Magnetic resonance-detected subchondral bone marrow and cartilage defect characteristics associated with pain and X-ray-defined knee osteoarthritis

OBJECTIVE

To assess whether the presence of subchondral bone marrow abnormalities (bone marrow edema (BME)) and cartilage defects, determined by magnetic resonance imaging (MRI), would explain the difference between painful osteoarthritis of the knee (OAK) compared with painless OAK or pain without OAK.

METHOD

Four groups of women (30 per group), aged 35-55 years, were recruited from the southeast Michigan Osteoarthritis cohort (group 1: painful OAK; group 2: painless OAK; group 3: knee pain without OAK; and group 4: no OAK or knee pain). OAK was defined by a Kellgren-Lawrence score of 2 or greater, while pain was based on self-report. BME and cartilage defects were identified from MRI.

RESULTS

BME lesions were identified in 56% of all knees. BME lesions were four times (95% CI=1.7, 8.7) more likely to occur in the painless OAK group as compared with the group with pain, but no OAK. BME lesions >1cm were more frequent (OR=5.0; 95% CI=1.4, 10.5) in the painful OAK group than all other groups. While the frequency of BME lesions was similar in the painless OAK and painful OAK groups, there were more lesions, >1cm, in the painful OAK group. About 75% of all knees had evidence of some cartilage defect, of which 35% were full-thickness defects. Full-thickness cartilage defects occurred frequently in painful OAK. One-third of knees with full-thickness defects and 47% of knees with cartilage defects involving bone had BME >1cm. Women with radiographic OA, full-thickness articular cartilage defects, and adjacent subchondral cortical bone defects were significantly more likely to have painful OAK than other groups (OR=3.2; 95% CI=1.3, 7.6).

CONCLUSION

The finding on MRI of subchondral BME cannot satisfactorily explain the presence or absence of knee pain. However, women with BME and full-thickness articular cartilage defects accompanied by adjacent subchondral cortical bone defects were significantly more likely to have painful OAK than painless OAK.

Natural history of bone loss over 6 years among premenopausal and early postmenopausal women

The aims of this prospective cohort study were to determine rates of premenopausal and early postmenopausal bone loss, age at onset of bone loss, and whether rates of bone loss depend on baseline bone mineral density (BMD). The cohort of 614 women aged 24-44 years at baseline from the longitudinal Michigan Bone Health Study was followed for 6 years beginning in 1992-1993. Up to five BMD measurements of the lumbar spine (L(2-4)) and the femoral neck were obtained through 1998-1999 by using dual x-ray absorptiometry and were standardized (as z scores) relative to a young adult, female BMD distribution. Regression models were used to estimate rates of BMD change and to examine BMD as a function of age. At the lumbar spine, the rate of BMD change for premenopausal women varied with time. At the femoral neck, the rate of change was -1.6% (95% confidence interval: -0.9%, -2.3%) of a z score annually (annual loss of 0.3% of baseline BMD (g/cm(2))). Evidence for age at onset of bone loss at the lumbar spine was inconclusive. Bone loss began by the midtwenties at the femoral neck. Additional annual change of -0.7% (95% confidence interval: -0.2%, -1.2%) of a z score was observed at the femoral neck for each unit increase in BMD z score at baseline.

IGF-I, osteocalcin, and bone change in pregnant normotensive and pre-eclamptic women

Pre-eclampsia is a pregnancy disorder of uncertain etiology that affects 5-10% of all pregnancies, with symptoms typically presenting around or after 20 wk gestation. We hypothesized that IGF-I, osteocalcin, and bone loss would be different among women with pre-eclampsia compared with normotensive pregnant women. There were 962 pregnant healthy women, aged 12-35, who were assessed at entry to care, at 28 wk, and at delivery for osteocalcin and IGF-I concentrations. Bone ultrasound was measured at entry to care and at 6 wk postpartum, whereas bone mineral density was measured by dual x-ray densitometry at delivery. There were 64 women (6.7%) among the women being followed who developed pre-eclampsia. In women with pre-eclampsia, IGF-I concentrations were 74% greater in the third trimester compared with the first trimester, whereas there was little change in osteocalcin concentrations. In contrast, normotensive women had an average increase of 43% in IGF-I concentrations accompanied by a 63% decline in osteocalcin concentrations. In women with pre-eclampsia, IGF-I and osteocalcin concentrations were significantly correlated (r = 0.48 and 0.43) at both the first and third trimester time points, but only in the third trimester among normotensive women (r = 0.27). The bone change difference between the two groups was not statistically significant. Women with pre-eclampsia appear to have an exaggerated IGF-I responsiveness compared with women who are normotensive; however, the strong correlation between IGF-I and osteocalcin in women with pre-eclampsia suggests that the IGF-I is able to retain its role as a local regulator of bone remodeling, as indicated by the osteocalcin concentrations.

The experience of pain and emergent osteoarthritis of the knee

Discrepancies exist between radiographic osteoarthritis of the knee (OAK) and report of knee joint pain. Little is known about how these two definitions of osteoarthritis (OA) and their correlates differ between African American (AA) and Caucasian (CA) women.

OBJECTIVE

We compared the prevalence of radiographic OAK and knee joint pain in AA and CA women, and the congruency of these outcomes according to age, body size, and knee injury.

DESIGN

A cross-sectional study of African American and Caucasian women aged 40-53 years (N=829) in Southeast Michigan used the Kellgren and Lawrence Atlas of Standard Radiographs of Arthritis to characterize radiographs of both knee joints (weight bearing) and self-report of knee pain.

RESULTS

Current pain was a significantly more sensitive predictor of radiographic OAK among AA women (Se=0.51) compared to CA women (Se=0.35). Specificity was similar between AA women (Sp=0.77) and CA women (Sp=0.82). Positive predictive value was significantly greater for AA compared with CA women (PV+=0.40 and PV+=0.15, respectively). The odds of having radiographic OAK increased with BMI >32 kg/m(2) in both groups. Knee pain was related to BMI in CA women, but not AA women. Previous knee injury was associated with knee pain in both AA and CA women (OR=3.0 and OR=2.4).

CONCLUSIONS

Joint pain in AA women was more likely to be associated with radiographic OAK as compared with CA women. This suggests differences in these two groups in both how pain is experienced in the OAK process and in the prevalence of non-OAK related pain in knee joints.

Testosterone concentrations in women aged 25-50 years: associations with lifestyle, body composition, and ovarian status

While there is substantial evidence of the importance of endogenous and exogenous estrogen in reproductive health and chronic disease, there is little consideration of androgens in women's health. In the Michigan Bone Health Study (1992-1995), the authors examined the correlates of testosterone concentrations in pre- and perimenopausal women (i.e., age, menopausal status, body composition, and lifestyle behaviors) in a population-based longitudinal study including three annual examinations among 611 women aged 25-50 years identified through a census in a midwestern community. Current smokers had the highest testosterone concentrations with decreasing values in former and nonsmokers (p = 0.0001). Body composition measures (body mass index, body fat (%), weight (kg), lean body mass (kg), and fat mass (kg)) were significantly and positively associated with total testosterone concentrations in a dose-response manner. Hysterectomy with oophorectomy was associated with significantly lower testosterone concentrations. Alcohol consumption, physical activity, and dietary macronutrient intake were not associated with testosterone concentrations. This is one of the first studies to examine correlates of serum testosterone concentrations in anticipation of the growing interest in the role of androgens in women's health. The greater circulating levels of testosterone in obese women and smokers suggest that testosterone concentrations should be considered in the natural history of disease conditions where obesity and smoking are risk factors, including cardiovascular disease.

Bone loss in adolescent and adult pregnant women

OBJECTIVE

To determine the amount of change in bone ultrasound measures among pregnant adolescent girls and women and whether that change was associated with adolescence, maternal growth during pregnancy, limited weight gain during pregnancy, hypertension in pregnancy, or poor diet.

METHODS

We used bone ultrasound measurements of attenuation and sound velocity to assess changes in quantitative ultrasound indices of 252 pregnant adolescent girls and women age 12-34 years. Bone ultrasound measurement of the os calcis was performed at 16 +/- 7 weeks' gestation (mean +/- standard deviation and 6 +/- 1 weeks postpartum.

RESULTS

On average, the bone quantitative ultrasound index was 3.6% lower 6 weeks postpartum than at entry into care (P <.001). Nulliparous patients had significantly greater bone loss than did parous subjects. Still-growing adolescents had greater quantitative ultrasound index decreases than did grown women (-5.5% versus -1.9%, P <.02). Patients in the upper tertile of baseline quantitative ultrasound index lost more bone than did patients in the lower tertile (-5% versus 0.5%, P <.02). Pregravid weight, weight change during pregnancy, gynecologic age, and age at menarche predicted bone change in subgroups defined by parity or age; however, none of the differences in those variables were statistically significant. Greater dietary calcium intake, less physical activity, and pregnancy hypertension and preeclampsia were not associated with bone change.

CONCLUSION

There has been inconsistent evidence of maternal bone loss during pregnancy. The findings of this study challenge the assumption that because of increased calcium absorption from the maternal intestine, no transitory bone loss occurs in pregnancy. The amount of bone loss among growing adolescents and nulliparous patients was consistent with the demands of fetal mineralization and the continued demands of the maternal skeleton during growth.

Genetic markers, bone mineral density, and serum osteocalcin levels

We evaluated five genetic markers for products that contribute to skeletal mineralization including the Sp1 polymorphism for type I collagen Ai (COLIA1), the vitamin D receptor (VDR) translation initiation site polymorphism, the promoter of the osteocalcin gene containing a C/T polymorphism, the estrogen receptor (ER) gene containing a TA repeat, and the polymorphic (AGC)n site in the androgen receptor. These markers were evaluated for their potential relationship with bone mineral density (BMD), measured by dual-energy X-ray densitometry, or its 3-year change. Additionally, potential associations of these genotypes and with baseline osteocalcin concentration or its 3-year change (assessed using radioimmunoassay) were evaluated. The study was conducted in 261 pre- and perimenopausal women of the Michigan Bone Health Study, a population-based longitudinal study of musculoskeletal characteristics and diseases. The polymorphic (AGC)n site in the androgen receptor showed a strong association with BMD of the femoral neck (FN) and lumbar spine and remained highly significant after adjusting for body mass index (BMI), oophorectomy/hysterectomy, oral contraceptive (OC) use and hormone replacement use (p < 0.001). The TA repeat at the 5' end of the ER gene was associated with total body calcium (p < 0.05) after adjusting for BMI, oophorectomy and hysterectomy, and OC use. The frequency of oophorectomy and hysterectomy within selected genotypes explained much of the statistically significant association of the ER genotypes with BMD of the FN and spine. There was no association of measures of BMD or bone turnover with the Sp1 polymorphism for COLIA1, the VDR translation initiation site polymorphism, or the C/T promoter polymorphism of the osteocalcin gene. These findings suggest that sex hormone genes may be important contributors to the variation in BMD among pre- and perimenopausal women.

The reproducibility of ultrasound bone measures in a triethnic population of pregnant adolescents and adult women

We used bone ultrasound technology with its measurement of attenuation (broadband ultrasound attenuation [BUA] as dB/MHz) and sound velocity (speed of sound as m/s) for assessing the quantitative ultrasound index (QUI) summary measure in a triethnic population of 280 pregnant women. The study purpose was to describe the reproducibility of the ultrasound technology and determine if the correlations of age, weight, and ethnicity with the bone status measures in this population are consistent with the correlations of age, weight, and ethnicity that have been reported with other technologies that measure bone mass. We evaluated the first 280 women enrolled in our longitudinal study of lead turnover from maternal bone during pregnancy and lactation. Enrollees were pregnant, aged 12-29 years, and self-classified as black, white, or Hispanic. Bone ultrasound was measured twice at entry to prenatal care, which, on average, was at 14 weeks gestation. Reproducibility was described with intraclass correlations and the standard error of measurement. Age, weight, and ethnicity were associated with bone status measures using Spearman correlations and generalized linear models. The reproducibility of the summary bone measure, QUI, was high (96-97%). Variation in age and ethnicity did not alter reproducibility; however, the reproducibility of the attenuation measure (BUA as dB/MHz) lessened with increasing weight, declining from 95% to 89%. Since this attenuation is included in the summary QUI measure, there was a slight, and nonsignificant, decline in QUI reproducibility (from 97% to 96%) as women increased in size. There were no statistically significant differences in mean bone ultrasound measures according to age, where ages ranged from 12-29 years. Women who categorized themselves as black had, on average, an 8.5% greater QUI than did women who classified themselves as Hispanic or white. There were no significant pair-wise differences in mean ultrasound measures of bone between women classifying themselves as Hispanic or white. The use of ultrasound is a highly reproducible measure to assess bone characteristics in a population of pregnant adolescent and young adult women and its summary measure of bone mass is correlated with ethnic as well as body size characteristics.

Bone mineral density and its change in pre-and perimenopausal white women: the Michigan Bone Health Study

There is a need to better understand potential bone mineral density (BMD) loss during the menopausal transition since this period may include the initiation of interventions. The study purpose was to determine if there was BMD loss at the femoral neck, lumbar spine, or total body bone sites in a population-based study of women approaching or transitioning the midlife. The 583 enrollees were 25-45 years of age at the first of four annual measurements from 1992 through 1996. Bone mineral content and bone width were measured using dual-energy X-ray absorptiometry. Considering all enrollees collectively, there was a significant 3-year decline (1%) in BMD at the femoral neck over the 3-year period (p = 0.076). There was no significant annual change in the lumbar spine (p = 0.11), and a significant annual increase in the total body BMD (p = 0.0003). Within subgroups and cross-sectionally, BMD values of the femoral neck were 5% lower in women classified as perimenopausal compared with premenopausal enrollees; BMD was 3% and 1% lower at the lumbar spine and total body site, respectively. Longitudinally, among perimenopausal women, a double oophorectomy was associated with BMD loss in the spine (p = 0.0003), even though 75-85% of these women had a hormone replacement prescription at some time during the study period. In summary, the site with evidence of loss was the femoral neck, specifically among perimenopausal women. There was little evidence of substantial total body or lumbar spine BMD loss in premenopausal women with ovaries who maintained follicle-stimulating hormone levels < 20 mIU/l in the early follicular period. Double oophorectomy, even with hormone replacement, was associated with bone loss.

Prevalence of renal stones in a population-based study with dietary calcium, oxalate, and medication exposures

Little is known about the epidemiology of renal stones, in spite of the relative frequency of this painful condition. This population-based study examined reported renal stone diagnosis in 1,309 women aged 20-92 years to determine whether renal stones are associated with 1) food or water exposures or 2) lower bone mineral density and an increased likelihood of fractures. Results indicated a renal stone prevalence of 3.4%. The average age at diagnosis was 42 years. Renal stone formation was not associated with community of residence, hypertension, bone mineral density, fractures, high-oxalate food consumption, or ascorbic acid from food supplements. Women with renal stones consumed almost 250 mg/day less dietary calcium (p < 0.01) than did women without stones and had a lower energy intake (p < 0.04). The authors' findings do not support the hypothesis that increased dietary calcium is associated with a greater prevalence of renal stones, nor do they identify renal stones as a risk factor for low bone mineral density. Furthermore, lack of other identifiable environmental correlates and the relatively young age at initial diagnosis suggest that genetic components of renal stone formation need further study.

Bone mineral density and its change in white women: estrogen and vitamin D receptor genotypes and their interaction

Low bone mineral density (BMD) is a major risk factor for development of osteoporosis; increasing evidence suggests that attainment and maintenance of peak bone mass as well as bone turnover and bone loss have strong genetic determinants. We examined the association of BMD levels and their change over a 3-year period, and polymorphisms of the estrogen receptor (ER), vitamin D receptor (VDR), type I collagen, osteonectin, osteopontin, and osteocalcin genes in pre- and perimenopausal women who were part of the Michigan Bone Health Study, a population-based longitudinal study of BMD. Body composition measurements, reproductive hormone profiles, bone-related serum protein measurements, and life-style characteristics were also available on each woman. Based on evaluation of women, ER genotypes (identified by PvuII [n = 253] and XbaI [n = 248]) were significantly predictive of both lumbar spine (p < 0.05) and total body BMD level, but not their change over the 3-year period examined. The VDR BsmI restriction fragment length polymorphism was not associated with baseline BMD, change in BMD over time, or any of the bone-related serum and body composition measurements in the 372 women in whom it was evaluated. Likewise, none of the other polymorphic markers was associated with BMD measurements. However, we identified a significant gene x gene interaction effect (p < 0.05) for the VDR locus and PvuII (p < 0.005) and XbaI (p < 0.05) polymorphisms, which impacted BMD levels. Women who had the (-/-) PvuII ER and bb VDR genotype combination had a very high average BMD, while individuals with the (-/-) PvuII ER and BB VDR genotype had significantly lower BMD levels. This contrast was not explained by differences in serum levels of osteocalcin, parathyroid hormone, 1,25-dihydroxyvitamin D, or 25-dihydroxyvitamin D. These data suggest that genetic variation at the ER locus, singly and in relation to the vitamin D receptor gene, influences attainment and maintenance of peak bone mass in younger women, which in turn may render some individuals more susceptible to osteoporosis than others.

A prospective study of bone density and pregnancy after an extended period of lactation with bone loss

OBJECTIVES

To determine if pregnancy after an extended period of lactation curtails the recovery of maternal bone mineral density.

METHODS

Twenty-five women who fully breast-fed their infants for at least 6 months and had a subsequent pregnancy within 18 months of initiating lactation were studied longitudinally. Twenty controls breast-fed similarly, but had no subsequent pregnancy. The women were healthy, well-nourished, and between 20-40 years old. Bone mineral density was measured by dual x-ray energy absorptiometry at the spine and hip.

RESULTS

Both cases and controls lost bone mineral density with extended lactation. The case group had a bone mineral density recovery comparable to the controls.

CONCLUSION

Women with the dual calcium demands of extended lactation and a subsequent pregnancy are not at risk for failure of bone recovery to pre-lactation levels.

Radial bone mineral density in pre- and perimenopausal women: a prospective study of rates and risk factors for loss

Radial bone mineral density (BMD) of 217 white women aged 22-54 years from a single rural community was evaluated in 1984 using single-photon absorptiometry. BMD was measured at a site one-third the distance from the wrist to the elbow, a site that represents predominantly cortical bone tissue. Most of these women (181; 83%) were reexamined 5 years later. The overall average 5 year radial BMD loss was -5.6%. The average rate of loss was -4.5% for women retaining positive estrogen status at follow-up (n = 108) and -7.4% for women who were in negative estrogen status at follow-up (n = 73). Baseline radial BMD measures were highly predictive of the follow-up BMD values (r = 0.80). Women with positive estrogen status and greater baseline BMD also had less BMD change. Greater baseline BMD did not predict the amount of change in women with negative estrogen status. The bone turnover markers osteocalcin and bone-specific alkaline phosphatase were significantly associated with BMD change in women with negative, but not positive estrogen status. There was no conclusive evidence of a "peak age" in the baseline and follow-up BMD measures. Based on rates of BMD change, "peak" bone mineral content appears to occur before age 25 years. Factors significantly associated with lower levels of BMD were menopause without estrogen replacement, nulliparity, smoking, and age at first pregnancy. Factors associated with more bone loss were menopause without estrogen replacement, smoking, shorter duration of oral contraceptive use, and older age. Quetelet index, muscle area, number of lost pregnancies, ever breast-feeding, or calcium intake were not associated with BMD level or its 5 year rate of loss. Physical activity and alcohol intake were not associated with BMD level or change after data were adjusted for age or estrogen status.

A prospective evaluation of bone mineral change in pregnancy

During pregnancy, mineralization of the fetal skeleton creates a demand for approximately 30 g of calcium from maternal sources. We examined whether this fetal demand results in maternal femoral bone mineral loss. Femoral bone mineral density was measured twice by dual photon densitometry, once before conception and again within 15 days of parturition, in 32 white women aged 20-40 years. Femoral bone mineral density was also measured twice in 32 non-pregnant controls matched to the cases for weight, height, age, and parity. There was no significant mean bone mineral density loss in cases compared with controls (P greater than .63). Pregnant women with smaller body size, expressed as Quetelet index, were more likely to have femoral neck bone mass increase than their matched controls (P less than .03). This study provides evidence that fetal demand for calcium has a minimal effect on bone mineral density at parturition. Smaller women may experience a slight increase in femoral bone mineral density compared with controls.

Prospective study of radial bone mineral density in a geographically defined population of postmenopausal Caucasian women

The radial bone mineral density (BMD) mass of 324 Caucasian women, aged 55-80 years, from geographically defined areas was evaluated in 1983 using single photon absorptiometry; 271 of these women (86%) were reexamined 5 years later in 1988. More than 65% of women lost radial BMD in excess of 1%/year in the 5-year follow-up. Thirty percent of women lost at least 2%/year. Baseline radial BMD measures taken in 1983 were highly predictive of the 1988 radial BMD values, explaining approximately 82% of the variability. The rate of bone change, expressed as percent change or 5-year difference (g/cm2), was not associated with baseline radial BMD value. Rate of change was not strongly associated with chronologic age or years since menopause, even when data were restricted to those women who reported no previous use of perimenopausal estrogen or thiazide medication. We conclude that BMD loss in a general population may be more substantial than previously believed.

Health and hormonal characteristics of premenopausal women with lower bone mass

A study of clinical renal and endocrinologic status was undertaken to determine whether the lowest maximal bone mass observed in premenopausal women, aged 20-40 years, was a result of undiagnosed disease or represented a continuum of measurement in young adult women. A clinical sample (n = 53) was generated from an epidemiologic cross-sectional study (n = 535) designed to characterized correlates of maximal bone mass. Cases were 28 premenopausal women whose femoral bone mass as in the lowest 5th percentile of the distribution, less than 0.75 g/cm2 at the femoral neck. Controls were 25 randomly selected premenopausal women whose femoral bone mass was within 1 SD of the mean of the femoral bone mass distribution. There was no indication of increased frequency of disease among the cases as compared with the controls. No occult hypogonadism, thyrotoxicosis, hyperparathyroidism, myeloma, or renal insufficiency was observed to explain lower bone mass measurement. However, cases had significantly lower estradiol levels (75 versus 106 pg/ml, P less than 0.05) and higher luteinizing hormone levels (3.8 versus 3.1 mIU/ml, P less than 0.07) than controls. Though preliminary, these findings suggest that lower estradiol levels may contribute to significant differences in bone mass even among healthy women at the time of maximal bone accumulation.

The prevalence of hepatitis B in employees of small, rural hospitals--implications for vaccine administration

The Centers for Disease Control Advisory Committee on Immunization Practices has based recommendations for hepatitis B vaccine for hospital employees on studies done in large urban hospitals. Data on the prevalence of hepatitis B in employees of small hospitals have been lacking. We measured hepatitis B surface and core antibody in 422 employees of six small, rural hospitals who were exposed to blood. The overall prevalence among those "high-risk" employees was 5.5%. The highest prevalence was found in General Nursing, Intensive Care Nursing, Recovery Room, IV Therapy, Laboratory, and Respiratory Therapy, although differences were seen between hospitals. Results of such testing for individual hospitals may have a major impact on the cost-effectiveness of vaccination programs for their employees.