CASE STUDY:

Repetitive Strain Injury in a Postal Worker

Barbara Burgel, R.N., M.S., C.O.H.N.-S., F.A.A.N.

A 42 year old female postal worker has been referred to the occupational medicine clinic for evaluation. She says that for the past five months she has had intermittent bilateral hand and wrist pain (right greater than left), associated with right hand weakness. She also reports numbness and tingling in bilateral fifth digits intermittent over the past two months, and mild right elbow pain.

For the past eight years, the patient has worked full time as a Letter Sorting Machine (LSM) operator for the U.S. Postal Service.

Figure 1. Letter Sorting Machine
Please note: the Letter Sorting Machine (LSM) has been phased out by the U.S. Postal Service, and replaced by newer technology that requires limited keying. However, it requires repetitive feeding and sweeping.

LSM keying requires repetitious flexion and extension of digits, hands, and wrists, at a fixed speed. A 60 speed refers to keying in the zip codes for 60 letters in one minute, one letter per second. Employees key for 30 minutes at a time, preceded by 15 minutes to load the LSM ("feeding") and followed by 15 minutes to remove letters from the machine ("sweeping").

The work environment is dusty. It is noisy when all machines are running, especially on the night shift which has the heaviest mail volume. The patient complains of some cross-cultural conflicts with her supervisor, and fears harassment if she goes on limited duty. She has no hobbies or other non-work activities that involve repetitive motion.

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