Effects of Extracorporeal Shock Wave Therapyon Distraction Osteogenesis in Rat Mandible.

BACKGROUND: Distraction osteogenesis (DO) has widespread clinical use in the treatment of congenital and acquired craniofacial deformities. Nonetheless, during the prolonged consolidation period, the newly regenerated bone carries the risk of complications. One of the proposed methods to enhance bone healing and shorten the consolidation period is extracorporeal shock wave therapy (ESWT). In the field of orthopedics, ESWT has been shown to induce neovascularization and promote tissue regeneration. We investigated whether ESWT can accelerate bony consolidation and regeneration in distraction osteogenesis of the rat mandible and at which stage of DO it should be applied.

METHODS: 24 male Sprague Dawley rats were subjected to DO of the right mandible (latency period, 3 days; distraction period, 10 days, 0.5 mm/day). Experimental groups: group I (control) no ESWT: group II received ESWT (0.18 mJ/mm) at the latency period; group III received ESWT (0.18 mJ/mm) at the consolidation period. Explants were removed for evaluation following four weeks of consolidation.

RESULTS: Histological evaluation showed well developed cortical cortex and a higher degree of bone formation and mature bone in group III; µCT showed significantly increased bone mineral density, bone volume fraction and trabecular thickness; immunohistochemistry demonstrated significantly increased expression of Bone Morphogenetic Protein-2, Vascular Endothelial Growth Factor and PCNA.

CONCLUSIONS: ESWT application at the consolidation period during DO in the rat mandible enhances bone formation, osteogenic and angiogenic growth factors, improves bone mechanical properties and accelerates bone mineralization.