Mary Ruth Stegman

The impact of lifestyle factors on stress fractures in female Army recruits

Abstract: Estimates are that stress fractures during basic training (BT) occur in as many as 14% of US female military recruits. Injuries of this type lead to morbidity ranging from minor pain to serious lifetime disability. Since women are assuming an increasing role in the military, this high risk of stress fracture is of concern. The purpose of this prospective study was to determine factors that predict stress fracture during BT in US Army female recruits. The analysis was part of an investigation using quantitative ultrasound (QUS) to determine risk of stress fracture during BT. Prior to the start of BT, we obtained QUS measurements and asked each subject to complete a risk factor questionnaire. We completed assessments for 3758 recruits who then proceeded to 8 weeks of BT, during which time any diagnosed stress fractures were reported to us by Army clinicians. Stress fractures were confirmed with radiographs. The incidence of stress fracture was 8.5% per 8 weeks. Factors associated with stress fracture include: QUS, age, race, alcohol and tobacco use, weight-bearing exercise, lowest adult weight, corticosteroid use, and, in white women only, use of depo-medroxyprogesterone acetate (DMPA). Women who fractured were older than women who remained fracture-free, and black women were less likely to sustain a fracture than whites and other races. Compared with their non-stress-fracture counterparts, recruits who developed stress fractures were more likely to report current or past smoking, alcoholic drinking of > 10 drinks/week, corticosteroid use and lower adult weight. A history of regular exercise was protective against stress fracture, and a longer history of exercise further decreased the relative risk of fracture. Although current weight was not associated with stress fracture, lowest adult weight was inversely related to the risk of fracture. We conclude that prevention of stress fractures in female military recruits should include a thorough assessment of lifestyle factors such as exercise patterns, alcohol and tobacco habits, and corticosteroid and DMPA use. Assessment of risk factors may be helpful in pinpointing female recruits who should have further evaluation of their bone health or additional preparation, such as gradual increases in physical activity, prior to being exposed to the rigor of BT.

Prevalence and severity of vertebral fracture: The saunders county bone quality study

Vertebral fracture prevalence and severity were analyzed by sex and age in an age-stratified proportionate sample of the enumerated population of women and men 50 years of age and older in Saunders County, Nebraska. The sample consisted of 899 women and 529 men. Of these, all but 10 women and 2 men had readable lateral spine radiographs. For both sexes, fracture prevalence rises with age. Women in their fifties have 10% vertebral fracture prevalence, and women in their eighties, 45% prevalence. Men in their fifties have 29% prevalence, and men in their eighties, 39% prevalence. The rise in prevalence and total spinal deformity with age is much greater for women than for men, but the prevalence of vertebral deformity in the fifties is much greater in men than in women.

Determination of bone mineral density of the hip and spine in human pedigrees by genetic and life-style factors

In 40 human pedigrees with 563 subjects, we evaluated the contribution of genetic and life‐style factors (exercise, smoking, and alcohol consumption) and the interactions between non‐genetic factors in determining bone mineral density (BMD) of the hip and spine. In our analysis, we adjusted for age, weight, height, menopausal status in females, life‐style factors, and the significant interactions among these factors. For the spine and hip BMD, heritabilities (h2) (± SE) were, respectively, 0.68 (0.21) and 0.86 (0.28) in males and 0.64 (0.13) and 0.67 (0.14) in females. Exercise had significant beneficial effects for male spine BMD and female hip BMD. Alcohol consumption experienced in our sample had significant beneficial effects on hip BMD in both sexes. Although the main effect of smoking was not significant, there were significant interaction effects between smoking and other important factors (e.g., exercise, weight, alcohol consumption). For example, for female spine BMD, exercise had significant beneficial effects in smokers; however, its effect in non‐smokers was non‐significant. This result indicates that exercise may reduce deleterious effects of smoking (if any) on BMD, but may have minor effects in increasing BMD in non‐smokers. The various interaction effects among risk factors explicitly revealed here for the first time indicate that the detailed effects and direction of individual risk factors may depend on the presence and magnitude of other factors. Weight invariably affected BMD of the hip and spine in both sexes. Age effects were significant for hip BMD, but not for male spine BMD. Genet. Epidemiol. 19:160–177, 2000.

Cortical ultrasound velocity as an indicator of bone status

Normative population data are reported here for velocity of ultrasound in tibial cortical bone in a population-based sample of both men and women (n=371). The cortical measurement is highly precise with reproducibility of the order of 0.5%. As with heel and patellar trabecular velocity, tibial cortical velocity declines with age from the fourth through the ninth decades. The rate is 1.7 m/s per year in men and 4.1 m/s per year in women. Tibial cortical velocity values correlate with patellar velocity and with forearm mineral, with correlation coefficients ranging from + 0.46 to +0.54 in women and +0.27 to +0.43 in men (P<0.002 for all). Tibial velocity averaged 77–104 m/s lower (2–3%: equal to about 1 SD of the young adult normal distribution) in individuals with a history of low-energy appendicular fractures (P<0.05), and the difference remained significant after adjusting for age. However, there were no perceptible differences in tibial velocity for those with and without vertebral fractures. Odds ratios derived from logistic regression showed an approximate twofold increase in likelihood of low-energy appendicular fracture for every standard deviation decrement in velocity. Comparison of tibial velocity with patellar velocity and forearm density in the same individuals revealed tibial velocity to be more strongly associated with appendicular fractures than patellar velocity for women and about the same for men, and less strongly associated than patellar velocity for vertebral fractures. We conclude that tibial cortical velocity provides useful information about bone status in populations at risk for osteoporosis, and seems particularly well suited for assessing appendicular fracture risk.

Genetic Determination of Variation and Covariation of Peak Bone Mass at the Hip and Spine

The likelihood of low trauma fracture in the elderly is highly predictable by peak bone mass (PBM) at age approximately 25-50 yr. We estimated the magnitude of genetic determination of the variation and covariation of PBM of the spine and hip (adjusted by age, gender, and ethnicity) in 47 independent healthy full-sib pairs and 27 healthy mother-offspring pairs. For the spine and hip, the narrow-sense heritabilities (h(2)) (mean +/- SE) were 0.76 +/- 0.34 and 0.84 +/- 0.36, respectively, when estimated from full sibs, and 0.86 +/- 0.38 and 0.84 +/- 0.39, respectively, when estimated from parent-offspring. Some genetic loci underlying PBM variation at the hip and spine are the same or closely linked, as is reflected by the high genetic correlation of 0.95 +/- 0.05 between them when estimated from full sibs, and 0.57 +/- 0.27 when estimated from parent-offspring, respectively. Generally, common familial environmental effects shared by relatives may bias these estimates. However, these effects may be small, since our results reported herein and those in other earlier studies indicate that common familial environmental effects are probably negligible in causing similarity of bone mass among family members. The correlation of bone mass among randomly sampled couples living in the same household is small and nonsignificant as measured either by densitometry at the radius and ulna or by quantitative ultrasound at the patella. The problem of shared environmental effects notwithstanding, we conclude that much of the PBM variation and covariation at the hip and spine is determined genetically.

Fracture risk as determined by prospective and retrospective study designs

Both retrospectively and prospectively designed studies consistently show low bone mass and/or bone mineral content (BMC) to be risk factor for low-trauma fractures in postmenopausal women. Along with the reports of such studies there has been concern expressed that BMC measurements overlap between fracture groups, i.e., some women with high BMC develop fractures and some women with low BMC do not. In these commonly used epidemiologic study designs, BMC does not discriminate between those who have and have not experienced the untoward event at some level of the exposure factor. The ability to discriminate is more properly determined by the sensitivity and specificity of the measured value. To contrast the concepts of risk and sensitivity, a nested case-control study was conducted within a 24-year cohort study of women at risk for osteoporosis. We found that for each 1.0 decrement of BMCz-scores, the adjusted relative risk for the prospective study design was 1.67, while the odds ratio obtained from the most recent BMCz-score measurements was 1.87. A receiver operating characteristic (ROC) curve, calculated from the nested case-control study data, showed that BMCz-scores, measured after low-trauma fracture, have both low sensitivity and low specificity to detect existing fracture status.

Ultrasound, densitometry, and extraskeletal appendicular fracture risk factors: a cross-sectional report on the Saunders County Bone Quality Study.

The Saunders County Bone Quality Study was designed to determine the feasibility of ultrasonic bone measurement, at the patella, as a predictor of low-trauma fractures in a runal population-based study. At the first visit of this 4-year longitudinal study, anthropometric and clinical measurements and medical, surgical, and fracture histories were obtained for the 1428 participants (899 women and 529 men). Explored risk factors for low-trauma fractures included age, sex, calcium intake, alcohol and caffeine ingestion, tobacco use, body mass and grip strength, age of menopause, estrogen replacement therapy, propensity to fall, distal radius and ulna bone mineral content, and bone density. Forward multivariate logistic regression analysis showed that lower ultrasound values are more consistently associated with reported low-trauma appendicular fractures than the commonly reported forearm absorptiometry measures of radius mineral content and density. When ultrasound, age, and the extra skeletal risk factors were included in an additional multivariate model, only age and ultrasound were significantly associated with appendicular fracture history in women (P=0.0003), whereas only ultrasound was associated in the men (P=0.001). We conclude that ultrasound is a better measure of association with reported low-trauma fractures than the commonly reported forearm SPA measures. Even after adjustment for many of the extra skeletal risk factors, low AVU is highly associated with low-trauma fracture status for both women and men.

Patellar ultrasound transmission velocity in healthy children and adolescents

Apparent velocity of ultrasound (AVU) (Signet, Osteo-Technology Cambridge, MA) at the patella was measured on 568 children and adolescents, aged 8 to 18 years. Trend analysis revealed a significant trend (p < 0.004) toward increasing AVU with increasing age and increasing Tanner stage. Height and weight were positively correlated with AVU in both sexes, while dietary intake of calories, protein, and calcium were positively correlated with AVU in males, but not in females. Multiple linear regression revealed that 29% of the variance of AVU in females was described by Tanner stage (p < 0.002) and height (p < 0.007). The best regression model for males accounted for 48% of the variance in AVU and included age (p < 0.0001) and protein intake (p < 0.01). Bone quality has a distribution in children which is similar to the distribution of bone mass and density. Our patellar AVU values can be used as a baseline for much-needed prospective research with children and adolescents.

The association of patellar ultrasound transmissions and forearm densitometry with vertebral fracture, number and severity: the Saunders County Bone Quality Study.

Ultrasonic measures of bone have been available for clinical research purposes for nearly 10 years, yet there still seems to be a need to compare ultrasound with the accepted gold standard of densitometry. Recently there have been published reports showing that ultrasound measures are associated with both appendicular and hip fracture, in particular after adjustment for densitometry measures. We present here a comparison between speed of sound through the patella and forearm bone densitometry, using their association with prevalent vertebral fractures in a population-based study of women and men. The prospective phase of the Saunders Bone Quality Study includes 1401 women and men who had baseline spine radiographs, patellar ultrasound, and forearm densitometry measurements. Multivariate forward logistic regression was used to determine the age-adjusted odds of vertebral fracture, the number of fractures, and the severity of these fractures, when patellar ultrasound and each of four forearm densitometry measures were entered into the model. Age is the most important factor associated with vertebral fractures, their number, and severity for women, while age is not significantly related to vertebral fractures for men. Of the bone status measures, patellar ultrasound entered the logistic regression models more consistently than any other measure except ulnar bone mineral density for women. The ultrasound measure entered every model for men. We conclude that patellar ultrasound velocity is more consistently associated with the odds of vertebral fractures than radius bone mineral content.

The effect of the anastomotic size on gastric emptying after hemigastrectomy with Billroth II reconstruction

OBJECTIVE To determine if the size of the gastrojejunal anastomosis after Billroth II reconstruction was the rate-limiting factor in gastric emptying in the postoperative period. METHODS Twelve mongrel dogs were randomized to have either 1.5 cm or 5 cm gastrojejunal anastomoses prior to Billroth II hemigastrectomy. Each dog had three solid and three liquid radiolabelled emptying studies pre- and postoperatively. Data were collected using a gamma camera. For liquid studies, images were obtained at 0 min, 2 min, 4 min, 6 min, 8 min, 10 min, 20 min, 30 min, 40 min, 50 min and 60 min. For solid studies, images were obtained at 0 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min and 120 min. Means were compared by analysis of variance using the repeated measures option. RESULTS Postoperative liquid emptying was significantly faster in the first 10 min with both 1.5 cm and 5 cm anastomoses compared with preoperative scans in the same animals (45% versus 20% and 48% versus 29%, respectively). On the other hand, solid gastric emptying was much slower postoperatively with the 1.5 cm anastomosis compared with preoperative scans (29% versus 65%) as well as compared with postoperative 5 cm anastomosis (29% versus 62%) at the end of 120 min. CONCLUSIONS Our model suggests that the gastric emptying of solids is affected by the size of the gastrojejunal anastomosis and not by the diameter of the efferent limb of the small intestine following Billroth II reconstruction.