Читать книгу Materials for Biomedical Engineering - Mohamed N. Rahaman - Страница 36

Based on the foregoing discussion, we can summarize the materials currently used in implants for total joint surgery (Figure 1.8). Ti6Al4V is used almost exclusively for the femoral stem and the shell of the acetabular cup, while Co–Cr and UHMWPE are the most commonly used combination for the femoral head (ball) and liner of the acetabular cup, respectively. Stainless steel balls are used far less often than Co–Cr. The ball is impacted on to a tapered end of the stem to hold it firmly in place and to allow its removal, if necessary. AMC finds use for both the ball and the liner but far less frequently when compared to the Co–Cr on UHMWPE couple. While AMC bearing couples show the lowest wear rates and the longest average lifetime when compared to all articulating couples used in hip implants, they are expensive to manufacture, their brittleness can be a concern, and a small fraction can suffer from a squeaking noise in vivo. AMC balls articulating against UHMWPE liners are also used. They show lower wear than Co–Cr on UHMWPE bearing couples but higher wear than AMC on AMC bearing couples.

Figure 1.8 Various combinations of materials currently used in implants for total hip replacement.