男女性在腰椎骨分佈及其老化時變動之差異

Abstract

骨密度測量可有效預測日後發生骨折 之風險。目前脊椎骨之骨密度測量，一般 是以正面方式測量，測量之部位包括脊椎 體(vertebral body, VB)及其後方之脊突等 (posterior segment, PS)，唯脊椎骨之骨質疏 鬆壓迫性骨折，幾全發生在VB 。若VB 與PS 之骨量分佈產生變異，正面測量只能 測得總量(VB 與PS 之和)將降低其預測骨 折風險之能力。本研究以側面測量方式， 分別測量VB 與PS 之骨量，在65 位男性 及112 女性觀察年齡、停經及性別對VB 佔骨總量比率之影響。結果顯示在停經年 齡前，女性之比率(mean±SEM: 39.1±0.9%) 較同齡男性(50.0±1.7%)為低(p<0.0001)。在 停經年齡之後，女性隨老化VB 佔總骨量 之比率逐年減少(每年0.22%, p=0.0001)， 但在男性則與年輕時無異。此外，本研究 也顯示總骨量在男性均隨年齡減少，但各 年齡層之男性均較女性為多。是以女性在 總骨量己較男性為少之狀況下，在停經後 因VB 內之海綿骨較多，損耗較快，反而 有更低之VB 所佔總量比率，不利於抗壓 之需求。此因素應是停後女性易有壓迫性 骨折之原因之一。此外，因男女性之骨量 分佈狀況不同，以傳統正面方式測量骨密 度時，宜考量性別及年齡因素，才能準確 評估脊椎體壓迫性骨折之風險。

Compression fractures occur mainly at the vertebral body. Variations in the distribution of bone mass in a vertebra, if undefined, may bias the ability of the acquired bone mineral density values, which was usually measured posteroanteriorly, to predict the risk of fractures. To evaluate the effects of age and gender on the distribution of bone mineral content in the third lumbar vertebrae. We performed a cross sectional study on the distribution of bone mineral content in the third lumbar vertebrae. The bone mineral content of the whole L3 including the L3 vertebral body and the posterior segment was measured using a lateral approach with a dual energy x-ray absorptiometer on 177 healthy Taiwanese adults including 65 men, and 55 premenopausal and 57 postmenopausal women. The proportion of bone mineral content (BMC) in the vertebral body was significantly lower in premenopausal women than in age-matched men (39.1±0.9% vs. 50.0±1.7%, P< 0.0001). Furthermore, while postmenopausal women showed a decreased proportion of BMC in the vertebral body with increased age (about -0.0022 per year, p=0.0001), premenopausal women and men showed a sustained proportion. Thus, the proportion of BMC distributed in the body of L3 vertebrae was lower in women than in men. The discrepancy of this parameter between the genders was even larger with increased ages.