Background: Stress-related disorders are widespread and responsible for high societal costs e.g. sick leave payment and reduced productivity. The aim of this study was to evaluate the effect of an intervention program on return to work or labour market.

Objectives: Follow-up study after two years to measure the effects of an implementation strategy consisting of information, education and training in the use of new tools and working-methods for the purpose of reducing knee strain and knee complaints in floor layers. Methods: Training of floor layers (n = 292) in using new working methods was evaluated by questionnaires during the courses. Two years later, this follow-up included questionnaires for the course participants (n = 216) and a control group of floor layers (not trained on courses) (n = 454). Results: Two years after training, 38% used the new working methods weekly or daily compared to 37% three months after the courses, and 10% before. Among controls, only 16% had used the new working methods weekly or daily. The risk of knee complaints .30 days (OR 2.46, 95% CI 1.03 to 5.83) or locking of the knees (OR 2.89, 95% CI 1.11 to 7.5) was more than double among floor layers who had used the new workingmethods for less than one year compared to those who had used them more. The results were adjusted for age, body mass index, and stress. The reduction in more severe knee complaints was greatest if floor layers started to use the new working methods before they developed knee problems. Other musculoskeletal complaints did not increase. Conclusion: This indicates that, within a two-year perspective, the implementation strategy to introduce new working methods in the floor laying trade has been effective; the number of floor layers using the new working-methods has increased, and severe knee problems have reduced.Earlier studies have shown that floor layers spend more than half their working day in knee-straining working positions [1][2][3][4] and have an increased frequency of knee disorders compared with other trades in the construction industry. [2][3][4][5][6] In Denmark, around 900 floor layers are members of the trade union, which is about 90% of all floor layers in Denmark. Floor and carpet layers (collectively referred to as floor layers in this paper) install linoleum, carpet and vinyl floorings. Their work tasks include priming, grinding, filling, gluing and welding. Nearly all floor layers in Denmark use knee pads (98%) and this frequency of use was equal before and after the courses. During recent years, new tools have been introduced which make it possible to carry out some of the job tasks, such as gluing and welding, from a standing position. In spite of campaigns and the development of the new tools, a study from 2000 showed that only 13% of floor layers used the new working methods during the previous 12 months. 7 The floor layers reported that the reason for the lack of change was that the new methods required instruction and that educational training was necessary. In general, the floor layers would only take suggestions from people who were experienced in their trade. These results agree with the findings of other studies. [8][9][10] From 2002-3, 292 floor layers were therefore trained in using new working methods. The effects were ...

Within a 2-year time period, the introduction of new working methods in the floor-laying trade has succeeded. More efforts are needed to sustain the use of the methods among those workers who have been trained and to introduce the methods to those workers who do not yet use them.

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