Wight Christian M, Whyne Cari M, Bogoch Earl R, Zdero Radovan, Chapman Ryan M, van Citters Douglas W, Walsh William R, Schemitsch Emil
Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, Toronto, Ontario, Canada.
Bone Jt Open. 2021 Nov;2(11):1004-1016. doi: 10.1302/2633-1462.211.BJO-2021-0147.R1.
This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads.
In all, six 28 mm and six 36 mm titanium stem-cobalt chrome head pairs with polyethylene sockets were tested in a novel instrumented hip simulator. Samples were tested using simulated gait data with incremental increasing loads to determine corrosion onset load and electrochemical activity. Half of each head size group were then cycled with simulated gait and the other half with gait compression only. Damage was measured by area and maximum linear wear depth.
Overall, 36 mm heads had lower corrosion onset load (p = 0.009) and change in open circuit potential (OCP) during simulated gait with (p = 0.006) and without joint movement (p = 0.004). Discontinuing gait's joint movement decreased corrosion currents (p = 0.042); however, wear testing showed no significant effect of joint movement on taper damage. In addition, 36 mm heads had greater corrosion area (p = 0.050), but no significant difference was found for maximum linear wear depth (p = 0.155).
Larger heads are more susceptible to taper corrosion; however, not due to frictional torque as hypothesized. An alternative hypothesis of taper flexural rigidity differential is proposed. Further studies are necessary to investigate the clinical significance and underlying mechanism of this finding. Cite this article: 2021;2(11):1004-1016.
本研究在一种新型髋关节模拟器中，研究不同头部尺寸下的头颈锥度腐蚀情况，该模拟器可在扭转载荷下测量与腐蚀相关的电活动。
总共对六对28毫米和六对36毫米的钛柄-钴铬合金头与聚乙烯髋臼杯进行了新型仪器化髋关节模拟器测试。使用模拟步态数据和逐渐增加的载荷对样本进行测试，以确定腐蚀起始载荷和电化学活性。然后，每个头部尺寸组的一半样本进行模拟步态循环，另一半仅进行步态压缩循环。通过面积和最大线性磨损深度来测量损伤。
总体而言，36毫米的头部在模拟步态时（p = 0.006）和无关节运动时（p = 0.004）具有较低的腐蚀起始载荷（p = 0.009）和开路电位（OCP）变化。停止步态的关节运动会降低腐蚀电流（p = 0.042）；然而，磨损测试表明关节运动对锥度损伤没有显著影响。此外，36毫米的头部有更大的腐蚀面积（p = 0.050），但最大线性磨损深度没有显著差异（p = 0.155）。
较大的头部更容易发生锥度腐蚀；然而，并非如假设的那样是由于摩擦扭矩。提出了锥度抗弯刚度差异的另一种假设。有必要进一步研究这一发现的临床意义和潜在机制。引用本文：2021；2（11）：1004 - 1016。
