J Gerontol A Biol Sci Med Sci 2005 (May); 60 (5): 633637 ~ FULL TEXT
Kado DM, Huang MH, Barrett-Connor E, Greendale GA
Division of Geriatrics,
Department of Medicine,
David Geffen School of Medicine at UCLA,
10945 Le Conte Ave., Suite 2339,
Los Angeles, CA, USA.
BACKGROUND: Physical functional decline is often the determining factor that leads to loss of independence in older persons. Identifying risk factors for physical disability may lead to interventions that may prevent or delay the onset of functional decline. Our study objective was to determine the association between hyperkyphotic posture and physical functional limitations.
METHODS: Participants were 1578 older men and women from the Rancho Bernardo Study who had kyphotic posture measured as the distance from the occiput to table (units = 1.7-cm blocks, placed under the participant's head when lying supine on a radiology table). Self-reported difficulty in bending, walking, and climbing was assessed by standard questionnaires. Physical performance was assessed by measuring grip strength and ability to rise from a chair without the use of the arms.
RESULTS: Men were more likely to be hyperkyphotic than were women (p <.0001). In multiply adjusted comparisons, there was a graded stepwise increase in difficulty in bending, walking and climbing, measured grip strength, and ability to rise from a chair. For example, the odds ratio (OR) of having to use the arms to stand up from a chair increased from 1.6 (95% confidence interval [CI]: 0.9-3.0) for individuals defined as hyperkyphotic by 1 block to 2.9 (95% CI: 1.7-5.1) for individuals defined as hyperkyphotic by 2 blocks to 3.7 (95% CI: 2.1-6.3) for individuals defined as hyperkyphotic by > or = 3 blocks compared to those who were not hyperkyphotic (p for trend < .0001).
CONCLUSION: Older persons with hyperkyphotic posture are more likely to have physical functional difficulties.
From the FULL TEXT Article:
MAINTAINING physical functional ability is an important prerequisite for preserving independence in later life. Many studies have shown that being physically active is associated with less morbidity and mortality . In general, a physically active lifestyle should be promoted to maintain good health; however, there may be certain populations that are at particular risk for poor physical function and that could potentially benefit from early intervention. If risk factors for poor physical function can be identified before the onset of disability, targeted interventions for those at risk may potentially prevent or delay the onset of dependence.
Hyperkyphosis, or an increased thoracic curvature, is commonly observed in older persons and may be an important determinant of poor physical function. Of the studies that have investigated the association between hyperkyphosis and physical function, three of four found a strong association between having excess kyphosis and poor physical functioning, by self-reported and objective measures . However, most of these studies included a small number of participants and only one included men, probably because it is generally assumed that hyperkyphosis is more common in women.
Although most studies on hyperkyphosis have focused on women, men also suffer from postural changes with age [8, 9] and little is known about how these postural changes might affect mens overall health. To gain a better understanding of hyperkyphotic posture and its effects on physical function in a larger general population of older community-dwelling men and women, we assessed the association of hyper-kyphotic posture with self-reported and measured physical performance in 1578 older adults.
In this cohort, older men and women with hyperkyphotic posture were more likely to have self-reported difficulty in bending, walking, and/or climbing; worse measured hand grip; and more trouble performing the chair stand exercise five times without using their arms. Furthermore, the odds of having difficulty in each of these measures increased, in a dose-dependent manner, with worsening kyphotic posture. Regardless of the physical function outcome studied, the association between hyperkyphotic posture and poorer function was remarkably consistent and independent of age, sex, body size, BMD, clinical spinal fractures, other comorbidities, and health-related behaviors.
These results are concordant with those of previous studies that reported a cross-sectional association between hyperkyphosis and impaired physical function . In the sole prior study that found no significant association between kyphosis and self-reported activity level , the study sample was small and very high functioning so that there might not have been enough variability to detect significant differences. To date, the Rancho Bernardo Study is the largest cohort study reporting the effects of clinical hyperkyphosis on physical function.
In the present study, older men were approximately twice as likely as women to be classified as having hyperkyphotic posture based on a simple clinical measurement. These findings are in contrast to the commonly held belief that hyperkyphosis is more prevalent in older women than men, and are likely due to differences in the kyphosis measurement method. Whereas the traditional radiologic measurement of kyphosis angle includes only the thoracic spine (approximately T4T12), clinical measurements such as the measure we used incorporate some of the cervical spine curvature because the measurement begins at the occiput or lower cervical spine [5, 6]. Men in our study may have been classified as hyperkyphotic more than women because the block measurement includes the cervical lordotic curvature that tends to flatten with age, particularly in males .
Hyperkyphosis is thought to result mainly from underlying vertebral fractures, and has not gained much clinical interest other than as a marker for osteoporosis. Previous studies [10, 11] have reported that some of those individuals with the most severe hyperkyphosis have no evidence of underlying vertebral fractures. Moreover, those persons with hyperkyphosis and no spinal deformity suffer a similar degree of physical and emotional impairments as do those persons who have hyperkyphosis and underlying vertebral deformities . Similarly, women who report height loss of >5 cm or kyphosis, without prior fracture, have significantly more physical difficulty and more adaptations to their lives as a result of physical disability than do women who reported only a prior fracture and no postural changes . Likewise, the results of our study reveal that hyperkyphotic posture is associated with poor physical function, independent of spine or hip BMD and clinical spine fractures. Although vertebral fractures can lead to substantial height loss and postural deformities, there are clearly other poorly defined causes.
Why might hyperkyphosis be associated with physical functional limitations? With increased kyphotic posture, the resultant thoracic deformation that occurs is associated with a restrictive ventilatory defect , and impaired pulmonary function can limit physical functional ability. It is also hypothesized that hyperkyphosis may lead to changes in balance that presumably could lead to worse physical function, but this remains to be definitively shown . An alternative explanation may be that hyperkyphosis is a marker for an increased rate of physiologic aging. Several mouse knockout models have been developed in which the affected mice demonstrate an increased rate of aging and hyperkyphosis . In humans, accelerated physiologic aging might occur through dysregulated stress responses and/or underlying inflammation, both of which are associated with decline in physical function. A high allostatic load, or cumulative measure of dysregulation across multiple physiologic systems, is an independent predictor of physical functional decline . Similarly, high levels of interleukin 6, a marker of inflammation, are associated with the development of disability in older persons .
There are some limitations to our study. First, it was cross-sectional, so we are unable to determine the direction of the association. Although it seems intuitive that hyperkyphotic posture may precede difficulties in physical function, this remains to be shown in a prospective study. Second, we used a novel measure of kyphotic posture that required participants to be in a supine position. Because gravity can affect standing posture, the supine measure may underestimate the true degree of hyperkyphosis; even so, we were able to demonstrate strong and consistent associations with poor physical function. Furthermore, this measure has been shown to be associated with other adverse outcomes [20, 21], suggesting that it has construct validity.
Our study also possesses some strengths. First, it included both community-dwelling older men and women. Second, it used both self-reported as well as objective measures of physical function. Lastly, it used a measure of clinical hyperkyphosis that is inexpensive and simple to perform, and could potentially be applied in a clinical setting.
As the percentage of older persons increases in the population, more and more emphasis is being placed on healthy aging, and an integral part of aging successfully is maintaining physical functional ability. Our study demonstrates a strong and graded association between worsening hyperkyphotic posture and poor self-reported and measured physical function. We conclude that hyperkyphotic posture affects both older men and women and that it is a marker of poor health. Whether preventing or treating hyperkyphotic posture improves health outcomes remains unknown.