Journal of Back and Musculoskeletal Rehabilitation 21 (2008) 113–120 113 IOS Press Can clinical measures of upper quarter postural muscle performance predict neck pain in visual display terminal operators? Peter G. Osmotherly a,∗ , John Attia b,c and Ammarin Thakkinstian d a Discipline of Physiotherapy, School of Health Sciences, Faculty of Health, The University of Newcastle, Newcastle, NSW, Australia b Centre for Clinical Epidemiology and Biostatistics, University of Newcastle, Newcastle, NSW, Australia c Department of Medicine, John Hunter Hospital, New Lambton, NSW, Australia d Clinical Epidemiology Unit, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand Abstract. Objective: The prevalence of neck and shoulder pain in visual display terminal operators is estimated between 40% and 69%. One theory proposed for this is inadequate low load functioning of the postural muscles of the neck and shoulder girdle leading to microtrauma of cervical spine structures. A temporal sequence linking muscle performance to the subsequent development of neck pain has never been established. This pilot study sought to determine whether postural muscle performance factors are associated with neck pain in a population of visual display terminal users. Methods: Twenty-eight subjects underwent a baseline physical examination. Clinical measurements of low-load deep cervical flexor muscle performance, shoulder girdle muscle endurance, neck column length, head and neck posture and body mass index were made and demographic factors collected. Following the examination, a Neck Pain and Disability Scale questionnaire was administered. Variables were analysed in a regression analysis with the questionnaire scores. Questionnaires were readministered at six months follow up. Results: Descriptive variables “years of occupational screen based keyboard use” (p = 0.021) and “use of reading glasses” (p = 0.027) were statistically significantly correlated with Neck Pain and Disability Scale score at baseline, while “hours of home computer use” (p< 0.001) was associated with the change in questionnaire score at 6 months follow up. Muscle performance factors did not contribute to either model. Conclusions: Given the sample size in this pilot study, we cannot rule out an association between muscle parameters and the onset of neck pain and disability. However, the influence of any such association would be weaker than other identified associated variables. 1. Introduction Musculoskeletal pains are probably the most com- monly reported complaint in office workers [19], with VDT operators experiencing an increased rate of prima- ry neck and shoulder pain compared to people perform- ing other office duties [41]. Estimates of the prevalence * Address for correspondence: Peter Osmotherly, Discipline of Physiotherapy, Box 24, Hunter Building, The University of Newcas- tle, Callaghan, NSW, 2308, Australia. E-mail: Peter.Osmotherly@ newcastle.edu.au. of neck pain in VDT operators ranges from 40% [32] to 69% [4] and pain increases with the daily duration of VDT use [1,32]. The aetiology of work related neck pain appears complex, involving physical, psychosocial and individ- ual factors [7,29]. Mechanisms previously suggested for the persistence of neck problems in this popula- tion include selective over usage of low-threshold mus- cle fibres [7,35], nociceptor sensitisation [7] and fear avoidance [24]. Other proposed mechanisms focus on muscular causes and posture including: elevated levels of muscle activity in response to small changes in sagit- ISSN 1053-8127/08/$17.00  2008 – IOS Press and the authors. All rights reserved