult and presents challenges to job designers. Method: Using the existing FMs for 1, 2, and 8 hr of task durations, we developed a continuous FM (FMP) that extends to 12 hr per day. We simulated 157,500 jobs consisting of two tasks each and, using different combinations of Frequency Independent Lifting Index, lifting frequency and duration of lifting. Biomechanical stresses were estimated using the CULI, time-weighted average (TWA), and peak exposure. Results: The median difference between FME and FMP was ±1% (range: 0%–15%). Compared to CULI, TWA underestimated risk of low-back pain (LBP) for 18% to 30% of jobs, and peak exposure for an assumed 8-hr work shift overestimated risk of LBP for 20% to 25% of jobs. Peak task exposure showed 90% agreement with CULI but ignored one of two tasks. Conclusion: The CULI partially addressed the underestimation of physical exposure using the TWA approach and overestimation of exposure using the peak-exposure approach. Application: The proposed FM and CULI may provide more accurate physical exposure estimates, and therefore estimated risk of LBP, for workers with job rotation.

Objective: The aim of this study was to evaluate long-term efficacy of an ergonomics program that included patient-handling devices in six long-term care facilities (LTC) and one chronic care hospital (CCH). Background: Patient handling is recognized as a major source of musculoskeletal disorders (MSDs) among nursing personnel, and several studies have demonstrated effectiveness of patient-handling devices in reducing those MSDs. However, most studies have been conducted in a single facility, for a short period, and/or without a comprehensive ergonomics program. Method: Patient-handling devices along with a comprehensive ergonomics program was implemented in six LTC facilities and one CCH. Pre- and post-intervention injury data were collected for 38.9 months (range = 29 to 54 months) and 51.2 months (range = 36 to 60 months), respectively. Results: Postintervention patient-handling injuries decreased by 59.8% (rate ratio [RR] = 0.36, 95% confidence interval [CI] [0.28, 0.49], p < .001), lost workdays by 86.7% (RR = 0.16, 95% CI [0.13, 0.18], p < .001), modified-duty days by 78.8% (RR = 0.25, 95% CI [0.22, 0.28], p < .001), and workers' compensation costs by 90.6% (RR = 0.12, 95% CI [0.09, 0.15], p < .001). Perceived stresses to low back and shoulders among nursing staff were fairly low. A vast majority of patients found the devices comfortable and safe. Longer transfer times with the use of devices was not an issue. Conclusion: Implementation of patient-handling devices along with a comprehensive program can be effective in reducing MSDs among nursing personnel. Strategies to expand usage of patient-handling devices in most health care settings should be explored.

This is a case report of a 17‐year‐old male patient with chronic autoimmune active hepatitis (CAAH) who was referred to our clinic for dental treatment prior to his undergoing liver transplant surgery. Coagulation problems and the implications of long‐term corticosteroid usage in patients with chronic hepatitis are presented. Differences in the etiology, histology, clinical features, laboratory findings, treatment, and prognosis are reviewed for the three separate but related forms of chronic hepatitis — persistent, lobular, and active hepatitis.SummaryIt is important to be aware of a patient's total medical picture, and how any preexisting conditions and their treatments might affect the dental care to be provided, especially in cases of invasive dental procedures. Such procedures, like any surgery of similar magnitude, have inherent risks, and the preoperative medical evaluation and postoperative care of these patients should be the same as those provided for other comparable surgeries, thus minimizing the risks of the operative procedure.In our case, the patient's condition had been previously diagnosed, and we were able to develop our treatment plan accordingly. Sometimes, though, a patient presents with problems that may be a manifestation of a more serious systemic disorder (e.g., bleeding gums in the absence of obvious periodontal disease). Thus, the dentist should be alert to the possible presence of other underlying medical disorders and, if any are suspected, should consult with a physician prior to undertaking elective dental procedures.

A literature survey on recommendations for the maximum weight of the load and work loads is presented. Three different criteria are reviewed to determine the "safe" weight and permissible work loads that a person can lift. These are biomechanical, psychophysical, and metabolic/heart rate. A comparison of recommended load limits based on each of the three criteria is presented. Maximum weight of the load and work loads based on the three criteria are also compared. The comparison shows that (1) the recommendations based on a given criterion are not in agreement, (2) the maximum permissible weights of the load based on psychophysical studies are lower than those based on biomechanical criteria, and (3) the psychophysical fatigue criteria, as compared to physiological fatigue criteria, will result in greater work loads at higher frequencies of lifting. Load-pace tradeoff and effects of lifting technique and location of load on acceptable work loads are also discussed.

A laboratory study was conducted to evaluate the effects of three different types of harnesses (lap belt, lap belt with crossed shoulder harness, and lap belt with parallel shoulder harness) on functional arm reach. Six male college students grasped a rotatable cylindrical handle as far away from the seat reference vertical line as was comfortably possible. Three different vertical heights and eight different azimuth angles were used. Contour curves for the reach envelopes are presented. The type of harness and height level had a significant effect on arm reach. Reach envelopes for the crossed and parallel harnesses were, on the average, 15 and 24% lower than the reach envelope for the lap belt. Of the three reach heights compared, the 110.5-cm reach envelope provided the greatest functional arm reach.

A set of push/pull experiments was performed by six men and women of varying anthropometry who were asked to exert maximal one-handed and two-handed push and pull forces on a load cell set at three different heights (67, 109, and 152 cm). They were each permitted to experiment with their postures to determine that which they sensed would permit the largest push or pull force, though no direct feedback was given as to their actual performance. Once they achieved what they believed to be their optimal posture, sagittal-plane photographs were taken. The angles of major body joints were then recorded along with the isometric force produced. It is shown that foot placement, handle height, and body postures affect push and pull force capability in a manner that is reasonably logical, using biomechanical concepts. It is proposed that future biomechanical models of push an pull strengths and workplace layouts must be carefully assessed with reference to the postural variations reported.

A laboratory study was conducted to assess the effects of lift angle on biomechanical stresses to the musculoskeletal system, and in particular, on the lower back. Male subjects were required to lift four different tote boxes from the floor to a height of 0.81 m using two different lifting techniques. Maximum acceptable weights were determined using a psychophysical method. The motion trajectory of lift was studied by means of stroboscopic photography. Moments and forces at various body joints were computed using a biomechanical strength model. Maximum acceptable weights were 16% (range = 9 to 23%) greater for the free-style lifting technique as compared with the squat method of lifting. There were large differences between the maximum acceptable weights and the "maximum permissible limits" recommended by NIOSH. The results showed that the subjects pulled the load toward the body when lifting psychophysically determined maximum weights. The lift angle increased with an increase in box width. The lift angle was greater for the free-style lifting method as compared with the squat lifting technique for lifting compact loads. Lifting at an angle resulted in a decrease in moment at the elbow, shoulder, L5IS1 disc, and hips, and an increase in moment at the knees and ankles. The estimated compressive force on the lumbar spine was, on the average, 11% lower for lifting at an angle as compared with a straight vertical lift.

Objective:The objective of this article is to evaluate the impact of the Revised National Institute for Occupational Safety and Health Lifting Equation (RNLE).Background:The RNLE has been used extensively as a risk assessment method for prevention of low back pain (LBP). However, the impact of the RNLE has not been documented.Methods:A systematic review of the literature on the RNLE was conducted. The review consisted of three parts: characterization of the RNLE publications, assessment of the impact of the RNLE, and evaluation of the influences of the RNLE on ergonomic standards. The literature for assessing the impact was categorized into four research areas: methodology, laboratory, field, and risk assessment studies using the Lifting Index (LI) or Composite LI (CLI), both of which are the products of the RNLE.Results:The impact of the RNLE has been both widespread and influential. We found 24 studies that examined the criteria used to define lifting capacity used by the RNLE, 28 studies that compared risk assessment methods for identifying LBP, 23 studies that found the RNLE useful in identifying the risk of LBP with different work populations, and 13 studies on the relationship between LI/CLI and LBP outcomes. We also found evidence on the adoption of the RNLE as an ergonomic standard for use by various local, state, and international entities.Conclusion:The review found 13 studies that link LI/CLI to adverse LBP outcomes. These studies showed a positive relationship between LI/CLI metrics and the severity of LBP outcomes.

Objective:The objective of this study was to investigate the association between job physical exposure (JPE) and incidence of flexor tendon entrapment of the digits (FTED).Background:FTED, commonly known as trigger digit, is associated with age, gender, and certain health disorders. Although JPE has been suggested as a risk factor for FTED, there are no prospective cohort studies.Method:A cohort of 516 workers was enrolled from 10 diverse manufacturing facilities and followed monthly for 6 years. Worker demographics, medical history, and symptoms of FTED were assessed. JPE was individually measured using the Strain Index (SI) and American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value for hand activity level (TLV for HAL). Changes in JPE (assessed quarterly) and symptoms (assessed monthly) were recorded during follow-up. FTED was defined as demonstrated triggering on examination.Results:Point prevalence of FTED at baseline was 3.6%. During follow-up there were 23 incident FTED cases (left and/or right hands). The incident rate for first occurrence of FTED from enrollment was 1.38 per 100 person-years. Risk factors were JPE, age, gender, diabetes mellitus, carpometacarpal osteoarthrosis, and rheumatoid arthritis. In multivariate models, the SI showed strong association with risk of FTED when treated as a continuous variable and marginal association when dichotomized (SI > 6.1). TLV for HAL showed a statistical trend of increasing risk of FTED using the ACGIH limits, but no association as a continuous variable.Conclusions:Both JPE and personal risk factors are associated with FTED development. The SI and TLV for HAL are useful tools for estimating JPE.

An epidemiological study was performed to evaluate the relation between lowback discomfort ratings and use of the revised NIOSH lifting guide to assess the risk of manual material handling (MMH) tasks. We surveyed 97 MMH workers on site in 15 factories and designed a questionnaire to systematically collect jobrelated information. Approximately 90% of the workers had suffered various degrees of lower back discomfort, and 80% had sought medical treatment. The survey showed that 42 of the 97 jobs analyzed had a recommended weight limit of 0, which was attributed to either a horizontal distance or a lifting frequency that exceeded the bounds of the NIOSH lifting index. Apparently, the limits for horizontal distance and maximum allowable frequency are too stringent to accommodate many existing MMH jobs. For the remaining 55 jobs, the significant positive correlation obtained between the lifting index and the severity of low-back discomfort suggests that the lifting index is reliable in assessing the potential risk of low-back injury in MMH. These findings provide useful information on the application of the NIOSH lifting guide to the assessment of lowback pain.

Objective: The aim of this study was to systematically evaluate prevalence based on variations in case definitions used for epidemiological studies of musculoskeletal disorders (MSDs). Background: Prior studies of MSDs have mostly relied on a single case definition based on questionnaires. Method: In a multicenter prospective cohort study, we systematically collected data to evaluate impacts of differences in case definitions of MSDs on prevalence of three common musculoskeletal disorders: (a) shoulder tendinosis, (b) lateral epicondylalgia, and (c) carpal tunnel syndrome. Production workers were from 21 employment settings in three diverse U.S. states and performed widely varying work. All workers completed laptop-administered structured interviews, two standardized physical examinations, and nerve conduction studies (NCS). Case definitions included symptoms only, and symptoms plus physical examinations and/or NCS. Results: A total of 1,227 subjects had complete health data at baseline. The prevalence for shoulder tendinosis is 23.0% if only glenohumeral pain is used for a case definition, compared with 8.0% if a combination of pain plus a positive supraspinatus test is used. The prevalence for lateral epicondylalgia varied on the basis of lateral elbow pain (12.0%), pain plus tenderness on palpation (9.9%), or pain plus tenderness on palpation plus resisted wrist or middle finger extension (3.5%). Carpal tunnel syndrome prevalence varied on the basis of tingling or numbness in a median nerve–served digit (29.9%) or tingling or numbness plus NCS abnormalities consistent with carpal tunnel syndrome (9.0%). Conclusion: Variations in epidemiological case definitions have major impacts on prevalence of common MSDs. Wide-ranging differences in prevalence may have impacts on purported risk factors that need to be determined.

Objective: This manuscript systematically quantifies multiple measures of low-back pain (LBP) prevalence by pain rating in a large, multisite cohort of workers. Background: Published LBP prevalence rates vary. Studies rely on one measure of LBP and none report prevalence stratified by pain rating. Method: Cross-sectional analyses of baseline data from a multicenter prospective cohort study were performed to evaluate differences in lifetime prevalence, 1-month period prevalence, and point prevalence of LBP. Workers were from 28 different employment settings in 4 diverse U.S. states. All workers completed computerized questionnaires and structured interviews. LBP prevalence measures were stratified by pain ratings. Results: A total of 828 subjects had complete health data at baseline. Lifetime prevalence, 1-month period prevalence, and point prevalence for any LBP (≥1/10) were 63.4%, 44.0%, and 20.8% respectively. Prevalence of LBP decreased with increasing pain ratings. As an example, using a threshold of LBP ≥ 3/10 pain, prevalence measures were 61.0%, 37.6%, and 16.7% respectively. A threshold of LBP ≥ 5/10 had prevalence measures of 51.2%, 22.9%, and 9.9% respectively. Age, systolic and diastolic blood pressure, high cholesterol, high blood pressure, and tobacco use were statistically significantly related to lifetime prevalence of LBP. Conclusion: Lifetime LBP prevalence, 1-month period prevalence, and point prevalence stratified by pain ratings demonstrate a wide variation of prevalence measures of LBP and self-reported pain ratings. Higher pain rating thresholds yield lower prevalence measures and may impact assessments of risk factors. Differences in pain ratings may allow for focused surveillance within an occupational cohort.