Carpal tunnel pressure during hand maneuvers.
NIOSH 1996 Dec; :1-5
Static loading of the fingertip to forces of 6, 9, and 12 N significantly increased carpal tunnel pressure above a no load state. The pressures remained elevated and constant as long as the load was present. The effect of loading on carpal tunnel pressure was independent of (and additional to) the effect of wrist posture. Postures of the wrist, thumb, finger, and forearm influence carpal tunnel pressure in complicated ways. For some joints and postures the direction and magnitude of effects are consistent across the health subjects tested (N=37). When tested in combinations most of the postures were found to have an interaction effect (e.g., wrist extension and finger flexion) although some did not (eg., ulnar-radial deviation and finger flexion). Some of the relationships between carpal tunnel pressure and joint postures (e.g., forearm rotation, extension-flexion, ulnar-radial deviation) and fingertip load can be described by simple mathematical models. However, the specific equations should be used with caution because for some joints and postures the variability between subjects is high. Carpal tunnel pressure during the performance of a repetitive task is influenced in a complicated manner by the pinch force applied during the task (e.g., moving cans) and the joint postures (e.g., keyboard work). for example, during typing the pressure rises above baseline and remains elevated for as long a typing continues. the magnitude of pressure increase is strongly influenced by wrist posture deviation from neutral.
Carpal-tunnel-syndrome; Musculoskeletal-system-disorders; Ergonomics; Arm-injuries; Chronic-inflammation; Chronic-trauma
Ergonomics Program, University of California at San Francisco, 1301 South 46th Street, building 12, Richmond, California, 94804
Final Grant Report
National Institute for Occupational Safety and Health
Division of Environmental and Occupational Medicine, University of California at San Francisco, Richmond, California