In order to obtain a secure taper connection it is advised to clean and dry the metal cup before assembling a ceramic insert. A slight axial tap using a plastic impactor completes the insertion procedure. There are a few reported cases that the taper connection failed intraoperatively although it was inserted and impacted as recommended. A conceivable reason seems to be a high amount of fluid in the gap between insert and cup (e.g. from rinsing process, blood) that prevent the insert from being securely fixed due to its incompressibility. Cups embedded in a cast resin have been used in an appropriate impaction test setup. Four different amounts of 1.75% polyvinyl pyrrolidone solution with comparable viscosity to that of blood were filled into the metal cups (figure 1). To obtain reference values, tests were made with dry metal cups (0%), too. Three different The fluid
cannot escape from the gap can permeate through a low permeable screen cloth can permeate through a high permeable screen cloth. The screen cloth should represent different cancellous bone densities. Ten Ceramic inserts of each size (28 and 36 mm) made of pure alumina (BIOLOX® INTRODUCTION:
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