OBJECTIVE-Increased physical activity and menstrual irregularity have been associated with increased risk for stress fracture among adult women active in athletics. The purposes of this study were to determine whether menstrual irregularity is also a risk factor for stress fracture in active female adolescents and to estimate the quantity of exercise associated with an increased risk for this injury.PATIENTS AND METHODS-A case-control study was conducted of 13-to 22-year-old females diagnosed with their first stress fracture, each matched prospectively on age and selfreported ethnicity with 2 controls. Patients with chronic illnesses or use of medications known to affect bone mineral density were excluded, including use of hormonal preparations that could alter menstrual cycles. The primary outcome, stress fracture in any extremity or the spine, was confirmed radiographically. Girls with stress fracture had bone mineral density measured at the lumbar spine by dual-energy x-ray absorptiometry.RESULTS-The mean ± SD age of the 168 participants was 15.9 ± 2.1 years; 91.7% were postmenarchal, with a mean age at menarche of 13.1 ± 1.1 years. The prevalence of menstrual irregularity was similar among cases and controls. There was no significant difference in the mean hours per week of total physical activity between girls in this sample with stress fracture (8.2 hours/week) and those without (7.4 hours/week). In multivariate models, case subjects had nearly 3 times the odds of having a family member with osteoporosis or osteopenia. In secondary analyses, participants with stress fracture had a low mean spinal bone mineral density for their age.CONCLUSIONS-Among highly active female adolescents, only family history was independently associated with stress fracture. The magnitude of this association suggests that further investigations of inheritable skeletal factors are warranted in this population, along with evaluation of bone mineral density in girls with stress fracture. NIH Public Access Author ManuscriptPediatrics. Author manuscript; available in PMC 2011 October 25. Stress fractures are particularly concerning in active female adolescents and young adults because they may signify insufficiency of the bones to withstand repetitive loading. Although a "fracture threshold"is not yet defined for children and adolescents, ~80% to 90% of in vitro skeletal strength in adults is determined by bone mineral density (BMD). 12 A woman's peak bone mass is achieved by her early 20s 13,14 and is one of the strongest predictors of her long-term risk of osteoporosis. 15,16 Understanding the risk factors that predispose to stress fracture in this population could, therefore, indirectly elucidate the risk factors for a low BMD.To our knowledge, no data exist regarding risk factors for stress fracture in adolescents younger than age 17 years. We, therefore, constructed a pathogenetic model of stress fracture on the basis of studies in the adult literature and the observations of experienced clinicians. The risk factors deem...

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Objective-To compare quantitative ultrasound (QUS) measurements in adolescents with anorexia nervosa (AN) with that in healthy control subjects and to determine the utility of QUS as a tool to evaluate skeletal status in these patients.Study design-Female adolescents with AN (n = 41) and healthy control subjects (n = 105) were recruited. Speed of sound (SOS) was measured at the radius and tibia. Participants with AN also had hip and spinal areal bone mineral density measurements by dual-energy x-ray absorptiometry (DXA); bone mineral apparent density (BMAD) was calculated.Results-Subjects with AN had higher mean radial SOS (4044 ± 99 m/s) than did control subjects (3947 ± 116 m/s; P < .0001). These results were replicated at the tibia (AN, 3918 ± 85 m/ s vs control subjects, 3827 ± 106 m/s; P < .0001). Neither DXA measures of areal bone mineral density nor BMAD were correlated with SOS. Weight and body mass index were negative predictors of tibial but not radial SOS. AN status remained a significant predictor of SOS after controlling for body mass index, age, and race.Conclusions-Subjects with AN had higher mean tibial and radial SOS than did control subjects. QUS variables did not correlate with DXA measures, calculated BMAD, or anthropometric variables. QUS measurements of SOS do not appear to be appropriate for bone density screening in patients with AN.Bone loss is a well-established complication of anorexia nervosa (AN). [1][2][3][4] Given that adolescence is the crucial time for establishment of peak bone mass, this loss is clinically significant and may place these young women at higher risk for fracture. 5 Dual-energy x-ray absorptiometry (DXA) has been the most widely used tool for assessment of bone mass in this patient population. DXA measures bone in two dimensions and allows for calculation of areal bone mineral density (aBMD, g/cm 2 ). The greatest challenge in the interpretation of aBMD in the adolescent age group is that it is highly influenced by bone and body size. [6][7][8] Additionally, although DXA measures are highly correlated with bone strength, strength depends on skeletal properties such as geometry, elasticity, and internal architecture, which are not reflected directly in DXA measurements. 9,10 Quantitative ultrasound (QUS) is an attractive alternative method for the evaluation of skeletal status. QUS assesses peripheral bone by measuring the speed of sound (SOS) of an ultrasound wave as it is propagated along the bone. influenced by bone density, elasticity modulus, and the microarchitecture of bone. 7 Studies have shown that QUS can predict fracture risk in older women, independent of aBMD, and monitor skeletal responses to exercise with good sensitivity. [11][12][13][14] The use of QUS is appealing because of its portability, speed, low cost, and lack of ionizing radiation. QUS could also be used as a screening tool for low bone mass or provide information beyond that obtained by current bone density measurement techniques. However, to our knowledge, this modality has not b...

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Infants at elevated likelihood of developing autism display differences in sensory reactivity, especially hyporeactivity, as early as 7 months of age, potentially contributing to a developmental cascade of autism symptoms. Caregiver responsiveness, which has been linked to positive social communication outcomes, has not been adequately examined with regard to infant sensory reactivity. This study examined the multiplicative impact of infant sensory hypo- and hyperreactivity on caregiver responsiveness to sensory reactivity and regulation cues in 43 infants at elevated likelihood of autism. Sensory hyperreactivity was found to moderate the association between sensory hyporeactivity and caregiver responsiveness, such that caregivers of infants with moderately high sensory hypo- and hyperreactivity demonstrated higher responsiveness.