INTRODUCTION The majority of acetabular revisions can be performed with an uncemented, porous acetabular component with or without bone grafting. These are contained acetabular defects, with an intact acetabular rim (Paprosky type I and II). As defects of the medial wall of the acetabulum are a challenge situation revision surgery, we performed this biomechanical study on a pig pelvis model with contained acetabular defects to determine the size of medial wall defect at which the acetabular cup will have sufficient primary stability. MATERIALS AND METHODS In 24 pig pelvis models, different diameter of medial wall defects were created, followed by acetabular component placement. The acetabulum externally loaded, and the force at a level in which the acetabular component remains stable for each diameter of defect, or at which point the acetabular cup moves into the pelvis for >2 mm. RESULTS In the models with acetabular medial wall defects of 10 and 20 mm, 2 mm acetabular displacement occurred under a force between 1000 and 1500 N. In those with a medial wall defect of 25 mm, the force that caused acetabular instability was between 700 and 1000 N. In the models with 30 mm of medial wall defect all acetabular components were unstable under a force of 700 N. CONCLUSIONS According to our results, acetabular component should be stable if the defect of the medial wall of the acetabulum is less than 68% of the diameter of the acetabular component or if the uncovered surface area of the acetabular component is not greater than 27%, and the force <700 N. For a load of 1000 N, the medial wall defect should not exceed 45% of acetabular component diameter or 18% of uncovered acetabular component surface.

中文翻译：

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多孔杯髋关节翻修术中安全髋臼内侧壁缺损尺寸的测量。

简介 大多数髋臼翻修可以使用非骨水泥、多孔髋臼假体进行，有或没有植骨。这些包含髋臼缺损，具有完整的髋臼边缘（Paprosky I 型和 II 型）。由于髋臼内侧壁的缺损是一项具有挑战性的情况修复手术，我们对包含髋臼缺损的猪骨盆模型进行了这项生物力学研究，以确定髋臼杯具有足够初级稳定性的内侧壁缺损的大小。材料和方法 在 24 个猪骨盆模型中，创建不同直径的内侧壁缺损，然后放置髋臼假体。外部加载的髋臼，以及对于每个缺陷直径，髋臼组件保持稳定的水平的力，或此时髋臼杯移入骨盆 > 2 毫米。结果 在髋臼内侧壁缺损为 10 和 20 mm 的模型中，在 1000 和 1500 N 之间的力下发生 2 mm 的髋臼位移。在具有 25 mm 内侧壁缺损的模型中，导致髋臼不稳定的力在 700 和 1500 N 之间。 1000 N。在具有 30 mm 内侧壁缺损的模型中，所有髋臼假体在 700 N 的力下均不稳定。 结论 根据我们的结果，如果髋臼内侧壁缺损小于 68，则髋臼假体应该是稳定的髋臼假体直径的百分比，或者如果髋臼假体的未覆盖表面积不大于 27%，并且力 <700 N。对于 1000 N 的负载，