ORIGINAL ARTICLE Biopsychosocial Factors Are Associated with High Prevalence of Self-reported Musculoskeletal Symptoms in the Lower Extremities Among Office Workers Prawit Janwantanakul, a Praneet Pensri, a Wiroj Jiamjarasrangsi, b and Thanes Sinsongsook c a Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand b Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand c Department of Occupational Medicine, Samutprakarn Hospital, Samutprakarn, Thailand Received for publication November 1, 2008; accepted January 9, 2009 (ARCMED-D-08-00496). Published previously online April 9, 2009. Background and Aims. Little attention has been given to musculoskeletal symptoms in the lower extremities among office workers. The aim of this study was to investigate the rela- tionships between the self-reported prevalence of musculoskeletal symptoms in the hip, knee and ankle/foot and individual, work-related physical and psychosocial factors. Methods. A cross-sectional survey was conducted in which 2000 office workers from 54 workplaces in Bangkok registered at the Social Security Office of Thailand received a self-administered questionnaire. Of those, 1428 (71%) returned the questionnaire. After screening for exclusion criteria, 1185 office workers were eligible for the study. The prev- alence of self-reported musculoskeletal symptoms in the hip, knee and ankle/foot was associated with certain individual, work-related physical and psychosocial factors. Results. Mental demands and work repetitiveness were each significantly associated with the prevalence of experiencing hip symptoms. Suffering from a chronic disease, the average number of working hours/day, sleep quality and self-rated perception of air circulation in the office were significantly related to the prevalence of experiencing knee symptoms. Signif- icant associations were found between the prevalence of experiencing ankle/foot symptoms and sleep quality, self-rated perception of the ergonomics of the desk and size of office space and frequency of feeling frustrated during the previous 4 weeks. Conclusions. Results of this study indicated that several biopsychosocial factors were associated with a high prevalence of self-reported musculoskeletal symptoms in the lower extremities among office workers. Further prospective studies are required to substantiate the observed associations. Ó 2009 IMSS. Published by Elsevier Inc. Key Words: Occupational injuries, Pain, Hip, Knee, Ankle, Foot. Introduction Musculoskeletal symptoms are common among office workers. Previous research in this area has mainly focused on musculoskeletal symptoms in the upper extremities and spine (1e4). Little attention has been given to musculoskel- etal symptoms in the lower extremities. A recent survey of self-reported musculoskeletal symptoms in the general population of office workers revealed that some office workers experienced musculoskeletal symptoms in the lower extremities during the previous 12 months with a prevalence of 6% in the hip, 12% in the knee and 13% in the ankle/foot (5). It is generally agreed that the etiology of musculoskel- etal disorders is multifactorial and includes individual, physical and psychosocial factors (6e9). Apart from computer and document work, office workers frequently perform several physical activities during their normal working day, such as lifting, bending, twisting, reaching, carrying, and climbing stairs. These activities are associated with repetitive movements, awkward posture and forceful exertions, which are identified as the primary risk factors Address reprint requests to: Prawit Janwantanakul, Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand; E-mail: prawit.j@chula.ac.th 0188-4409/09 $esee front matter. Copyright Ó 2009 IMSS. Published by Elsevier Inc. doi: 10.1016/j.arcmed.2009.02.010 Archives of Medical Research 40 (2009) 216e222