From The Ergoweb® Learning Center

Instrument Test Fire Fixture


Longmate, Arthur R., 1996, Johnson & Johnson, Ergonomic Control Measures in the Health Care Industry, Occupational Ergonomics.

Task Prior to Abatement (Description)

Workers had to hand fire andescopic surgical instruments during the manufacturing process several times in order to ensure their proper function during medical procedures. Hand firing means power gripping a handle or trigger instrument configuration and squeezing to provide the power to form surgical staples or ligating clips. Some workers were squeezing the instrument much harder than required, believing they would do a better job. Some instruments required about 50th percentile maximum female grip strength.

Task Prior to Abatement (Method Which Identified Hazard)

Increasing medical cases of upper extremity disorders including tendinitis and other overuse syndromes.

Nearly all workers performing this task had experienced some type of medical symptom.

Ergonomic Risk Factor (Force)

Workers had to apply up to 50 lb of grip force on assembling lines.

Ergonomic Risk Factor (Repetition)

High repetition rate of up to a thousand hand firings was required while performing the task on the production line.

Ergonomic Solution (Administrative Controls)

  1. Training was provided to demonstrate the performance of the task.
  2. Training fixtures with a force indicator were provided to indicate the sufficient force.
  3. A job rotation matrix was developed.

Ergonomic Solution (Engineering Controls)

  1. Powered Test Fire Fixtures were provided to test the instruments. Workers now perform only one or two firings manually in order to test the actual feel of the instrument.

Ergonomic Solution (Benefits)

  • All workers that perform this task now have reduced exposure to upper extremity disorders.
  • Elimination of many injuries due to staples being accidentally fired into the fingers and hand.

Ergonomic Solution (Method Which Verified Effectiveness)

All incidence of CTD’s were eliminated by elimination of repetitive hand fire requirements.


The inconvenience of frequent job rotation provided speed on implementing powered test fire fixtures.