Novel indirect additive manufacturing for processing biomaterials

PhD ThesisThe aim of this work was to identify methods for the production of patient-specific biomedical devices via indirect additive manufacturing (AM) methods. Additive manufacturing has been shown to provide a good solution for the manufacture of patient specific implants, but in a limited range of materials, and at a relatively high cost. This research project considered what are known as “indirect” AM approaches, which typically consider AM in combination with one or more subsequent processes in order to produce a part, with a maxillofacial plate and mandible resection used as a demonstrator application. Three different approaches were considered: (i) using AM to produce moulds for powder pressing of bioceramic green parts for subsequent sintering; (ii) using AM to produce moulds for biopolymer sintering; and (iii) 3D printing of bioceramic powders into green parts for subsequent sintering. Apatite wollastonite glass ceramic (AW) and poly-Lactide-co-glycolide (PLGA) were selected as the bioceramic and biopolymer materials to process. These were characterised before and after processing in order to ensure that the processing route did not affect the material properties. Geometric dimensions, the morphological structure and mechanical properties were studied to establish the accuracy, shrinkage and strength of the fabricated biomaterial implants. The use of AM processes to produce moulds for PLGA sintering, and the 3D printing of bioceramic powders formed the best overall results in terms of the definition and properties of the manufactured parts. Parts produced were accurate to within 5% of the as designed dimensions for both the PLGA sintering and the bioceramic powders 3D printing. The indirect AM methods are considered to be promising processing routes for medical devices.University Malaysia Perlis and the Malaysian Higher Education Ministr

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

A study of affect in slices and support parameters on dimensional accuracy for FDM prototype

Rapid prototyping process enables creation of complex physical components in relatively shorter building time and wide materials utilization. Fused deposition modeling, often referred FDM, is a type of rapid prototyping (RP) technology commonly used within engineering design and manufacturing environment. FOM works on an "additive" principle by laying own material in layers. 3D models are translated into .STL file to be used in FDM machine. The model is built up from layers the plastic hardens immediately after extrusion from the , nozzle. The data preparation process in the FDM machine prior , prototype building involves lot of parameters setting. The ffect of these parameters on the product needs to be evaluated or obtaining product with optimum quality. This project study e effect of slice thickness and support parameters on the Water , luble System, Fused Deposition Modeling (FDM) product i~ality in terms of dimensional accuracy produced during part ~uilding. The results obtained show that considered parameters fluence the studied responses. The influences on the angular imensional accuracies are higher as compare to the linear dimensions. Future work studies are being conducted to hance the knowledge in understanding parameters setting that canbe utilized to produce better quality product

A preliminary study on FDM prototype surface roughness

Rapid prototyping (RP) is often used to describe the technologies that are used to fabricate physical objects directly from 3D CAD model. And sometime is also known as Solid Freeform Fabrication (SFF). These methods are generally similar to each other in that they add and bond materials in layer wise fashion to form 3 dimensional objects. Processes such as stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), layered object modeling (LOM) and 3D Printing (3DP) are part of this technology. This project study the effect of slice thickness and support parameters on the Water Soluble System, Fused Deposition Modeling (FDM) product quality in terms of surface roughness produced during part building. The results obtained show that slice thickness and support parameters influence the studied responses. The thickness of the support structures has affected the surface roughness obtained

Fracture risk prediction on children with osteogenesis imperfecta subjected to loads under activity of daily living

Children with Osteogenesis Imperfecta (OI) often vulnerable to fracture even on their daily basic tasks. The unpredicted fracture leads to intramedullary surgery. This study aims to investigate the fracture risk in children with OI in daily basic tasks including standing, walking, and jumping. Ten models of OI finite elements were reconstructed based on the radiography CT image of enrolled OI patients. An actual body weight of OI patient was used as the main force acting vertically towards the femoral head and then the fracture risk was observed. In standing and walking configuration, all ten OI models were found able to sustain the acted load. Whereas in jumping configuration, all OI models suffered to become fracture. Early prediction of fracture risk could help medical personnel and OI patients from fall or injury

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)