Biomechanical Analysis of Chlorhexidine Power Irrigation to Disinfect Contaminated Anterior Cruciate Ligament Grafts

Abstract

Background: Accidental graft contamination is a likely complication to occur in an orthopaedic sports medicine surgeon’s career. There are no clinical outcome studies to direct management, and a recent survey showed that preferred management varied. Three liters of 2% chlorhexidine power irrigation has been shown to be an efficient and effective disinfection protocol; however, the biomechanical sequelae of this disinfection protocol to the graft are unknown. Purpose: The purpose of this study was to determine if 3 L of 2% chlorhexidine power irrigation used to disinfect contaminated anterior cruciate ligament (ACL) grafts significantly weakens the graft at time zero. Study Design: Controlled laboratory study. Methods: Eight fresh bovine superficial digital flexor tendons underwent disinfection protocol with 3 L of 2% chlorhexidine power irrigation. Contralateral tendons served as the control. Tendons were preconditioned and loaded to failure. Results: The average ultimate failure load for the control tendons and disinfected tendons was 4081 ± 654.4 N and 4146 ± 723.2 N, respectively. The average ultimate failure stress for the control tendons and disinfected tendons was 97.10 ± 12.03 MPa and 95.18 ± 11.79 MPa, respectively. The average stiffness for the control tendons and disinfected tendons was 546.20 ± 28.16 N/mm and 539.2 ± 25.93 N/mm, respectively. The P values for ultimate failure load, ultimate failure stress, and stiffness showed no statistically significant difference between the chlorhexidine and control tendons. Conclusion: Disinfecting tendons with 3 L of 2% chlorhexidine power irrigation does not adversely weaken the tendon’s tensile mechanical properties. Clinical Relevance: Three liters of 2% chlorhexidine power irrigation can effectively disinfect a contaminated ACL graft without weakening the graft.