지각 불편도에 근거한 복합 손목 동작 및 외부 부하 분류 체계

Abstract

Objective: This study aims to investigate effects of complex wrist motions including flexion/extension and radial/ulnar deviation, and external load on perceived discomfort, and to develop a new complex wrist motion and external load classification scheme based on the perceived discomfort.BR Background: Although the wrist is used the most frequently in work and vulnerable to work-related musculoskeletal disorders such as carpal tunnel syndrome, sprain, study for exactly quantifying stressfulness of the complex wrist motions is seldom found. The posture classification schemes such as RULA, REBA classify wrist motions into 2~3 categories according to motions of flexion and extension, and simply add 1 or 2 to their corresponding postural stress scores depending upon the degree of radial/ulnar deviation or twist. This is very simple to assess wrist motions, but results in inaccurate wrist motion stress.BR Method: An experiment for measuring perceived discomfort for complex wrist motions was conducted, in which wrist motions of flexion/extension and radial/ulnar deviation, and external load were used as independent variables. Sixteen healthy male college students without histories of musculoskeletal disorders participated in the experiment, whose demographic data were as follows: Age - 24.3 ± 1.14 years; Stature - 174.5 ± 4.73cm; Body weight - 73.8 ± 11.90kg.BR Results: ANOVA showed that flexion/extension, radial/ulnar deviation, external load and interaction effects of flexion/extension and external load, and flexion/extension and radial/ulnar deviation were statistically significant on the discomfort at α = 0.01 or 0.05. The effect of external load is much larger, compared to wrist motions. Based on the experimental results, a new classification scheme reflecting quantity of external load as well as wrist motions was developed.BR Conclusion: The study investigated effects of wrist motions and external load on perceived discomfort, and developed a new classification scheme of wrist motion and external load.BR Application: The results of this study are useful for more precisely assessing postural load according to wrist motions and external load, and can be adopted as a part of a new posture classification scheme.