experimental tests on new titanium alloy interbody cervical cages

Abstract Degenerative diseases of the spine, when not solvable with clinical treatments or with suitable stabilization systems, can be cured by means of the technique of arthrodesis through the interbody fusion of two or more vertebrae. The paper deals with the tests carried out on commercial and innovative cervical cages, used in the primary stabilization of the vertebrae, able to maintain the right distance and to assure the interbody fusion. Additive manufacturing (AM) is a powerful new tool offering the necessary competitiveness to the biomedical manufacturing companies, having the possibility to create materials with controlled porosity combined with solid parts, providing to the workpiece excellent capacity in the subsequent phases of osseointegration. Based on the knowledge developed either in the biomechanics of the spine or in the properties of biocompatibility and osseointegration of titanium alloys, MT Ortho has developed some models of cervical cage made from modern additive printing techniques with titanium alloy. Three different cervical cage made of different materials were subjected to static compression test: a commercial cervical intervertebral cage in PEEK and two cervical intervertebral cages in Ti alloy produced by the EBM process by MT Ortho. Tests on the innovative cage produced by EBM have shown encouraging results. From this first preliminary analysis its showed that the mechanical and functional failure of the innovative devices made in melted Ti alloy by EBM is achieved by load values greater than physiological ones of the cervical spine

Experimental analysis of pedicle screws

AbstractAim of this study is to examine the mechanical properties of pedicle screws in titanium alloy obtained by the process of additive manufacturing (Electron Beam Melting, EBM) and compare them with those of screws obtained with traditional techniques. EBM is a methodology able to process metallic powders layer-by-layer. Pedicle screw-produced by the EBM process by the MT Ortho (VS), and commercial screws (VC and VT) were examined.VS screws showed lower resistance to pull-out tests than VC and VT screws. This behavior can be attributed to a lower sharpness and a lower depth of thread. These features, which may be negative from the point of view of the resistance to pull-out tests, could have positive effects from the point of view of stress concentration on bone. To analyze these effects, fatigue pull-out tests were also carried out and the different screw-bone interface behavior was evaluated using photoelasticity and finite element analysis.The results obtained by numerical simulation confirm what was previously stated, a thread with a geometry less sharpened ensures a better distribution of the loads and reduces the notch effect, allowing a balance of the disadvantage due to the lower primary stabilization.The fatigue limit and fatigue curve were obtained by the thermographic (Risitano) method. Even with a limited number of tests, the thermographic technique allows the prediction of the limit of fatigue and of the whole fatigue curve

Mandibular Reconstruction with Bridging Customized Plate after Ablative Surgery for ONJ: A Multi-Centric Case Series

Purpose: Computer-aided methods for mandibular reconstruction have improved both functional and morphological results in patients who underwent segmental mandibular resection. The purpose of this study is to evaluate the overlaying of virtual planning in terms of measures of the Computer Assisted Design/Computer Assisted Manufacturing CAD/CAM plate for mandibular reconstruction in patients who are ineligible for the insertion of reconstructing the titanium plate supported by fibular free flap, due to their poor health status, or in the presence of specific contraindications to autologous bone flap harvest. Materials and methods: The retrospective study performed analyzed the results of nine patients. The patients were treated at the Maxillofacial Surgery Unit of Policlinico S. Orsola of Bologna, Italy, and Policlinico San Marco, Catania, Italy, from April 2016 to June 2021. Superimposition between planning and post operative Computed Tomography CT scan was performed to assess the accuracy. Results: All reconstructive procedures were carried out successfully. No microsurgery-related complications occurred. In two cases, we had plate misplacement, and in one case, plate exposure that led to plate removal. The average accuracy of the series assessed after CT superimposition, as previously described, was 0.95 mm. Conclusions: Considering that microvascular bone transfer is a high-risk procedure in BRONJ patients, we can conclude that the positioning of a customized bridging mandibular prosthesis (CBMP), whether or not it is associated with a microvascular soft tissue transfer, is a safe technique in terms of surgical outcome and feasibility