Osteoporotic Vertebral Fractures

Garth E. Johnson, M.D., FRCSC
Ottawa, ON

The spectrum of osteoporotic vertebral fractures is extremely large: ranging from asymptomatic vertebral wedging which increases with aging, to acute symptomatic fractures occurring with minimal injury. The quoted prevalence of vertebral fractures depends primarily on the criteria for diagnosis with some additional variation from one population to another1,2,3. Generally speaking, a nine to 12 percent incidence is given for middle-aged women with a correlation between vertebral fracture prevalence and bone mineral density in the lumbar spine, height loss and chronic back symptoms. The male to female ratio also seems quite variable, varying from two to one in European population to a high of four to one in patients referred to a metabolic bone disease clinic. Several reports have shown a higher incidence in men, aged 45 to 54, in populations exposed to physically demanding activities and this may be due to occupationally-related vertebral fractures. The incidence is higher in Caucasions and Asians than in persons of dark skin colour4.

The factor of risk is an indication as to whether a fracture is likely during a given activity. The factor of risk is the ratio of the force applied to a bone during an activity divided by the force at which the bone fractures. A factor of risk higher than one indicates that the bone is overloaded and failure is likely5.

Eastell et al have classified vertebral fractures on the basis of their radiographic appearance. The distribution and type varied between their general population and that of women referred to the clinic with suspected osteoporosis6.

gjohnston_figure1.jpg

Figure 1: Myers, E.R. and Wilson, S. E. Biomechanics of Osteoporosis and Vertebral Fracture, Spine, Vol. 22, No. 24S, 1997. p. 28S.

Fragility fractures of the spine do not have the same initial impact as fractures of the hip. The disability related to these vertebral fractures is correlated with age and kyphosis (including postural changes and loss of height). When the kyphosis is greater than four standard deviations, chronic pain becomes a significant contributing factor to late disability. Four percent of patients with a vertebral fracture become completely dependent because of the fracture7. As expected, survivorship studies indicate a significant increase in mortality within one year of the diagnosis of the insufficiency fracture of the hip, however, after this mortality rate then parallels age-matched non-fracture group. The mortality rate associated with insufficiency fractures of the vertebrae shows a progressive increase over a much longer period of time, even when controlled for underlying comorbidities4. Women with radiographic evidence of vertebral fractures have an increased mortality rate, particularly from pulmonary disease and cancer.

gjohnstonfigure2.jpg

Figure 2: Eastell, R., Cedel, S. L., Wahner, H. W., Riggs, V. L., Melton, L. J., Classification of Vertebral Fractures, Journal of Bone and Mineral Research, Vol. 6, No. 3, 1991, p. 208.

The prevention of vertebral insufficiency fractures parallels those measures for the maintenance of bone mineral density, with special focus on dietary intake of sufficient elemental calcium and Vitamin D. Hormone replacement therapy remains controversial. Moderate physical activity in people with osteoporosis may stimulate bone gain and/or decrease bone loss but its effects are an adjunct to other interventions. Other benefits of physical activity are: 1) the reduction of fall risk, 2) decreased pain and improved fitness, and 3) overall quality of life10. Bisphosphonate may be considered an alternative to ovarian hormone therapy in post-menopausal, osteopenic or osteoporotic women, especially those who cannot or will not tolerate hormone replacement therapy. It is effective in men with osteoporosis in improving bone mass as well as fracture prevention. Alendronate therapy significantly decreases the risk of new vertebral fracture in post-menopausal women with osteoporosis who present with a new vertebral fracture. It also decreases the number of days of disability and days of limited activity caused by back pain11. Many insufficiency fractures that are symptomatic or minimally symptomatic and can be treated symptomatically with expected improvement over a one to two month period; with altered activity and analgesics. Calcitonin has been shown to given significant relief of pain, perhaps more from the release of endogenous opioids than an early direct effect on fracture healing.

Spinal orthoses are not effective for fractures above the T6 level. In acute fractures, pain relief can be obtained by use of a lumbosacral corset or chairback brace. For wedge deformity fractures, a Jewett brace will provide saggital plane support which may be important to avoid progression of the wedging. However, often the fractures contributing to progression of the kyphosis have occurred at different times so that some of the fractures contributing to the deformity may be old and healed12. The Jewett orthosis is not well tolerated in the elderly, is cumbersome to apply, creates a problem for sitting and is not well tolerated in a patient who already has significant kyphosis. Fractures caused by axial load such as biconcave and compression fractures could be treated by a TLSO within the limitations already mentioned. There are no clear guidelines as to which fractures are not amenable to nonoperative measures. The main indications for consideration of more invasive treatment are fractures remaining symptomatic or becoming increasingly symptomatic after the four to eight week interval or perhaps fractures which have an intraosseus vacuum phenomenon.

References

  1. Black, D. M.; Palermo, L.; Nevitt, M. C.; Genant, H. K.; Christensen, L. and Cummings, S.R. Defining Incident Vertebral Deformity: A Prospective Comparison of Several Approaches, Journal of Bone and Mineral Research, Vol. 14, Number 1, 1999
  2. Sauer, P.; Leidig, G.; Minne, H. W.; Duckeck, G.; Schwarz, W.; Siromachkostov, L. and Ziegler, R. Spine Deformity Index (SDI) Versus Other Objective Procedures of Vertebral Fracture Identification in Patients with Osteoporosis: A Comparative Study, Journal of Bone and Mineral Research, Volume 6, Number 3, 1991
  3. National Osteoporosis Foundation Working Group of Vertebral Fractures Report Assessing Vertebral Fractures, Journal of Bone and Mineral Research, Volume 10, Number 4, 1995
  4. Melton, L. J.; Epidemiology of Spinal Osteoporosis, Spine, Volume 22, Number 245, 1997, pp. 25-115 (also for Mortality)
  5. Myers, E. R.; Wilson, S. E. ; Biomechanics of Osteoporosis and Vertebral Fracture, Spine, Volume 22, Number 245, 1997, pp. 255-315 (also Figure 4)
  6. Eastell, R.; Cedel, S. L.; Wahner, H. W., Riggs, B. L.; Melton, L. J.; Classification of Vertebral Fractures, Journal of Bone and Mineral Research, Volume 6, Number 3, 1991, pp. 207-215 (also Diagram F1G1)
  7. Ettinger, B., Black, D. M.; Nevitt, M. C.; Rundle, A. C.; Cauley, J. A.; Cummings, S. R.; Genant, H. K.; and the Study of Osteoporotic Fractures Research Group. Contribution of Vertebral Deformities to Chronic Back Pain and Disability, Journal of Bone and Mineral Research, Volume 7, Number 4, 1992, pp. 449-456
  8. Cortet, B.; Houvenagel, E.; Puisieux, F.; Roches, E.; Garnier, P.; Delcambre, B. Spinal Curvatures and Quality of Life in Women with Vertebral Fractures Secondary to Osteoporosis. Spine, Volume 24, Number 18, pp.1921-1925, 1999
  9. Kado, D. M., Browner, W. S.; Palermo, L.; Nevitt, M. C.; Genant, H. K.;Cummings, S. R. Study of Osteoporotic Fractures Research Group, Vertebral Fractures and Mortality in Older Women, Arch Intern Med, Volume 159, June 14, 1999, pp. 1215-1220
  10. Hanley, D. A., Josse, R. G., et al. Prevention and Management of Osteoporosis Consensus Statements from the Scientific Advisory Board of Canada, 1-9, Canadian Medical Association, Oct. 1, 1996, 155 (7), pp. 921-965
  11. Nevitt, M. C., Thompson, D. E.; Black, D. M.; Rubin, S. R.; Ensrud, K.; Yates, J., Cummings, S. R..; Fracture Intervention Trial Research Group. Effect of Alendronate on Limited-Activity Days and Bed-Disability Days Caused by Back Pain in Post-Menopausal Women with Existing Vertebral Fractures. Arch Intern Med, Volume 160, January 10, 2000, pp. 77-85
  12. Patwardhan, A. G.; Li, S.; Gavin, T.; Lorenz, M.; Meade, K. P., Zindrice, M.; Orthotic Stabilization of Thoracolumbar Injuries, A Biomechanical Analysis of the Jewett Hyperextension Orthosis, Spine, Volume 15, Number 7, 1990, pp. 654-661.

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