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

Section 4: Prosthetic Joint Infections

components avoids the patient morbidity associated with removing the implants and the subsequent more difficult recovery. Surgical Technique The least-invasive surgical treatment of PJI is the arthroscopic DAIR procedure. A 2020 study reported only a 15% to 20% success rate for arthroscopic DAIR; subsequently, the procedure has become less common because of the low likelihood of success. 2 These results are most likely due to the inability to exchange modu lar components. The exchange of modular components (polyethylene in total knee arthroplasty [TKA] or head and liner in total hip arthroplasty) allows for not only removal of foreign material with a potential biofilm but also better visualization and the ability to perform a more thorough débridement. Therefore, there is no current role for arthroscopic DAIR in hip and knee PJI. 2 Appropriate DAIR procedures consist of an open arthrotomy, extensive débridement of the synovium, irrigation, and removal and exchange of modular compo nents. A 2020 study supported the exchange of modular components when possible. 3 The procedure itself differs among surgeons in the extent of the débridement/syn ovectomy as well as the local delivery of antibiotics and irrigation solutions. The optimal extent of débridement or local adjunct treatment of antibiotics and irrigation is yet to be determined. However, at the second International Consensus Meeting (ICM) on Musculoskeletal Infection, there was strong group consensus recommending irriga tion with 6 to 9 L of fluid. 4 Postoperatively, patients are treated with intravenous antibiotics for 6 weeks, followed by oral antibiotic sup pression for an extended period. A 2020 retrospective review supported giving 3 to 6 months of extended oral antibiotic treatment with one study advocating for 1 year. 5 Outcomes The overall success of a DAIR in the literature varies widely, from zero to 90%. 6,7 The likelihood of suc cess depends the timing of symptoms, microbiology, laboratory study results, the ability to exchange mod ular components, and patient comorbidities. 6-11 With recent protocols, one study from 2019 found that 84% of patients who underwent DAIR for PJI were free of infection at 2 years. 12 Another study has less-promising results, reporting a 4-year failure of 57% and a 5-year mortality of 20%. 13 The timing of symptoms is an important prognos tic indicator. In a retrospective analysis of 99 patients who underwent DAIR for PJI, 88% of patients with less than 2 days of symptoms were successfully treated in contrast to 55% with more than 2 days of symptoms. 7

In a 2019 study of 83 patients who underwent DAIR, the mean time from onset of symptoms to surgery was 6.2 days for successfully treated patients versus 10.7 days for those with treatment failure. 11 This shifts the urgency of the DAIR procedure, once indicated, to days rather than weeks. The infectious organism also plays a significant role in predicting successful treatment with a DAIR proce dure. Staphylococcus aureus PJIs have a higher failure rate when compared with Staphylococcus epidermidis or streptococcal species. 14 This finding has persisted throughout the literature with reports of 71% failure rate of S aureus PJI versus 30% failure rate of S epidermidis PJI. 8 Another study reported a success rate of 74% for streptococcal infections versus 50% for staphylococcal infection. 7 Reported outcomes with methicillin-resis tant S aureus continue to show a high failure rate of DAIR, as high as 84%. 9 Finally, two studies from 2019 reported that polymicrobial, antibiotic-resistant species, and fungal infections also have been shown to have a sig nificantly higher failure rate when performing DAIR. 15,16 Several host factors have been associated with failed DAIR treatment. A 2019 retrospective review of 199 patients who underwent DAIR for PJI found treatment failure associated with multiple factors after multivar iate analysis, including acute hematogenous infection, previous revision surgery, and increased Charlson Comorbidity Index. 15 Diabetes mellitus, chronic obstruc tive pulmonary disease, and history of malignancy were patient comorbidities associated with treatment failure. 15 Predictive algorithms have been developed to guide treat ment decisions. The KLIC-score (kidney, liver, index sur gery, cemented prosthesis, and C-reactive protein value) is shown to be predictive of early failure of DAIR. 17 The CRIME80 score (C-reactive protein greater than 150 mg/L, chronic obstructive pulmonary disease, rheuma toid arthritis, fracture as indication for the prosthesis, male sex, not exchanging the mobile components during débridement, and age older than 80 years [+2, +1, +3, +3, +1, +1, and +2, respectively]) can be useful in predicting treatment failure in late acute infections. A score of 3 or greater was associated with higher treatment failure and mortality with a DAIR procedure when compared with implant removal 10 ( Table 1 ).

Section 4: Prosthetic Joint Infections

There is a concern that undergoing a DAIR procedure causes worse outcomes for a subsequent two-stage revi sion. A multicenter retrospective cohort study demon strated 28 failures (34%) of 83 knees that underwent a two-stage revision TKA after previous DAIR. 18 The authors attribute this high failure rate for two-stage revi sion TKA to the initial DAIR procedure itself. This study has limitations because it lacks a comparative group of patients and no evidence that the DAIR procedure itself caused an increase in subsequent two-stage revision TKA Copyright © Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. 2023

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Orthopaedic Knowledge Update ® : Musculoskeletal Infection 2