Hsu Jui-Ting, Chang Chih-Han, An Kai-Nan, Zobitz Mark E, Phimolsarnti Rapin, Hugate Ronald R, Lai Kuo-An
Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan 701, Republic of China.
Int Orthop. 2007 Aug;31(4):451-5. doi: 10.1007/s00264-006-0226-4. Epub 2006 Sep 1.
One of the major failure modes of cementless acetabular components is the loosening of the acetabular cup, which is mostly attributable to insufficient initial stability. A hemispherical cup with a porous coating which is inserted with press-fit fixation and secured with several screws is one of the most widely used approaches. Many studies have found that bone screws are very helpful aids for cup fixation, but the optimal surgical technique for inserting screws has not been clearly reported. In this study, hemispherical cups were fixed into blocks of foam bone with zero to three screws. The effects of three types of screw eccentricity (a 1-mm offset and angular eccentricities of 15 degrees and 25 degrees ) on the initial stability of the acetabular cup were evaluated. The experimental results indicate that increasing the number of screws enhances the cup stability in the case of ideal screwing (i.e., with no eccentricity). An angular eccentricity of 15 degrees did not affect the cup stability for fixation with one or two screws. However, the presence of 25 degrees of angular eccentricity significantly reduced the stability of the cup, while 1 mm of offset eccentricity produced an even greater impact.
非骨水泥型髋臼假体的主要失效模式之一是髋臼杯松动，这主要归因于初始稳定性不足。一种带有多孔涂层的半球形髋臼杯，通过压配固定插入并使用多枚螺钉固定，是应用最广泛的方法之一。许多研究发现，骨螺钉对髋臼杯的固定非常有帮助，但关于螺钉置入的最佳手术技术尚未有明确报道。在本研究中，将半球形髋臼杯用零至三枚螺钉固定到泡沫骨块中。评估了三种类型的螺钉偏心情况（1毫米的偏移和15度及25度的角度偏心）对髋臼杯初始稳定性的影响。实验结果表明，在理想拧入（即无偏心）的情况下，增加螺钉数量可提高髋臼杯的稳定性。对于用一枚或两枚螺钉固定，15度的角度偏心不影响髋臼杯的稳定性。然而，25度的角度偏心显著降低了髋臼杯的稳定性，而1毫米的偏移偏心产生的影响更大。
