Instability and dislocation remain leading indications for revision of total hip arthroplasty (THA). Many studies have addressed the links between implant design and dislocation; however, an understanding of the impact of alignment and kinematic variability on constraint of modern THA constructs to provide joint stability is needed. The objective of this study is to provide objective data to be considered in the treatment algorithm to protect against joint instability. Joint contact and muscle forces were evaluated using musculoskeletal models of THA patients performing activities consistent with posterior and anterior dislocation. Position and joint loads were transferred to a finite element simulation with an experimentally calibrated hip capsule representation, where they were kinematically extrapolated until impingement and eventual dislocation. Cup anteversion and inclination were varied according to clinical measurements, and variation in imposed kinematics was included. The resistive moment provided by the contact force and joint capsule, and overall dislocation rate (dislocations/total simulations) were determined with neutral and lipped acetabular liners. Use of a lipped liner did increase the resistive moment in posterior dislocation, by an average of 5.2 Nm, and the flexion angle at dislocation by 1.4° compared to a neutral liner. There was a reduction in similar magnitude in resistance to anterior dislocation. Increased cup anteversion and inclination, hip abduction and internal rotation all reduced the occurrence of posterior dislocation but increased anterior dislocation. A quantitative understanding of tradeoffs in the dislocation risk inherent to THA construct options is valuable in supporting surgical decision making.

中文翻译：

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对准和运动学变化对带有唇线和中性线衬的THA的电阻矩和位错倾向的影响。

不稳定和脱位仍然是全髋关节置换术（THA）修订的主要指征。许多研究已经解决了种植体设计与脱位之间的联系。但是，需要了解对齐方式和运动学可变性对现代THA构造的约束以提供关节稳定性的影响。本研究的目的是提供治疗算法中要考虑的客观数据，以防止关节不稳。使用THA患者的肌肉骨骼模型评估关节接触和肌肉力量，其活动与前后脱位一致。将位置和关节负荷转移到具有经过实验校准的髋关节囊表征的有限元模拟中，在运动学上推断它们，直到撞击和最终脱臼。杯的前倾角和倾角根据临床测量而变化，并且包括运动学变化。由接触力和关节囊提供的阻力力矩以及总的脱位率（脱位/总模拟）由中性和唇状髋臼内衬确定。与中性衬管相比，使用唇形衬管确实使后脱位的阻力增加了平均5.2 Nm，并使脱位时的弯曲角度增加了1.4°。对前脱位的抵抗力下降了相似的幅度。杯前倾角和倾斜度增加，髋关节外展和内旋都减少了后脱位的发生，但增加了前脱位。