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J Knee Surg
DOI: 10.1055/a-2756-0215
Original Article

Predictors of Repeat Washout in the Isolated Septic Knee

Authors

  • Avinaash Korrapati

    1   Department of Orthopaedic Surgery, University of California San Diego, San Diego, California, United States

  • Kevin Y. Zhu

    1   Department of Orthopaedic Surgery, University of California San Diego, San Diego, California, United States

  • William T. Kent

    1   Department of Orthopaedic Surgery, University of California San Diego, San Diego, California, United States

Funding Information None.
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Abstract

Despite urgent operative management of septic knee arthritis with irrigation and debridement and culture-specific antibiotic therapy, the incidence of additional washouts in knee septic arthritis has been noted to be between 11.4 and 40%. The purpose of this study was to analyze preoperative and postoperative variables associated with failure of primary washout in septic knees. A retrospective review was conducted at a Level I trauma center for all patients with septic arthritis who underwent open irrigation and debridement from 2010 to 2023. Patients were excluded if they were noted to have a knee arthroplasty or additional infection source aside from bacteremia. Demographic information, comorbidities, dates of operative washouts, vitals, and inflammatory markers were noted. Ninety-seven patients met inclusion and exclusion criteria. Forty-two required an additional washout. The average number of days between the primary and secondary washouts was 4.9 days. Decreased age (p = 0.03) and primary Staphylococcus aureus culture (p < 0.01) were found to be significantly associated with failure of the primary washout. Preoperative vitals, inflammatory markers, age, body mass index, intravenous drug use, diabetes, and smoking were not found to be predictors of repeat septic knee washouts. Additional subgroup analysis on bacteremic patients and on C-reactive protein (CRP) trends postoperative day 1 and 2 found no significant predictors of single or repeat septic knee washout. Younger age and presence of S. aureus in aspiration cultures were significantly associated with failure of primary washout. Trending CRP in the immediate postoperative period is not an accurate predictor of repeat septic knee washout.

Keywords

septic knee arthritis - risk factors - predictors - incision and drainage

Ethical Approval

This study was conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments. Institutional Review Board (IRB) approval was obtained prior to initiation of the study (IRB #808374).


Data Availability Statement

The datasets generated during and/or analyzed during the current study are not publicly available, but are available from the corresponding author on reasonable request.




Publication History

Received: 18 August 2025

Accepted: 25 November 2025

Accepted Manuscript online:
27 November 2025

Article published online:
19 December 2025

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