Sensitivity of knee replacement contact calculations to kinematic measurement errors
Sensitivity of knee replacement contact calculations to kinematic measurement errors
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DOI：
10.1002/jor.20548
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发表时间：
2008-09-01
影响因子：
2.8
通讯作者：
Colwell, Clifford W., Jr.
中科院分区：
文献类型：
--
作者：
Fregly, Benjamin J.;Banks, Scott A.;Colwell, Clifford W., Jr.
准确测量体内膝关节运动学的能力使得直接从运动学数据计算体内接触力、压力和面积成为可能。然而，接触计算的灵敏度运动测量误差还没有得到充分的研究。为了解决这个问题，我们开发了一系列的灵敏度分析来自一个有效的在体内的步态计算模拟。该模拟使用弹性基础接触模型来再现从内固定膝关节置换术中收集的体内接触力、压力中心和X线透视运动数据。将模拟中的每个自由度（DOF）视为运动控制，我们首先进行量化。植入物组件测量的相对姿态误差如何影响接触计算。在整个步态周期中，+/- 0.1分钟或度的姿势变化分别使最大接触力、压力和面积变化204%、100%和117%。+/-0.5 mm或度数的较大变化分别使这些相同的量改变了1157、108和578%。在这两种情况下，最大的敏感性是上下平移和内翻-外翻旋转错误，一侧或两侧发生接触丢失。然后，我们量化了将敏感自由度从运动切换到负载控制如何影响灵敏度结果。其余自由度的+/- 0.5分钟或度的位姿变化改变了最多3%的最大接触量。这些结果表明，需要微米和毫弧度量级的精度油来直接从体内运动学测量中估计接触力、压力和面积，并且对于敏感的自由度使用载荷而不是运动控制可以提高体内接触计算的精度。(C)2008骨科研究学会。由威利期刊公司出版
The ability to measure in vivo knee kinematics accurately makes it tempting to calculate in vivo contact forces, pressures, and areas directly from kinematic data. However, the sensitivity of contact calculations to kinematic measurement errors has not been adequately investigated. To address this issue, we developed a series of sensitivity analyses derived from a validated in vivo computational simulation of gait. The simulation used an elastic foundation contact model to reproduce in vivo contact force, center of pressure, and fluoroscopic motion data collected from an instrumented knee replacement. Treating each degree of freedom (DOF) in the simulation as motion controlled, we first quantified. how errors in measured relative pose of the implant components affected contact calculations. Pose variations of +/- 0.1 min or degree over the entire gait cycle changed maximum contact force, pressure, and area by 204, 100, and 117%, respectively. Larger variations of +/- 0.5 mm or degree changed these same quantities by 1157, 108, and 578%, respectively. In both cases, the largest sensitivities were to errors in superior-inferior translation and varus-valgus rotation, with loss of contact occurring on one or both sides. We then quantified how switching the sensitive DOFs from motion to load control affected the sensitivity results. Pose variations of +/- 0.5 min or degree in the remaining DOFs changed maximum contact quantities by at most 3%. These results suggest that accuracy oil the order of microns and milliradians is needed to estimate contact forces, pressures, and areas directly from in vivo kinematic measurements, and that use of load rather than motion control for the sensitive DOFs may improve the accuracy of in vivo contact calculations. (C) 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.