In vitro Wear Testing

Alumina UHMWPE Zirconia UHMWPE CoCrMo CoCrMo 

CoCrMo Delrin CoCrMo Alumina Ti6A14V Alumina Alumina Alumina 

Pin-on-disc joint simulator (Miller et al, 1974 McKellop et al, 1978 McKellop and Rostliind, 1990) 

Pin-on-disc joint simulator (Galante, 1973 Semlitsch et al, 1977 Streicher et al, 1990  

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Radin, E.L. and Paul, I.L. Response of joints to impact loading I. In vitro wear tests. Arthritis Rheumatism 14,1971. 

Wang A, Essner A, Schmidig G The effects of lubricant composition on in vitro wear testing of polymeric acetabular 21. components. J Biomed Mater Res Part B Appl Biomater 2004 68 45-52. 

It must be noted that all the materials exhibit very good chemical durability. The weight loss of the glass-ceramics following immersion in 4% acetic acid (80°C, 16 h) was established according to ISO standards (see Table 4-19). In vitro wear tests have shown that this glass-ceramic is similar in wear to natural tooth structure (Sorensen et al., 1999). Section 4.4.2.6.C. describes the special optical characteristics, which can be achieved with additional assorted materials. Their use in the finished product is discussed. 

Other factors, including the ones listed in the following discussion for in vitro wear tests... 

Haider H, Alberts LR, Laurent MP, Johnson TS, Yao J, Gilbertson LN, Walker PS, Neff JR, Garvin KL. Comparison between force-controlled and displacement-controlled in-vitro wear testing on a widely used TKR implant. Trans Orthop Res Society, 48th Annual Meeting. Dallas, TX 2002 February. 

Brandt JM, Charron K, Zhao L, Medley JB, MacDonald SJ, Bourne RB, McCalden, RW. Development of a clinically relevant lubricant for in-vitro wear testing of total knee replacements. Proc. 75th Annual Meeting AAOS, Poster 137 477. 

Teoh, S.H., Lim, S.C., Yoon, E.T., and Goh, K.S. (1994a) A new method for in vitro wear assessment of materials used in mechanical heart valves, in Biomaterials Mechanical Properties, ASTM STP 1173, H.E. Kambic and A.T. Yokobori, Jr. (eds), American Society for Testing and Materials, Philadelphia, pp. 43-52. 

Wear debris of conventional UHMWPE has been clearly associated with osteolysis and loosening of implants [46, 47]. Currently, clinical studies up to 5 years have corroborated the in vitro simulator testing results of significantly decreased wear in highly crosslinked UHMWPEs compared to conventional UHMWPE [41, 48, 49]. Currently, there is no conclusion on the differences in the biological activity of the wear debris from highly crosslinked... 

Assessing tooth wear using an in situ approach falls somewhere between in vitro and in vivo approaches. Essentially, this approach involves human volunteers wearing test specimens in the mouth for a period of time, during which they may be exposed to one or more test treatments. Ideally, an in situ methodology should expose the test specimens to the interactions of the oral environment, whilst maintaining the sensitive measurement techniques which may be applied to laboratory analysis. 

Conclusions. Results from the biocompatibility studies in rabbit supratellar bursa, measurement of hydrophilic properties, lubrication and wear in-vitro studies, determination of viscoelastic properties, measurement of damping coefficient and impact test, total elbow joint replacement design and in-vivo percutaneous implant experiment, all indicate that this series of polyurethanes is an excellent candidate biomaterial for the prosthetic replacement of articular cartilage, artificial joint prostheses and percutaneous implantable devices. 

FIGtJRE 50.4 Relative cartilage wear based on hydroxyproline content of debris (in vitro tests with cartilage on stainless steel). 

It has already been shown and discussed — at least in in vitro tests with articular cartilage — that compounds which reduce friction do not necessarily reduce wear the latter was suggested as being more important [10]. It maybe helpful first of all to emphasize once again that friction and wear are different phenomena. Furthermore, certain constituents of synovial fluid (e.g., Swann s Lubricating Glycoprotein) may act to reduce friction in synovial joints while other constituents (e.g., Swann s protein complex or hyaluronic acid) may act to reduce cartilage wear. 

The general comment made here is that the use of synovial fluids — whether derived from human or animal sources and whether healthy or abnormal — is important in in vitro studies of synovial joint lubrication. The documented behavior of synovial fluid in producing low friction and wear with articular cartilage sets a reference standard and demonstrates that useful information can indeed come from in vitro tests. 

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