Basic and Clinical Study on Artificial Vertebral Body and Artificial Intervertebral Disc.

1. 人工椎体（AVB）是一种新型的人工椎体。通过力学试验、耐久性试验和动物实验，证实了其安全性和实用性。采用该AVB进行腰椎转移性脊柱肿瘤的椎体置换手术。新AVB由五个部分组成。它们是内杆、外杆、环、垫圈和螺钉。应用于脊柱后，可以通过旋转环轻松改变AVB的高度。AVB的特别设计的钢板部分使用骨水泥固定在椎体的骨槽中。固定的机械稳定性优于常规方法。将特制犬用AVB应用于犬第4腰椎，用显微x线摄影评价其稳定性。术后4周在骨水泥和终板周围发现新形成的骨组织。还观察到厚度为40微米的薄纤维组织层。人颈椎的AVB也用于猴第四腰椎。术后6个月AVB固定稳定。AVB周围未发现金属粉末和离子释放。在耐久性试验中，AVB经过3000N的10万次垂直压缩试验和20Nm.2的10万次扭转试验均未发生断裂。人工椎间盘：我们采用松质螺钉将人工椎间盘与椎体固定。对不同型号的螺钉进行了拉拔试验，螺距为1.8mm、螺纹高度为1.5mm的螺钉的拉拔力最大。我们还使用钛网制作多孔材料。兔股骨有骨长入网孔，犬椎间盘无骨长入网孔。为了验证该AID的安全性和实用性，还需要进一步使用更大的动物进行实验。

1. Artificial vertebral body (AVB)We made a new AVB. The safety and practicality were confirmed by mechanical test,endurance test, and animal experiment. An operation of vertebral body replacement using this AVB was performed on metastatic spinal tumor of lumbar spine.The new AVB is composed of five parts. They are inner rod, outer rod,ring,washer, and screw. The height of the AVB can be easily changed by revolving the ring after application to the spinal column. The specially designed plate-portion of the AVB is fixed into the bony groove of the vertebra using bone cement. The mechanical stability of the fixation is better than those of conventional methods.Specially made AVB for dogs were applied to canine 4th lumbar vertebrae to evaluate the stability using microradiograph. Newly formed bone tissue was found around the bone cement and endplates at 4 weeks after surgery. A thin fibrous tissue layer of 40micrometer in thickness was also obserbed. AVB's for human cervical spine were also used for 4th lumbar vertebra of monkey. AVB fixation was stable after 6months from operation. No metal powder nor ion release was found aroud AVB.In the endurance test, the AVB was not broken after 100000 vertical compression test with 3000N and after 100000 torsional tests with 20Nm.2.Artificial intervertebral disc (AID)We made new AID using cancellous screws for fixation of itself to vertebral body. Pull out tests on various types of screw were done and the screw with 1.8mm in pitch and 1.5mm in thread height showed maximum pull out force. We also made porous material using titanium mesh. Bone ingrowth occured into the mesh in rabbit femur but it didn't occured in dog's intervertebral discs.To confirm the safety and practicality of this AID, further experiment using bigger animal is necessary.