INFLUENCE OF PROSTHESIS SONICATION RESULTS ON CLINICAL OUTCOMES

Background Diagnosing periprosthetic joint infection (PJI) in patients who do not meet Musculoskeletal Infection Society (MSIS) criteria and have negative intraoperative cultures remains challenging. Implant sonication improves detection of biofilm-associated organisms; however, the clinical significance of positive sonication results in otherwise aseptic patients remains controversial. This study evaluated the impact of positive sonication in MSIS-negative, culture-negative patients. Methods A retrospective cohort study was performed on patients undergoing revision total joint arthroplasty between January 2016 and September 2025. Patients were stratified by MSIS criteria, tissue cultures, and sonication results. Cases with inconclusive MSIS classification, inadequate preoperative workup, or non-revision procedures were excluded. The aseptic cohort included patients who were MSIS-negative with negative tissue cultures and was stratified by sonication (positive vs negative). Outcomes included return to the operating room (RTOR), RTOR for PJI, RTOR within two years for PJI, and mortality. A subgroup analysis compared sonication-positive patients treated as PJI to a cohort with confirmed MSIS-positive PJI. Significance was set at p < 0.05. Results Among 751 aseptic cases, 119 were sonication-positive and 632 sonication-negative. The sonication-positive group had a higher proportion of THA (64.7% vs 36.6%, p < 0.001), was younger (64.5 vs 68.1 years, p = 0.0003), had lower ASA grade (2.55 vs 2.72, p = 0.002), and longer operative times (142.6 vs 125.2 minutes, p = 0.0004). No differences were observed in sex, BMI, anesthesia, or laterality. Overall RTOR rates were similar; however, RTOR for PJI (10.9% vs 4.1%, p = 0.002) and RTOR within two years for PJI (7.6% vs 3.0%, p = 0.016) were higher in the sonication-positive group. Mortality and time to death were similar. Of 119 sonication-positive patients, 22 were treated as PJI and compared to 318 MSIS-positive cases. The treated sonication-positive group had a higher proportion of THA (81.8% vs 38.1%, p < 0.001), was younger (61.5 vs 67.3 years, p = 0.006), and had lower ASA grade (2.50 vs 2.88, p = 0.0012). There were no significant differences in overall RTOR (31.8% vs 39.6%, p = 0.468), RTOR for PJI (13.6% vs 25.2%, p = 0.224), RTOR within two years for PJI (9.1% vs 21.1%, p = 0.177), or mortality between groups. Conclusion Positive sonication in aseptic patients is associated with increased infection reoperation rates. Patients treated as PJI based on sonication alone demonstrated outcomes comparable to confirmed PJI. This suggests sonication may identify early occult infection and guide management.