Total Knee Replacement with an Uncemented Porous Tantalum Tibia Component: A Failure Analysis

Tantalum Particles Promote M2 Macrophage Polarization and Regulate Local Bone Metabolism via Macrophage-Derived Exosomes Influencing the Fates of BMSCs

In this study, the regulatory role and mechanisms of tantalum (Ta) particles in the bone tissue microenvironment are explored. Ta particle deposition occurs in both clinical samples and animal tissues following porous Ta implantation. Unlike titanium (Ti) particles promoting M1 macrophage (Mϕ) polarization, Ta particles regulating calcium signaling pathways and promoting M2 Mϕ polarization. Ta-induced M2 Mϕ enhances bone marrow-derived mesenchymal stem cells (BMSCs) proliferation, migration, and osteogenic differentiation through exosomes (Exo) by upregulating miR-378a-3p/miR-221-5p and downregulating miR-155-5p/miR-212-5p. Ta particles suppress the pro-inflammatory and bone resorption effects of Ti particles in vivo and in vitro. In a rat femoral condyle bone defect model, artificial bone loaded with Ta particles promotes endogenous Mϕ polarization toward M2 differentiation at the defect site, accelerating bone repair. In conclusion, Ta particles modulate Mϕ polarization toward M2 and influence BMSCs osteogenic capacity through Exo secreted by M2 Mϕ, providing insights for potential bone repair applications.

Technology assistance in primary total knee replacement: hype or hope?

INTRODUCTION

Total knee replacement (TKR) reduces pain, it increases quality of life and it generally lasts a long time with revision rates of less than 5% at 10 years. Some authors have suggested that outcomes may be further improved by technology assistance.

AREAS COVERED

Technology assistance in primary TKR includes technologies such as navigated TKR, patient specific instrumentation TKR and robotic TKR.

EXPERT OPINION

In general, technology assistance results in higher accuracy of component positioning and alignment, but this is likely not clinically relevant as no clinically important difference in clinical outcomes, quality of life and complications such as revisions has been demonstrated in meta-analyses of randomized controlled trials. As technology assistance in primary TKR is increasingly used to capture patient and surgeon data, surgeons have an increasingly important role in protecting their patients' data and their own data. Real world evidence of implant registries has shown that TKR without technologically assistance can achieve perfectly acceptable outcomes. Although there is a genuine hope that technology-assisted TKR may further improve these outcomes, this hope is based on promises rather than solid evidence. At the same time, technology assisted TKR is heavily promoted including direct patient marketing, which are aspects of a hype.

Shock Wave-Activated Silver-Loaded Biopolymer Implant Coating Eliminates Staphylococcus epidermidis on the Surface and in the Surrounding of Implants

Bacterial biofilms on foreign surfaces are considered a primary cause of implant-related infections, which are challenging to treat. A new implant coating was developed, containing anti-infective silver within a biocompatible polymer carrier substance. In addition to its passive effect on the implant surface, highly concentrated anti-infective silver can be released as needed via the application of high-energy shock waves. This intervention could be applied transcutaneously in a clinical setting without the need for additional surgery. We investigated the inhibition of biofilm formation and the effectiveness of eradication after activation of the coating via shock waves in an in vitro biofilm model using Staphylococcus epidermidis RP62A. This was performed via scanning electron microscopy and quantitative microbiology. Additionally, we examined the cytotoxicity of the new coating on normal human fibroblasts and Saos-2 osteoblast-like cells, depending on the silver concentration. All studies were compared to uncoated titanium surfaces Ti6Al4V and a conventional electroplated silver coating. Cytotoxicity toward normal human fibroblasts and Saos-2 osteoblast-like cells increased with higher silver content but remained tolerable at 6%. Compared to uncoated Ti6Al4V and the electroplated silver coating, the new coating with a silver content of 4% and 6% exhibited a significant reduction in adherent bacteria by a factor of approximately 1000. This was also evident via microscopic examination of the surface morphology of the biofilms. Furthermore, following shock wave activation, no bacteria were detectable on either the implant or in the surrounding fluid after a 24 h period.

Cemented versus Cementless Stem Fixation in Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

The number of revision knee arthroplasties (rTKA) is growing significantly as is the use of intramedullary stems for optimized stability. The choice of the most appropriate stem fixation method is still controversial. The purpose of this meta-analysis is to compare cemented versus cementless stem fixation in rTKA. Publications with patients undergoing rTKA with a follow-up > 24 months were systemically reviewed. Extracted parameters included total revision and failure rates for any reason, incidence of aseptic loosening, periprosthetic infection, and radiolucent lines, as well as the clinical outcome. A statistical regression analysis was then performed on all extracted clinical and radiological outcome data. A total of 35 publications met the inclusion criteria and were included and analyzed. Overall, 14/35 publications compared cementless versus cemented stem fixation, whereas 21/35 publications investigated only one stem fixation method. There were no significant differences in revision (p = 0.2613) or failure rates (p = 0.3559) and no differences in the incidence of aseptic loosening (p = 0.3999) or periprosthetic infection (p = 0.1010). The incidence of radiolucent lines was significantly higher in patients with cemented stems (26.2% versus 18.6%, p < 0.0001). However, no differences in clinical outcomes were observed. No superiority of a specific stem fixation method in rTKA was found. Rates of revision or failure for any reason as well as incidence of aseptic loosening and periprosthetic infection in cemented versus cementless stem fixation showed no significant difference. A higher incidence of radiolucent lines was observed in cemented stem fixation; however, no effect was observed on the clinical outcome.

Could Hyaluronic Acid Be Considered as a Senomorphic Agent in Knee Osteoarthritis? A Systematic Review

BACKGROUND

Knee osteoarthritis (KOA) is one of the most common causes of disability in elderly patients and tends to be a major burden on social and health care spending. Despite its severe socioeconomic impact, KOA remains, to date, an incurable disease. Due to its proper characteristics, KOA represents a favorable disease model for experimenting with senotherapeutics, a group of treatments that counteract the development of age-related disorders and chronic diseases. In recent years, the use of intra-articular hyaluronic acid (IAHA) in the treatment of diseases related to the wear and tear of the articular cartilage has been gaining popularity. Given its ability in joint lubrification, shock absorption, and cell signaling, our aim is to investigate, through the existing scientific literature, its potential role as a senomorphic agent, emphasizing its crucial function in KOA patients. Indeed, senomorphics are a particular group of senotherapeutics capable of modulating the functions and morphology of senescent cells to those of young cells or delaying the progression of young cells to senescent cells in tissues.

METHODS

A search in the scientific literature (PubMed, Cochrane Library, and Google Scholar) was carried out from 2019 to 2023, thus the last 5 years.

RESULTS

One hundred thirty-eight articles were found concerning the role of hyaluronic acid injections in KOA patients. In these studies, its therapeutic efficacy, its anti-inflammatory properties, and its low risk of side effects emerged.

CONCLUSION

IAHA injections are a valuable treatment option for KOA while they can provide pain relief, improve joint function, and slow the progression of joint degeneration. The inhibitory effect of HA on MMP13 and its action as a senomorphic agent suggests that it may have additional benefits beyond its lubricating and shock-absorbing properties. In order to clarify its mechanisms of action and to optimize its clinical use, further studies are definitely needed.

On-Demand Release of Anti-Infective Silver from a Novel Implant Coating Using High-Energy Focused Shock Waves

Implant-related infections are a significant concern in orthopedic surgery. A novel anti-infective implant coating made of bioresorbable polymer with silver nitrate was developed. A controlled release of silver ions into the vicinity of the prosthesis can be triggered on-demand by extracorporeal shock waves to effectively combat all clinically relevant microorganisms. Microscopy techniques were used to examine the effects of shock wave application on coated titanium discs. Cytotoxicity was measured using a fibroblast proliferation assay. The anti-infective effect was assessed by monitoring the growth curves of three bacterial strains and by conventional culture. Microscopic analysis confirmed surface disruption of the coatings, with a complete release of silver in the focus area after shock wave application. Spectrometry detected an increase in silver concentration in the surrounding of the discs that surpassed the minimum inhibitory concentration (MIC) for both S. epidermidis RP62A and E. coli ATCC 25922. The released silver demonstrated an anti-infective effect, significantly inhibiting bacterial growth, especially at 6% and 8% silver concentrations. Cytotoxicity testing showed decreasing fibroblast viability with increasing silver concentration in the coating, with 6% silver maintaining viability above 25%. Compared to a commonly used electroplated silver coating on the market, the new coating demonstrated superior antimicrobial efficacy and lower cytotoxicity.

The Effects of Different Femoral Component Materials on Bone and Implant Response in Total Knee Arthroplasty: A Finite Element Analysis

Due to the high stiffness of the biomaterials used in total knee arthroplasty, stress shielding can lead to decreased periprosthetic bone mineral density and bone resorption. As different materials and 3D-printed highly porous surfaces are available for knee femoral components from the industry nowadays, this study aimed to compare the effects of two same-design cruciate-retaining femoral components, made with CoCr and titanium alloy, respectively, on periprosthetic bone stresses through a finite element model of the implanted knee in order to evaluate the induced stress shielding. Moreover, the effect of the cementless highly porous surface of the titanium implant was analyzed in comparison to the cemented interface of the CoCr implant. The von Mises stresses were analyzed in different periprosthetic regions of interest of the femur with different configurations and knee flexion angles. The titanium component induced higher bone stresses in comparison with the CoCr component, mostly in the medial compartment at higher knee flexion angles; therefore, the CoCr component led to more stress shielding. The model was revealed to be effective in describing the effects of different femoral component materials on bone stress, highlighting how a cementless, highly porous titanium femoral component might lead to less stress shielding in comparison to a cemented CoCr implant with significant clinical relevance and reduced bone resorption after total knee arthroplasty.

Mechanical complications after total knee arthroplasty

INTRODUCTION

With the increasing demand for total knee arthroplasty (TKA) and the burden of revision TKA on the healthcare system, as well as the quality of life implications for patients, it is extremely important for surgeons to be able to anticipate and prevent TKA mechanical complications. Surgeons must be familiar with the different causes and mechanisms of TKA complications so that they can properly treat patients with failed TKAs and better avoid these complications.

AREAS COVERED

This review addresses TKA mechanical complications and provides context for the topic. A detailed review of surgical factors, implant factors, and patient factors that contribute to mechanical complications after TKA is provided. All of the literature cited in this review was gathered from the PubMed online database using different keywords based on the section of the manuscript.

EXPERT OPINION

As surgeons and engineers solve certain issues in TKA, new challenges will inevitably arise. We must continue to push forward and innovate from both a surgical technique and implant design perspective.