Abstract：
BACKGROUND: A mobile polyethylene liner enables the dual mobility cup (DMC) to contribute to restoring hip joint range-of-motion, decreasing wear and increasing implant stability. However, more data is required on how liner orientation changes with hip joint movement. As a first step towards better understanding liner orientation change in vivo, this cadaver study focuses on quantifying DMC liner orientation change after different hip passive movements, using ultrasound imaging and motion analysis.
OBJECTIVE: The liner does not always go back to its initial orientation and its final orientation depends mainly on hip movement amplitude.
METHODS: 3D ultrasound imaging and motion analysis were used to define liner and hip movements for four fresh post-mortem human subjects with six implanted DMC. Abduction and anteversion angles of the liner plane relative to the pelvis were measured before and after hip flexion, internal rotation, external rotation, abduction, adduction.
RESULTS: Liner orientation changes were generally defined by angle variation smaller than 5°, with the liner nearly going back to its initial orientation. However, hip flexion caused liner abduction and anteversion angle variations greater than 15°. Except for hip adduction, only weak or no correlation was found between the final angle of the liner and the maximal hip joint movement amplitude.
CONCLUSIONS: This study is the first attempt to quantify liner orientation change for implanted DMC via ultrasound imaging and constitutes a step forward in the understanding of liner orientation change and its relationship with hip joint movement. The hypothesis that the final liner abduction and anteversion angles depend mainly on hip movement amplitude was not confirmed, even if hip flexion was the movement generating the most liner orientation changes over 15°. This approach should be extended to in vivo clinical investigations, as measured liner angle variation could provide important support for the wear and stability claims made for DMC.
METHODS: IV; cadaveric study.
OBJECTIVE: The liner does not always go back to its initial orientation and its final orientation depends mainly on hip movement amplitude.
METHODS: 3D ultrasound imaging and motion analysis were used to define liner and hip movements for four fresh post-mortem human subjects with six implanted DMC. Abduction and anteversion angles of the liner plane relative to the pelvis were measured before and after hip flexion, internal rotation, external rotation, abduction, adduction.
RESULTS: Liner orientation changes were generally defined by angle variation smaller than 5°, with the liner nearly going back to its initial orientation. However, hip flexion caused liner abduction and anteversion angle variations greater than 15°. Except for hip adduction, only weak or no correlation was found between the final angle of the liner and the maximal hip joint movement amplitude.
CONCLUSIONS: This study is the first attempt to quantify liner orientation change for implanted DMC via ultrasound imaging and constitutes a step forward in the understanding of liner orientation change and its relationship with hip joint movement. The hypothesis that the final liner abduction and anteversion angles depend mainly on hip movement amplitude was not confirmed, even if hip flexion was the movement generating the most liner orientation changes over 15°. This approach should be extended to in vivo clinical investigations, as measured liner angle variation could provide important support for the wear and stability claims made for DMC.
METHODS: IV; cadaveric study.
摘要：
背景：移动式聚乙烯衬里使双活动杯（DMC）有助于恢复髋关节的活动范围，减少磨损和增加植入物的稳定性。然而,更多的数据是需要如何随着髋关节运动衬垫方向的变化。作为更好地理解体内衬里取向变化的第一步，这项尸体研究的重点是量化不同髋关节被动运动后的DMC衬里方向变化，使用超声成像和运动分析。
目的：衬垫并不总是回到其初始方向，其最终方向主要取决于髋部运动幅度。
方法：使用3D超声成像和运动分析来定义四名植入了DMC的新鲜死后人类受试者的衬里和髋部运动。测量髋部屈曲前后衬垫平面相对于骨盆的外展角度和前倾角度。内部旋转,外部旋转,绑架,诱导。
结果：衬板方向变化通常由小于5°的角度变化定义，班轮几乎回到了最初的方向。然而,髋部屈曲引起内胆外展和前倾角变化大于15°。除了髋关节内收,衬里的最终角度与最大髋关节运动幅度之间仅发现微弱或没有相关性。
结论：这项研究是首次尝试通过超声成像量化植入DMC的衬垫方位变化，并在理解衬垫方位变化及其与髋关节运动关系方面向前迈出了一步。最终的衬里外展和前倾角主要取决于髋部运动幅度的假设没有得到证实，即使髋部屈曲是产生最多的衬里方向变化超过15°的运动。这种方法应该扩展到体内临床研究，测量的衬角变化可以为DMC的磨损和稳定性声明提供重要支持。
方法：IV；尸体研究。
目的：衬垫并不总是回到其初始方向，其最终方向主要取决于髋部运动幅度。
方法：使用3D超声成像和运动分析来定义四名植入了DMC的新鲜死后人类受试者的衬里和髋部运动。测量髋部屈曲前后衬垫平面相对于骨盆的外展角度和前倾角度。内部旋转,外部旋转,绑架,诱导。
结果：衬板方向变化通常由小于5°的角度变化定义，班轮几乎回到了最初的方向。然而,髋部屈曲引起内胆外展和前倾角变化大于15°。除了髋关节内收,衬里的最终角度与最大髋关节运动幅度之间仅发现微弱或没有相关性。
结论：这项研究是首次尝试通过超声成像量化植入DMC的衬垫方位变化，并在理解衬垫方位变化及其与髋关节运动关系方面向前迈出了一步。最终的衬里外展和前倾角主要取决于髋部运动幅度的假设没有得到证实，即使髋部屈曲是产生最多的衬里方向变化超过15°的运动。这种方法应该扩展到体内临床研究，测量的衬角变化可以为DMC的磨损和稳定性声明提供重要支持。
方法：IV；尸体研究。
