A Case-Control Study of Femoral Neck Fracture in Aged Japanese Women

Abstract

Femoral Neck fracture of the elderly is becoming an increasingly important health problem in Japan these days. We carried out a retrospective case-control study of the fracture in order to explore the risk factors. Forty matched pairs of women were taken from the Tokyo Metropolitan Homes for the Aged and affiliated orthopedic service. Cases were defined as having experience of femoral neck fracture within three years without history of bone diseases. Twenty cases each were selected from home and hospital. An equal number of control was selected from home and the same hospital service matching for age (± 5 years). The average age was 79.5 for cases and 78.9 for controls. Information on milk, bread, meat, fish and tofu (popular Japanese food made from soy bean and rich in calcium) intake, smoking, drinking and exercise habits, menstrual and reproductive histories, experiences of falls during past three years, types of daily clothing (kimono or western clothes) and daily footwear (sandals or shoes), mental health condition, height and weight, blood pressure, blood hemoglobin content, serum albumin, calcium, phosphate and alkaline phosphatase, the metacarpal index (MCI) and the maximum density of the metacarpal cortex (GSmax), number of remaining teeth, grasping power and balance test standing on one leg was obtained through personal interviews and by use of medical records. Cases more often ate meat (p<0.05) and less tofu (p<0.05). Morever the cases experienced menopause earlier (p<0.01) and weighed less (p<0.06) than controls. Cases were more likely to be judged as having some degree of dementia (29% vs 2.5%, p<0.01) and a larger proportion of cases experienced “frequent” falls (i.e., more than 3 falls during 3 years prior to the fracture event or to the date of interview) (p<0.10). Mean serum albumin was lower (p<0.01) in hospital cases but not in home cases. The other items including MCI and GSmax appeared to have no significant differences between cases and controls. We did not measure their calcium nor protein intake quantitatively. But, as tofu is the major source of calcium in the Japanese elderly, it may be assumed that women who frequently ate tofu were taking more calcium than who did not. Early menopause and low body weight are both well known risk factors for this fracture and our observations coincided with the previous reports. Dementia can be either a cause or a consequence, or both of the fracture. Radiological indices of osteoporosis using the metacarpal bone seem to be insensitive to predict the risk of femoral neck fracture. © 1986, The Japan Geriatrics Society. All rights reserved.