Adam S. Tenforde

Influence of Sports Participation on Bone Health in the Young Athlete: A Review of the Literature

Peak bone mass is attained during the second and third decades of life. Sports participation during the years that peak bone mass is being acquired may lead to adaptive changes that improve bone architecture through increased density and enhanced geometric properties. A review of the literature evaluating sports participation in young athletes, ages 10‐30 years, revealed that sports that involve high‐impact loading (eg, gymnastics, hurdling, judo, karate, volleyball, and other jumping sports) or odd‐impact loading (eg, soccer, basketball, racquet games, step‐aerobics, and speed skating) are associated with higher bone mineral composition, bone mineral density (BMD), and enhanced bone geometry in anatomic regions specific to the loading patterns of each sport. Repetitive low‐impact sports (such as distance running) are associated with favorable changes in bone geometry. Nonimpact sports such as swimming, water polo, and cycling are not associated with improvements in bone mineral composition or BMD, and swimming may negatively influence hip geometry. Participating in sports during early puberty may enhance bone mass. Continued participation in sports appears to maintain the full benefits of increased peak bone mass, although former athletes who do not maintain participation in sports may retain some benefits of increased BMD. Long‐term elite male cycling was reported to negatively influence bone health, and female adolescent distance running was associated with suppressed bone mineral accrual; confounding factors associated with participation in endurance sports may have contributed to those findings. In summary, young men and women who participate in sports that involve high‐impact or odd‐impact loading exhibit the greatest associated gains in bone health. Participation in nonimpact sports, such as swimming and cycling, is not associated with an improvement in bone health.

Overuse Injuries in High School Runners: Lifetime Prevalence and Prevention Strategies

To evaluate lifetime prevalence and risk factors for overuse injuries in high school athletes currently participating in long‐distance running and provide recommendations for injury prevention strategies.

To modulate or not to modulate: Differing results in uniquely shaped Williams syndrome brains

Voxel based morphometry (VBM) studies of Williams syndrome (WS) have demonstrated remarkably consistent findings of reduced posterior parietal gray matter compared to typical controls. Other WS VBM findings have been inconsistent, however. In particular, different findings have been reported for hypothalamus and orbitofrontal gray matter regions. We examined a sample of 8 WS and 9 control adults and show that the hypothalamus and orbitofrontal cortex results depend on whether the images undergo Jacobian modulation. Deformation based morphometry (DBM) analysis demonstrated that major brain shape differences between the groups accounted for the Jacobian modulated gray matter findings. These results indicate that cautious interpretations of modulated gray matter findings are warranted when there are gross shape and size differences between experimental groups. This study demonstrates the importance of methodological choices towards understanding a disorder like WS, but also highlights the consistency of parietal lobe, orbitofrontal, and midbrain findings for this disorder across methodologies, participants, and research groups.

Identifying sex-specific risk factors for stress fractures in adolescent runners.

PURPOSE Adolescent females and males participating in running represent a population at high risk of stress fracture. Few investigators have evaluated risk factors for prospective stress fracture in this population. METHODS To better characterize risk factors for and incidence of stress fractures in this population, we collected baseline risk factor data on 748 competitive high school runners (442 girls and 306 boys) using an online survey. We then followed them prospectively for the development of stress fractures for a mean ± SD of 2.3 ± 1.2 total seasons of cross-country and track and field; follow-up data were available for 428 girls and 273 boys. RESULTS We identified prospective stress fractures in 5.4% of girls (n = 23) and 4.0% of boys (n = 11). Tibial stress fractures were most common in girls, and the metatarsus was most frequently fractured in boys. Multivariate regression identified four independent risk factors for stress fractures in girls: prior fracture, body mass index < 19, late menarche (age menarche ≥15 yr), and previous participation in gymnastics or dance. For boys, prior fracture and increased number of seasons were associated with an increased rate of stress fractures, whereas prior participation in basketball was associated with a decreased risk of stress fractures. CONCLUSIONS Prior fracture represents the most robust predictor of stress fractures in both sexes. Low body mass index, late menarche, and prior participation in gymnastics and dance are identifiable risk factors for stress fractures in girls. Participation in basketball appears protective in boys and may represent a modifiable risk factor for stress fractures. These findings may help guide future translational research and clinical care in the management and prevention of stress fractures in young runners.

Atypical femur fractures among breast cancer and multiple myeloma patients receiving intravenous bisphosphonate therapy

PURPOSE Atypical femur fractures represent a potential complication of chronic oral bisphosphonate therapy in women with osteoporosis, but the risk of atypical femur fractures among cancer patients receiving intravenous bisphosphonates at higher cumulative doses remains unclear. We examined femur fractures occurring in cancer patients treated with intravenous bisphosphonates (IVBP) to determine whether a subset may be atypical fractures. METHODS Between 2005 and 2010, we identified patients with known IVBP therapy for multiple myeloma or metastatic breast cancer, who subsequently sustained a femur fracture based on hospitalization, oncology, pharmacy and chemotherapy visit records. Radiographs were examined by an orthopedic surgeon to determine anatomic fracture site and pattern. An atypical fracture was defined as a transverse or short oblique fracture occurring below the lesser trochanter with evidence of focal hypertrophy of the lateral cortex and absence of biopsy-proven malignancy or radiation therapy at the fracture site. RESULTS A total of 62 patients with breast cancer (N=39) or multiple myeloma (N=23) with femur fracture and prior IVBP treatment for bone malignancy were identified. There were 30 proximal hip, 18 subtrochanteric and 14 femoral shaft fractures. Intraoperative bone samples were sent in 29 of 58 fracture cases undergoing operative repair, with 76% positive for malignancy. Six cases (4 breast cancer, 2 multiple myeloma) of atypical femur fracture were identified, two with negative intraoperative pathology and four with no bone biopsy samples sent. Five of the six patients with atypical fracture had bilateral femur findings, including two with transverse fracture in the contralateral femur and three with focal hypertrophy of the contralateral cortex. Two atypical fracture cases also experienced osteonecrosis of the jaw compared to 3 in the remaining cohort (33% vs. 5%, p=0.07). Patients with atypical fracture received more IVBP (median 55 vs. 15 doses) and zoledronic acid (32 vs. 12 doses) and had longer treatment duration (median 5.9 vs. 1.6 years) compared to patients without atypical fracture (all p≤0.01). CONCLUSIONS Among 62 patients who received IVBP for skeletal malignancy and experienced a femur fracture, we identified six cases of atypical fracture. While fractures in this population are often assumed to be pathologic, prospective studies investigating fracture pattern, microscopic bone pathology and pharmacologic exposures should be conducted to further examine the association of IVBP and atypical femur fractures.

Evaluating the Relationship of Calcium and Vitamin D in the Prevention of Stress Fracture Injuries in the Young Athlete: A Review of the Literature

Calcium and vitamin D are recognized as 2 components of nutrition needed to achieve and maintain bone health. Calcium and vitamin D have been clearly shown to improve bone density and prevent fractures at all ages. However, the literature is conflicting as to the role of these nutrients in young athletes ages 18 to 35 years, both for bone development and for the prevention of bone overuse injuries. Differences in findings may relate to study design. Although retrospective and cross‐sectional studies have had mixed results, the authors of prospective studies have consistently demonstrated a relationship of increased calcium intake with an improvement in bone density and a decrease in fracture risk. A randomized trial in female military recruits demonstrated that calcium/vitamin D supplementation reduced the incidence of stress fractures. A prospective study in young female runners demonstrated reduced incidence of stress fractures and increased bone mineral density with increased dietary calcium intake. Findings from both studies suggest female athletes and military recruits who consumed greater than 1500 mg of calcium daily exhibited the largest reduction in stress fracture injuries. To date, no prospective studies have been conducted in male athletes or in adolescent athletes. In most studies, males and nonwhite participants were poorly represented. Evidence regarding the relationship of vitamin D intake with the prevention of fractures in athletes is also limited. More prospective studies are needed to evaluate the role of calcium and vitamin D intake in prevention of stress fracture injuries in both male and female adolescent athletes, particularly those participating in sports with greater incidences of stress fracture injury.

Update on stress fractures in female athletes: epidemiology, treatment, and prevention

Stress fractures are a common type of overuse injury in athletes. Females have unique risk factors such as the female athlete triad that contribute to stress fracture injuries. We review the current literature on risk factors for stress fractures, including the role of sports participation and nutrition factors. Discussion of the management of stress fractures is focused on radiographic criteria and anatomic location and how these contribute to return to play guidelines. We outline the current recommendations for evaluating and treatment of female athlete triad. Technologies that may aid in recovery from a stress fracture including use of anti-gravity treadmills are discussed. Prevention strategies may include early screening of female athlete triad, promoting early participation in activities that improve bone health, nutritional strategies, gait modification, and orthotics.

Anomalous Hypothalamic Responses to Humor in Cataplexy

Background Cataplexy is observed in a subset of patients with narcolepsy and affects approximately 1 in 2,000 persons. Cataplexy is most often triggered by strong emotions such as laughter, which can result in transient, yet debilitating, muscle atonia. The objective of this study was to examine the neural systems underlying humor processing in individuals with cataplexy. Methodology/Principal Findings While undergoing functional Magnetic Resonance Imaging (fMRI), we showed ten narcolepsy-cataplexy patients and ten healthy controls humorous cartoons. In addition, we examined the brain activity of one subject while in a full-blown cataplectic attack. Behavioral results showed that participants with cataplexy rated significantly fewer humorous cartoons as funny compared to controls. Concurrent fMRI showed that patients, when compared to controls and in the absence of overt cataplexy symptoms, showed pronounced activity in the emotional network including the ventral striatum and hypothalamus while viewing humorous versus non-humorous cartoons. Increased activity was also observed in the right inferior frontal gyri -a core component of the inhibitory circuitry. In comparison, the one subject who experienced a cataplectic attack showed dramatic reductions in hypothalamic activity. Conclusions These findings suggest an overdrive of the emotional circuitry and possible compensatory suppression by cortical inhibitory regions in cataplexy. Moreover, during cataplectic attacks, the hypothalamus is characterized by a marked decrease in activity similar to that observed during sleep. One possible explanation for these findings is an initial overdrive and compensatory shutdown of the hypothalamus resulting in full cataplectic symptoms.

Parallels with the Female Athlete Triad in Male Athletes

Participation in sports offers many health benefits to athletes of both sexes. However, subsets of both female and male athletes are at increased risk of impaired bone health and bone stress injuries. The Female Athlete Triad (Triad) is defined as the interrelationship of low energy availability (with or without disordered eating), menstrual dysfunction, and low bone mineral density. The Triad may result in health consequences, including bone stress injuries. Our review presents evidence that an analogous process may occur in male athletes. Our review of the available literature indicates that a subset of male athletes may experience adverse health issues that parallel those associated with the Triad, including low energy availability (with or without disordered eating), hypogonadotropic hypogonadism, and low bone mineral density. Consequently, male athletes may be predisposed to developing bone stress injuries, and these injuries can be the first presenting feature of associated Triad conditions. We discuss the evidence for impaired nutrition, hormonal dysfunction, and low bone mineral density in a subset of male athletes, and how these health issues may parallel those of the Triad. With further research into the mechanisms and outcomes of these health concerns in active and athletic men, evidence-based guidelines can be developed that result in best practice.

Quantification of Particle Residence Time in Abdominal Aortic Aneurysms Using Magnetic Resonance Imaging and Computational Fluid Dynamics

Hemodynamic conditions are hypothesized to affect the initiation, growth, and rupture of abdominal aortic aneurysms (AAAs), a vascular disease characterized by progressive wall degradation and enlargement of the abdominal aorta. This study aims to use magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) to quantify flow stagnation and recirculation in eight AAAs by computing particle residence time (PRT). Specifically, we used gadolinium-enhanced MR angiography to obtain images of the vessel lumens, which were used to generate subject-specific models. We also used phase-contrast MRI to measure blood flow at supraceliac and infrarenal locations to prescribe physiologic boundary conditions. CFD was used to simulate pulsatile flow, and PRT, particle residence index, and particle half-life of PRT in the aneurysms were computed. We observed significant regional differences of PRT in the aneurysms with localized patterns that differed depending on aneurysm geometry and infrarenal flow. A bulbous aneurysm with the lowest mean infrarenal flow demonstrated the slowest particle clearance. In addition, improvements in particle clearance were observed with increase of mean infrarenal flow. We postulate that augmentation of mean infrarenal flow during exercise may reduce chronic flow stasis that may influence mural thrombus burden, degradation of the vessel wall, and aneurysm growth.