Reilly D, Walker P S, Ben-Dov M, Ewald F C
Clin Orthop Relat Res. 1982 May(165):273-82.
Knee specimens were loaded in combinations of compression, anteroposterior force, rotational torque, and varus-valgus moment. The strains on the outer surface of the tibia at four levels were determined from strain gauges. Tibial components of the central peg type were cemented in place and the strains again measured for the same loading combinations, thus obtaining comparisons with the normal. Strain readings were also taken around the central pegs. The variables of the tibial components were all-plastic versus a metal tray; short, medium, and long post; and complete versus incomplete upper surface coverage. For varus-valgus or anteroposterior loading, there were high strains due to bending around the proximal part of the plastic stem compared with the metal stem; the metal stem carried a much higher bending moment than did the plastic stem. In direct loading, there was a rim of low-stressed bone around the proximal perimeter for incomplete contact, and a metal stem longer than the standard, transmitted some load directly to the cortex; a plastic stem carried only small axial loads, probably because of its low axial stiffness. Metal backing is not without disadvantages; notably, some load by-passing, cost, and comparatively difficult removal.
对膝关节标本施加压缩、前后向力、旋转扭矩和内外翻力矩的组合载荷。通过应变片测定胫骨四个水平外表面的应变。将中央栓柱型胫骨部件用骨水泥固定到位，并对相同的载荷组合再次测量应变，从而与正常情况进行比较。还在中央栓柱周围读取应变读数。胫骨部件的变量包括全塑料与金属托盘；短、中、长柱；以及上表面完全覆盖与不完全覆盖。对于内外翻或前后向加载，与金属柄相比，塑料柄近端周围弯曲导致的应变较高；金属柄承受的弯矩比塑料柄高得多。在直接加载时，对于不完全接触，近端周边存在一圈低应力骨，比标准长度更长的金属柄将一些载荷直接传递至皮质；塑料柄仅承受较小的轴向载荷，可能是因为其轴向刚度较低。金属背衬并非没有缺点；特别是存在一些载荷旁通、成本以及相对难以移除的问题。
