Orthopaedic Knowledge Update®: Musculoskeletal Infection 2 Print + Ebook (AAOS - American Academy of Orthopaedic Surgeons)

Chapter 16: Surgical Treatment of Hip and Knee Prosthetic Joint Infections

than 2 g of vancomycin per 40-g bag of cement in the spacer construct, as a decrease in treatment failure has been reported. 20 Two randomized controlled trials comparing static and articulating spacers, one published in 2020 for knees 30 and the other published in 2021 for hips, 31 demonstrate favorable outcomes with articulating spacers. Sixty-eight patients undergoing two-stage exchange for knee PJI were randomized to either static spacer or articulating spacer made intraoperatively with the use of silicone molds. The static spacer group had a longer hospital stay (6.1 versus 5.1 days), decreased arc of motion at follow-up (100° versus 113°), and lower Knee Society Score (69.8 versus 79.4). Although not statistically signifi cant, there was also a greater need for extensile exposure at the time of reimplantation (16.7% versus 4.0%) and a higher reoperation rate (25.0% versus 8.0%) in the static spacer group. 30 Fifty-two patients undergoing two-stage exchange for hip PJI were randomized to either static spacer or articulating spacer made intraoperatively with the use of silicone molds. There was no difference in sur gical time at second-stage reimplantation (143 minutes static versus 145 articulating). Hospital stay was longer in the static cohort after stage one (8.6 versus 5.4 days) and stage two (6.3 versus 3.6 days). Although it did not reach statistical significance, the static cohort was more often discharged to an extended care facility after stage one (65% versus 30%, P = 0.056). 31 The optimal spacer construct has yet to be determined. In a systematic meta-analysis of 34 articles containing

B

A

FIGURE 2 A and B , Plain lateral and AP radiographs show a total knee arthroplasty prosthetic knee infection treated with a prefabricated cement spacer.

The antibiotics used in the spacer should be tailored to the infectious organism, as well as bactericidal, water soluble, and thermodynamically stable. These include most commonly tobramycin, gentamycin, and vancomy cin. Spacers have varying antibiotic compositions with no randomized controlled trials to compare them. 28 However, there is evidence to support the use of more

Section 4: Prosthetic Joint Infections

A FIGURE 3 A , AP and Lateral radiographs showing an articulating spacer dislocation. B , Revision spacer exchange to a static spacer created with antibiotic cement and intramedullary placement of an external fixator bar. Copyright © Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. 2023 B

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Orthopaedic Knowledge Update ® : Musculoskeletal Infection 2