THE EFFECT OF CONFORMITY, THICKNESS, AND MATERIAL ON STRESSES IN ULTRAHIGH MOLECULAR-WEIGHT COMPONENTS FOR TOTAL JOINT REPLACEMENT
THE EFFECT OF CONFORMITY, THICKNESS, AND MATERIAL ON STRESSES IN ULTRAHIGH MOLECULAR-WEIGHT COMPONENTS FOR TOTAL JOINT REPLACEMENT
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DOI：
10.2106/00004623-198668070-00010
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发表时间：
1986-09-01
影响因子：
5.3
通讯作者：
WRIGHT, TM
中科院分区：
文献类型：
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作者：
BARTEL, DL;BICKNELL, VL;WRIGHT, TM
全关节置换术的聚乙烯部件表面损坏导致的碎屑先前已被证明会导致长期问题，如松动和感染。表面损伤与这些假体中金属和聚乙烯部件之间接触产生的应力引起的疲劳过程相关。在本研究中，我们使用弹性和有限元解来确定这些应力从头部直径为22和28毫米的全髋关节置换术和髁全膝关节置换术。我们还研究了使用碳纤维增强聚乙烯代替普通聚乙烯的这些应力的影响。与全膝关节置换术中胫骨部件表面损伤相关的应力远大于髋关节置换术中的应力。接触应力与胫骨部件聚乙烯衬垫厚度的函数关系分析表明，在可能的情况下，厚度应保持在8 - 10 mm以上。当关节面在内外侧方向上更加贴合时，胫骨部件中的接触应力降低最多。接触应力对前后方向的几何形状变化不太敏感。对于髋关节部件，28 mm置换的髋臼部件的应力较低。使用碳纤维增强聚乙烯导致应力高出40%。由于关节面之间的接触区域在屈曲过程中发生移动，部分表面将承受循环应力。膝关节屈曲置换的接触面积小于髋关节置换，最大主应力的范围较大。因此，与髋臼部件相比，胫骨部件中较高应力和移动接触面积的组合更可能因疲劳而导致表面损坏，这与临床观察结果一致。临床相关性：本研究为选择当代全髋关节和膝关节置换术提供了重要指南。例如，当可以选择时，应选择在内外侧方向上最贴合的膝关节置换术，以最大限度地降低表面损伤的风险。同样，当使用28 mm股骨头代替22 mm股骨头时，全髋关节置换术中表面损伤的风险也会降低。在可能的情况下，膝关节置换用胫骨部件中聚乙烯层的厚度应至少为8 - 10 mm。碳纤维增强聚乙烯不应用于全关节置换术中的关节部件。
Debris resulting from damage to the surface of polyethylene components of total joint replacements has previously been shown to contribute to long-term problems such as loosening and infection. Surface damage has been associated with fatigue processes due to stresses arising from contact between the metal and polyethylene components in these prostheses. In the present study, we used elasticity and finite-element solutions to determine these stresses from total hip replacements with head diameters of twenty-two and twenty-eight millimeters and for a condylar total knee replacement. We also examined the effect of these stresses of using carbon-fiber-reinforced polyethylene instead of plain polyethylene. Stresses associated with surface damage in the tibial component of the total knee replacement were much larger than those in the hip replacements. The analysis of contact stress as a function of thickness of the polyethylene insert for tibial components showed that a thickness of more than eight to ten millimeters should be maintained when possible. The contact stress in the tibial components was reduced most when the articulating surfaces were more conforming in the medial-lateral direction. Contact stresses were much less sensitive to changes in geometry in the anterior-posterior direction. For the hip components, the stresses were lower in the acetabular component of the twenty-eight-millimeter replacement. The use of carbon-fiber-reinforced polyethylene results in stresses that were higher by as much as 40 per cent. Because the contact area between articulating surfaces moves during flexion, portions of the surface will be subjected to cyclic stresses. The contact area for the knee replacements of flexion was smaller than for the hip replacements, and the range of the maximum principal stress was larger. Consequently, the combination of the higher stress and the moving contact area is more likely to cause surface damage due to fatigue in tibial components than in acetabular components, which is consistent with clinical observations. CLINICAL RELEVANCE: This study provides important guidelines for making choices between contemporary total hip and knee replacements. For example, when a choice is possible, the knee replacement that is most conforming in the medial-lateral direction should be chosen to minimize the risk of surface damage. Similarly, the risk of surface damage in total hip replacements should be less when a twenty-eight-millimeter head is used instead of a twenty-two-millimeter head. Whenever possible, the thickness of the polyethylene layer in tibial components for knee replacements should be at least eight to ten millimeters. Carbon-fiber-reinforced polyethylene should not be used for articulating components in total joint replacements.