[Risk assessment comparison of biomechanical overloading of the musculoskeletal system: 10 years' applied experience]

Risk assessment for upper extremity work related muscoloskeletal disorders by applying six methods of ergonomic: a ten years experience. The objective of this research was to verify and validate the multiple step method suggested by SIMLII guidelines and to compare results obtained by use of these methods: Washington State Standard, OCRA, HAL, RULA, OREGE and STRAIN INDEX.

598 workstations for a total of 1800 analysis by different methods were considered, by adopting the following multiple step procedure: prelinminary evaluation by Washington State method and OCRA checklist in all the working stations, RULA or HAL as first level evaluation, OREGE or SI as second level evaluation.

The preliminary evaluation resulted negative (risk absent) in the 75% of examined work stations and by using checklist OCRA optimal-acceptable condition was found in 58% by HAL in 92% of analysis, by RULA in 100%, by OREGE in 64%; by SI in 70% of examined working positions. We observed similar evaluation of strain among methods and main differences have been observed in posture and frequency assessment.

The preliminary evaluation by State of Washington method appears to be an adequate instrument for identify the working condition at risk. All the adopted methods were in a good agreement in two estreme situations: high risk or absent risk, expecially in absent risk conditions. Level of accordance varied on the basis of their rationale and of the role of their different components so SIML indications about the critical use of biouzechanical methods and about the possible use of more than one of them (considering working chlaracteristics) have been confirmed.