Mandibular resection in patients with head and neck cancer: acute and long-term complications after reconstruction

Biocompatibility Evaluation of an Artificial Metallic Bone with Lattice Structure for Reconstruction of Bone Defect

Mandibular reconstruction for large bone defects is performed with consideration of patients' specific morphology and sufficient strength. Metal additive manufacturing techniques have been used to develop biomaterials for mandibular reconstruction. Titanium artificial mandibles with a lattice structure have been proposed, and the optimal conditions for their strength to withstand mechanical stress around the mandible have been reported. This study investigated the biocompatibility of a titanium artificial bone with a lattice structure fabricated under optimal conditions. The samples were fabricated using metal additive manufacturing. Body diagonals with nodes (BDN) were selected as suitable lattice structures. Dode medium (DM) was selected for comparison. The samples were implanted into rabbit tibial defects and resected with the surrounding bone at two and four weeks. Specimens were evaluated radiographically, histologically, and histomorphometrically. Radiopacity in each lattice structure was observed at two and four weeks. Histological evaluation showed trabecular bone-like tissue inside the BDN compared to the DM at four weeks. No significant differences were noted in the bone volume inside the structures. This study demonstrated the in vivo compatibility of artificial metallic bones with a BDN structure under mechanical stress conditions.

Investigation of the Mechanical Strength of Artificial Metallic Mandibles with Lattice Structure for Mandibular Reconstruction

Mandibular reconstructive surgery is necessary for large bone defects. Although various reconstruction methods have been performed clinically, there is no mandibular reconstruction method that meets both sufficient strength criteria and the patient's specific morphology. In this study, the material strength of the cylindrical lattice structures formed by electron-beam melting additive manufacturing using titanium alloy powder was investigated for mandibular reconstruction. The virtual strengths of 28 lattice structures were compared using numerical material tests with finite element method software. Subsequently, to compare the material properties of the selected structures from the preliminary tests, compression test, static bending test and fatigue test were conducted. The results showed that there were correlations with relative density and significant differences among the various structures when comparing internal stress with deformation, although there was a possibility of localized stress concentration and non-uniform stress distribution based on the lattice structure characteristics. These results suggest that the lattice structure of body diagonals with nodes and a cell size of 3.0 mm is a potential candidate for metallic artificial mandibles in mandibular reconstruction surgery.

Safety and reliability of the internal jugular vein for venous anastomoses in head and neck oncological reconstruction: A retrospective study

This study aimed to assess the efficacy of utilizing the internal jugular vein (IJV) as the primary recipient site for venous anastomoses in head and neck oncological reconstruction. Patients who underwent a free flap reconstruction of the head and neck were retrospectively included. Venous anastomoses were preferentially performed less than 1 cm from the IJV, either end-to-side (EtS) on the IJV, or end-to-end (EtE) on the origin of the thyrolingofacial venous (TLF) trunk. When the pedicle length was insufficient to reach the IJV, anastomoses were performed EtE to a size-matched cervical vein. Of the 246 venous anastomoses, 216 (87.8%) were performed less than 1 cm from the IJV, including 150 EtS on the IJV (61.0%), and 66 EtE on the TLF trunk (26.8%). Thirty veins (12.1%) were anastomosed EtE on other cervical veins more than 1 cm from the IJV. Two venous thromboses occurred (0.9%) and were successfully managed after revision surgery. There was no evidence of an increased thrombosis rate in high-risk or pre-irradiated patients. These findings suggest that the internal jugular vein is safe and reliable as a first-choice recipient vessel for free flap transfers in head and neck oncological reconstruction.