羟基磷灰石涂层钢板螺钉改善骨折稳定性的实验研究

目的　比较国产羟基磷灰石 (hydroxyapatite ,HA)涂层钢板螺钉与非涂层钢板螺钉在体负重情况下对骨折的内固定效果。方法　四孔钢板螺钉 2 4套 ,附加螺钉 60枚 ,对其中 12套钢板、30枚螺钉行HA等离子喷涂 ,其余的钢板、螺钉不喷。 12只成年杂种犬 ,每只犬的两侧肱骨线型骨折后分别以HA涂层钢板、螺钉或非涂层钢板、螺钉内固定 ,每只犬的右胫骨间隔 2cm交递置入HA涂层钉和非涂层钉共 5枚。按术后即刻、3、6周将犬分成 3组。处死后行组织学观察和生物力学测试。结果　组织学观察 :术后 3、6周组HA涂层均无明显降解 ,其与不锈钢基底结合良好 ,与骨组织结合紧密 ,3、6周组HA涂层钢板下都有不同程度的皮质骨上新生骨形成 ,该处未见明显的骨质疏松。相反非涂层钢板、螺钉与骨接触不紧密 ,其间有薄层纤维组织生长 ,钢板下可见不同程度的骨质疏松。力学测试 :3、6周组犬中HA涂层组的三点折弯强度及螺钉拔出强度均比非涂层组大。结论　国产HA涂层的钢板螺钉可增加骨折内固定的稳定性。

Improvement of stability of fracture healing with hydroxyapatite coated plate and pin: an in vivo short term experimental study

Objective This is a short term exerimental study for the evaluation of the internal fixation effect in weight bearing conditions with the use of two types of plants and pins, the uncoated and coated with domestic made hydroxyapatite (HA). Methods Twenty four pairs of plate and pins with 60 screws were made into two kinds:the one of plasma sprayed with HA and the other remained uncoated. 12 adult dogs were selected for the experimental study. Over the fracture line of the humeri of the animals, fixation was done on one side with the coated plates and pins and the other side with the uncoated plate and pins. Over the right tibia shaft, the coate screws and the uncoated ones were inserted alternatively in between distances of 2 cm and totally 5 screws of each kind were inserted. The dogs were scarificed in three groups: one immediately after surgery,and the orther two groups in 3 and 6 weeks after surgery. Histomorphological studies and biomechanics measurement was carried out. Results No degradation was found in the HA coated specimens. The integration of the interface between HA coating and the stainless steel substrate was solid and HA coating of the implant formed tight bonding with the surrounding bony tissue in different periods.The new bone formation beneath the coated plate was seen at 3 and 6 weeks and there was no obvious osteoporosis. Conversely, there were the crack and fibrous tissue between bone and uncoated plate and pin. Different degrees of osteoporotic bone beneath uncoated plate was observed. Biomechanical measurement showed the three points bend strength and extraction strength being higher in the HA coated groups compared with the uncoated ones at both 3 and 6 weeks after surgery. Conclusion HA-coated plates and pins improved the stability of internal fixation for fracture healing.