Brånemark R, Ohrnell L O, Nilsson P, Thomsen P
The Institute for Applied Biotechnology, Department of Orthopaedics, Sahlgren Hospital, Göteborg University, Sweden.
Biomaterials. 1997 Jul;18(14):969-78. doi: 10.1016/s0142-9612(97)00018-5.
This study reports torsion tests and pull-out tests on osseointegrated commercially pure titanium fixtures. The tests were performed in vivo on a total of 26 rats. Three fixtures with a diameter of 2.0 mm were installed bilaterally in the proximal tibia in each animal. The mechanical testing was performed immediately after installation, after 2, 4, 8 and 16 weeks of unloaded healing. The torsional strength started to increase after 4 weeks of unloaded healing and there was a significant increase with time during the initial 16 weeks. The pull-out load increased rapidly during the first 4 weeks; thereafter, a moderate increase occurred during the following 12 weeks. A histological evaluation was performed after 0, 4, 8 and 16 weeks. There were significant (P < 0.01) correlations between torque and percentage of bone in contact with the fixture, and between pull-out load and the bone thickness around the fixture (P < 0.001). Estimations of shear stresses and shear moduli in the bone tissue (pull-out test) and at the interface (torque test) indicated that the increase in bone volume around the implant substantially improved the mechanical capacity.
本研究报告了对骨整合的商业纯钛固定装置进行的扭转试验和拔出试验。试验在总共26只大鼠体内进行。在每只动物的近端胫骨双侧安装三个直径为2.0毫米的固定装置。在安装后、无负载愈合2周、4周、8周和16周后立即进行力学测试。无负载愈合4周后扭转强度开始增加，在最初的16周内随时间显著增加。拔出载荷在最初4周内迅速增加；此后，在接下来的12周内有适度增加。在0周、4周、8周和16周后进行组织学评估。扭矩与与固定装置接触的骨百分比之间以及拔出载荷与固定装置周围骨厚度之间存在显著（P < 0.01）相关性（P < 0.001）。对骨组织（拔出试验）和界面（扭矩试验）中的剪应力和剪切模量的估计表明，植入物周围骨体积的增加显著提高了力学性能。
