EXECUTIVE SUMMARY
Researchers have determined that bones age in very different ways, setting the groundwork for new ways to identify women at risk of bone fractures far in advance.
- Bone fragility is a concern for women as they age. Factors that may alter bone structure and mass during aging are not well understood.
- The new study, which examined the bone traits of 198 midlife women 42-52 years of age who were followed for 14 years, focused on identifying women who will experience bone fragility well in advance of fracture.
New research suggests that bones age in very different ways, setting the groundwork for new ways to identify women at risk of bone fractures far in advance.1
Bone fragility is a concern for women as they age. Factors that may alter bone structure and mass during aging are not well understood. The new study, which examined the bone traits of 198 midlife women transitioning through menopause for 14 years, focused on identifying women who will experience bone fragility well in advance of fracture.
Current identification for bone fragility takes place when the patient is around 65 years of age, says the study’s lead author, Karl Jepsen, PhD, associate chair of research and professor of orthopaedic surgery at The University of Michigan.
“We were hopeful that this study would give us an opportunity to identify those patients as early as 30 years before they fracture based on their bone traits,” Jepsen said in a statement accompanying the study’s publication. “That means we would have an opportunity to intervene before the fracture happens, instead of after the fact.”
Check the Data
Researchers studied women who participated in the Study of Women’s Health Across the Nation, a multisite longitudinal, epidemiologic study designed to examine the health of women during their middle years. Women who enrolled had to be 42-52 years of age, present with an intact uterus, and experienced at least one menstrual period in the previous three months. In addition, the subjects underwent approximately 14 annual study visits that included measurements, such as bone density scans, of their hip and spine. The research team looked at dual-energy X-ray absorptiometry (DXA) images of the hip during the 14-year period to determine what changes, if any, were occurring in the study subjects.
The researchers observed that women experienced different changes in bone mineral content and bone area within the hip, yet incurred similar changes in areal bone mineral density. In addition, the change in bone mineral content and bone area correlated negatively with baseline external size of the neck of the femur just below the ball of the hip joint. Bone mineral density measured by DXA does not represent the volumetric density (grams per cubic centimeter), but rather the areal density (grams per square centimeter).
This finding means that the women showed similar changes in areal bone mineral density for different structural and biological reasons, Jepsen explains.
“Essentially, we found that women with narrow femoral necks showed smaller changes in bone mineral content, but greater increases in bone area compared to women with wide femoral necks who showed greater losses in bone mineral content, but didn’t appear to be experiencing compensatory increases in bone area,” he says.
This finding is opposite to expectations that periosteal expansion acts to mechanically offset bone loss, the researchers noted. Thus, changes in femoral neck structure and mass during menopause vary widely among women and are predicted by baseline external bone size but not areal bone mineral density (grams per square centimeter).1
What’s the Next Step?
The U.S. Preventive Services Task Force currently recommends screening for osteoporosis in women 65 years of age and older and in younger women whose fracture risk is equal to or greater than that of a 65-year-old white woman who has no additional risk factors.2
Guidance from the American College of Obstetricians and Gynecologists (ACOG) calls for a fracture risk assessment tool (FRAX), developed by the World Health Organization, as an addition to screening. FRAX, which can help predict a person’s risk of bone fracture in the next decade, can be used to determine if a patient is at high risk for fracture if her initial scan indicates low bone mass. The tool considers risk factors such as age, body mass index, fracture history, alcohol consumption, smoking habits, rheumatoid arthritis, and other secondary causes of osteoporosis. In the absence of new risk factors, ACOG says DXA screening should not be performed more than every two years. Further, ACOG says FRAX should be used annually to monitor the effect of age on fracture risk.3
Anita Nelson, MD, professor and chair of the obstetrics and gynecology department at Western University of Health Sciences in Pomona, CA, says that clinical trials will be needed to see if it is appropriate to treat women earlier than what is prescribed now because they have been identified as being higher risk.
Jepsen says the current study demonstrates for the first time that scientists can track bone changes happening individually in women during menopause. He looks to these results as a stepping stone for additional research.
“With further research, our goal is to use simple bone traits to identify those women that may benefit from early intervention when it comes to bone fragility, instead of the current strategy, which treats individuals after they have lost appreciable bone mass and strength,” he adds.
REFERENCES
- Jepsen KJ, Kozminski A, Bigelow EM, et al. Femoral neck external size but not aBMD predicts structural and mass changes for women transitioning through menopause. J Bone Miner Res 2017; doi: 10.1002/jbmr.3082.
- Nordin C. Screening for osteoporosis: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2011;155:276.
- Committee on Practice Bulletins-Gynecology, The American College of Obstetricians and Gynecologists. ACOG Practice Bulletin N. 129. Osteoporosis. Obstet Gynecol 2012;120:718-734.
New research suggests that bones age in very different ways, setting the groundwork for new ways to identify women at risk of bone fractures far in advance.
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