骨质疏松性骨折愈合过程中Ⅰ,Ⅱ型胶原蛋白表达与其力学性能

Correlations between type Ⅰ and Ⅱ collagen expressions and mechanical strength in osteoporotic fracture healing

背景:研究显示骨质疏松症是涉及Ⅰ型胶原数量及理化性质改变的一种复杂病理生理过程,但有关骨质疏松与Ⅰ,Ⅱ型胶原间的相关性,至今少有报道。目的:观察骨质疏松性骨折愈合中Ⅰ,Ⅱ型胶原蛋白表达的变化规律,及其与生物力学性能的相关性。方法:将大鼠随机分为骨质疏松性骨折组与一般性骨折组。骨质疏松性骨折组切除卵巢建立骨质疏松模型。分别于骨折损伤后1,2,4,5,8,12周采用Western blot方法检测骨痂中Ⅰ,Ⅱ型胶原的蛋白表达,于损伤后4,8,12,16周进行骨密度测定与生物力学性能测试。结果与结论:骨质疏松性骨折组Ⅰ,Ⅱ型胶原的表达及骨密度值在损伤后各时间点与一般性骨折组相比均差异有显著性意义(P<0.05),且随着损伤时间的延长,下降趋势更明显。骨质疏松性骨折组中Ⅰ,Ⅱ型胶原与最大转矩、弹性模量、最大扭转角均有相关性(P<0.05)。结果显示,骨质疏松性骨折愈合过程中Ⅰ,Ⅱ型胶原的分泌异常改变导致了其力学强度乃至骨折愈合质量的降低,影响骨折愈合,是再次骨折发生的主要原因。

BACKGROUND：Studies have demonstrated that osteoporosis is a complex pathophysiological process involves changes of type Ⅰ collagen number and physical or chemical properties.However,reports addressing correlations between type Ⅰ and Ⅱ collagen expression are few.OBJECTIVE：To disclose the change rules of type Ⅰ and Ⅱ collagen protein during osteoporotic fracture healing in rats and the correlation of them with mechanical strength.METHODS：Rats were randomly divided into osteoporotic fracture and general fracture groups.Rats in the former group received ovariectomy.The expressions of type Ⅰ,Ⅱ collagen were observed by Western blot at 1,2,4,5,8 and 12 weeks.The bonemineral density was examined by dual-energy X-ray absorptiometry,and biomechanical testing were performed at 4,8,12 and 16 weeks postoperatively.RESULTS AND CONCLUSION：There were significant differences between the osteoporotic fracture group and general fracture group in type Ⅰ and Ⅱ collagen expression and bonemineral density at different time points after injury （P0.05）.With the injury time prolonged,the downward trend was more obviously.The type Ⅰ and Ⅱ collagen were correlated with maximum torque,elastic modulus,and maximum torsion angle in the osteoporotic fracture group （P0.05）.The results showed that abnormal secretion of type Ⅰ and Ⅱ collagen osteoporotic fracture healing decreases mechanical strength and reduce the quality of fracture healing,which is the main reason for re-fracture.