AutoRSA Research Group, Orthopeadic Research Unit Aarhus University Hospital, Aarhus.
Biomechanics and Imaging Group, Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
Acta Orthop. 2022 Mar 21;93:375-381. doi: 10.2340/17453674.2022.2253.
Dual-mobility hip arthroplasty utilizes a freely rotating polyethylene acetabular liner to protect against dislocation. As liner motion has not been confirmed in vivo, we undertook this using dynamic radiostereometry (RSA).
6 patients with Anatomical Dual Mobility acetabular components were included. Markers were implanted in the liners using a drill guide. Static RSA recordings and patient-reported outcome measures were obtained postoperatively and at 1-year follow-up. Dynamic RSA recordings were obtained at 1-year follow-up during passive hip movement: abduction/external rotation, adduction/internal rotation (modified FABER-FADIR), to end-range and at 45° hip flexion. Liner and neck movements were described as anteversion, inclination, and rotation.
Liner movement during modified FABER-FADIR was detected in 12 of 16 patients. Median (range) absolute liner movements were: anteversion 10° (5-20), inclination 6° (2-12), and rotation 11° (5-48) relative to the cup. Median absolute change in the resulting liner/neck angle (small articulation) was 28° (12-46) and in liner/cup angle (larger articulation) was 6° (4-21). Static RSA showed changes in median liner anteversion from 7° (-12 to 23) postoperatively to 10° (-3 to 16) at 1-year follow-up and inclination from 42° (35-66) postoperatively to 59° (46-80) at 1-year follow-up. Liner/neck contact was associated with high initial liner anteversion (p = 0.01).
The polyethylene liner moves over time. 1 year after surgery the liner can move with or without liner/neck contact. The majority of movement is in the smaller articulation between head and liner.
双动髋关节置换术采用可自由旋转的聚乙烯髋臼内衬来防止脱位。由于尚未在体内确认内衬运动，我们使用动态放射立体测量术（RSA）对此进行了研究。
纳入 6 例使用解剖型双动髋臼组件的患者。使用钻头导向器将标记物植入衬垫中。术后和 1 年随访时获得静态 RSA 记录和患者报告的结果测量值。在 1 年随访时，在被动髋关节运动期间（外展/外旋、内收/内旋（改良 FABER-FADIR）、至极限位置和 45°髋关节屈曲）进行动态 RSA 记录。描述衬垫和颈部的运动为前倾角、倾斜角和旋转角。
在 16 例患者中的 12 例中检测到改良 FABER-FADIR 期间的衬垫运动。衬垫的绝对运动中位数（范围）为：前倾角 10°（5-20），倾斜角 6°（2-12），相对于髋臼的旋转角 11°（5-48）。衬垫/颈角度（小关节）的平均绝对变化为 28°（12-46），衬垫/杯角度（大关节）为 6°（4-21）。静态 RSA 显示，术后中位衬垫前倾角从 7°（-12 至 23）变为 1 年随访时的 10°（-3 至 16），术后倾斜角从 42°（35-66）变为 1 年随访时的 59°（46-80）。衬垫/颈接触与初始衬垫前倾角较高有关（p=0.01）。
聚乙烯衬垫会随时间移动。手术后 1 年，衬垫可能会移动，也可能不会与衬垫/颈接触。大部分运动发生在头与衬垫之间的小关节中。
