CLINICAL USE OF HYDRAULIC PROPERTY OF HYDROXYAPATITE THERMAL DECOMPOSITION PRODUCT

羟基磷灰石热产物通过与水溶液(HAP水泥)混合而硬化。硬化后，HAP水泥又变成纯净的羟基磷灰石。对这种新型生物材料在去卵巢大鼠股骨中的亲和力、机械强度、生物安全性和组织学反应进行了研究。(1)将HAP骨水泥注入28只兔股骨。注射后2周、4周、9周和12周的X-射线衍射分析表明，注射后的分解产物为固体纯羟基磷灰石。组织学检查显示，注射后两周以上，新生骨形成与HAP骨水泥表面直接接触。羟基磷灰石水泥对骨具有良好的亲和力。(2)将羟基磷灰石骨水泥植入兔股骨，分别于注射后3d、1周、4周、8周测定其机械强度。从注射部位切开的股骨的压缩试验表明，硬化的羟基磷灰石水泥在压缩…下不会断裂。更大的离子作用力可达50 Mpa，相当于PMMA的70%。在抗挤试验中，HAP水泥的强度高于PMMA水泥。(3)考察了HAP水泥的生物安全性。在急性试验中，将从保存在盐水中的HAP水泥中提取的水注入大鼠静脉。未见急性毒性反应。在亚急性实验中，将羟基磷灰石水泥植入大鼠的皮下、腹膜和肌肉组织中。这些大鼠在注射后一周、两周和四周被处死。一般情况、血液检查和组织学检查均未显示HAP水泥的亚急性毒性。在慢性实验中，18只兔注射羟基磷灰石骨水泥，方法与(1)相同。一半的兔子被处死，26只，半52周。实验项目与亚急性实验相同，说明HAP骨水泥无慢性毒性。(4)将HAP骨水泥注入去卵巢大鼠股骨(骨质疏松大鼠模型)。注射后8周以上，注射部位可见新骨形成，而对照组为4周。但即使在去卵巢的大鼠，新骨形成的面积也逐渐增加。提示HAP骨水泥也具有良好的骨传导性，有望作为生物活性骨水泥成功应用于临床。较少

Hydroxyapatite thermal product was hardened by mixing with water solution (HAp cement). After hardening, HAp cement became pure hydroxyapatite again. This new biomaterial was investigated with respect to (1)affinity to bone, (2)mechanical strength, (3)biological safety, and (4)histological reaction in the ovariectomized rat's femur.(1)HAp cement was injected into the femora of twenty-eight rabbits. The injected decomposition product was confirmed to be solid and pure HAp by X-ray diffraction of two, four, nine and twelve weeks after injection. Histological examination revealed new bone formation in direct contact with the surface of HAp cement more than two weeks after injection. HAp cement apparently has a good affinity to bone.(2)The mechanical strength of HAp cement was measured three days, one, and four, and eight weeks after injection into the femur of rabbits. A compression test with femur cut from the injected site revealed that hardened HAp cement did not break under a compress … More ion force up to 50MPa; that strength was corresponds to 70% of PMMA. HAp cement was stronger than PMMA cement in the case of a push-out test. (3)We investigated the biological safety of HAp cement. In the Acute test, water extracted from HAp cement preserved in a saline water was injected into the vein of rats. No acute toxicity was seen. in the Subacute test, HAp cement was inserted into the subcutaneous, intraperitoneal, and intramuscular tissues of rats. Those rats were sacrificed one, two, and four weeks after injection. General state, blood examination, and histological inspection didn't indicate subacute toxicity of HAp cement. In the Chronic test, HAp cement was injected into eighteen rabbits using the same method as (1). Half the rabbits were sacrificed twenty-six and half fifty-two weeks. The items investigated were the same as in the subacute test, and it was revealed that HAP cement has no chronic toxicity.(4)HAp cement was injected into the femur of ovariectomized rats (an osteoporotic model in rats). New bone formation was seen at the injected site more than eight weeks after injection, in contrast to four weeks in the control rats. But even in the ovariectmized rats, the area of new bone formation increased gradually. That indicated HAp cement also has a good osteoconductility.It is expected that HAp cement can be successfully applied clinically as a bioactive bone cement. Less