Bone by Ray Sahelian, M.D. Bone health improvement

Bone is a type of hard connective tissue found in many vertebrate animals. Bones support body structures, protect internal organs, and (in conjunction with muscles) facilitate movement; are also involved with cell formation, calcium metabolism, and mineral storage. The bones of an animal are, collectively, known as the skeleton. Bone has a different composition than cartilage.
   Running, jumping and other high impact activities during childhood benefits bone health by increasing the size and strength of the growing skeleton. The benefits in bone size and strength induced by exercise during growth persist lifelong -- even if exercise is ceased.

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Bone Density and Androgen Deprivation
Bone mineral density (BMD) decreases during the first 2 years of androgen deprivation therapy in men with prostate cancer. Dr. Morote and colleagues from Vall d'Hebron Hospital, Autonoma University School of Medicine, Barcelona, Spain evaluated the dynamics of BMD in the lumbar spine and four hip sites over a 2-year period in 62 men with locally advanced nonmetastatic prostate cancer. Men receiving androgen deprivation therapy experienced bone mineral density losses ranging from 2% to 5% at all analyzed locations at 12 months. Bone mineral density did not change significantly in men not on androgen suppression. The area that best reflected the ADT-induced bone loss was Ward's triangle,a region between the principal compressive group of the femoral head and the principal tensile group and the secondary compressive group of the femoral neck. A DEXA scan of the wrist may not accurately reflect the greatest extent of bone loss which may lead to a delay in appropriate treatment. Journal of Urology 2006;175:1679-1683.
   In the year following coronary artery bypass grafting (CABG), bone mineral content declines significantly in men. A decline in bone mineral density increases the risk of bone fracture.

Measuring Bone Mineral Density

Several methods are available to measure bone density, but currently the most widely used technique is DEXA (Dual Energy Xray Absorptiometry). Older methods such as single photon absorptiometry do not predict hip fractures as well as DEXA. Three companies manufacture these densitometers: Hologic, Norland, and Lunar.

Bone density
The high-impact tumbling of gymnastics increases young girls' muscle mass and bone density. The more time young men spend engaging in high-impact physical exercise, the greater their bone mineral density.

Bone test - how often to take a bone test
Repeat bone mineral density testing up to 8 years after the initial bone test does not improve the ability of doctors to predict fractures in older women. Dr. Teresa A. Hillier, from Kaiser Permanente Northwest/Hawaii in Portland, Oregon, and colleagues assessed the predictive ability of repeat bone mineral density testing in 4,124 women with an average age of 72 years. Bone mineral density testing was first performed from 1989 to 1990 and then again 8 years later. During an average follow-up period of over 5 years after the second bone mineral density test, 877 women sustained a nontraumatic nonspine fracture and 340 sustained a spine fracture. Adding a second bone mineral density test did not improve the predictive ability of the first for future fracture. This held true even after adjusting for initial bone mineral density scores, hormonal therapy, or high bone loss. Archives of Internal Medicine, January 22, 2007.

Smoking and Bone Healing
Exposure to cigarette smoke delays the early phases of bone and ligament repair in mice. Dr. Linda J. Sandell and colleagues from Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, Missouri investigated the effects of cigarette smoke exposure on early events in bone fracture healing, especially cartilage formation. Mice were randomly assigned to a control group or to a group in which they were exposed to smoke in a chamber for 6 days per week for a month, before experiment leg fracture under anesthesia. Smoking significantly reduced cartilage formation, an important step in bone healing. By day 14 after bone fracture, the cartilage was still developing in the smoke-exposed animals, whereas it had already been replaced by bone in the normal controls. In the second study, the same team of researchers investigated whether smoking cigarettes would interfere with the ability of mice to synthesize support tissue at the site of ligament injury. Ligaments are tough fibrous bands that hold bone to bone, whereas tendons are bands that hold muscle to bone. Synthesis of the support tissue needed for ligament repair was significantly delayed in the animals exposed to smoke. Journal of Orthopedic Research, December 2006.

Bone mass and cycling
Compared with men who run, men whose primary physical activity is bicycling are much more likely to have low bone density in the hips or spine. In general, cyclists have lower bone mass throughout the body and a higher incidence of osteopenia in the spine or hip. Osteopenia refers to abnormally low bone mass that could progress to the brittle-bone disease osteoporosis. Running, jumping and other weight-bearing activities put the bones under stress. This forces the bones to respond by becoming stronger; whereas low-impact exercise, like biking or swimming, works the heart and trims the waistline, but puts little strain on the bones. Metabolism, November 2007.

Hip bone fracture protection
Padded undergarments meant to protect against hip bone fractures could help elderly adults stay out of the nursing home, and cut healthcare costs along the way. The garments, known as hip protectors, are designed to cushion a fall, which for elderly adults -- particularly those with osteoporosis -- can lead to a disabling hip bone fractures. Widely used in Europe, hip protectors are less popular in North America, though, several studies have suggested they can prevent bone fractures and save medical costs although other studies have disputed these claims.