Risk Factors for Knee Osteoarthritis in Japanese Women: Heavy Weight, Previous Joint Injuries, and Occupational Activities

NORIKO YOSHIMURA, SHINGO NISHIOKA, HIROFUMI KINOSHITA, NORIAKI HORI, TAIRA NISHIOKA, MASAHIKO RYUJIN, YOSHIHIKO MANTANI, MARIKO MIYAKE, DAVID COGGON, and CYRUS COOPER

ABSTRACT.

Objective. Risk of knee osteoarthritis (OA) associated with constitutional factors, history of joint injuries, and occupational factors was assessed in a case-control study among women in Japan. Results were contrasted with a comparable study in Britain.

Methods. The study covered 3 health districts in Japan. Cases were women aged ³ 45 years old, diagnosed with knee OA by orthopedic physicians utilizing radiography. No cases displayed established causes of secondary OA. Controls selected randomly from the general population were individually matched to each case for age, sex, and residential district. Subjects were interviewed using structured questionnaires to determine medical history, including history of joint injury, physical activity, socioeconomic factors, and occupation. Height and weight were measured.

Results. Interviews were obtained from 101 female cases and controls. The highest third of heaviest body weight in the past [high (> 62.0 kg) vs low (< 55 kg) odds ratio = 4.42, 95% confidence interval 1.17–16.64], previous injury to the knee (OR 7.11, 95% CI 2.40–21.09), sedentary work during initial employment (OR 0.35, 95% CI 0.15–0.84), and total working years (OR 1.05, 95% CI 1.01–1.08) represented independent factors associated with knee OA, after controlling for other potential risk factors.

Conclusion. Heavy weight in the past appears to represent a risk factor for knee OA among women in Japan, as reported in Britain. Constitutional factors may represent important determinants for knee OA, regardless of race. Previous injury to the knee and occupational factors are also associated with knee OA in both Britain and Japan, although characteristic activities for work vary. (J Rheumatol 2004;31:157-62)

Key Indexing Terms:

OSTEOARTHRITIS
KNEE JOINT
CASE-CONTROL STUDY
HEAVY WEIGHT
JOINT INJURIES
OCCUPATIONAL ACTIVITIES

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From the Department of Public Health and 2nd Department of Internal Medicine, Wakayama Medical University School of Medicine, Wakayama; Saiseikai Wakayama Hospital, Wakayama; Hori Hospital, Sennan; Nishioka Orthopaedic Hospital, Arita; Ryujin Clinic, Wakayama; Tamai Orthopaedic Hospital, Hannan; and Yamomoto Clinic, Shimotsu, Japan; and the MRC Environmental Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, United Kingdom.

Supported by Grants-in-Aid for Scientific Research A11770200 from the Ministry of Education, Science, Sports and Culture in Japan, Japan Society for the Promotion of Science, Research Society for Metabolic Bone Diseases, 1998 Wakayama Medical Award for Young Researchers, Japan; and the Arthritis Research Campaign, UK.

N. Yoshimura, MD, Lecturer of Public Health; S. Nishioka, MD, Professor Emeritus of Internal Medicine, Wakayama Medical University School of Medicine; H. Kinoshita, MD, Consultant of Orthopaedics, Saiseikai Wakayama Hospital; N. Hori, MD, Director, Hori Hospital; T. Nishioka, MD, Director, Nishioka Hospital; M. Ryujin, MD, Director, Ryujin Clinic; Y. Mantani, MD, Consultant of Internal Medicine, Tamai Orthopaedic Hospital; M. Miyake, MD, Consultant, Yamomoto Clinic; D. Coggon, DM, Professor of Occupational and Environmental Medicine; C. Cooper, DM, Professor of Rheumatology, University of Southampton, Southampton General Hospital.

Address reprint requests to Dr. N. Yoshimura, Department of Public Health, Wakayama Medical University School of Medicine, 811-1 Kimiidera, Wakayama 641-0012, Japan.

Submitted June 4, 2002; revision accepted July 3, 2003.

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