Ryszard Uklejewski

Selective laser melted prototype of original minimally invasive resurfacing hip endoprosthesis

Purpose – The 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/approach – Computer 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...

Preliminary Results of Implantation in Animal Model and Osteoblast Culture Evaluation of Prototypes of Biomimetic Multispiked Connecting Scaffold for Noncemented Stemless Resurfacing Hip Arthroplasty Endoprostheses

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 Content of the 14 Metals in Cancellous and Cortical Bone of the Hip Joint Affected by Osteoarthritis.

The aim of the study was to determine the content of particular elements Ca, Mg, P, Na, K, Zn, Cu, Fe, Mo, Cr, Ni, Ba, Sr, and Pb in the proximal femur bone tissue (cancellous and cortical bone) of 96 patients undergoing total hip replacement for osteoarthritis using ICP-AES and FAAS analytical techniques. The interdependencies among these elements and their correlations depended on factors including age, gender, place of residence, tobacco consumption, alcohol consumption, exposure to environmental pollution, physical activity, and type of degenerative change which were examined by statistical and chemometric methods. The factors that exerted the greatest influence on the elements in the femoral head and neck were tobacco smoking (higher Cr and Ni content in smokers), alcohol consumption (higher concentrations of Ni, Cu in people who consume alcohol), and gender (higher Cu, Zn, and Ni concentrations in men). The factors influencing Pb accumulation in bone tissue were tobacco, alcohol, gender, and age. In primary and secondary osteoarthritis of the hip, the content and interactions of elements are different (mainly those of Fe and Pb). There were no significant differences in the concentrations of elements in the femoral head and neck that could be attributed to residence or physical activity.

Effectiveness of various deproteinization processes of bovine cancellous bone evaluated via mechano-biostructural properties of produced osteoconductive biomaterials

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.

Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses—Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation

We present here—designed, manufactured, and tested by our research team—the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold) interfacing the components of resurfacing arthroplasty (RA) endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like) coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine) and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP) activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the enhancement of the osteoinduction/osteointegration potential by the Ca-P surface modification of the Ti-alloy MSC-Scaffold prototype. Planned further research on the prototype of this biomimetic MSC-Scaffold for a new generation of RA endoprostheses is also given.

Structural-Geometric Functionalization of the Additively Manufactured Prototype of Biomimetic Multispiked Connecting Ti-Alloy Scaffold for Entirely Noncemented Resurfacing Arthroplasty Endoprostheses

The multispiked connecting scaffold (MSC-Scaffold) prototype, inspired by the biological system of anchorage of the articular cartilage in the periarticular trabecular bone by means of subchondral bone interdigitations, is the essential innovation in fixation of the bone in resurfacing arthroplasty (RA) endoprostheses. The biomimetic MSC‐Scaffold, due to its complex geometric structure, can be manufactured only using additive technology, for example, selective laser melting (SLM). The major purpose of this work is determination of constructional possibilities for the structural-geometric functionalization of SLM‐manufactured MSC‐Scaffold prototype, compensating the reduced ability—due to the SLM technological limitations—to accommodate the ingrowing bone filling the interspike space of the prototype, which is important for the prototype bioengineering design. Confocal microscopy scanning of components of the SLM‐manufactured prototype of total hip resurfacing arthroplasty (THRA) endoprosthesis with the MSC‐Scaffold was performed. It was followed by the geometric measurements of a variety of specimens designed as the fragments of the MSC-Scaffold of both THRA endoprosthesis components. The reduced ability to accommodate the ingrowing bone tissue in the SLM‐manufactured prototypes versus that in the corresponding CAD models has been quantitatively determined. Obtained results enabled to establish a way of compensatory structural‐geometric functionalization, allowing the MSC‐Scaffold adequate redesigning and manufacturing in additive SLM technology.