Faculty Bibliography

The goal of this study was to demonstrate the feasibility of using 7-Tesla (7T) magnetic resonance imaging (MRI) and micro-finite element analysis (microFEA) to evaluate mechanical and structural properties of whole, cortical, and trabecular bone at the distal femur and proximal tibia in vivo. 14 healthy subjects were recruited (age 40.7 +/- 15.7 years). The right knee was scanned on a 7T MRI scanner using a 28 channel-receive knee coil and a three-dimensional fast low-angle shot sequence (TR/TE 20 ms/5.02 ms, 0.234 mm x 0.234 mm x 1 mm, 80 axial images, 7 min 9 s). Bone was analyzed at the distal femoral metaphysis, femoral condyles, and tibial plateau. Whole, cortical, and trabecular bone stiffness was computed using microFEA. Bone volume fraction (BVF), bone areas, and cortical thickness were measured. Trabecular bone stiffness (933.7 +/- 433.3 MPa) was greater than cortical bone stiffness (216 +/- 152 MPa) at all three locations (P < 0.05). Across locations, there were no differences in bone stiffness (whole, cortical, or trabecular). Whole, cortical, and trabecular bone stiffness correlated with BVF (R >/= 0.69, P < 0.05) and inversely correlated with corresponding whole, cortical, and trabecular areas (R 0.05). Whole, cortical, and trabecular stiffness correlated with body mass index (R >/= 0.62, P < 0.05). In conclusion, at the distal femur and proximal tibia, trabecular bone contributes 66-74% of whole bone stiffness. 7T MRI and microFEA may be used as a method to provide insight into how structural properties of cortical or trabecular bone affect bone mechanical competence in vivo.

With the aging of the population, low bone mass states will be an increasing clinical issue for both men and women. More than 2 million osteoporotic fractures occur annually in the United States and it is estimated that nearly half of American Caucasian women over the age of 50 will experience at least one fragility fracture in their lifetime. Identifying subjects at increased risk for fracture and defining rational treatment strategies that balance risks with therapeutic benefits promises to be a major focus in the decade ahead. This review focuses on several areas of active interest in osteoporosis including the use of fracture assessment tools that help quantify time sensitive fracture risks by using patient specific data, advances in bone imaging and the relationship between structure and strength, new and future drug treatments for osteoporosis, and several unusual adverse clinical syndromes linked to the use of bisphosphonates. The topics chosen for this review highlight the increased understanding of bone structure and aging and how this knowledge can help clinicians in their treatment of osteoporosis

Regional migratory osteoporosis (RMO) is a rare, self-limited disease of unknown etiology, characterized by migratory arthralgia of the weight-bearing joints of the lower extremities. RMO is most commonly seen in middle-aged adults, particularly men. Several case reports suggest that bone changes seen in RMO may be detected as focal decreases in bone mineralization, but the utility of serial bone density studies has yet to be formally evaluated in this syndrome. We describe a case of RMO with dramatic focal changes in bone mineral density that corresponded to the underlying clinical course. Serial bone density testing clearly documented significant bone loss and subsequent recovery of bone density in areas affected by RMO. Our data suggest that sequential densitometric examination of affected areas may be useful to confirm the diagnosis of RMO, and for subsequent monitoring of bone loss and therapeutic response

The need to initiate treatment for a postmenopausal woman with a low bone mass should be based on that individual's fracture risk over a fnite period of time. Fracture assessment tools, such as the recently introduced FRAX(TM) model, allows the clinician to estimate an individual's absolute fracture risk over the next decade of their life. Such estimates are particularly useful for younger postmenopausal females with bone density values in the osteopenic range. Fracture risk increases with age and is inversely related to bone mineral density values. A history of previous fracture after the age of 45 and within 10 years of assessment increases subsequent fracture risk

Estimating an individual's fracture risk is the most significant factor for determining the need to initiate bone strengthening treatment in the postmenopausal woman. Fracture risk in inversely and most strongly related to an individual's bone mineral density values, but other factors including age, prior fracture history, body mass index, general health, family history of fractures, corticosteroid use, and smoking history also influence the risk of subsequent fractures. Fracture risk assessment tools such as the World Health Organization's FRAX tool and the Study of Osteoporotic Fractures Index provide 10- and 5-year fracture probability estimates, respectively, and using these tools can be particularly helpful in assessing the immediate need to initiate treatment in younger postmenopausal women. Perimenopausal and postmenopausal bone loss averages about 1% per year with more annual bone loss occurring in trabecular than cortical bone and during a normal life span such bone loss can exceed 35% of an individual's bone mass. Younger postmenopausal women with low bone mineral density values, a history of a previous fracture, greater rates of bone loss as measured by bone turnover markers are more likely to need bone strengthening treatment at an earlier age in the postmenopausal period. Treatment measures include adequate amounts of dietary and supplemental calcium and vitamin D, a routine of regular exercises and medications that reduce the rate of new fractures

PURPOSE OF REVIEW: The female athlete triad - anorexia, athletics, and amenorrhea - is a clinical problem found among young women who are engaged in intense physical activity. This review describes the psychological factors involved in the triad and the endocrine and skeletal consequences of the disorder. This subject is particularly timely and important as eating disorders are increasing in frequency among young women athletes. RECENT FINDINGS: Concern about body weight and its effect on athletic performance can lead to chronic undernutrition. Complications of low body weight include hormonal disturbances, bone loss and fracture. The potential endocrine abnormalities seen in this group of women include anovulatory cycles, chronic elevation in glucocorticoids and lower serum leptin concentrations. Lower insulin-like growth factor-1 and resistance to growth hormone have also been described. Treatment of consequent bone loss with hormones, and most recently, with bisphosphonates, provides conflicting, but also encouraging data. SUMMARY: The pressures to improve peak athletic performance often underlie the abnormal behavior and eating disorders characteristic of the female athlete triad, with subsequent life-long consequences. Physicians should be made aware of such pressures, and their psychological and physical consequences. Prevention is the best medicine; but more research in ways to effectively and safely treat bone loss in young women is needed