Longmate, Arthur R., 1996, Johnson & Johnson, Ergonomic Control Measures in the Health Care Industry, Occupational Ergonomics.
Workers had to adjust the knob at the end of instruments in assembling intestinal staplers. Some of the adjustments required less than one complete knob rotation while other required extensive twisting, up to 10 twists, occasionally in both directions. In one case, the worker had to forcefully twist the knob loose to break weld adhesions which required torque up to 40 in-lb.
OSHA log revealed that about 67% of these injuries were related to different types of elbow tendinitis.
Increasing CTD incidence rate up to 2-3 times the overall plant average.
The majority of the twisting required negligible torque, except one case which required substantial torque – up to 40 in-lb.
The task was highly repetitive, sometimes over 10,000, 90-110 degree forearm rotations per 8 hour work shift.
Within 6 months, new elbow trauma incidence cases were eliminated (95% reduction).
A 300 instrument fixture validation study was conducted to ensure the functionality of the instrument using the new fixtures. Another validation study was conducted to ensure that the torque achieved by the fixture was within process limits.