Field Study on Occupational Knee Loading in the Construction Industry

Introduction: Work-related knee straining activities like kneeling or squatting are regarded as risk factors for diseases of the knee, e.g. osteoarthritis. The aim of this study was to investigate knee straining activities in several construction tasks to gain a new insight into the quality and quantity of occupational knee loading as a base for the development of adequate preventive measures. Methods: Field measurements were carried out on a total of 216 real work places in 11 different professions known for the occurrence of knee straining tasks, e.g. floor layers, roofers, and installers. Posture capturing was performed using an ambulatory measuring system (CUELA). The system allows time-continuous recording of body angles and the calculation of postures and movements of the trunk and lower limb. Thus, the occurrence, frequency, and duration of five different knee postures were continuously measured. A simultaneous video documentation completed the measuring setup. Results: The daily amount of knee loading widely varied within the analysed occupations, e.g. from 5.3 % to 65.8 % per day (installers) or from 3.7 % to 64.7 % per day (roofers). The highest average percentages of daily knee load were measured for pavers (82.5 %, task: laying cobblestones) and parquet layers (74.1 %, laying strip parquet). The different quality of knee loading in each task module was illustrated by the proportions of the single knee postures, showing some specific characteristics, e.g. predominating squatting (pavers) or a comparatively high percentage of crawling (floor layers). Discussion: The study showed a wide variation in the daily knee loading between occupations and within a single occupation. Therefore, task-specific knowledge about the knee loading is important for the development of tailored preventive measures. In addition, the technical analysis of the knee loading may contribute to a better understanding of the pathomechanism of knee disorders.