gms | German Medical Science

Objectives: A feared complication of anterior cruciate ligament (ACL) reconstruction is postoperativ septic knee arthritis. Studies revealed that in vancomycin-soaking of hamstring autografts can drastically reduce the incidence of postoperative infections following ACL-Recontruction, 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 1,000 ug/ml as critical threshold. Therefore, the aim of the present study was to measure the Vancomycin-concentration in the synovial fluid following ACL-Reconstruction with vancomycin-soaked autografts.

Methods: This prospective observational study included 10 patients undergoing an ACL-Reconstruction using four-strand semitendinosus 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 of each patient. Time was measured from soaking to implantation and from implantation to aspiration. In addition, the graft size was noted and whether 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. A p-value of < 0.05 was considered statistically significant.

Results and conclusion: 10 patients (2 women, 28.4 ± 11.6 years; 8 men, 31.7 ± 12.4 years) were included in the study. The mean concentration of Vancomycin measured in the synovial fluid was 21.44 ug/ml (± 22.37 ug/ml) with a minimal concentration of 2.32 ug/ml and a maximal concentration 71.56 ug/ml. Significant positive correlation (r = .644 p <0.05) was observed between the concentration of Vancomycin and the duration (13.4 min ± 6 min) from Vancomycin soaking to graft 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 6.0-9.0mm r=0.031 p =0.931). There was no significant difference regarding the concentration of Vancomycin in the synovial fluid with and without a preserved remnant (p=.108).

Chondrotoxic concentrations of equal to or greater 1,000 ug/ml were not reached in any aspiration of synovial fluid following ACL-Reconstruction using semitendinosus autografts that were intraoperatively soaked in a 5 mg/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 chondrotoxic side effects of this method.