Tiltdown To Type

Alan Hedge
Human Factors Laboratory
Cornell University

The most recent report on workplace injuries and illnesses from the Occupational Safety and Health Administration (OSHA) states that in 1994, repeated trauma was associated with nearly two-thirds of workplace illnesses such as carpal tunnel syndrome (CTS). There were 332,000 cases reported--up 10 percent from the previous year. At an average treatment cost of more than $8,000 per case, the incentive for preventing this type of injury is high.

Prevention efforts for CTS focus on ergonomic solutions intended to lower the stress put on the wrists while working at a keyboard, thus reducing CTS incidence. A wide variety of keyboards with innovative designs are now available. Additional solutions include wrist rests and keyboard trays with adjustable heights. Cornell researcher Alan Hedge, director of the Human Factors Laboratory in the College of Human Ecology, has compared a variety of combinations of these technologies with a new and elegantly simple approach--a preset, tiltdown keyboard tray.

In the laboratory, Hedge and his associates mechanically recorded the movements of the wrists of office professionals as they typed on various keyboard configurations. The results of the comparisons confirmed the researchers' suspicions that the typists would experience less stress using the tiltdown keyboard system. However, it wasn't until they could see the wrists in action that they got a clear picture of the mechanism behind this improvement.

Using new data visualization techniques and the supercomputing resources of the Cornell Theory Center, they followed the movements of each typist through a standardized activity. They found that the wrist was put into potentially stressful positions less frequently using the tiltdown tray (even with the conventional keyboard) than it was using any of the other combinations studied.

The tiltdown keyboard tray shows great potential for preventing injury from repeated trauma. "The height and angle of the tiltdown keyboard tray system that we tested can be adjusted to create an optimum keyboard arrangement for any user working at almost any kind of furniture," says Hedge. "The tray system eliminates the main postural risks from both keyboard and mouse use. Our next step is to explore how to best combine the tray system with innovative keyboards."


Credits

Carpal Tunnel Syndrome
Workplace Laboratory
The Neutral Zone

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