Rapid Office Strain Assessment (ROSA)
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This ergonomic assessment tool is designed to quickly provide a quantification the risks work related to computer usage at a computer workstation, which can in turn provides the level of change based on the risk associated with the work task. The ROSA final scoring ranges from 1 to 10 , with the higher score indicating an increased risk for work related musculoskeletal disorders.
Development of the tool
This tool was formulated based on the CSA Z412 guidelines of office ergonomics from the Canadian Risk factors of computer usage were identified in various office designs from the Canadian Center of Occupational Health and Safety. Also standard ergonomic books were used to formulate the worksheet. These were developed to match office subsection against each other.
The outcome user must observe the postures from the computer users workstation and work out the components of the ROSA scoresheet.
There are 4 sections of score charts in ROSA. The sub sections include seat pan height and seat pan depth telephone and monitor, seat pan depth, backrest and arm supports, and keyboard and mouse. The scores from the chair subsection and the peripheral subsection (including telephone, keyboards and mouse) are then compared in another chart. These scores are obtained by summing the values for the individual risk factors identified
Office chair scores: the chair section is divided into 4 smaller subsections: seat pan height, seat pan depth, armrest position and back support position
Seat pan height: A neural seated posture involves knees bent at 90 degrees with the feet flat on the ground. Risk factors include sitting at the edge of the chair, low chair, Seat pan must allow 5cm to 7cms space between the back of the knee and the edges of the chair.Arm rest must be positioned so that the elbows are at 90 degrees and shoulders are relaxed. Lumbar supports should be adjusted to fit in the small of the back comfortably, maintaining the normal lordotic curve. The worker needs to be sitting at an angulation of 95-110 degrees.
Monitor scores: The monitor needs to be positioned between 40 to 75 cms or at one arms distance. the height of the monitor needs to be at or just below the workers eye level at seated position.Also the monitor must not be greater than 30 degrees below the seated workers eye level. The monitor needs to be positioned directly in front of the subjects and not
Telephone scores: The position is 300 mm of the worker to reduce extensive reach of the subject. Positioning the telephone in between the neck and head isn't advisable however as it uses static contraction from a lot of muscles around. Thus a hands free device usage is advised.
Mouse scores: Positioned at the same level as keyboard. It also must not cause any wrist extension or deviation while moving the wrist. The size of the mouse must accommodate the workers hand size and mus not cause pinch grip pressure.
Keyboard scores: Workers are supposed keep the elbows at approximately 90 degrees , with the shoulders relaxed. Wrists in a straight position without any elevation of the shoulder or arms. There should not be extreme deviations of the wrist. There should not be hard surfaces that cause any pressure at the area of the carpal tunnel.
Other workstation scores:
- Reaching overhead
- Predominantly upper limb movement
- Work surface too high
- Back support
Duration of use scores:
Working with a piece of equipment for more than 1 hour continuously or 4 hours per day gets additionally adds stress to the body causing fatigue. Less than 30 minutes of continuous work is considered good and a point is taken away from the total score in case of the same.
Properties of the scale:
- Correlation between discomfort levels with an increase in the ROSA score
- The Intra and Inter rater reliability has been established as good to very good
- Scores greater than 5 are referred to as high risk and workstations need to be assessed with ergonomic interventions implemented.