Syracuse Biomedical Institute, Syracuse University, Syracuse, NY; Department of Bioengineering, Clemson University, Charleston, SC.
Stryker, Joint Replacement Division, Mahwah, NJ.
J Arthroplasty. 2018 Jun;33(6):1953-1961. doi: 10.1016/j.arth.2018.01.039. Epub 2018 Feb 2.
Mechanically assisted crevice corrosion of modular tapers continues to be a concern in total joint arthroplasties. A surgical factor that may affect taper fretting corrosion during cyclic loading is seating load magnitude. In this study, modular head-neck taper junctions were seated, capturing load-displacement, over a range of axially oriented loads, and electrochemical and micromotion data were captured during short-term incremental cyclic fretting corrosion (ICFC) tests. The hypothesis is low seating loads result in greater motion and fretting corrosion in ICFC tests. The effect of assembly load on pull-off force post-ICFC testing was also evaluated.
The study employed custom-built test fixtures which measured head-neck micromotion and an electrochemical chamber to monitor electrochemical reactions. Head-neck motion measurements were captured using 2 noncontact differential variable reluctance transducers mounted to the head. Seating experiments ranged from 1000 to 8000 N.
Significant differences due to seating loads were reported in seating displacement, ICFC subsidence, and fretting current at 4000 N cyclic load. Seating load decreased but did not eliminate currents. Fretting onset load remained fixed (approximately 1200 N) for tapers seated above 2000 N. Fretting subsidence was negligible for seating loads of 4000 N or higher, and increased subsidence was observed below 4000 N.
This short-term test method evaluated the acute performance of modular implants which were assembled under various loads and demonstrated the link between seating loads, fretting motions, and electrochemical reactions. While increased seating loads reduced fretting corrosion and taper subsidence, it did not prevent fretting corrosion even at 8 kN seating.
机械辅助的接骨螺钉缝隙腐蚀仍然是全膝关节置换术中的一个关注点。在循环加载过程中，可能影响锥度微动腐蚀的手术因素是坐立负荷的大小。在这项研究中，对模块化的头-颈锥度连接进行了坐立，在一系列轴向加载下捕获了载荷-位移，并在短期增量循环微动腐蚀（ICFC）试验中捕获了电化学和微动数据。假设低坐立负荷会导致在 ICFC 试验中产生更大的运动和微动腐蚀。还评估了装配负荷对 ICFC 测试后拔出力的影响。
该研究采用了定制的测试夹具，该夹具测量头-颈的微动，并使用电化学室监测电化学反应。头-颈运动的测量使用安装在头上的 2 个非接触式差动可变磁阻传感器进行。坐立实验的范围从 1000 到 8000 N。
在 4000 N 循环负荷下，由于坐立负荷的差异，在坐立位移、ICFC 沉降和微动电流方面有显著差异。坐立负荷的降低并没有消除电流。对于坐立负荷高于 2000 N 的锥度，微动起始负荷保持固定（约 1200 N）。当坐立负荷为 4000 N 或更高时，微动沉降可以忽略不计，而当坐立负荷低于 4000 N 时，沉降增加。
这种短期测试方法评估了在不同负荷下装配的模块化植入物的急性性能，并展示了坐立负荷、微动运动和电化学反应之间的联系。虽然增加坐立负荷可以减少微动腐蚀和锥度沉降，但即使在 8 kN 的坐立负荷下，也不能防止微动腐蚀。
