Background and objective

Total hip arthroplasty is known as one of the best advancements in orthopedics in the 20th century. Due to age or trauma hip joint has to replace by an artificial implant. After the hip arthroplasty, the patients can return to normal day-to-day activities with a normal range of motion. There are several types and designs are currently available. These designs usually depend upon the anatomy of the patients. There is a need for revision surgery due to dislocation and aseptic loosening in these joints over time in actively younger patients. Minor changes in the design stage can certainly improve the life expectancy of the implant and will also further reduce the revision rate.

Methods

In this current work, finite element analysis is carried out by varying the neck length with a change in femoral head size for a circular-shaped stem. The effects of using a shorter neck are analyzed. A total of nine combinations are considered for analysis. Modeling is carried out in CATIA V-6 and analysis is performed in ANSYS R-19. A femoral head of 36, 40, and 44 mm and taper neck length of 18, 16, and 14 mm is considered. CoPE is considered as the material combination for all the models.

Results

It was observed that the von Mises stresses in the complete implant tend to decrease with an increase in the femoral head size. Maximum 5% variation in stress values when 36 mm femoral head is compared with 44 mm. The stresses in the taper neck region tend to decrease with a decrease in the neck length. Minimum von Mises stress of 161.83 MPa was found for the complete implant and in the head-neck region, a minimum von Mises stress found 91.9 MPa.

Conclusions

Performance evaluation of hip implant under static loading conditions gives a clear idea about the behavior of implant. It was found that a decrease in the von Mises stresses with a decrease in the taper length. However, these variations won't affect much in the performance of the hip implant. Also, a reduction in taper length can significantly increase the dislocation in the implant. So it is advised to consider the optimal taper length with an increase in the femoral head size.

中文翻译：

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不同锥颈长度的髋关节假体在静态载荷条件下的有限元分析

背景和目的

全髋关节置换术被称为 20 世纪骨科的最佳进步之一。由于年龄或外伤，髋关节必须由人工植入物代替。髋关节置换术后，患者可以以正常的运动范围恢复正常的日常活动。目前有多种类型和设计可供选择。这些设计通常取决于患者的解剖结构。由于活动较年轻的患者随着时间的推移，这些关节会出现脱位和无菌性松动，因此需要进行翻修手术。设计阶段的微小变化肯定可以提高种植体的预期寿命，也会进一步降低翻修率。

方法

在目前的工作中，通过改变圆形柄的股骨头尺寸改变颈部长度来进行有限元分析。分析了使用较短颈部的效果。总共考虑九种组合进行分析。建模在 CATIA V-6 中进行，分析在 ANSYS R-19 中进行。考虑了 36、40 和 44 毫米的股骨头和 18、16 和 14 毫米的锥形颈长度。CoPE 被视为所有模型的材料组合。

结果

据观察，随着股骨头尺寸的增加，整个种植体中的 von Mises 应力趋于降低。36 mm 股骨头与 44 mm 股骨头相比，应力值的最大变化为 5%。锥形颈部区域中的应力倾向于随着颈部长度的减小而减小。发现完整种植体的最小 von Mises 应力为 161.83 MPa，而在头颈部区域，发现最小 von Mises 应力为 91.9 MPa。

结论

在静态负载条件下对髋关节植入物的性能评估给出了关于植入物行为的清晰概念。发现随着锥度长度的减小，von Mises 应力减小。然而，这些变化不会对髋关节植入物的性能产生太大影响。此外，锥形长度的减少会显着增加植入物中的位错。因此，建议随着股骨头尺寸的增加，考虑最佳锥度长度。