BACKGROUND Long-term survival of hip implants is of increasing relevance due to the rising life expectancy. The biomechanical effect of strain shielding as a result of implant insertion may lead to bone resorption, thus increasing risk for implant loosening and periprosthetic fractures. Patient-specific quantification of strain shielding could assist orthopedic surgeons in choosing the biomechanically most appropriate prosthesis. METHODS Validated quantitative CT-based finite element models of five femurs in intact and implanted states were considered to propose a systematic algorithm for strain shielding quantification. Three different strain measures were investigated and the most appropriate measure for strain shielding quantification is recommended. It is used to demonstrate a practical femur-specific implant selection among three common designs. FINDINGS Strain shielding measures demonstrated similar trends in all Gruen zones except zone 1, where the volumetric strain measure differed from von-Mises and maximum principal strains. The volumetric strain measure is in better agreement with clinical bone resorption records. It is also consistent with the biological mechanism of bone remodeling so it is recommended for strain shielding quantification. Applying the strain shielding algorithm on three different implants for a specific femur suggests that the collared design is preferable. Such quantitative biomechanical input is valuable for practical patient specific implant selection. INTERPRETATION Volumetric strain should be considered for strain shielding examination. The presented methodology may potentially enable patient-specific pre-operative strain shielding evaluation so to minimize strain shielding. It should be further used in a longitudinal study so to correlate between strain shielding predictions and clinical bone resorption.

中文翻译：

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水泥骨髋关节植入物的应变屏蔽。

背景技术由于预期寿命的延长，髋关节植入物的长期存活与日俱增。植入物插入导致应变屏蔽的生物力学作用可能导致骨吸收，从而增加植入物松动和假体周围骨折的风险。针对患者的应变屏蔽量化可以帮助骨科医生选择生物力学最合适的假体。方法考虑验证的基于CT的完整和植入状态的五个股骨的有限元模型，提出了一种用于应变屏蔽量化的系统算法。研究了三种不同的应变措施，并建议了最适合应变屏蔽量化的措施。它用于演示三种常见设计中实用的股骨特异性植入物选择。结果应变屏蔽措施在所有Gruen区域都显示出相似的趋势，但区域1的体积应变措施不同于von-Mises和最大主应变。体积应变测量与临床骨吸收记录更好地吻合。它也与骨骼重塑的生物学机制一致，因此建议用于应变屏蔽量化。将应变屏蔽算法应用于特定股骨的三种不同植入物上表明，领状设计是更可取的。这种定量的生物力学输入对于实际的患者特定植入物选择是有价值的。解释应变屏蔽检查应考虑体积应变。所提出的方法可能潜在地使得能够进行针对患者的术前应变屏蔽评估，从而使应变屏蔽最小化。应该在纵向研究中进一步使用它，以便在应变屏蔽预测和临床骨吸收之间建立关联。