CNRS, Université Paris Diderot, Laboratoire de Biomécanique Biomatériau Ostéo Articulaire, UMR CNRS 7052, 10 avenue de Verdun, Paris, 75010, France.
J Mech Behav Biomed Mater. 2012 Apr;8:194-203. doi: 10.1016/j.jmbbm.2011.12.012. Epub 2012 Jan 2.
Endosseous cementless implants are widely used in orthopaedic, maxillofacial and oral surgery. However, failures are still observed and remain difficult to anticipate as remodelling phenomena at the bone-implant interface are poorly understood. The assessment of the biomechanical strength of the bone-implant interface may improve the understanding of the osseointegration process. An experimental approach based on a mode III cleavage mechanical device aims at understanding the behaviour of a planar bone-implant interface submitted to torsional loading. To do so, coin-shaped titanium implants were inserted on the tibiae of a New Zealand white rabbit for seven weeks. After the sacrifice, mode III cleavage experiments were performed on bone samples. An analytical model was developed to understand the debonding process of the bone-implant interface. The model allowed to assess the values of different parameters related to bone tissue at the vicinity of the implant with the additional assumption that bone adhesion occurs over around 70% of the implant surface, which is confirmed by microscopy images. The approach allows to estimate different quantities related to the bone-implant interface such as: torsional stiffness (around 20.5 N m rad(-1)), shear modulus (around 240 MPa), maximal torsional loading (around 0.056 N.m), mode III fracture energy (around 77.5 N m(-1)) and stress intensity factor (0.27 MPa m(1/2)). This study paves the way for the use of mode III cleavage testing for the investigation of torsional loading strength of the bone-implant interface, which might help for the development and optimization of implant biomaterial, surface treatment and medical treatment investigations.
骨内非骨水泥植入物广泛应用于矫形、颌面和口腔外科。然而，仍然观察到失败，并且由于对骨-植入物界面的重塑现象了解甚少，因此仍然难以预测。评估骨-植入物界面的生物力学强度可能有助于更好地了解骨整合过程。一种基于 III 型劈裂力学装置的实验方法旨在了解承受扭转载荷的平面骨-植入物界面的行为。为此，将硬币形钛植入物插入新西兰白兔的胫骨中 7 周。牺牲后，对骨样本进行 III 型劈裂实验。开发了一个分析模型来理解骨-植入物界面的脱粘过程。该模型允许评估与植入物附近骨组织相关的不同参数的值，假设骨粘附发生在植入物表面的约 70%左右，这通过显微镜图像得到了证实。该方法允许估计与骨-植入物界面相关的不同数量，例如：扭转刚度（约 20.5 N m rad(-1))、剪切模量（约 240 MPa)、最大扭转加载（约 0.056 N.m)、III 型断裂能（约 77.5 N m(-1)) 和应力强度因子（0.27 MPa m(1/2))。这项研究为 III 型劈裂测试在研究骨-植入物界面扭转强度方面的应用铺平了道路，这可能有助于植入物生物材料、表面处理和医学治疗研究的开发和优化。
