The impact of surgical timing on reoperation after arthroscopic versus open treatment of acute native knee septic arthritis.

PURPOSE: To investigate the effect of surgical timing and surgical technique on reoperation rates and early clinical outcomes in acute native knee septic arthritis.

METHODS

This retrospective cohort study included adult patients who underwent surgical treatment for acute native knee septic arthritis between 2018 and 2025. Patients were treated with either arthroscopic or open debridement according to the treating surgeon's assessment. Time from symptom onset to surgery was recorded in hours, and an a priori defined 48-h threshold was used to classify early versus delayed lavage. All cases received standardized joint irrigation with nine L of normal saline. The primary outcome was the need for reoperation due to persistent or recurrent infection. Secondary outcomes included knee range of motion at discharge and length of hospital stay. Culture-positive cases were analyzed separately. Multivariable logistic regression analysis was performed to identify independent predictors of reoperation.

RESULTS

A total of 129 patients were included (mean age 58.3 ± 12.3 years; 62.8% male). Baseline demographic and comorbidity characteristics were similar between surgical technique groups; however, early lavage was more frequent in the arthroscopy group (p < 0.001). In early lavage cases, reoperation rates did not differ between arthroscopy and arthrotomy (p = 0.432). In delayed lavage cases, arthroscopy was associated with a significantly higher reoperation rate compared to arthrotomy (p < 0.001). Arthroscopy resulted in greater postoperative range of motion across all subgroups (p < 0.001). Length of hospital stay was shorter with arthroscopy in early lavage but longer in delayed lavage. Early lavage was independently associated with a reduced risk of reoperation (OR 0.02; 95% CI 0.00-0.10; p < 0.001).

CONCLUSION

In acute native knee septic arthritis, our findings suggest that surgical timing may influence the relative outcomes of arthroscopic and open treatment. Early arthroscopic lavage may provide functional advantages without increasing the risk of reoperation, whereas delayed arthroscopy may be associated with higher reoperation rates. Prospective studies are warranted to confirm these observations.