Can a more neutral position of the forearm when operating a computer mouse reduce the pain level for visual display unit operators? A prospective epidemiological intervention study: Part II
01 January 2001
The aim of this study was to investigate if participants with pain experience reduced pain development when using a mouse allowing a more neutral position of the wrist (Anir) compared with development of pain using a traditional mouse. The study population consisted of 67 participants with mean intensity of pain of approximately 50 mm on a 100-mm Visual Analog Scale (VAS). The total group was randomly divided into 1 intervention group and 1 control group. The study was performed as a prospective parallel group study. VAS was used to assess the average level of pain in the musculoskeletal system during a 6-month period. An earlier article on this study found that after using the Anir mouse for 6 months, a significant reduction was reported in neck pain (48.9 to 33.9). Corresponding data for other areas of the upper extremities were shoulder (54.1 to 31.8), forearm (52.9 to 32.8), and wrist and hand (42.5 to 22.3), respectively (Aaras, Ro, & Thoresen, 1999). The control group using the traditional mouse reported no significant changes in pain level. This article describes the results after giving an identical intervention to the control group. After 6 months, the former control group reported a significant reduction in average pain for the following body areas: shoulder, M = 48.0 (Cl = 32.5-63.5) to M = 28.7 (CI = 18.7-38.8); forearm, M = 45.6 (Cl = 30.8-60.4) to M = 15.6 (CI = 5.5-25.7); and wrist and hand, M = 34.8 (CI = 20.1-49.5) to M = 15.8 (6.4-25.2). Neck pain was marginally significantly reduced, M = 39.4 (CI = 25.2-53.6) to M = 27.4 (CI = 15.2-39.6), p = .07. The group getting the initial intervention did not report any significant changes in any of the body areas from 6 to 12 months after the study period; that is, the reduction in pain level obtained still existed. The results from this study indicate clearly the importance of using a more neutral position of the forearm when using a computer mouse. Laboratory tests on performance measures (speed and accuracy) showed that the Anir mouse falls well within the range of performance measures associated with already existing commercially available input devices.