Comparison of instantaneous and cumulative loads of the low back and neck in orthodontists

The primary objective of this study was to quantify instantaneous and cumulative spinal loads in orthodontic practice. The study consisted of two parts. The first part of the study included the mailing out of the standardized nordic questionnaire to all orthodontists residing in the province of Alberta, Canada to find out the prevalence of musculoskeletal disorders (MSDs) within the occupation. There was a 56 percent response rate: 32 respondents out of 57 distributed questionnaires. Of the 32 respondents, 19 (59%) reported low back trouble, 18 (56%) neck trouble and 15 (47%) shoulder trouble. The second part of the study included a sample of graduate orthodontic students (n = 9) from the University of Alberta. The subjects were videotaped performing their regular duties and the recorded postures were printed for biomechanical analysis of instantaneous compression and shear loads on the low back and neck. Cumulative loads were calculated from the instantaneous loads. A postural discomfort questionnaire was also administered to the subjects to be completed at four different times during the work day. The results showed the average instantaneous lumbosacral compression loads for males and females to be 1,383 N and 936 N respectively. The average daily cumulative lumbosacral compression loads for males and females were 16.2 MNs and 9.9 MNs respectively. The conclusion arises from the results that instantaneous loads are not indicative of cumulative loads, particularly for the occupation of orthodontistry. Furthermore, prolonged static sitting exerts large cumulative loads on the spine, which is compelling evidence to show and confirm that orthodontic practice is of high risk for MSDs.Validerat; 20101217 (root