Spacer-related problems in two-stage revision knee arthroplasty

Although articulated cement spacers are frequently used in a staged approach of an infected total knee arthroplasty (TKA), no data are available on the incidence and type of spacer-related problems in these patients. A retrospective analysis of 154 patients who underwent a two-stage revision procedure for an infected TKA was performed. All patients received an articulating cement spacer at the implant removal procedure; their radiographs were analyzed for spacer-related issues such as spacer dislocation, fracture, tilting or translation, and knee subluxation. In 43% of the patients, the spacer was considered as optimal. The main finding of this study is the large incidence (57%) of spacer-specific problems in two-stage revision knee arthroplasty for infected TKA. Spacer tilting and mediolateral translation were found to be the most frequent spacer-specific problems, in 24% and 21% of the cases respectively. These were considered as minor problems. Major problems were seen in 12 % : in 3% of the knees the spacer had dislocated, in 5% the spacer fractured and in 4%, although the spacer seemed to be adequately positioned relative to the femoral and tibial bone, frank knee subluxation could be noted. The impact of spacer-specific problems with articulating cement spacers on final outcome in two-stage revision knee surgery will be further investigated.