Vancomycin presoaking of hamstring autografts in ACL reconstruction is associated with higher MRI graft signal without influencing clinical outcome.

PURPOSE To present the clinical and imaging results of a series of patients undergoing anterior cruciate ligament reconstruction (ACLR) with vancomycin presoaking of the hamstring autograft, compared to patients in the immediate period prior where no vancomycin was used. METHODS A retrospective sequential series of patients with ACLR using either a non-vancomycin presoaking graft protocol (group 1, January 2013-October 2015) or vancomycin presoaking graft protocol (group 2, November 2015-December 2018). Lysholm and International Knee Documentation Committee (IKDC) scores were obtained at a minimum 24-month follow-up. Graft ruptures were recorded. Between 6-12 months follow-up, magnetic resonance imaging (MRI) was obtained to evaluate graft healing and integration. RESULTS There were 102 patients (72% male), with 40 in group 1 (mean age 32.2 years) and 62 in group 2 (mean age 32.3). Five patients (13%) had a graft rupture in group 1 and six patients (10%) in group 2 (p=0.65). The median Lysholm score in group 1 was 95 [86-100] and 95 [90-100] in group 2 (p=0.37). The median IKDC score was 93 [82-99] in group 1 and 94 [86-99] in group 2 (p=0.22). MRI evaluation of integration found 87 patients (90%) had no synovial fluid at the tunnel-graft interface without differences between groups (p=0.24). Graft signal appearance found 45 patients hyperintense (46%), 45 (46%) isointense and 7 (7%)hypointens. Group 1 had a higher prevalence of hypointense grafts while group 2 had a higher prevalence of hyperintense and isointense grafts (p=0.003) CONCLUSIONS: Vancomycin presoaking of hamstrings grafts increased the number of hyperintense and isointense grafts on MRI. Additionally, more hypointense grafts were noted when vancomycin was not used, suggesting the presence of more mature grafts in the non-vancomycin group.