Department of Orthopedics, Jena University Hospital, Campus Eisenberg, Klosterlausnitzer Straße 81, 07607, Eisenberg, Germany.
Department of Orthopedics, Laboratory of Biomechanics, Jena University Hospital, Campus Eisenberg, Klosterlausnitzer Straße 81, 07607, Eisenberg, Germany.
Arch Orthop Trauma Surg. 2019 Jul;139(7):991-998. doi: 10.1007/s00402-019-03160-4. Epub 2019 Mar 29.
Easy revisability is gaining increasingly in importance. The removal of well-fixed cemented stems is very demanding and is often associated with increased operative morbidity. Implant design may be here a decisive impact factor, and the best way to ascertain it is experimentally. Aim of this study is to assess different cemented stems of established knee revision implants in regard to their removal capability.
Based on their sagittal profile, five stem extensions from known manufacturers were divided in conical, conical-cylindrical and cylindrical designs. The pedicles were also characterized in respect to their cross section, diameter and surface roughness. The cemented stems were dismounted six times each in a reproducible biomechanical setup. The explantation energy required was determined and statistical analyzed.
The conical shaft needed significantly the slightest explantation energy with 19.2 joules (p = 0.004). There was a strong negative linear correlation between conicity proportion and explantation energy of the cemented stems (R = 0.983). The removal of the three purely cylindrical shafts-regardless of their differences in diameter, cross-sectional design and surface- was the most demanding (98.3, 105, and 116.7 joules) with only secondary differences between them.
The longitudinal stem profile may have a primary impact on the explantability of well-fixed cemented shafts with conical designs showing superiority. Cross-sectional profile and surface roughness had here a less decisive influence on the explantability. Surgeons can choose proper implants and removal techniques depending on potential implant-associated revision risks and re-revisions to be expected.
易于修改的性能越来越受到重视。去除固定牢固的水泥固定柄非常困难，通常会增加手术的发病率。植入物的设计可能是一个决定性的影响因素，而确定这一点的最好方法是进行实验。本研究的目的是评估不同的已建立的膝关节翻修植入物的水泥固定柄在去除能力方面的差异。
根据其矢状轮廓，将来自已知制造商的五个柄的延伸部分分为锥形、锥形-圆柱形和圆柱形设计。还对这些柄的节段特征进行了研究，包括其横截面、直径和表面粗糙度。在可重复的生物力学设置中，将每个柄的水泥固定柄拆卸六次。确定所需的拆卸能量，并进行统计分析。
锥形柄所需的拆卸能量最小，为 19.2 焦耳（p=0.004）。锥形比例与水泥固定柄的拆卸能量之间存在强烈的负线性相关性（R=0.983）。三个纯圆柱形柄的去除（无论其直径、横截面设计和表面粗糙度的差异如何）是最困难的（分别为 98.3、105 和 116.7 焦耳），但彼此之间只有次要差异。
纵向柄的形状可能对固定牢固的水泥柄的可去除性有主要影响，锥形设计具有优越性。横截面形状和表面粗糙度对可去除性的影响较小。根据潜在的植入物相关翻修风险和预期的再次翻修，外科医生可以选择合适的植入物和移除技术。
