Enhanced osseointegration through direct energy deposition porous coating for cementless orthopedic implant fixation

Direct energy deposition (DED) is a newly developed 3D metal printing technique that can be utilized on a porous surface coating of joint implants, however there is still a lack of studies on what advantages DED has over conventional techniques. We conducted a systematic mechanical and biological comparative study of porous coatings prepared using the DED method and other commercially available technologies including titanium plasma spray (TPS), and powder bed fusion (PBF). DED showed higher porosity surface (48.54%) than TPS (21.4%) and PBF (35.91%) with comparable fatigue cycle. At initial cell adhesion, cells on DED and PBF surface appeared to spread well with distinct actin stress fibers through immunofluorescence study. It means that the osteoblasts bind more strongly to the DED and PBF surface. Also, DED surface showed higher cell proliferation (1.27 times higher than TPS and PBF) and osteoblast cell activity (1.28 times higher than PBF) for 2 weeks culture in vitro test. In addition, DED surface showed better bone to implant contact and new bone formation than TPS in in vivo study. DED surface also showed consistently good osseointegration performance throughout the early and late period of osseointegration. Collectively, these results show that the DED coating method is an innovative technology that can be utilized to make cementless joint implants.

Total ankle replacement

Introduction Total ankle replacement is definitely a tough issue for both orthopedic surgeons treating patients with ankle pathology and engineers who develop optimal implant constructs. Extreme short-time kinetic loads, complex motion biomechanics, anatomic features of the ankle result in high demands for ankle joint implants. In general, there is a positive tendency in an annual increase of the number of total ankle replacements. Alongside, a significant lagging in performing this procedure and the tendency for ankle arthrodesis has been observed in Russia. Aim To review the literature data about development and current status of total ankle replacement. To evaluate the use of modern implants for distal tibia replacement. Material and methods The given literature review includes analysis of foreign and domestic publications focused on issues of treatment of osteoarthritis of the ankle joint and tumors of the distal tibia. The information was searched for using GoogleScholar, PubMed, eLIBRARY, PubMedCentral in the Russian and English languages with the following keywords: total ankle replacement, ankle arthrodesis, ankle osteoarthritis, distal tibia replacement. Discussion Currently, there are controversies in selection of biomaterials and constructive parameters for ankle implants. Separately, there is an unsolved issue of selecting the optimal friction pair for bearing surfaces, as well as of operative technique features, such as implant fixation, surgical approach, modeling and restoration of the capsular-ligamentous complex. Conclusion Total ankle replacement is an effective alternative procedure to ankle arthrodesis and limb-sacrificing operations. To improve treatment results, optimal implant construction, fixation methods, selecting appropriate friction pair and capsular-ligamentous complex restoration should be further investigated in complex studies.

Deciphering the low abundance microbiota of presumed aseptic hip and knee implants

16S rRNA gene sequencing of DNA extracted from clinically uninfected hip and knee implant samples has revealed polymicrobial populations. However, previous studies assessed 16S rRNA gene sequencing as a technique for the diagnosis of periprosthetic joint infections, leaving the microbiota of presumed aseptic hip and knee implants largely unstudied. These communities of microorganisms might play important roles in aspects of host health, such as aseptic loosening. Therefore, this study sought to characterize the bacterial composition of presumed aseptic joint implant microbiota using next generation 16S rRNA gene sequencing, and it evaluated this method for future investigations. 248 samples were collected from implants of 41 patients undergoing total hip or knee arthroplasty revision for presumed aseptic failure. DNA was extracted using two methodologies—one optimized for high throughput and the other for human samples—and amplicons of the V4 region of the 16S rRNA gene were sequenced. Sequencing data were analyzed and compared with ancillary specific PCR and microbiological culture. Computational tools (SourceTracker and decontam) were used to detect and compensate for environmental and processing contaminants. Microbial diversity of patient samples was higher than that of open-air controls and differentially abundant taxa were detected between these conditions, possibly reflecting a true microbiota that is present in clinically uninfected joint implants. However, positive control-associated artifacts and DNA extraction methodology significantly affected sequencing results. As well, sequencing failed to identify Cutibacterium acnes in most culture- and PCR-positive samples. These challenges limited characterization of bacteria in presumed aseptic implants, but genera were identified for further investigation. In all, we provide further support for the hypothesis that there is likely a microbiota present in clinically uninfected joint implants, and we show that methods other than 16S rRNA gene sequencing may be ideal for its characterization. This work has illuminated the importance of further study of microbiota of clinically uninfected joint implants with novel molecular and computational tools to further eliminate contaminants and artifacts that arise in low bacterial abundance samples.

Novel Polishing Media for Finishing Hip Joint Implants

Automating the finishing process of the femoral head in hip joint implants is one of the greatest concerns in industrial and academic societies. To achieve this goal, first, a negative replica is developed for the femoral head in the abrasive flow finishing (AFF) process. Then, a novel polishing media by combining the viscoelastic carrier and coarse sisal fiber is proposed for finishing. Finally, the performance of the finishing procedure through the proposed polishing media is assessed experimentally by evaluating the influential parameters of the AFF process on the surface roughness of the femoral head, which is made from ASTM F138 (SS 316L). Experimental results prove the effectiveness of the proposed polishing media in negative replica for finishing of femoral head owing to the severe mechanical disintegration. This is validated with the substantial reduction of surface roughness in the femoral head from 134.6 nm to 36.96 nm. Furthermore, AFM results confirm the improved surface topography parameters of Ra, Rq, and Rt in the femoral head under optimized conditions by 72.54%, 70.50%, and 64.79%, respectively. Generally, it can be said that promising results for future application of the polishing media in the AFF process are obtained.