Evaluation of the Mechanical Reliability

One of the most important factors that causes the failure of a knee prosthesis is the infection that can arise in the tissues after implantation due to an incorrect surgical procedure, to a difficult repairing process or to other patient’s pathological conditions. The infection can arise soon after implantation as well as in one or two years after the operation. In order to let the infection heal and to restore the knee physiological conditions, the prosthesis must be removed and antibiotic therapy must be performed. Between the removal of the prosthesis and the re-implantation of a new one, a knee spacer is implanted in the knee: the spacer has the same shape and geometry of a knee prosthesis (Figure 1) and is made of polymethylmethacrylate (PMMA) with gentamicin sulphate additive in order to obtain a locally focused therapy for infection healing.