Biotribological Study On The Wear Testing Methodology Of Orthopedic Biomaterials

Wear has been recognized as the key factor affecting the long-term performance of orthopaedic implants such as hip, knee and spine prostheses. During the development of orthopedic implants, in-vitro wear tests are required for the prediction of the wear which will be occurred in vivo. Such wear tests have been recognized as mandatory testing items in U.S. and EU. FDA.Since the tribological property of orthopaedic biomaterials has significant influence on the wear performance of implants, the bench wear evaluation of orthopaedic biomaterials is regarded as another important testing methodology. A proper bench wear test can be used to develop an understanding of wear mechanisms and the influence of environmental, design, and material parameters on wear behaviour. Moreover, due to the low productivity, complex structure and high cost of joint simulator wear testing, a reliable and effective wear testing methodology for orthopaedic biomaterials is expected and required.In this thesis, a new wear testing apparatus for orthopedic implant materials was designed and developed. Validation tests were carried out by using artificial joint biomaterials. Moreover, the influences of different trajectories on wear were investigated and analyzed. Main contents are shown as below:(1) According to the characteristics and requirements of orthopedic implant material wear tests, an orthopedic biomaterials wear test device was designed and developed. The device was to simulate and predict the wear properties of orthopaedic biomaterials in clinical application, especially in the form of hip, knee and spine prostheses. Meanwhile, the debris generated by the experiment was extracted, and the particle morphology and distribution were analyzed.(2) Considering the effect of sliding path on wear, the motion of the knee and hip joint were analyzed and extracted. The wear of ultra-high molecular weight polyethylene(UHMWPE)counter with cobalt chromium alloy under rectangular path of different length-width ratio was investigated experimentally.(3) Based on the testing results from Biotribo POD Pro and related ISO and ASTM standards, wear testing operation procedure of orthopaedic biomaterials has been discussed and summarized.