Department of Orthopaedics, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, J118-119, 8200, Aarhus, Denmark.
Department of Orthopaedics, Leiden University Medical Center, 2333, Leiden, ZA, The Netherlands.
Eur Radiol Exp. 2021 Dec 15;5(1):55. doi: 10.1186/s41747-021-00253-x.
Investigation of polyethylene liner movement in total hip arthroplasty requires bead-marking for radiographic visibility of the liner. However, occlusion of markers poses a challenge for marker registration in radiographs.
The polyethylene of a dual mobility acetabular system was marked with twelve 1-mm tantalum markers (four groups of three markers) using a custom-made drill guide. Liner motion in a phantom and a patient was investigated with dynamic radiostereometry analysis (dRSA) at 1-year follow-up and static radiostereometry analysis (sRSA) postoperatively and at 1- and 2-year follow-up. A combined marker configuration (CMC) model was calculated from the registered positions of the liner markers and the femoral head in several images. Furthermore, the CMC model and the theoretic marker positions from computer-assisted models of the drill guide were combined in a hybrid model.
The CMC model included eleven markers in the phantom and nine markers in the patient, which was sufficient for dRSA. Liner movement in the phantom followed liner contact with the femoral neck, while liner movement in the patient was independent. The hybrid model was necessary to determine liner orientation in sRSA recordings, which clearly changed from postoperative to 1- and 2-year follow-up even though the patient was positioned similarly.
Polyethylene liner motion in dual mobility hip prosthesis can be assessed with CMC models in dRSA recordings. In sRSA, the liner position between follow-ups is unpredictable and analysis requires inclusion of all markers in the model, accomplished with a hybrid marker model.
ClinicalTrials.gov [ NCT02301182 ], 25 October 2015.
研究全髋关节置换术中聚乙烯衬垫的运动需要对衬垫进行珠标记，以提高射线照相的可见性。然而，标记物的遮挡给射线照相中的标记物配准带来了挑战。
使用定制的钻头导向器，在双动髋臼系统的聚乙烯上标记了 12 个 1 毫米钽标记物（四组，每组三个标记物）。在 1 年随访时，使用动态放射立体测量分析（dRSA）和术后以及 1 年和 2 年随访时的静态放射立体测量分析（sRSA）对假体和患者中的衬垫运动进行了研究。从几个图像中标记的衬垫和股骨头的注册位置计算了组合标记物配置（CMC）模型。此外，将 CMC 模型和钻头导向器的计算机辅助模型中的理论标记物位置组合到混合模型中。
在假体中，CMC 模型包括 11 个标记物，在患者中包括 9 个标记物，这足以进行 dRSA。假体中的衬垫运动遵循衬垫与股骨颈的接触，而患者中的衬垫运动是独立的。在 sRSA 记录中，需要使用混合模型来确定衬垫的方向，即使患者的体位相似，其在术后到 1 年和 2 年随访期间的衬垫位置也会发生明显变化。
双动髋关节假体中的聚乙烯衬垫运动可以通过 dRSA 记录中的 CMC 模型进行评估。在 sRSA 中，随访之间的衬垫位置不可预测，分析需要在模型中包含所有标记物，这可以通过混合标记物模型来实现。
ClinicalTrials.gov [NCT02301182]，2015 年 10 月 25 日。
