Kempthorne Josh, Kieser David C, Walker Cameron G
1 Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand.
2 Department of Engineering Science, University of Auckland, Auckland, New Zealand.
Hip Int. 2018 Nov;28(6):657-662. doi: 10.1177/1120700018760243. Epub 2018 May 21.
The requirement for lateral plate fixation in the presence of a hip arthroplasty stem is increasing, yet the optimal plate construct necessary to reduce inter-prosthetic strain and prevent subsequent fractures is unknown. Therefore, the purpose of this study was to determine the optimal position of a lateral femoral plate in relation to a femoral stem.
We used 4th Generation Composite Sawbones, a collarless polished cemented femoral stem and a broad Peri-loc™ plate with varying overlap of the stem. Each construct was subjected to torsion, axial compression and 3-point lateral bending, with the strain measured at the tip of the femoral stem and the force-to-failure recorded.
In all three loading directions a plate, which extended at least two shaft diameters proximal to the tip of the stem, experienced the lowest strain ( p < 0.001). Constructs with no overlap, and particularly those with a small gap between the tip of the stem and the proximal extent of the plate experienced the highest strain ( p < 0.001). This high strain resulted in lower forces required to cause fracture in the clinically significant scenarios of femoral torsion and lateral bending.
Optimal plate fixation is achieved by extending a lateral femoral plate at least two shaft diameters proximal to the tip of the stem and using a spread of proximal screws. Distal fixation increases the strain experienced at the tip of the stem and higher strains are noted the smaller the gap between the proximal extent of the femoral plate and the tip of stem.
在存在髋关节置换柄的情况下，对侧板固定的需求日益增加，但降低假体间应变并预防后续骨折所需的最佳钢板结构尚不清楚。因此，本研究的目的是确定股骨外侧钢板相对于股骨干的最佳位置。
我们使用了第四代复合人工骨、无领抛光骨水泥型股骨干以及带有不同柄部重叠长度的宽型Peri-loc™钢板。每种结构均承受扭转、轴向压缩和三点侧向弯曲，在股骨干尖端测量应变，并记录破坏力。
在所有三个加载方向上，在柄尖近端至少延伸两个骨干直径的钢板经历的应变最低（p < 0.001）。无重叠的结构，尤其是柄尖与钢板近端之间间隙较小的结构，经历的应变最高（p < 0.001）。这种高应变导致在股骨扭转和侧向弯曲等具有临床意义的情况下导致骨折所需的力较低。
通过将股骨外侧钢板在柄尖近端至少延伸两个骨干直径并使用近端螺钉分散固定，可实现最佳钢板固定。远端固定会增加柄尖处的应变，并且股骨干近端与柄尖之间的间隙越小，应变越高。
