Nicotine Exposure Via Electronic Cigarettes Significantly Impedes Biomechanical Healing Properties of Tendon Healing in a Rat Model.

Abstract

PURPOSE\nThe purpose of this study was to evaluate the biomechanical and histological effects on Achilles tendon repair between inhaled combusted tobacco versus nicotine exposure via electronic cigarette versus a control group in a small animal (Sprague Dawley Rat) model.\n\n\nMETHODS\nFifty-four Sprague Dawley rats were randomized to three groups: 1) combusted tobacco, 2) e-cigarettes 3) control. Experimental rats were exposed in a smoking chamber for 4 weeks with research cigarettes or electronic cigarette vapor. Surgical transection and repair of the Achilles tendon was then completed, followed by 2 additional weeks of exposure. Achilles tendons were harvested, and biomechanical tensile testing was performed. Histology was completed including hematoxylin and eosin (H&E) staining, Trichrome staining, and immunohistochemistry analysis for collagen type I and Type III.\n\n\nRESULTS\nThe control group demonstrated the highest mean tensile load to failure of 41.0 ± 10.4 N (18.3-55.1 N), the cigarette cohort had the second highest mean at 37.3 ± 11.1 N (14.0-54.7 N), and finally the vaping group had the lowest mean at 32.3 ± 8.4 N (17.8-45.1 N). One-way ANOVA showed a significant difference in load to failure when comparing controls to e-cigarettes (p=0.026). No statistical difference was detected between controls vs cigarettes (p=0.35) or e-cigarettes vs cigarettes (p=0.23). Stiffness and qualitative histological analysis demonstrated no difference among groups.\n\n\nCONCLUSION\nThe investigation demonstrates that in a rat model, nicotine exposure via electronic cigarette significantly impedes biomechanical healing properties of Achilles tendon surgical repair.