Préconditionnement laser en site osseux membraneux : mise au point d’un modèle d’étude

Abstract

Objective The application of a supraphysiologic stress (preconditioning) prior to an injury induces cellular and tissular resistance on soft tissues. The aim of this study is to evaluate X-ray irradiated bone healing with and without laser preconditioning. Materials and methods The laser shot is defined to induce a controlled increase of the bone temperature. Then, bone healing is in vivo observed through the evolution of the vascularization process. Optical chambers implanted on the skull of 20 rabbits allow the weekly observation of bone vascular plexus during 12 weeks. An original image processing determines the vascular density (VD) on four groups: #1: control group ( n = 5); #2: laser treatment ( n = 5); #3: X-ray irradiation ( n = 5); #4: laser preconditioning prior to X-ray irradiation ( n = 5). Results Preconditioning is performed by a diode-laser (815 nm, 36 J/cm 2). VD remains stable during the 12-week follow up for groups #1 and #2. X-ray radiation induces a significant decrease of the vascular network in groups #3 and #4 compared to the group #1 ( p < 0.001). However, the decrease of the vascularization is limited in group #4 versus group #3 ( p < 0.05). Discussion This in vivo original model reproducibly evaluates VD and the impact of different stresses on bone healing. Laser treatment is a controlled heating method, which preserves the vascular network of X-ray irradiated bone. This innovative approach promotes the bone healing in which the vascular supply has been damaged.