Comparison of outcomes between static spacers versus articulating spacers in the setting of revision periprosthetic knee infections: a systematic review

Background: Two-stage exchange arthroplasty is the standard of care treatment for periprosthetic joint infection (PJI) of knee in the United States. This procedure involves implantation of antibiotic-loaded spacer in order to eradicate the infection prior to reimplantation of the prosthesis. While traditionally static spacer was used in interim period between explantation and reimplantation, articulating spacer has become the spacer of choice recently. The purpose of this review is to describe differences in surgical techniques, and clinical outcomes (complications, reinfections) between static and articulating spacers. Methods: A literature search was performed on PubMed focusing on two-stage revision for infected total knee arthroplasty (TKA) using the search string: [Knee AND (arthroplasty OR replacement) AND (revision OR infection) AND (spacer OR spacers) AND (static or dynamic or articulating or articulated) NOT hip] AND "last 10 years" [PDat] AND Humans [Mesh] AND English [lang]. Results: Initial search yielded 72 results and nine studies with sufficient data were finally included in our systematic review. The total number of knee procedures were 1,977. Static and articulating spacer groups had 871 and 1,106 knees, respectively. The mean time till reimplantation was significantly more in case of articulating (4.5 months) versus static spacers (2.8 months, P<0.001). The mean range of motion (ROM) after surgery was also significantly higher in articulating (101.9 degrees) as compared to static group (93.3 degrees, P<0.001). The mean reinfection and complication rate were not significantly different between articulating and static spacer groups [reinfection: 9.3% vs. 14.7%, P=0.190; complication: 7.2% vs. 10.6%, P=0.446]. Conclusions: In the setting of two-stage exchange knee arthroplasty, articulating spacers result in better postoperative ROM, but comparable complication and reinfection rates. However, selection bias in the evaluated studies must be considered when comparing outcomes between types of knee spacers. There remain special circumstances of limited soft tissue coverage, ligamentous instability or poor bone stock where static spacer should be considered. Background: Two-stage exchange arthroplasty is the standard of care treatment for periprosthetic joint infection (PJI) of knee in the United States. This procedure involves implantation of antibiotic-loaded spacer in order to eradicate the infection prior to reimplantation of the prosthesis. While traditionally static spacer was used in interim period between explantation and reimplantation, articulating spacer has become the spacer of choice recently. The purpose of this review is to describe differences in surgical techniques, and clinical outcomes (complications, reinfections) between static and articulating spacers. Methods: A literature search was performed on PubMed focusing on two-stage revision for infected total knee arthroplasty (TKA) using the search string: [Knee AND (arthroplasty OR replacement) AND (revision OR infection) AND (spacer OR spacers) AND (static or dynamic or articulating or articulated) NOT hip] AND "last 10 years" [PDat] AND Humans [Mesh] AND English [lang]. Results: Initial search yielded 72 results and nine studies with sufficient data were finally included in our systematic review. The total number of knee procedures were 1,977. Static and articulating spacer groups had 871 and 1,106 knees, respectively. The mean time till reimplantation was significantly more in case of articulating (4.5 months) versus static spacers (2.8 months, P<0.001). The mean range of motion (ROM) after surgery was also significantly higher in articulating (101.9 degrees) as compared to static group (93.3 degrees, P<0.001). The mean reinfection and complication rate were not significantly different between articulating and static spacer groups [reinfection: 9.3% vs. 14.7%, P=0.190; complication: 7.2% vs. 10.6%, P=0.446]. Conclusions: In the setting of two-stage exchange knee arthroplasty, articulating spacers result in better postoperative ROM, but comparable complication and reinfection rates. However, selection bias in the evaluated studies must be considered when comparing outcomes between types of knee spacers. There remain special circumstances of limited soft tissue coverage, ligamentous instability or poor bone stock where static spacer should be considered.