Identification of emerging determinants linked to the risk of MSDs: ergonomic and biomechanical analysis of the activity of meat cutting

Outline of reasons and objectives
The meat-cutting sector is one of the sectors that is most affected by musculoskeletal disorders (MSDs). Organisational changes, in particular when subcontracting is used, can mean that employees from a variety of enterprises (user enterprises (UEs) and external enterprises (EEs)) can work on the same production site, in particular for performing certain knife maintenance operations, such as sharpening or grinding. Divergences of viewpoint on the cutting quality of the knives have been observed, particularly when subcontractors are used. The objective of this study is to propose new prevention responses by identifying new MSD risk determinants in the activity of meat cutting. To this end, various criteria for assessing knife cutting power (KCP) that were indicated by cutting operatives and knife sharpeners or grinders were analysed in varied organisational and contractual contexts.

Approach
An ergonomics and biomechanics approach was implemented by combining quantitative and qualitative assessments of the cutting power of the knife before and after the sharpening and grinding operations. Sharpening activities were analysed and operatives were interviewed alone and in pairs (intra-profession, between cutting operatives or between sharpeners/grinders; and inter-profession, between cutting operatives and sharpeners/grinders). The methodology was implemented on four meat cutting sites (29 cutting operatives and 7 sharpeners/grinders), including three different modes of organising the sharpening/grinding.

Main results
The study made it possible: to identify KCP assessment criteria specific to each profession (cutting operative and sharpener/grinder): physical, visual, auditory, and productivity criteria; and to compare them. Among those criteria, auditory and productivity criteria appeared as being new. In addition, new physical and visual criteria came to supplement the ones that already existed in the literature, in particular: the “sensation” experienced when the knife comes into contact with the sharpening/grinding tool or in contact with the test paper; twist in the blade of the knife; colouring of the knife as a sign of quality or of a defect in the cutting edge of the knife; or meat-cutting quality indices.
As regards the determinants of the cutting power of the knife, differences in opinion were identified depending on the profession (cutting operative or sharpener/grinder). Other determinants, such as lack of exchange between the cutting operatives and the sharpeners/grinders, organisational dependence, or lack of training or inappropriate training were also identified.

Discussion and conclusion
These results will enable enterprises and professionals in this sector to act on organisation of knife maintenance in a context of subcontracting involving user enterprises and external enterprises, while taking into account the ties between sharpener and cutting operative. To this end, depending on the mode of organisation of the sharpening/grinding, thought needs to be given on creating intra- and inter-profession discussion spaces. Working on these issues will enable progress to be made in optimising knife maintenance and, in doing so, in controlling the MSD risk, while taking account of the organisational contexts of the enterprises. These results may also bring about changes in the training aids made available by INRS for meat-cutting enterprises and in the contents of training in knife maintenance (sharpening and grinding). Such changes will emphasise the close ties between these two tasks (cutting and sharpening) and the operatives that perform them. Those operatives need to incorporate to the same extent knowledge common to both professions and knowledge that is specific to each profession. The results of this study have already been the subject of various presentations at international conferences, and will be incorporated into INRS training aids.