A geometric method to measure the wear of hip joint

摘要

Accurate measurement of the wear during a hip joint wear study is a challenge. The most widely used method involves the calculation of the wear volume from the difference in sample mass pre- and post-test. However, drift in the weighing balance, sample contamination, variation of the environmental conditions and sample damage from the test fixtures; all compromise the accuracy of the measurement. This study describes a novel geometry based method of quantifying the wear directly from the worn surface. The method involves measuring the wear patch with a contacting roundness machine and using a numerical model to calculate the wear volume. The results of this study demonstrate that the geometric method offers a more accurate means of determining the wear volume from hip joint wear studies, free from the sources of inaccuracy affecting the gravimetric method. The method can also be applied to the assessment of wear volume from clinical retrievals for which the baseline weight cannot be determined. The proposed method is a valuable alternative to the gravimetric method for measuring wear in hip joints, especially for large samples and clinical retrievals where the gravimetric method becomes more difficult or even impossible.