Comparing RULA and Strain index methods for the assessment of the potential causes of musculoskeletal disorders in the upper extremity in an electronic company in Tehran

Musculoskeletal disorders (MSDs) are the most common problems in the work settings. This study aimed to assess the potential causes of the musculoskeletal disorders in the upper extremity among the workers of an electronic company to determine the risk level.

In this cross-sectional study، 50 workers were randomly selected from assembly line workers. Data were collected using the RULA and Strain index (SI) methods and Nordic questionnaire. The safe and unsafe jobs were determined and the risk factors for MSDs were evaluated.

According to the RULA method، 52% of the cases for the right hand and 54% for the left hand were at grade 3، 2% for both hands were at grade 4 and in the automatic PC board tester job، 25% of the cases in both hands were at grade 4. According to the SI scoring، 64% of the cases in the right hand and 42% of them in the left hand were unsafe. Moreover، the most prevalent disorders were seen in waist and shoulder (48%)، wrist (32%)، neck (28%) and back (24%). There was a correlation between work experience and shoulder pain (P=0. 016) and leg pain (P=0. 032) and between the results of the SI method in the left hand and shoulder pain (P=0. 002). Kappa coefficient showed the agreement between the results of both RULA and SI methods.

The frequency of the MSDs، especially in waist، shoulder، neck and back، the unsafe cases in the SI method and also the high risk levels in RULA method are considerable.