MacKenzie J R, Callaghan J J, Pedersen D R, Brown T D
Department of Orthopaedic Surgery, University of Iowa, Iowa City 52242.
Clin Orthop Relat Res. 1994 Jan(298):127-36.
Contact between porous surfaces and bone and initial stable fixation of the implant to bone are required to achieve bone ingrowth into prosthetic devices. To avoid the potential problems associated with screws that are often used to obtain initial stability of uncemented acetabular components, oversizing of the component has been recommended. This study investigated the shape of the reamed surface compared with the acetabular reamers used, the areas of bone implant contact obtained with oversizing, and the extent of polar area gaps created by this surgical technique. In embalmed hemipelvises, using surface fitting algorithms, the average departure from sphericity, of the reamed acetabular surface, was 0.56 mm. Using Pressensor film, extensive peripheral cup contact but minimal polar area contact was demonstrated when oversizing the components. In addition, large polar area gaps were demonstrated using polyvinylsiloxane epoxy molds. This study confirms the potential concerns associated with oversizing the acetabular component in relation to the reamed acetabular surface. Although excellent peripheral contact was obtained using this technique, polar area contact was demonstrated to be minimal or nonexistent, and large polar area gaps were observed. In addition, this study demonstrates that a precisely reamed surface can be obtained in the acetabulum when accurately sized reamers are used.
为实现骨长入假体装置，多孔表面与骨之间的接触以及植入物与骨的初始稳定固定是必需的。为避免与常用于获得非骨水泥髋臼部件初始稳定性的螺钉相关的潜在问题，建议增大部件尺寸。本研究调查了与所使用的髋臼扩孔钻相比扩孔表面的形状、增大尺寸后获得的骨植入物接触面积以及该手术技术造成的极区间隙程度。在防腐处理的半骨盆中，使用表面拟合算法，扩孔后的髋臼表面平均偏离球形度为0.56毫米。使用压力传感薄膜，增大部件尺寸时显示出广泛的髋臼杯周边接触但极区接触极少。此外，使用聚硅氧烷环氧树脂模具显示出大的极区间隙。本研究证实了与相对于扩孔后的髋臼表面增大髋臼部件尺寸相关的潜在问题。尽管使用该技术获得了良好的周边接触，但极区接触极少或不存在，并且观察到了大的极区间隙。此外，本研究表明，当使用尺寸精确的扩孔钻时，髋臼中可获得精确扩孔的表面。
