February 2010 Archives

Anterior Cruciate Ligament Injuries

Anterior cruciate ligament (ACL) tears are one of the most debilitating sport injuries sustained by recreational and elite athletes. An estimated 250,00 ACL ruptures occur in the US each year and nearly half of those are repaired by surgical reconstruction. Conventional wisdom suggests that nearly all athletes fully return to play after ACL reconstructive surgery. However, recent data suggests that of NFL players who experience an ACL tear, over 20% never return to play, and those who do return perform at only 1/3 of pre-surgery levels. Consequences of some ACL reconstructive procedures, as well as pre- and post-operative mechanical unloading, lead to neuromuscular function and bone and muscle mass losses. In addition, new data shows that bone loss occurs and remains low even several years after surgery, which may contribute to increased risk of osteoarthritis in later life.

Childhood Obesity

Understanding how bone adapts in mass, geometry, strength to weight gain during childhood is important from both a public health and basic bone biology standpoint. While the prevailing thought is that obesity is protective of bone and lowers the risk of fractures, there is evidence to suggest that the opposite may be true. While obese adults have increased risk of forearm and lower leg fractures, obese children may be at a higher risk of forearm fractures. Therefore, it is important to understand how bone adapts its mass, geometry and strength during weight gain leading to obesity during childhood.

Previous studies have used dual energy x-ray absorptiometry (DXA) outcomes of areal bone mineral density (aBMD, g/cm2) and bone mineral content (BMC, g) to estimate bone strength. DXA outcomes provide an important predictor of fracture risk; more bone generally confers greater strength. However, bone geometric adaptations may not be elucidated in aBMD outcomes, but may provide greater information regarding parameters of bone strength. In the LMH we have the opportunity to study bone adaptation through the use of peripheral quantitative computed tomography (pQCT), which allows for three-dimensional imaging of the peripheral skeleton.

Musculoskeletal Health Following Bariatric Surgery

The prevalence of morbid obesity among adults and adolescents has risen dramatically over the last several decades. While other approaches have failed, bariatric surgery has become an increasingly popular treatment option for the significant and sustained weight loss of morbidly obese individuals. With a greater than ten-fold increase in adult procedures over the last decade, adolescent bariatric surgeries have also increased five-fold in the U.S. between 1997 and 2003. Research in adult bariatric populations demonstrates improvements in related co-morbidities. However, bariatric surgery and subsequent weight loss is associated with accelerated rates of bone loss, as measured by dual energy x-ray absorptiometry (DXA). This raises public health concerns over bone loss leading to osteoporosis and fracture. Given these concerns, it is important to understand how the physiological adaptation of bone applies to weight loss.

In addition, little is also known about the effects of bariatric surgery on skeletal health parameters in youth. Given that adolescence is a critical time for development of a strong skeleton, determining the physiological implications of this procedure during this critical time of growth is important.

We are currently conducting two studies in the LMH in collaboration with bariatric surgeons at the University of Minnesota Weight Loss Surgery Center and also the Pediatric Weight Management Clinic. If you are interested in further information, please contact Lesley Scibora at scibo002@umn.edu.

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