Changhui Song

Intraoperative anthropometric measurements of tibial morphology: comparisons with the dimensions of current tibial implants

PurposesThis study analyzed morphological differences in the resected proximal tibial surfaces of Chinese males and females undergoing total knee arthroplasty (TKA) and compared the measurements with the dimensions of five currently used tibial implants.MethodsThe mediolateral (ML), middle anteroposterior (AP), medial anteroposterior (MAP), and lateral anteroposterior (LAP) dimensions of the resected tibial surfaces of 976 Chinese TKA knees (177 male, 799 female) were measured. The ML/AP ratio of every knee was calculated. These morphological data were compared with the dimensions of five currently used tibial implants.ResultsThe ML, AP, MAP, and LAP dimensions of the resected proximal tibias showed significant differences according to gender. Compared with currently used tibial implants, the smaller implants showed tibial ML undersizing and the larger implants showed tibial ML overhang. The ML/AP aspect ratio progressively decreased with increasing AP dimension in the resected proximal tibias, which contrasts with the relatively constant or increased (NexGen) aspect ratio in currently used tibial implants. Males showed a higher ML/AP aspect ratio than females for a given AP dimension. This indicates that for an implant with a given AP dimension, the tibial ML dimension tends to be undersized in males and to overhang in females.ConclusionThe results of this study may provide fundamental data for designing suitable tibial implants for use in the Chinese population, especially for design of gender-specific prostheses.Level of evidenceII.

Characteristics of typical geometrical features shaped by selective laser melting

3D models that consisted of thin walls, sharp corners, cylinders, tetrahedrons, round and square holes were designed and constructed for this study, so that the capability of selective laser melting (SLM) to fabricate typical geometrical features could be ascertained and useful guidance for the direct manufacture of metallic parts presented. These geometrical features were produced via SLM using three devices (EOSING M270, SLM 250HL, and DiMetal-100) using 316 L stainless steel metal powders with optimized processing parameters. The similarities and differences between the geometrical features fabricated by three devices were compared and analyzed. Based on the experiments above, the additional geometrical features were further investigated to analyze the limits of both size and accuracy of each SLM-fabricated geometrical feature. Subsequently, the ability of SLM to produce inclined planes was studied, specifically the effects of inclination angle, scanning speed, and laser power on the quality of SLM-fab...

Personalized femoral component design and its direct manufacturing by selective laser melting

Purpose This paper aims to achieve rapid design and manufacturing of personalized total knee femoral component. Design/methodology/approach On the basis of a patient’s bone model, a matching personalized knee femoral component was rapidly designed with the help of computer-aided design method, then manufactured directly and rapidly by selective laser melting (SLM). Considered SLM as manufacturing technology, CoCrMo-alloyed powder that meets ASTM F75 standard is made of femoral component under optimal processing parameters. The feasibility of SLM forming through conducting experimental test of mechanical properties, surface roughness, biological corrosion resistance was analyzed. Findings The result showed that the tensile strength, yield strength, hardness and biological corrosion resistance of CoCrMo-alloyed personalized femoral component fulfill knee joint prosthesis standard through post-processing. Originality/value Traditional standardized prosthesis implantation manufacturing approach was changed by computer-aided design and personalized SLM direct manufacturing, and provided a new way for personalized implanted prosthesis to response manufacturing rapidly.

Structural optimization design for antenna bracket manufactured by selective laser melting

This paper aims to summarize design rules based on the process characteristics of selective laser melting (SLM) and structural optimization and apply the design rules in the lightweight design of an aluminum alloy antenna bracket. The design goal is to reduce 30 per cent of the weight while maintaining the stress levels in the original part.,To reduce weight as much as possible, the titanium alloy with higher specific strength was selected during the process of optimization. The material distribution of the bracket was improved by the topology optimization design. The redesign for SLM was used to obtain an optimization model, which was more suitable for SLM. The component performance was improved by shape optimization. The modal analysis data of the structural optimization model were compared with those of the stochastic lightweight model to verify the structural optimization model. The scanning data were compared with those of the original model to verify whether the model was suitable for SLM.,Structural optimization design for antenna bracket realized the mass decrease of 30.43 per cent and the fundamental frequency increase of 50.18 per cent. The modal analysis data of the stochastic lightweight model and the structural optimization model indicated that the optimization performance of structural optimization method was better than that of the stochastic lightweight method. The comparison results between the scanning data of the forming part and the original data confirmed that the structural optimization design for SLM lightweight component could achieve the desired forming accuracy.,This paper summarizes geometric constraints in SLM and derives design rules of structural optimization based on the process characteristics of SLM. SLM design rules make structural optimization design more reasonable. The combination of structural optimization design and SLM can improve the performance of lightweight antenna bracket significantly.

Effect of energy input on the UHMWPE fabricating process by selective laser sintering

Purpose This study aims to achieve customized prosthesis for total joint arthroplasty and total hip arthroplasty. Selective laser sintering (SLS) as additive manufacturing could enable small-scale fabrication of customized Ultra High Molecular Weight Polyethylene (UHMWPE) components; however, the processes for SLS of UHMWPE need to be improved. Design/methodology/approach This paper begins by improving the preheating system of the SLS fabricating equipment and then fabricating cuboids with the same size and cuboids with same volume and different size to study the warpage, demonstrating the effect of the value and uniformity of the preheating temperature on component fabrication. Warpage, density and tensile properties are investigated from the perspective of energy input density. Finally, complicated industrial parts are produced effectively by using optimized technological parameters. Findings The results show that components can be fabricated effectively after the optimization of the SLS technological parameters i.e. the preheating temperature the laser power the scanning interval and the scanning speed. The resulting warpage was found to be less than 0.1 mm along with the density as 83.25 and the tensile strength up to 14.1 Mpa. UHMWPE sample parts with good appearance and strength are obtained after ascertaining the effect of each factor on the fabrication of the sample parts. Originality/value It is very challenging to fabricate UHMWPE sample parts by SLS. This is a new step in the fabrication of customized UHMWPE sample parts.

Design and direct manufacture of non-assembly abacus by Selective Laser Melting

Selective Laser Melting (SLM), as an additive manufacturing technology, can directly manufacture desired functional metal parts. With the ability to freeform manufacture, SLM has had breakthroughs on design and manufacture compared with traditional methods. SLM apparatus in Dimetal series, DiMetal-100 developed by SCUT research group, has been used to study non-assembly mechanism. Taking copper cash abacus and collapsible abacus as examples, this article had studied the design rules and the key points to manufacture the non-assembly mechanism based on the SLM. An investigation into the capability of SLM technology, such as the geometric features resolution, critical incline angle, provided theoretical basis for designing the clearance of the joint and manufacturing direction of non-assembly mechanism. Then, the experiment of manufacturing copper cash abacus and collapsible abacus were conducted. The results proved that non-assembly mechanism can be well manufactured by SLM. This study provides basis for designing and manufacturing of creative non-assembly mechanism based on SLM technique.