Soft-tissue injuries related to use of the computer keyboard. A clinical study of 53 severely injured persons.

We studied 53 disabled keyboard operators who complained of pain in the forearms, elbows, wrists, shoulders, and hands. Passive wrist flexion and dorsiflexion impairment to less than 70 degrees due to myofascial shortening associated with an increase in forearm muscle pain on palpation was a useful clinical indicator of injury. Isometric muscle testing was useful in detecting injury to specific muscles. Ligamentous hypermobility of finger joints (72%) and harmful inefficient keyboard styles (intrinsic ergonomic factors) were noted, videotaped, and analyzed. Changes in the workstation (extrinsic ergonomic factors) alone may not be adequate treatment. Individual intrinsic ergonomic factors must also be recognized, addressed, and corrected by a combination of physical therapy, conditioning, technique retraining, education, and counseling. A taxonomy of keyboard technique is proposed as an aid to recognizing potentially harmful postures.