Department for Trauma Surgery and Orthopaedics, UKE University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany.
J Arthroplasty. 2020 Nov;35(11):3318-3325. doi: 10.1016/j.arth.2020.06.035. Epub 2020 Jun 17.
The aim of this study is to investigate the effects of different stem lengths and types including cones on primary stability in revision total knee arthroplasty with different femoral bone defects and fixation methods in order to maximize bone preservation. It is hypothesized that longer stems provide little additional mechanical stability.
Thirty-five human femurs were investigated. A distal bone defect, Anderson Orthopedic Research Institute classification (s. 33) type-F2a, was created in group 1-3 and type-F3 in group 4-6. A cemented, rotating hinge femoral component was combined with different stems (100 and 160 mm total or hybrid cemented cones, or a 100-mm custom-made anatomical cone stem). The femora were loaded according to in vivo loading during gait. Relative movements were measured to investigate primary stability. Pull-out testing was used to obtain a parameter for the primary stability of the construct.
Relative movements were small and similar in all groups (<40 μm). For small defect, the pull-out forces of cemented long (4583 N) and short stems (4650 N) were similar and about twice as high as those of uncemented stems (2221 N). For large defects, short cemented stems with cones showed the highest pull-out forces (5500 N). Long uncemented stems (3324 N) and anatomical cone stems (3990 N) showed similar pull-out forces.
All tested stems showed small relative movements. Long cemented stems show no advantages to short cemented stems in small bone defects. The use of cones or an anatomical cone stem with hybrid cementation seems to offer good stability even for larger bone defects. The use of a short cemented stem (with or without cone) may be a suitable choice with a high potential for bone preservation in total knee arthroplasty revision with respective bone defects.
本研究旨在探讨不同类型的股骨骨缺损和固定方法下，不同长度和类型的股骨柄（包括骨锥）对翻修全膝关节置换术初始稳定性的影响，以最大程度地保留骨量。假设较长的柄并不能提供额外的机械稳定性。
本研究共研究了 35 个人体股骨。在第 1-3 组中创建了一个远端骨缺损，安德森骨科研究协会（s.33）分类-F2a 型，而在第 4-6 组中创建了 F3 型。采用骨水泥固定、旋转铰链股骨组件与不同的柄（100 和 160 毫米全长或混合骨水泥固定骨锥，或 100 毫米定制解剖锥形柄）结合。股骨按照步态时的体内载荷进行加载。测量相对运动以研究初始稳定性。采用拔出试验获得构建物初始稳定性的参数。
所有组的相对运动都较小且相似（<40μm）。对于小缺损，骨水泥固定的长（4583 N）和短柄（4650 N）的拔出力相似，约为非骨水泥固定柄（2221 N）的两倍。对于大缺损，短骨水泥固定的带骨锥的柄显示出最高的拔出力（5500 N）。长非骨水泥固定的柄（3324 N）和解剖锥形柄（3990 N）显示出相似的拔出力。
所有测试的柄都显示出较小的相对运动。在小骨缺损中，长骨水泥固定的柄与短骨水泥固定的柄相比没有优势。使用骨锥或混合骨水泥固定的解剖锥形柄似乎即使对于较大的骨缺损也能提供良好的稳定性。在有相应骨缺损的翻修全膝关节置换术中，使用短骨水泥固定的柄（带或不带骨锥）可能是一种保留骨量的合适选择，具有较高的潜力。
