Cornell University Ergonomics Web
The Problem
SP is left handed and, as a faculty member, she works for long periods of time on her computer. She was experiencing increasing amounts of pain in the left side of her neck, her left shoulder, and discomfort in her left arm and wrist. She had received extensive physical therapy treatment. However, her symptoms were not alleviating when she contacted the Cornell Ergonomics group for advice.
Pre-intervention Workstation Arrangement
SP worked at a 28" office desk. Her keyboard was placed on the desk with the rear legs extended to raise the angle of the keys, her mouse was placed to the left of this, and her phone to the left of the mouse. The keyboard was placed away from the desk edge because SP needs space for paperwork. Her monitor was placed on the desk. She used a footrest. (see Figures 1, and 2).
Figures 1 and 2 clearly show that this keyboard arrangement forced her to type with her arms extended, and her wrists in extension. After prolonged working at the keyboard SP tended to hunch forwards, which created greater strain on the neck, shoulders, arms and wrists.
Figure 1 Pre-intervention keyboard arrangement. 
Figure 2 Pre-intervention keyboard and mouse
arrangement.
SP works at a PowerMac computer and makes extensive use of the mouse with her left hand. Figures 3 and 4 show that when she used the mouse her left arm was abducted, her left shoulder was raised and her neck was laterally bent. Also, her phone was placed to her far left because of a lack of space in her immediate work area. This layout encouraged frequent postural deviations that aggravated her symptoms.
Figure 3 Pre-intervention mouse arrangement. 
Figure 4 Pre-intervention mouse arrangement.
Ergonomic Intervention
Analysis of SP's working posture indicated that she needed a keyboard and mouse arrangement that would allow her to work with her arms relaxed and within the immediate work zone, from elbow to elbow, and with her wrists sustained in a neutral posture. To test the benefits of improving her work posture, a preset tiltdown keyboard system was installed .
Post-intervention Workstation Arrangement
The Preset tiltdown keyboard system was fitted to SP's desk (see Figure
5). This system allows SP to sit back in her chair without the need of a
footrest. The height adjustable keyboard platform allows the keyboard to
be used with her arms relaxed and her wrists in a neutral posture. The position
adjustable mouse platform (see Figure 6) allows SP to work with her left
arm relaxed, and close to the body. In this posture her left shoulder is
relaxed and her neck is upright. Her monitor has been raised by using two
"Adjustors", so that this is appropriate for eye level (see Figure
7). The monitor position allows her to work without either a twisted or
awkward neck posture, which also allows her shoulders to relax.
Figure 5 Post-intervention keyboard arrangement. 
Figure 6 Post-intervention mouse position.
Figure 7 Post-intervention workstation arrangement. 
Analysis of SP's new working posture with the Preset tilt-down keyboard system shows that she can now perform all of her computer work with her arms relaxed and within the immediate work zone, from elbow to elbow, and with her wrists in a relaxed, neutral posture.
For further information on this case study contact Alan Hedge by email at ah29@cornell.edu