Pierre Haen1, Guillaume Dubois2, Patrick Goudot3, Thomas Schouman3. 1. Service de stomatologie et chirurgie maxillo-faciale, Hôpital Laveran, Boulevard Laveran, 13013, Marseille, France; Service de stomatologie et chirurgie maxillo-faciale, DHU FAST, groupe hospitalier Pitié-Salpêtrière Charles-Foix, AP-HP, 75013, Paris, France. Electronic address: pierre.haen@yahoo.fr. 2. OBL, Materialise Compagny, Châtillon, France; Arts et Métiers, ParisTech, Institut de Biomécanique Humaine Georges Charpak, Paris, France. 3. Service de stomatologie et chirurgie maxillo-faciale, DHU FAST, groupe hospitalier Pitié-Salpêtrière Charles-Foix, AP-HP, 75013, Paris, France.
Abstract
INTRODUCTION: Parietal bone grafts are commonly used in cranio-maxillo-facial surgery. Both the outer and the internal layer of the calvarium can be harvested. The bone defect created by this harvesting may induce significant weakening of the skull that has not been extensively evaluated. Our aim was to evaluate the consequences of parietal bone graft harvesting on mechanical properties of the skull using a finite element analysis. METHODS: Finite elements models of the skull of 3 adult patients were created from CT scans. Parietal external and internal layer harvest models were created. Frontal, lateral, and parietal loading were modeled and von Mises stress distributions were compared. RESULTS: The maximal von Mises stress was higher for models of bone harvesting, both on the whole skull and at the harvested site. Maximal von Mises stress was even higher for models with internal layer defect. CONCLUSIONS: Harvesting parietal bone modifies the skull's mechanical strength and can increase the risk of skull fracture, mainly on the harvested site. Outer layer parietal graft harvesting is indicated. Graft harvesting located in the upper part of the parietal bone, close to the sagittal suture and with smooth internal edges and corners should limit the risk of fracture.
INTRODUCTION: Parietal bone grafts are commonly used in cranio-maxillo-facial surgery. Both the outer and the internal layer of the calvarium can be harvested. The bone defect created by this harvesting may induce significant weakening of the skull that has not been extensively evaluated. Our aim was to evaluate the consequences of parietal bone graft harvesting on mechanical properties of the skull using a finite element analysis. METHODS: Finite elements models of the skull of 3 adult patients were created from CT scans. Parietal external and internal layer harvest models were created. Frontal, lateral, and parietal loading were modeled and von Mises stress distributions were compared. RESULTS: The maximal von Mises stress was higher for models of bone harvesting, both on the whole skull and at the harvested site. Maximal von Mises stress was even higher for models with internal layer defect. CONCLUSIONS: Harvesting parietal bone modifies the skull's mechanical strength and can increase the risk of skull fracture, mainly on the harvested site. Outer layer parietal graft harvesting is indicated. Graft harvesting located in the upper part of the parietal bone, close to the sagittal suture and with smooth internal edges and corners should limit the risk of fracture.