Osteoporosis: the state of the art in 1987: a review

The Quest for Osteoporosis Mechanisms and Rational Therapies: How Far We've Come, How Much Further We Need to Go

During the last 40 years, understanding of bone biology and the pathogenesis of osteoporosis, the most common and impactful bone disease of old age, has improved dramatically thanks to basic and clinical research advances, genetic insights from humans and rodents, and newer imaging technologies. Culprits of osteoporosis are no longer a matter of speculation based on in vitro observations. Instead, they can be identified and dissected at the cellular and molecular level using genetic approaches; and their effect on distinct bone envelopes and anatomic regions can be functionally assessed in vivo. The landscape of pharmacotherapies for osteoporosis has also changed profoundly with the emergence of several potent antiresorptive drugs as well as anabolic agents, displacing estrogen replacement as the treatment of choice. In spite of these major positive developments, the optimal duration of the available therapies and their long-term safety remain matters of conjecture and some concern. Moreover, antiresorptive therapies are used indiscriminately for patients of all ages on the assumption that suppressing remodeling is always beneficial for bone, but rebound remodeling upon their discontinuation suggests otherwise. In this invited perspective, I highlight the latest state of knowledge of bone-intrinsic and extrinsic mechanisms responsible for the development of osteoporosis in both sexes; differences between the mechanisms responsible for the effects of aging and estrogen deficiency; and the role of old osteocytes in the development of cortical porosity. In addition, I highlight advances toward the goal of developing drugs for several degenerative diseases of old age at once, including osteoporosis, by targeting shared mechanisms of aging. © 2018 American Society for Bone and Mineral Research.

Setting a standard for a "silent" disease: defining osteoporosis in the 1980s and 1990s

Osteoporosis, a disease of bone loss associated with aging and estrogen loss, can be crippling but is 'silent' (symptomless) prior to bone fracture. Despite its disastrous health effects, high prevalence, and enormous associated health care costs, osteoporosis lacked a universally accepted definition until 1992. In the 1980s, the development of more accurate medical imaging technologies to measure bone density spurred the medical community's need and demand for a common definition. The medical community tried, and failed, to resolve these differing definitions several times at consensus conferences and through published articles. These experts finally accepted a standard definition at an international consensus conference convened by the World Health Organization in 1992. The construction of osteoporosis as a disease of quantifiable risk diagnosed by medical imaging machines reflects contemporary trends in medicine, including the quantification of disease, the risk factor model, medical disciplinary boundaries, and global standardization of medical knowledge.

A preliminary study on discrimination of osteoporotic fractured group from nonfractured group using support vector machine

Osteoporosis is characterized by an abnormal loss of bone mineral content, which leads to a tendency to non-traumatic bone fractures or to structural deformations of bone. Thus, bone density has been considered as a most reliable parameter to assess osteoporotic fracture risk. In past decades, by the way, bone texture measures have been studied to estimate other aspect of bone quality. Some studies have been performed on CT or MR images to assess bone quality using trabecular structure analysis. Other studies have been performed on plain x-ray images or ultrasound images to assess trabecular structure. However, most of the studies are focused on individual parameters to distinguish between osteoporotic fractured group and nonfractured group. In this preliminary study, we combine various texture parameters with bone density parameters using a support vector machine and point out the most promising combination of parameters to distinguish between osteoporotic fractured group and nonfractured group.

The preliminary study of differentiating osteoporotic fractured group from nonfractured group

Osteoporosis is characterized by an abnormal loss of bone mineral content, which leads to a tendency to nontraumatic bone fractures or to structural deformations of bone. Thus bone density measurement has been considered as a most reliable method to assess bone fracture risk due to osteoporosis. In past decades bone texture measures have been also studied in connection with the bone quality estimation. However, most studies have been focused on texture analysis of CT or MR images. Though studies on plain radiographs have been also performed to assess in vivo trabecular structure these studies are mainly done on anatomic sites such as femur, spine, and calcaneus. In this preliminary study we apply various texture measures to distal radius plain radiographs and point out several promising texture measures that significantly distinguish between osteoporotic fractured group and nonfractured group.

Bone mineral density estimation using the filling factor of the radius X-ray image

Osteoporosis is characterized by an abnormal loss of bone mineral content, which leads to a tendency to non-traumatic bone fractures or to structural deformations of bone. Thus, bone density measurement has been considered as a most reliable method to assess bone fracture risk due to osteoporosis. In past decades, x-ray images have been studied in connection with the bone mineral density estimation. However, the estimated bone mineral density from the x-ray image can undergo a relatively large accuracy or precision error. The most relevant origin of the accuracy or precision error may be unstable x-ray image acquisition condition. In the previous study, we presented a bone mineral density estimation method that uses the trabecular bone filling factor in the radius x-ray image and that is relatively insensitive to the x-ray image acquisition condition. In this paper, we investigate the method using larger patient data and point out a preliminary result related to the fracture risk prediction using the method.

Age and trabecular features of alveolar bone associated with osteoporosis

OBJECTIVE

To determine the utility of clinical features, combined with optical density measurements and morphologic analysis of periapical images, for identifying individuals with low lumbar or femoral bone mineral density.

STUDY DESIGN

Study subjects consisted of 37 females and 29 males. Bone mineral densities (BMD) of lumbar spine and proximal femur were measured by dual-energy x-ray absorptiometry. Clinical variables included subjects' age, height, and weight. Optical density and morphologic features were measured from subjects' posterior maxilla and mandible. Classification and regression tree analysis was used to assess agreement between actual and predicted BMD status.

RESULTS

The combination of clinical and morphological analysis of trabecular pattern are associated with femoral/lumbar BMD. Significant associations were found in the maxilla and mandible. The most important clinical variable was age.

CONCLUSION

This study showed that morphologic analysis of periapical radiographs, combined with clinical variables, can assist in identifying individuals with low femoral/lumbar BMD.

Distal radius bone mineral density estimation using the filling factor of trabecular bone in the x-ray image

Osteoporosis is characterized by an abnormal loss of bone mineral content, which leads to a tendency to non-traumatic bone fractures or to structural deformations of bone. Thus, bone density measurement has been considered as a most reliable method to assess bone fracture risk due to osteoporosis. In past decades, X-ray images have been studied in connection with the bone mineral density estimation. However, the estimated bone mineral density from the X-ray image can undergo a relatively large accuracy or precision error. The most relevant origin of the accuracy or precision error may be unstable X-ray image acquisition condition. Thus, we focus our attentions on finding a bone mineral density estimation method that is relatively insensitive to the X-ray image acquisition condition. In this paper, we develop a simple technique for distal radius bone mineral density estimation using the trabecular bone filling factor in the X-ray image and apply the technique to the wrist X-ray images of 20 women. Estimated bone mineral density shows a high linear correlation with a dual-energy X-ray absorptiometry (r=0.87).

Usefulness of panoramic radiography in the diagnosis of postmenopausal osteoporosis in women. Width and morphology of inferior cortex of the mandible

OBJECTIVES

To evaluate the usefulness of width and morphology of the inferior cortex of the mandible on panoramic radiographs in the diagnosis of postmenopausal osteoporosis.

METHODS

The width and morphology of the mandibular inferior cortex on panoramic radiographs were compared with trabecular bone mineral density (TBMD) of the 3rd lumbar vertebrae (L3) measured by dual energy quantitative computed tomography in 29 premenopausal and 95 postmenopausal women.

RESULTS

There was a significant negative correlation between the width (Kendall's tau = -0.36, p < 0.001) and morphology (Kendall's tau = -0.49, p < 0.001) of the mandibular inferior cortex and the L3 TBMD. Regression analysis showed that significant linear relationships were observed between the L3 TBMD and age (p < 0.001), cortical width (p < 0.05), morphology (p < 0.05), controlling body mass index, number of teeth present and menopausal status (R2 = 0.42).

CONCLUSION

Our results suggest that panoramic radiography could be reliable in screening for osteoporosis.

Estrogen replacement therapy after treatment for localized breast carcinoma. Patient responses and opinions

BACKGROUND

Women who reach menopause after receiving treatment for breast carcinoma have been advised to avoid estrogen replacement therapy (ERT), but the validity of this practice is being reappraised and the need for prospective studies is discussed. The likely response of potential participants to the tangible rather than theoretic option for ERT provides not only useful information for planning such studies but also important insights into the attitudes and expectations of breast cancer survivors.

METHODS

Women with a history of localized breast carcinoma, potentially eligible for participation in this prospective ERT study, were interviewed in person or by telephone and were asked to consider participation in a prospective, randomized study of ERT. In addition, information was obtained regarding their disease stage, estrogen receptor (ER) status, age at diagnosis, age at interview, and elapsed time since cancer treatment.

RESULTS

The authors contacted 555 women; 137 did not meet criteria for study participation. Among the 418 women eligible for the program, one-third indicated a lack of interest and cited travel, financial, or age considerations. One-third of the women were apprehensive about ERT risk and declined. Forty women (13%) were either already receiving ERT or were seeking a prescribing physician. Finally, 17% of the women enrolled in our study. There were no differences among the groups with respect to disease stage, ER status, age at diagnosis and interview, or time elapsed since cancer treatment.

CONCLUSIONS

Women with a history of breast carcinoma harbor considerable reluctance regarding ERT for the management of menopausal health concerns. However, a significant minority have already opted for ERT and up to 20% may become participants in clinical programs. Plans for large scale trials of ERT in this subset of women require careful attention to patient attitudes and concerns.

Oral signs as indicators of possible osteoporosis in elderly women

The relationship between oral signs and osteoporosis was investigated to assess the possibility of using this as an indicator of postmenopausal osteoporosis. Sixty-four women between the ages of 50 and 70 years were evaluated. Osteoporotic signs consisted of thoracic spine fracture as demonstrated on lateral chest radiographs. Oral signs were the number of teeth present, mandibular cortical width, alveolar bone resorption, and the morphologic classification of the inferior cortex on panoramic radiographs. The number of teeth present (N) was highly related to the probability of thoracic spine fracture and was used to derive the probability equation for the presence of thoracic spine fracture: probability value = 1/(1 + e-z), Z = 18.68-0.29 age -0.27N. A probability value higher than 0.5 suggests the possibility of thoracic spine fracture. It was concluded that this equation could serve as a simple and useful tool for dentists to assess the possibility of latent osteoporosis.

Tooth loss and mandibular osteopenia

The relationship between mandibular bone mass and tooth loss was studied in 269 patients who had neither metabolic disease nor local lesions affecting the mandibular cortex. In all of the subjects, the outline of the mental foramen was distinctly disclosed on unilateral or bilateral panoramic radiographs. Mandibular bone mass was evaluated by determining the mandibular cortical width in the mental region with the use of panoramic radiographs. The relationships of mandibular cortical width to patient age and sex and the number of teeth present were also investigated. In male subjects, there was no significant correlation between the number of teeth present and the mandibular cortical width. Among women in their seventh decade, those with 15 or more teeth showed significantly greater mandibular cortical width than those with fewer teeth. Decrease of mandibular bone mass was positively correlated with tooth loss in female subjects.

Estrogen replacement therapy in women at increased risk for breast cancer

The topic of estrogen replacement (ERT) after the onset of menopause remains controversial and charged with considerable emotion within both the medical community and the lay public. This is especially true for women at increased risk for breast cancer as well as those who reach menopause after the diagnosis of this disease. ERT clearly protects postmenopausal women from the morbidity and mortality of cardiovascular disease and osteoporosis, and it alleviates vasomotor and genitourinary symptoms. However, there remains uncertainty whether and for which subgroups of women these benefits may be offset by a potential increased risk for breast cancer. With screening programs, breast cancer is being diagnosed at an earlier stage: with improved therapy, survival rates are improving. Adjuvant chemotherapy is increasingly incorporated in the treatment program of localized disease and accelerates the arrival of menopause. Thus, more and younger women with excellent survival prognosis will develop early menopause after treatment for early breast cancer. For these women, the decision regarding ERT is likely to affect the quality and quantity of their life for several decades. It is important to weigh the relative risks and benefits of ERT for each individual woman in order to develop a meaningful health maintenance plan.

Reproductive correlates of bone mass in elderly women. Study of Osteoporotic Fractures Research Group

Results from previous studies of reproductive factors and bone density have been conflicting; some demonstrate a beneficial effect, but others show a detrimental effect on bone density. The present study investigates the association of parity, lactation, and menstruation with radial bone density in 2230 white women, 65 years of age and older. Bone density was assessed by single-photon absorptiometry. Linear multiple regression was utilized to determine if reproductive factors were associated with radial bone density. The number of births, duration of menstrual bleeding, age at menarche, and years menstruating were significant independent predictors of postmenopausal bone density of the radius. A 1.4% increase in distal radius bone density was observed with each additional birth. Women who began menstruation at age 9 had 6.3% higher bone density than women who began at age 16. Women who menstruated for 3 days during each menstrual cycle had 2.8% less distal radius bone density than women who bled for 7 days. Each decade of menstruation was associated with a 2% greater distal radius bone density. No difference in bone density was demonstrated for women who breast-fed and women who did not. Length of the menstrual cycle, amount of menstrual flow, and irregularity of the menstrual cycle were not significantly associated with radial bone mineral density. In conclusion, pregnancy and menstruation are associated with postmenopausal bone density of the radius.

Reduction of risk factors for osteoporosis among adolescents and young adults

Osteoporosis is the most common of all skeletal disorders. The most commonly accepted definition of osteoporosis is a decrease in the amount of calcified bone tissue to the point that fractures occur with minimal trauma. Researchers have shown that peak bone mass at skeletal maturity may be the single most important factor in the development of osteoporosis. At present, no satisfactory way to replace lost bone exists, and the ideal treatment for osteoporosis is prevention, which must begin early in life. The most promising approach in the primary prevention of osteoporosis is to help each person achieve as high a peak skeletal mass and bone density as genetically possible prior to skeletal maturity. Furthermore, identifying those adolescents and young adults at risk is of clinical value for prediction and counseling purposes. Recommendations for achieving the maximal bone mass prior to skeletal maturity, as well as methods of assessing and minimizing the risk factors for osteoporosis, will be discussed.

Estrogen replacement therapy in women with breast cancer: a survey of patient attitudes

Estrogen replacement therapy (ERT) is suggested for women with symptomatic estrogen deficiency, but patients with breast cancer are advised against ERT because of concerns that ERT may precipitate cancer recurrence. The attitudes of women with breast cancer regarding ERT is critical in the design of appropriate strategies for the management of their menopause. A randomly selected group of 224 women with breast cancer responded to an anonymous survey that addressed the presence of menopause, antecedent therapies, symptoms related to estrogen deficiency, concerns about osteoporosis or heart disease, attitude about ERT, and perception about ERT-related cancer risk. Among women who completed the survey, 77% were postmenopausal and 81% had had multimodality therapy. Of menopausal women, 27% believed they needed some treatment for menopause and 8% had taken ERT since cancer diagnosis. Most women were afraid that ERT may precipitate cancer recurrence (78%) but they also were concerned about the menopause-related risk of osteoporosis (70%) and heart disease (72%). Overall, 44% of menopausal women were willing to consider ERT under medical supervision. Those treated with surgery alone were distinct in that 71% would consider ERT (p < 0.04). Premenopausal women were more concerned about osteoporosis (82% vs. 66% for postmenopausal), heart disease (92% vs. 73%), and the possibility that ERT may precipitate cancer recurrence (98% vs. 73%). Yet, at the same time, they were more willing to consider ERT under medical supervision (59% vs. 40% for menopausal). The present study underscores that women with breast cancer are very aware and concerned about the adverse health consequences of estrogen deficiency and would consider ERT under medical supervision.(ABSTRACT TRUNCATED AT 250 WORDS)

A clinical dilemma: estrogen replacement therapy in postmenopausal women with a background of primary breast cancer

It is common practice to forego the prescribing of estrogen replacement therapy (ERT) for patients with a history of breast cancer. The consequences of estrogen deprivation particularly cardiovascular morbidity and osteoporosis are reviewed in the context of the potential risks of ERT in patients with prior breast cancer. The published data regarding breast cancer risks with oral contraceptive use and ERT in healthy women is reviewed. The rationale for a clinical trial of ERT in breast cancer patients, the proposed appropriate patient group and positive end points for assessing benefit of ERT in the population are presented. Lack of reliable clinical data makes ERT in breast cancer patients an unresolved clinical dilemma.

Estrogen replacement therapy: an overview

Levels of circulating estrogen fall during the perimenopausal period, resulting in changes in the postmenopausal woman's genitourinary tract, central nervous and cardiovascular systems, skin, and bone. Exogenous estrogen minimizes the benign symptoms and prevents the increased incidence of osteoporosis and atherosclerotic heart disease that accompany estrogen deficiency. Thus to avoid the recognized problems of estrogen deficiency, nearly all women should begin a lifelong course of estrogen replacement therapy during the perimenopausal period.

Noninvasive methods of bone-mass measurement

The most widely used noninvasive methods of bone mass measurement include: single photon absorptiometry (SPA), quantitative computed tomography (QCT), dual photon absorptiometry (DPA and DEXA). SPA is used to measure bone mineral content (BMC) of the distal radius. Its advantages are low cost and high precision in vivo (less than 2%), however, correlation between axial and appendicular bone values is poor. Since vertebral fracture is the first complication of osteoporosis, spinal values are the most useful. QCT measurements are performed using available CT scanners and either single or dual energy scanning techniques, computed radiographs for localizing regions-of-interest (ROI) and mineral reference standards for calibration. The advantage of QCT is that it can evaluate pure trabecular bone at the midplane of two to four lumbar vertebral bodies. Single energy in vivo reproducibility is 2-5% in osteoporotics. Radiation exposure with most systems is 100-500 mRem. With DPA scanners, the commonest radiation source used is Gadolinium-153 (44-100keV). The areas of measurement are lumbar vertebrae L2, L3 and L4 and the femoral neck. In vivo lumbar measurement precision is at least 1-2% and radiation exposure is low (less than 10 mRem). DEXA scanners use an X-ray rather than gamma ray source to emit dual energy photons. The advantages of the technique are shorter scan time, lower radiation exposure (less than 3 mRem) and higher precision (less than 1%). In conclusion, measurement of vertebral bone, particularly using DPA and DEXA, is of value in assessing the risk of osteoporosis and in monitoring changes in bone mineral content.