Association of Bacterial Biofilm with Tunnel Widening in Anterior Cruciate Ligament Revision Surgery

Abstract

Revision Anterior Cruciate Ligament Reconstruction (rACLR) surgery demonstrates to be a challenging issue for both patients and their surgeons, where its long-term outcomes have proven to be poorer to primary ACL reconstruction surgery. Although tunnel lysis or enlargement after ACL reconstruction surgery is well documented, little is known about its mechanisms and etiology. Using novel microbial detection technologies, studies have not only shown the presence of biofilms in failed orthopedic procedures but also confirmed different bacterial cultures between failed reconstructions and the normal flora. The aim of the current study was to determine if there is a difference in tibial and femoral tunnel widening between cases with and without bacterial biofilm presence. This was a cross-sectional analysis of data collected from patients who underwent ACL reconstruction surgery between 2014 to 2018. This study included 62 rACLR cases and were evaluated for inclusion in the study through chart review. The tibial tunnel widening was assessed using magnetic resonance imaging (MRI) by examining the long, short, and diagonal measurements at an axial view. Femoral tunnel widening was assessed using MRI and measuring the diameter of the tunnel three consecutive times through a sagittal view. Bacterial biofilms were defined as a measurement of bacterial DNA >10 ng or a positive AGAR culture. Summary statistics and analysis was performed. The mean age for the cohort was 28.02 years (SD=10.34) with a mean of 5 .14 years till failure (SD=5.71). Of the patients who had their tibial tunnel measured, those who had biofilms observed (n=19) had a mean tibial tunnel measurement of 12.62 mm and those who had no biofilm present (n=42) had a mean tibial tunnel size of 11.25 mm (P=0.05). The mean femoral tunnel size for patients with biofilms present (n=19) was 10.69 mm compared to a mean of 9.69 mm for those without biofilms (n=42) (P=0.28). The current study suggests that patients with observed bacterial biofilms after ACL reconstructions have greater increase in tibial tunnel widening than those without infection. This study provides further evidence on the role bacteria may play in tunnel widening and prompts additional research on this association.