Bone Quality: Getting Closer to a Definition
Bone Quality: Getting Closer to a Definition
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骨质量：更接近定义
DOI：
--
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发表时间：
2002
影响因子：
6.2
通讯作者：
N. Watts
中科院分区：
文献类型：
--
作者：
N. Watts
A GENTLEMAN CAME OUT of a nightclub and encountered a drunk on his hands and knees. When asked what he was doing, the drunk replied, “I’m looking for my car keys.” The gentleman looked for a while, but soon was certain that the car keys were not there. When the drunk was asked why he was looking in that spot, he pointed to the street lamp overhead and said, “Because I can see over here. I think I dropped the keys on the other side of the street, but it’s dark over there.” Until about 10 years ago, osteoporosis was defined as a reduced amount of bone that was qualitatively normal (as opposed to osteomalacia, in which the bone was qualitatively abnormal). We now have accurate and precise ways to measure bone mass at a variety of skeletal sites. Bone mass measurement has become the “gold standard” for the prefracture diagnosis of osteoporosis. In untreated patients, there is an almost linear correlation between bone density and bone strength (based on biomechanical testing). In older women, reduced bone mineral density (BMD) is associated with a high risk of fragility fracture. We know that the drugs used to treat osteoporosis increase bone mass and reduce fracture risk. It seemed logical to assume that the mechanism by which they reduce the risk for fracture is through increases in bone density. However, we now know that bone density does not tell the whole story. In untreated subjects with the same BMD, fracture risk varies with age and perhaps with gender and race. Patients treated with agents that produce different effects on BMD at different skeletal sites have similar reductions in fracture at those sites; alendronate has little effect on BMD in the forearm, a somewhat greater effect in the hip, and the largest effect in the spine (Fracture Intervention Trial [FIT]-1) and yet reduces the risk of fractures by 50% at all three sites. Agents that have different effects on BMD in the spine (e.g., calcitonin, raloxifene, and bisphosphonates) or different doses of the same agent that produce different effects on BMD (e.g., parathyroid hormone [PTH]) reduce the risk of vertebral fractures to a similar degree. The reduction in the risk of fracture is seen soon after treatment is begun, well before change in BMD has reached its maximum. Patients receiving the same drug but have different effects on BMD may have similar reductions in fractures. A 1991 consensus conference produced a new definition of osteoporosis: “a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration with a consequent increase in bone fragility with susceptibility to fracture.” To paraphrase this definition, osteoporosis is a disorder of bone quantity and bone quality. Although it has been 10 years since this “new” definition of osteoporosis, the definition of bone quality remains elusive. Patients who have already had one or more fractures have a much higher risk of future fracture than patients with similar BMD but who have not had a fracture, even after adjusting for other risk factors. The presence of a fracture might be considered a “field test” for poor quality. Is it possible to assess bone quality before the first fracture occurs? Dr. Watts serves as a consultant for Aventis, Eli Lilly, Merck, Novartis, and Procter and Gamble Pharmaceuticals. He has also received research support from Procter and Gamble Pharmaceuticals. In addition, Dr. Watts received honoraria for speaking from Aventis, Eli Lilly, Merck, Novartis, and Procter and Gamble Pharmaceuticals.
影响因子：
15.9
作者：
HUI, SL;SLEMENDA, CW;JOHNSTON, CC
通讯作者：
JOHNSTON, CC