Background
Studies revealed that vancomycin-soaking of hamstring autograft could drastically reduce the incidence of postoperative infections following ACL-Reconstruction. However, it remains unclear whether chondrotoxic thresholds of Vancomycin in the synovial fluid are reached. Several studies investigated the chondrotoxic concentration of Vancomycin in in-vitro experiments and described 1000 µg/ml as a critical threshold. The purpose of this study was to measure the Vancomycin-concentration in the synovial fluid following Anterior Cruciate Ligament (ACL)-Reconstruction with vancomycin-soaked autografts. It was hypothesized that intra-articular Vancomycin-concentrations in synovial fluid do not reach a chondrotoxic threshold of 1000 µg/ml following Vancomycin-Soaking of autologous Semitendinosus and soft tissue quadriceps grafts for ACL Reconstruction.
Methods
This study included 10 patients undergoing an ACL-Reconstruction using four-strand semitendinosus tendon autografts and 10 patients undergoing an ACL-Reconstruction using soft tissue quadriceps tendon autografts. Each graft was intraoperatively wrapped in 5 mg/ml vancomycin-soaked gauze swabs prior to implantation. Following wound closure, an aspirate of 5 ml synovial fluid was taken from each patient. Time was measured from soaking to implantation and from implantation to aspiration. In addition, the graft size was noted, and remnant ACL tissue was preserved. The aspirates were analyzed using high-performance liquid chromatography and mass spectrometry (HPLC/MS) regarding the vancomycin concentration. Spearman-Rho correlation coefficients were used to identify relations between the parameters and t-test to test for differences between the grafts. A p-value of < 0.05 was considered statistically significant.
Results
20 patients ( 15 women; 5 men, 29.35 ± 11.3 years) were included in the study. The mean concentration of Vancomycin measured in the synovial fluid was 23.229µg/ml (± 21.68 µg/ml) with a minimal concentration of 2.324µg/ml and a maximal concentration of 71.564µg/ml. There was no significant difference between the two grafts (p=0.911). A significant positive correlation (r = .644 p <0.05) was observed between the concentration of Vancomycin and the duration (13.4min ± 6min) from Vancomycin soaking of semitendinosus grafts to implantation. No correlations were observed between the concentration of Vancomycin and the duration from implantation to fluid aspiration (r=-0.73 p=0,841) as well as the concentration of Vancomycin and the graft diameter (Median 8.5mm Range 6.0-10.0mm r=-0.026 p =0.914) for both grafts.
Conclusion
Chondrotoxic concentrations of equal to or greater than 1000µg/ml were not reached in any aspiration of synovial fluid following ACL-Reconstruction using soft tissue autografts that were intraoperatively soaked in a 5mg/ml vancomycin solution. Against the backdrop of multiple studies showing significantly reduced infection rates after ACLR when using vancomycin-soaking of the graft, this study distinctly attenuates the counter-argument of the chondrotoxic side effects of this method.