Hansjürgen Gebhardt

Individual and occupational risk factors for knee osteoarthritis: results of a case-control study in Germany

IntroductionA number of occupational risk factors are discussed in relation to the development and progress of knee joint diseases (for example, working in a kneeling or squatting posture, lifting and carrying heavy weights). Besides the occupational factors, a number of individual risk factors are important. The distinction between work-related and other factors is crucial in assessing the risk and in deriving preventive measures in occupational health.MethodsIn a case-control study, patients with and without symptomatic knee osteoarthritis (OA) were questioned by means of a standardised questionnaire complemented by a semi-standardised interview. Controls were matched and assigned to the cases by gender and age. Conditional logistic regression was used in analysing data.ResultsIn total, 739 cases and 571 controls were included in the study. In women and men, several individual and occupational predictors for knee OA could be described: obesity (odds ratio (OR) up to 17.65 in women and up to 12.56 in men); kneeling/squatting (women, OR 2.52 (>8,934 hours/life); men, 2.16 (574 to 12,244 hours/life), 2.47 (>12,244 hours/life)); genetic predisposition (women, OR 2.17; men, OR 2.37); and sports with a risk of unapparent trauma (women, OR 2.47 (≥1,440 hours/life); men, 2.58 (≥3,232 hours/life)). In women, malalignment of the knee (OR 11.54), pain in the knee already in childhood (OR 2.08), and the daily lifting and carrying of loads (≥1,088 tons/life, OR 2.13) were related to an increased OR; sitting and smoking led to a reduced OR.ConclusionsThe results support a dose-response relationship between kneeling/squatting and symptomatic knee OA in men and, for the first time, in women. The results concerning general and occupational predictors for knee OA reflect the findings from the literature quite well. Yet occupational risks such as jumping or climbing stairs/ladders, as discussed in the literature, did not correlate with symptomatic knee OA in the present study. With regards to occupational health, prevention measures should focus on the reduction of kneeling activities and the lifting and carrying of loads as well as general risk factors, most notably the reduction of obesity. More intervention studies of the effectiveness of tools and working methods for reducing knee straining activities are needed.

The Key Indicator Method for Manual Handling Operations (KIM-MHO) - evaluation of a new method for the assessment of working conditions within a cross-sectional study

BackgroundUpper extremity musculoskeletal symptoms and disorders are common in the working population. The economic and social impact of such disorders is considerable. Long-time, dynamic repetitive exposure of the hand-arm system during manual handling operations (MHO) alone or in combination with static and postural effort are recognised as causes of musculoskeletal symptoms and disorders. The assessment of these manual work tasks is crucial to estimate health risks of exposed employees. For these work tasks, a new method for the assessment of the working conditions was developed by the Federal Institute for Occupational Safety and Health (BAuA) and released as a draft in the year 2007. The draft of the so-called Key Indicator Method for Manual Handling Operations (KIM-MHO) was developed in analogy with the existing KIM for Lifting/Holding/Carrying (KIM-LHC) and Pulling/Pushing (KIM-PP) of loads. The KIM-MHO is designed to fill the gap existing in risk assessment of manual work processes, since the existing KIMs deal only with manual handling of loads.This research project focused on the following:- Examination of the validity of workplace assessment with the KIM-MHO comparing expert ratings with the results of the observations.- Examination of the objectivity of workplace assessment with the KIM-MHO applied by different examiners.- Examination of the criterion validity of the risk assessment provided by KIM-MHO with respect to the association between exposure and the occurrence and prevalence of health related outcomes.Methods/DesignTo determine the objectivity and validity of workplace assessment, the KIM-MHO is applied by occupational health and safety officers at different workplaces involving manual handling operations.To determine the criterion validity of risk assessment, a survey of employees at different workplaces takes place with standardised questionnaires and interviews about symptoms in the neck and upper extremities. In addition, physical examinations of these employees following a standardised medical diagnostic procedure are also carried out.DiscussionThis research project will provide scientific evaluation of the new KIM-MHO and, if necessary, indicate areas for modification to improve this new method for assessment of the health risk of manual handling operations at diverse workplaces.

Evaluation of objectivity, reliability and criterion validity of the key indicator method for manual handling operations (KIM-MHO), draft 2007.

Upper extremity musculoskeletal symptoms and disorders are common in the working population. The economic and social impact of such disorders is considerable. Long-time, dynamic repetitive exposure of the hand-arm system during manual handling operations (MHO) alone or in combination with static and postural effort are recognised as causes of musculoskeletal symptoms and disorders. The assessment of these manual work tasks is crucial to estimate health risks of exposed employees. For these work tasks, a new method for the assessment of the working conditions was developed and a validation study was performed. The results suggest satisfying criterion validity and moderate objectivity of the KIM-MHO draft 2007. The method was modified and evaluated again. It is planned to release a new version of KIM-MHO in spring 2012.

Validation of newly developed and redesigned key indicator methods for assessment of different working conditions with physical workloads based on mixed-methods design: a study protocol

Introduction The impact of work-related musculoskeletal disorders is considerable. The assessment of work tasks with physical workloads is crucial to estimate the work-related health risks of exposed employees. Three key indicator methods are available for risk assessment regarding manual lifting, holding and carrying of loads; manual pulling and pushing of loads; and manual handling operations. Three further KIMs for risk assessment regarding whole-body forces, awkward body postures and body movement have been developed de novo. In addition, the development of a newly drafted combined method for mixed exposures is planned. All methods will be validated regarding face validity, reliability, convergent validity, criterion validity and further aspects of utility under practical conditions. Methods and analysis As part of the joint project MEGAPHYS (multilevel risk assessment of physical workloads), a mixed-methods study is being designed for the validation of KIMs and conducted in companies of different sizes and branches in Germany. Workplaces are documented and analysed by observations, applying KIMs, interviews and assessment of environmental conditions. Furthermore, a survey among the employees at the respective workplaces takes place with standardised questionnaires, interviews and physical examinations. It is intended to include 1200 employees at 120 different workplaces. For analysis of the quality criteria, recommendations of the COSMIN checklist (COnsensus-based Standards for the selection of health Measurement INstruments) will be taken into account. Ethics and dissemination The study was planned and conducted in accordance with the German Medical Professional Code and the Declaration of Helsinki as well as the German Federal Data Protection Act. The design of the study was approved by ethics committees. We intend to publish the validated KIMs in 2018. Results will be published in peer-reviewed journals, presented at international meetings and disseminated to actual users for practical application.

Risk assessment of manual handling operations at work with the key indicator method (KIM-MHO) — determination of criterion validity regarding the prevalence of musculoskeletal symptoms and clinical conditions within a cross-sectional study

BackgroundManual handling operations (MHO) are known to be risk factors for work-related upper limb disorders (WRULDs), e.g. symptoms and conditions such as carpal tunnel syndrome. To estimate the risk of WRULDs, a Key Indicator Method (KIM) for the risk assessment of MHO was developed. The method was validated in regard to different criteria, including face validity, criterion validity, reliability and further aspects concerning utility. This paper describes the KIM-MHO and criterion validity of this method with reference to prevalence of musculoskeletal disorders (MSDs).MethodsA cross-sectional sample of 643 employees exposed to MHO was compared to a reference group of 804 unexposed subjects predominantly working at visual display terminals. The Nordic Questionnaire and a standardized clinical examination were used to obtain the 7-day and 12-months prevalence of symptoms and clinical conditions of the musculoskeletal system. Job specific exposure levels to MHO were assessed by ergonomists using the KIM-MHO. The resulting risk scores were categorized into risk categories 1 - low risk (reference group), 2 - increased risk, 3 - highly increased risk, and 4 - high risk. Log-linear Poisson regression models were applied to obtain adjusted prevalence ratios (PR) with 95%-confidence intervals.ResultsThe 7-day prevalence of symptoms for subjects in risk category 3 compared to risk category 1 was significant for the regions shoulder [women (w): PR 1.8 (1.2–2.7), men (m): PR 2.3 (1.2–4.4)], elbow [w: PR 3.3 (1.5–7.2), m: PR 2.4 (0.8–7.3)], and hand/wrist [w: PR 3.0 (1.7–5.3), m: PR 5.5 (2.7–11.3)]. The 7-day prevalence of symptoms for risk category 4 was also significant for the regions shoulder [w: PR 1.9 (1.3–2.8), m: PR 1.9 (1.3–2.7)], elbow [w: PR 4.5 (2.3–8.7), m: PR 3.3 (2.1–5.4)], and hand/wrist [w: PR 4.2 (2.6–6.9), m: PR 5.5 (3.5–8.5)]. The 12-months prevalence in these joint regions show comparable increases in the risk categories 3 and 4.ConclusionsThe KIM-MHO is valid in regard to criterion validity. The hypothesis could be confirmed, that high risk scores were associated with an increased prevalence of symptoms and clinical conditions especially in the shoulder, elbow and hand/wrist regions among employees exposed to MHO.

Considerations for the dimensions of a test finger according to anthropometric data

BACKGROUND: Standardized test fingers are used for testing products against mechanical and electrical hazards. The dimensions of the most common test finger, mentioned in several standards, have remained unchanged for many decades. In the meantime, the corresponding anthropometric dimensions of the human being as well as the safety standard and safety awareness have changed. OBJECTIVE: Starting from the dimensions of the most common test finger for adult persons, length and diameter of the test finger were analysed, whether they are still in accordance with the anthropometric considerations and whether they represent a sufficient safety-level. METHODS: Current distributions of relevant body dimensions from literature and own measurements were considered and compared with the dimensions of the common test finger. RESULTS: The analysis of anthropometric data reflects that in the past decades people are on average getting larger and wider. This refers to the German and European population, but also to large other parts of the world’s population. CONCLUSIONS: The current diameter of the common test finger still offers a high level of protection. However, the changes of the last decades, both in what concerns the anthropometric measurements as well as the safety standard and safety awareness, seems to require an adaptation of the length of the test finger to ensure the same level of safety protection as the chosen diameter.

State of scientific knowledge about the need of recovery time at specific workplaces and recomendations for further research

Research activities to determine the need of recovery time at work were mainly performed in the 1970s and 1980s. Previous studies were largely based on expert opinions or were generated within small and non-representative groups. Often, laboratory experiments were carried out with a low number of subjects. Especially during the last decade, only little additional scientific knowledge was generated on this topic. The very resource intensive development of more detailed results based on the existing level of scientific knowledge is assumed as one reason for this. In general, it seems to be reasonable to continue further research on the knowledge generated in previous studies, but implement larger samples and more representative groups. Besides, according to monotonous manual work, more research is especially needed regarding relative operating forces and operation frequencies taken grip conditions and hand/body position into account.

Prädiktoren und Schadensbilder der Kniegelenksarthrose

ZusammenfassungDie Kniegelenksarthrose (Gonarthrose) zeichnet sich durch eine hohe Prävalenz auch in der Allgemeinbevölkerung sowie durch eine multifaktorielle Ätiologie aus. In der ArGon-Studie (ArGon = Arbeit und Gonarthrose) wurden für Männer und Frauen Übergewicht/Adipositas, kumulatives Knien/Hocken, genetische Prädisposition und bestimmte Sportarten sowie für Frauen zusätzlich Beinachsenfehlstellungen, kumulatives Heben/Tragen von Lasten und Knie-Beschwerden bereits in der Kindheit als Prädiktoren für Kniegelenksarthrose ermittelt. In Subgruppenanalysen des Fallkollektivs zu den physischen Belastungsfaktoren ließen sich in diesem Kollektiv spezifische Schadensbilder nur für Beinfehlstellungen aufzeigen.SummaryKnee osteoarthritis (OA) shows a high prevalence in the general population. The etiology is multifactorial. Within the ArGon-Study (ArGon = an acronym for „Arbeitsbedingungen“ [working conditions] and „Gonarthrose“ [knee OA]), overweight/obesity, cumulative kneeling/squatting, heredity and specific sports were in a significant connection to knee OA in women and men. In addition, malalignment of the knee, pain in the knee already during childhood and cumulative daily lifting/carrying of loads were identified as predictors for knee OA in women.Subgroup analysis among cases with respect to physical exposures indicated that a specific pattern of cartilage damage only resulted for malalignment of the knee.