Predictors of Repeat Washout in the Isolated Septic Knee

Area of Science:

• Orthopedic Surgery
• Infectious Diseases
• Clinical Research

Background:

• Septic knee arthritis requires prompt surgical intervention, including irrigation and debridement, alongside antibiotics.
• Despite treatment, 11.4-40% of patients need further surgical washouts.

Purpose of the Study:

• To identify preoperative and postoperative factors predicting the failure of initial washout in septic knees.
• To analyze variables associated with repeat surgical interventions for knee septic arthritis.

Main Methods:

• Retrospective review of 97 patients with septic arthritis undergoing open irrigation and debridement (2010-2023) at a Level I trauma center.
• Exclusion criteria included knee arthroplasty and non-bacteremic infection sources.
• Data collected: demographics, comorbidities, washout dates, vitals, inflammatory markers.

Main Results:

• Forty-two of 97 patients (43.3%) required an additional washout, averaging 4.9 days post-primary surgery.
• Younger age (p=0.03) and positive Staphylococcus aureus cultures (p<0.01) were significantly associated with primary washout failure.
• Preoperative factors (vitals, BMI, comorbidities) and postoperative C-reactive protein trends did not predict repeat washouts.

Conclusions:

• Younger patient age and S. aureus infection are key indicators for potential failure of primary washout in septic knee arthritis.
• Postoperative CRP trends are not reliable predictors for repeat washouts in septic knee arthritis.