PurposeThe aim of this paper is to present the main results of a research project finished in 2008 which concerned the selective laser melted (SLM) prototype of a new kind of minimally invasive resurfacing hip arthroplasty (RHA) endoprosthesis with the original multi‐spiked connecting scaffold (MSC‐Scaffold). Previous attempts performed in pre‐Direct Metal Manufacturing (DMM) era demonstrated that it was impossible to manufacture suitable prototypes of this RHA endoprosthesis (especially of the MSC‐Scaffold) using traditional machining technologies. Owing to an extensive development of DMM technologies observed in recent years the manufacturing of such prototypes has become possible.Design/methodology/approachComputer aided design models of pre‐prototypes and the prototype of the RHA endoprosthesis with MSC‐Scaffold were designed and initially optimized within the claims and the general assumptions of international patents by Rogala. Prototyping in SLM technology was subcontracted to SLM Tech Center (Paderborn, Germany). Macroscopic and SEM microscopic evaluation of the MSC‐Scaffold was performed using SLM manufactured prototypes and paying special attention to the quality and precision of manufacturing.FindingsIt was found that SLM can be successfully applied to manufacturing of prototypes of the original minimally invasive RHA endoprosthesis. The manufacturing quality of the 3D spikes system of the MSC‐Scaffold, which mimics the interdigitations of articular subchondral bone, has been proved to be geometrically corresponding to the biological original. Nevertheless, some pores and non‐melted zones were found in SLM prototyped RHA endoprosthesis cross‐sections which need to be eliminated to minimize the potential risk of clinical failure.Research limitations/implicationsThe presented case study was performed with a limited number of samples. More research needs to be performed on the rapid prototyped samples including microstructural and mechanical tests. The results may enable the optimization of the SLM manufacturing process of the prototypes of the minimally invasive RHA endoprosthesis with MSC‐Scaffold.Practical implicationsThe SLM can be considered as potentially suitable for the fabrication of patient‐fitted minimally invasive RHA endoprostheses with MSC‐Scaffold.Originality/valueFor the first time, largely owing to SLM technology, it was possible to manufacture the prototype of the original minimally invasive RHA endoprosthesis with MSC‐Scaffold suitable for further research.
We present the new fixation method for RHA (resurfacing hip arthroplasty) endoprostheses by means of the biomimetic multispiked connecting scaffold (MSC-Scaffold). Such connecting scaffold can generate new type of RHA endoprostheses, that is stemless and fixed entirely without cement. The preprototypes of this MSC-Scaffold were manufactured with modern additive laser additive technology (SLM). The pilot surgical implantations in animal model (two laboratory swine) of MSC-Scaffold preprototypes have showed after two months neither implant loosening, migration, and nor other early complications. From the results of performed histopathological evaluation of the periscaffold spikes bone tissue and 10-day culture of human osteoblasts (NHOst) we can conclude that (1) the scaffolding effect was obtained and (2) to improve the osseointegration of the scaffold spikes, their material surface should be physicochemically modified (e.g., with hydroxyapatite). Some histopathological findings in the periscaffold domain near the MSC-Scaffold spikes bases (fibrous connective tissue and metallic particles near the MSC-Scaffold spikes bases edges) prompt considering the necessity to optimize the design of the MSC-Scaffold in the regions of its interspike space near the spikes bases edges, to provide more room for new bone formation in this region and for indispensable post-processing (glass pearl blasting) after the SLM manufacturing.
The purpose of this work was to characterize the results of five different processes of bovine tissue deproteinization, resulting in the fabrication of deproteinized xenogenic osteoconductive biomaterials for bone tissue regeneration as an alternative to autogenic bone grafts. The studies on deproteinization processes of bovine cancellous bone specimens, excised from fresh femoral bovine heads, included the following five processes: thermal deproteinization and four chemical deproteinization processes using the solutions 2.6 wt% sodium hypochlorite, 7 wt% hydrogen peroxide, 1 N potassium hydroxide and 1 N sodium hydroxide. The optimal parameters of the thermal deproteinization were designed on the basis of thermogravimetric analysis (TGA) of bovine bone specimens during a pilot study of the process. Periodical evaluation of all the processes of chemical deproteinization was performed via the assessment of protein concentration in bone specimens by the Lowry method. The mechanical properties of deproteinized bone specimens were evaluated by compression testing in the air-dry condition. The compressive strength of the completely deproteinized bone specimens after the thermal deproteinization process was remarkably lower compared with those after the chemical deproteinization processes: 6.5 times lower compared with those deproteinized with 7 wt% hydrogen peroxide solution and 3 times lower compared with those deproteinized with 2.6 wt% sodium hypochlorite solution. The SEM examination of deproteinized bone specimens showed microcracks on the trabecular surfaces generated by thermal deproteinization stresses. The presence of microcracks in the biomaterial resulted in a decrease in its ultimate compressive strength.
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