Low grip strength is associated with bone mineral density and vertebral fracture in women

Abstract

Grip strength has been reported to be associated with bone mass locally at the forearm and also at distant skeletal sites, including the spine and hip. Less is known about the association between low grip strength and risk of vertebral fracture. The aim of this study was to examine the association between low grip strength, bone mineral density at the hip and spine, and vertebral fracture in middle-aged and elderly European men and women. Men and women aged 50 yr and over were recruited for participation in a screening survey of vertebral osteoporosis across Europe. Subjects who agreed to take part had an interviewer-administered questionnaire and lateral spinal radiographs performed. Subjects were assessed also for grip strength using a handgrip dynamometer (range 0-300 mmHg). A subsample of those recruited had bone mineral density measurements performed at the spine and femoral neck. Subjects had repeat lateral spine radiographs performed a mean of 3.8 yr following the baseline survey. Linear regression analysis was used to determine the association between low grip strength and bone mineral density at the hip and spine. Logistic regression was used to determine the association between grip strength and both prevalent and incident vertebral fracture. One thousand two hundred and sixty-five men and 1380 women with data concerning grip strength and bone mineral density were included in the analysis. In women, after age adjustment, compared with those with 'normal' grip, those with 'impaired' (231-299 mmHg) and low grip (<231 mmHg) had significantly lower bone mass at the spine and femoral neck. In men, those with low grip strength had a lower BMD at the spine and hip than those in the normal group. However, because of the small numbers with submaximal grip strength, the confidence intervals around all estimates included zero. Adjustment for body size and levels of physical activity had little effect on the results. In addition, among women, after adjustment for age, body mass index and physical activity levels, compared with those with normal grip, those with low grip strength had an increased risk of developing incident vertebral fracture (odds ratio = 2.67; 95% confidence interval 1.13, 6.30). Further adjustment for spine bone density had little influence on the association (odds ratio = 2.60). In women, low grip strength is associated with low bone mineral density at both the spine and hip and an increased risk of incident vertebral fracture. These associations cannot be explained by differences in body size or lifestyle.