Peak Serum Vancomycin Levels Are Achieved Between 6 and 24 Hours After Implantation of Vancomycin-Soaked Anterior Cruciate Ligament Grafts.

PURPOSE: To examine systemic exposure and elution characteristics of liquid vancomycin-soaked anterior cruciate ligament (ACL) grafts in vivo by assessing serum vancomycin levels over 48 hours after ACL reconstruction and comparing the resulting concentrations with the toxic threshold of 15 to 20 μg/mL. METHODS: Patients consenting between October 2023 and January 2024 and undergoing isolated ACL reconstruction or 2-stage revision after tunnel bone grafting were included. Hamstring or quadriceps grafts were used, with or without meniscal surgery. Six blood samples were taken, first preoperatively and second 10 minutes after tourniquet release and each at 1, 6 to 8, 24, and 48 hours. Soaking time was measured. Vancomycin concentrations were analyzed by tandem mass spectrometry and high-performance liquid chromatography. Spearman rho correlation coefficients were used to identify relations between the parameters. A P value of <.05 was considered statistically significant. RESULTS: The study included 21 patients (17 men, 4 women, median age: 36, interquartile range [IQR] 16). The highest median levels of vancomycin detectable in peripheral blood were observed both 6 to 8 hours (0.0050 μg/mL, IQR 0.0079 μg/mL) and 24 hours (0.0050 μg/mL, IQR 0.0144 μg/mL) postoperatively. After 48 hours, a median concentration of 0.0021 μg/mL (IQR 0.0032 μg/mL) could still be detected. The maximum serum concentration of vancomycin in all samples was 0.704 μg/mL. Significant correlation was found between the soaking time and measured maximum vancomycin serum concentrations (r = 0.497; P = .022). CONCLUSIONS: Systemic vancomycin concentrations after implantation of a liquid vancomycin-soaked ACL graft remained well below the established toxic threshold for adverse effects. Additionally, peak systemic concentrations occurred 6 to 24 hours postoperatively, with graft soaking time identified as a factor that significantly influenced systemic levels. LEVEL OF EVIDENCE: Level IV, prospective case series.