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

Section 4: Prosthetic Joint Infections

Of the 40 patients in this study who underwent intended two-stage treatment, only 26 (65%) patients underwent the second stage for reimplantation and only 62% of these patients had treatment success. 23 During the two-stage protocol, there is a high attri tion and a high mortality rate following the first stage. One study of 616 patients found that 111 patients (18%) did not receive reimplantation. 49 Of the 111 patients, 29 (26.1%) did well with their retained spacer, 23 (20.7%) underwent salvage procedures, and 59 (53.2%) were med ically unfit, with 34 of the patients dying within 1 year of spacer insertion. In a smaller 2020 study of 89 patients, 56 28 (31%) did not undergo reimplantation. Of 61 patients whose reimplantation was completed, 9 (14.8%) had a reimplantation that failed with a repeat or recurrent PJI, and the mortality rate was 23.6% (21 of 89 patients) at a mean follow-up of 4.5 years. 56 With the high attrition rate in the interim between the first and second stage, there are emerging arguments to expand the indications for treatment strategies with one surgical procedure such as DAIR, single-stage, or 1.5-stage procedures. Two-stage revision remains the standard treatment for a chronic PJI. Articulating spacers have improved patient function during treatment without sacrificing infection control. Further studies are required to improve treat ment outcomes. The timing of stages, surgical protocols including ideal irrigation solutions used, and the duration and route of antibiotics remain areas of needed research. REVISION ARTHROPLASTY IN 1.5 STAGES A 1.5-stage revision arthroplasty as treatment for knee PJI is a novel technique that is gaining popularity at some centers. It is defined as a functional articulating antibi otic spacer implanted with the intention of being left in for an extended period, if not permanently. As with a single-stage procedure, many surgeons incorporate two surgical setups including a wound closure, reprepping, redraping, and reopening the incision into their protocol to simulate two separate surgical procedures. In addi tion, surgeons will properly balance the joint and use third-generation cementation technique with the goal of leaving the spacer as their functional joint. The ratio nale behind the technique is that patients are often very satisfied with their knee, as it can function as a normal knee replacement. Some patients choose to keep this knee and not undergo another surgical procedure. Some patients are deemed too high risk to undergo a revision and keep their spacer by default. The reasoning for a 1.5-stage instead of a true single-stage procedure is the potential for reinfection. If a patient becomes reinfected during a 1.5-stage construct, it is less morbid to remove the spacer than to perform a full revision that may have fully cemented stems with ingrown sleeves or cones.

A 2019 study reviewed 57 patients who underwent a 1.5-stage revision with a low-friction articulating spacer and 137 patients who underwent a traditional two stage revision with an all-cement articulating spacer. 57 Although no comparisons were statistically significant, at 2-year follow-up, the 1.5-stage group had a higher treatment success rate (78.9% versus 70.8%) and greater range of motion (105.8° versus 101.8°), with lower rates of reinfection (14.0% versus 24.1%) and revision surgery (19.3% versus 27.7%). Another study in 2022 compared 114 patients who underwent a 1.5-stage revision with low-friction articulating spacers and 48 patients who underwent a two-stage revision. 58 This showed a sur vival rate free of infection in the 1.5-stage group that was higher, but not significant. The Knee Injury and Osteoarthritis Outcome Score, Joint Replacement and postoperative complications were better in the 1.5-stage group as well, but this was biased because the population undergoing two-stage procedures was evaluated 5 years before the population undergoing 1.5-stage procedures, and not all of the two-stage spacers were the articulat ing type. In a 2021 study of 31 patients who planned to undergo a two-stage revision TKA, but were satisfied with their low-friction articulating spacer (28 patients) or medically unfit to undergo the reimplantation (3 patients), 25 of 31 initial spacers (81%) were in situ at a mean follow-up of 2.7 years. 59 Overall, a 1.5-stage revision is a reasonable option for patients who either choose not to have or are med ically unfit to undergo a second-stage surgical proce dure. Infection control and patient functional outcomes appear comparable with those of two-stage revision. Literature is limited at this time and protocols differ significantly. SINGLE-STAGE REVISION ARTHROPLASTY One-stage, also referred to as single-stage, revision for the treatment of PJI is highly used in Europe and is becom ing more common at some centers in the United States. As with any treatment for PJI, the goal of a single-stage revision is infection control. There are several purported benefits to single-stage revision, including less morbidity, reduced time in treatment for the patient, and less cost to the hospital system. Technique

Section 4: Prosthetic Joint Infections

Several high-volume centers in Europe have published their protocol for single-stage treatment of PJI. One example from the United Kingdom is published 60 and another from the Endo-Klinik, Germany. 61 These proto cols emphasize radical débridement with removal of all nonbleeding tissue and bone, including collateral liga ments, if necessary, followed by irrigation with minimum Copyright © Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. 2023

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Orthopaedic Knowledge Update ® : Musculoskeletal Infection 2