3D Printing Conference

Addressing the challenge of balancing rapid degradation and insufficient bio-regenerative capabilities in biodegradable magnesium (Mg) alloys for bone repair is a significant endeavor. In this study, we investigate the influence of Scandium (Sc) content on the microstructure, strength, degradation, cytotoxicity, angiogenesis, and osteogenesis of Mg-4Yttrium(Y)-xSc alloy system, and successfully develop a novel alloy Mg-4Y-2.25Sc (wt.%) that significantly inhibit degradation and promote bone regeneration. This achievement is contributed to the combination of the alloying and high-temperature oxidation (HTO) treatment, guided by a thermodynamic calculation model. The performance of our alloy notably surpasses that of the widely used biodegradable WE43 alloy. At the microstructural level, a thin and dense protective film of Y2O3/Sc2O3 is introduced to form a passivation effect. The synergetic release of Mg and Sc ions significantly promotes angiogenesis and osteogenesis. In vivo results verifies that Mg-4Y-2.25Sc implants promote osseointegration of implants during the bone healing cycle. In summary, the alloying system treated by HTO effectively modulates the degradation rate of Mg alloys without complex surface modification, providing a promising bone-repairing material for successful implantation.

Abstract

Additive Manufacturing (AM) has a great potential to reduce carbon emission and energy consumption compared to traditional subtractive manufacturing. Different research activities have been conducted for the life cycle assessment of AM. Most of the existing research considers that the product design solution has a big impact on the AM sustainability. There is a lack of systematic methods to investigate and optimize AM process parameters for daily AM operations to achieve the sustainable solution. This paper investigates process parameters for AM sustainability using design of experiment and machine learning (ML) methods. The objective is to reduce production time, energy and material consumptions in AM process to achieve the AM sustainability. AM process parameters considered in the investigation include the printing layer height, build orientation, number of shells, infill percentage, infill type, printing speed and temperature. Responses of different sets of parameters are AM sustainable measures including production time and consumptions of material and energy. Taguchi orthogonal array is formed based on different levels of factors for experiments of product samples to collect data for training and verifying the ML model. Analysis of variances with the contribution percentages is applied to find each parameter contributions for the variables. Machine learning methods are evaluated using the experimental data to search optimal parameter settings for the sustainable solutions.

Biography

Qingjin Peng received his Ph.D. degree in manufacturing engineering from the University of
Birmingham, U.K., in 1998. He is a Professor at the Department of Mechanical Engineering,
University of Manitoba, Canada. Dr. Peng has published more than 300 refereed papers in
international journals and conferences. He has served as chairs and committee members for many
organizations and conferences. His research interests include digital manufacturing, and sustainable
product development. Dr. Peng is a registered professional engineer in Manitoba.

Abstract

Patient custom 3D printed implant represent a novel strategy for managing segmental bone defects. This article illustrates the key technical points of this innovative method to treat segmental irregular-shaped bone defect in the lower limb bone defect. 20 cases with large segmental irregular-shaped bone defect of the lower limb were treated with 3D printed prosthesis combined intramedullary fixation without bone graft between 2017.12 and 2022.12. Routine clinical review is conducted with plain radiographs and computed tomography (CT) scan to assess bone incorporation and complications of internal fixation. The weight-bearing time and the joint function of the patients were recorded. 20 patients were followed up for an average of 16.4 months. The length of bone defect was 8.5-15.5 cm (average 12 cm).  The average time of partial weight-bearing was 12.7 days. The average time of full weight-bearing was 2.6 months. Three patients experienced complications such as prosthesis loosening and infection, requiring further surgical treatment. X-ray and CT scan demonstrated good osseous integration of the implant/bone interface. At the last follow-up, HSS score of knee joint was good in 17 cases. Meticulous designed 3D printed micro-porous prosthesis combined with intramedullary fixation without bone graft may be a cost-effective and an alternative strategy to treat segmental irregular-shaped lower limb bone defect, especially for cases with massive juxta-articular bone loss. Oeteogenesis can be achieved at the interface of prosthesis and bone stump without bone graft.

Biography

Yun Tian is a physician-in-charge from Peking University Third Hospital, Beijing, China.

Abstract

Management of critical-sized bone defects (CBDs) remains challenging in clinical practice. Our team has independently developed a Trauma Custom Bridge (TCBridge) system based on 3D printing technology specially for repairing CBDs and applied it clinically for over 7 years. In this study, we performed finite element analysis (FEA) using different types of 3D-printed prostheses to reconstruct femoral and tibial CBDs. The FEA confirmed that stress mainly concentrated on the proximal areas of the femur and tibia and the marginal ends of prostheses during the dynamic stepping process. Then, we systematically summarized the clinical experience and follow-up results.
Thirty-two patients (33 defects) were enrolled and divided into the Femoral and Tibial CBDs groups. The average length and percentage of defects in the total bones were 13.6 cm and 35.1%, respectively. After prosthesis implantation, the patients’ average beginning time of weight-bearing and follow-up periods were 10.5 days and 32.4 months. For bone length, patients from the Femoral and Tibial CBDs groups achieved an average lengthening length of 1.2 cm and 1.8 cm. New bone gradually grew from the healthy bone ends and then crawled and wrapped along the prosthesis. The average LEFS of patients in the Femoral and Tibial CBDs groups increased to 55.3 and 52.8 at the last follow-up, significantly higher than that recorded before surgery (P < 0.001). In conclusion,
applying TCBridge system is effective for repairing femur and tibia CBDs. Bone shortening was significantly improved, early weight-bearing was achieved, and new bone continued to regenerate and osseointegrate with the prosthesis, ultimately facilitating better limb function.

Biography

Liu bingchuan is a physician-in-charge from Peking University Third Hospital, Beijing, China. He received M.D. qualification from Peking University. Dr. Liu has been studying 3D printing technology and devoting to promote its clinical application for more than 5 years. He has published over eight related papers. Particularly, his team has completed the clinical transformation for a Trauma Custom Bridge (TCBridge) system, which is the first to repair critical-sized bone defects of limbs in China.