<p class="source">Source - <a href="http://www.9news.com/default.aspx" target="_blank" rel="nofollow"> 9News.com</a></p><p>In the U.S., the number of knee replacements has doubled in the last decade. More than 600,000 Americans had knee replacement surgeries in 2009, with the fastest growing segment under the age of 65. More than 4.7 percent of those over the age of 50 already have knee replacements.</p><p>Given Dietrich's age, 71, and his good health, Xenos recommended a Legion Total Knee, or as some surgeons call it, a "30-year knee." Research has suggested the Total Knee, built with an oxinium metal alloy, deteriorates at a rate about half as fast as most traditional cobalt chromium alloy knee replacements.</p><p class="hr"></p>