Geesink R G, de Groot K, Klein C P
Department of Orthopaedic Surgery, State University of Limburg, Maastricht, The Netherlands.
Clin Orthop Relat Res. 1987 Dec(225):147-70.
Sintered hydroxyl-apatite implants form very tight bonds with living bone but are susceptible to fatigue failure. Plasma-sprayed apatite coatings on titanium substrates overcome the fatigue problem. The static tensile substrate bond strength of the apatite coating is in excess of 85 megapascals (MPa) (12,000 psi). In a plug implant study designed to discount mechanical retention, a bone bonding shear strength of 64 MPa (9280 psi) was achieved, comparable to the strength of cortical bone. Histologic sections confirm the close bonding between apatite coating and living bone. In a canine total hip arthroplasty study, the apatite-coated implants proved far superior to the uncoated controls. Uncoated prostheses were surrounded by fibrous tissue and were easily extracted from the femur at any postoperative time. The apatite-coated implants were rigidly fixed within three weeks with demonstrable bone formation up to the implant surface. Bony defects up to 2 mm in depth were filled with bone within six weeks. The hypothetical mechanism of bone bonding is chemical. Hydroxyl-apatite coatings permit an implant fixation far superior to current methods using either cemented or cementless techniques. The plan is to study a human total hip prosthesis with hydroxyl-apatite coating for chemical fixation to bone.
烧结羟基磷灰石植入物与活骨形成非常紧密的结合，但易发生疲劳失效。钛基体上的等离子喷涂磷灰石涂层克服了疲劳问题。磷灰石涂层与基体的静态拉伸结合强度超过85兆帕（MPa）（12,000磅力/平方英寸）。在一项旨在排除机械固位作用的植入栓研究中，实现了64兆帕（9280磅力/平方英寸）的骨结合剪切强度，与皮质骨强度相当。组织学切片证实了磷灰石涂层与活骨之间的紧密结合。在一项犬全髋关节置换研究中，磷灰石涂层植入物被证明远优于未涂层的对照物。未涂层的假体被纤维组织包围，在术后任何时间都很容易从股骨中取出。磷灰石涂层植入物在三周内牢固固定，直至植入物表面有明显的骨形成。深度达2毫米的骨缺损在六周内被骨填充。骨结合的假设机制是化学性的。羟基磷灰石涂层允许植入物固定，其效果远优于目前使用骨水泥或非骨水泥技术的方法。计划研究一种用于骨化学固定的带羟基磷灰石涂层的人工全髋关节假体。
