Abstract
Two stage exchange has been the gold standard in North America for the treatment of infected knee replacements. The choice of static versus articulated spacers has been debated for a number of years.
At our institution our choice of spacer for two-stage exchanges is an articulated spacer. This allows motion between stages which facilitates recovery, and makes the second stage technically easier. In a study from our institution we followed 115 infected TKAs treated with the PROSTALAC articulated spacer for 5–9 years. Success for eradication of infection was 88%. With a repeat two stage overall infection control was 98%. In addition we compared functional outcomes to a group of aseptic knee revisions and found no difference in functional outcomes with standard quality of life outcome scores.
While the articulated spacer was our treatment of choice in two-stage exchange around 2012 the company that manufactured the PROSTALAC knee components ceased to manufacture them. At that time based on the work of 2 previous studies (Hofmann, Lee), our institution continued to use articulated spacers. However, this was now the so-called Hofmann technique with a new standard femoral component with an all-polyethylene tibia. The only difference from a standard knee revision was no stems and the utilisation of high dose antibiotics. We also followed the principles from Europe of one-stage exchange, such as wide debridement and soaking in dilute betadine for 15 minutes.
More recently, as of Sept 2015, we have used an all-polyethylene tibia with a keel. The hope being that this will give a more stable tibia than previous and perhaps make a second stage unnecessary. Our first case was September 2015. The intention was not to do a second stage if the infection was eradicated and the patient had good pain relief and function. To date we have implanted 12 of these and in all cases we have not had to do a second stage revision. Further study will reveal where this inadvertent one stage fits in our practice.
