Guest Lectures

Title:

“PMEDM Surface Modification for the Production of Antibacterial Implant Surfaces”

Summary:

"Periprosthetic joint infections (PJI) are a common reason for orthopedic revision surgeries. It has been shown that the silver surface modification of a titanium alloy (Ti–6Al–4V) by PMEDM (powder mixed electrical discharge machining) exhibits an anti-adhesive effect on Staphylococcus spp. The attachment of S. aureus on the PMEDM modified surfaces is significantly lower than on comparative control samples, independently of the roughness and thickness of the tested surface properties. Bacterial proliferation, however, is not affected by the silver content in the surface layer. We observed a long-term effect of antibacterial capacity in vitro, as well as in vivo. An induction of ROS, as indicator for oxidative stress, was observed in the bacteria, but not in osteoblast-like cells. No influence on the in vitro osteoblast function was observed, whereas osteoclast formation was drastically reduced on the silver surface. No changes in cell death, metabolic activity and oxidative stress was measured in osteoblasts. There is a slight release of silver ions under corrosive conditions, which can be adjusted by machining parameters. Therefore, PMEDM using silver nano-powder admixed to the dielectric represents a promising technology to shape and concurrently modify implant surfaces to reduce infections while at the same time optimizing bone ingrowth of endoprosthesis." (Source: Jessica Bertrand)

Title:

“Blood and tissue analysis in patients with failed Orthopaedic implants due to aseptic loosening and osteolysis”

Summary:

"This presentation outlines integrated blood and tissue analysis methods used to investigate failure mechanisms in orthopaedic implants, with a focus on aseptic loosening and periprosthetic osteolysis. Using retrieval analysis from revision surgeries, the study combines mechanical evaluation of explanted prostheses, histological assessment of periprosthetic tissues, and trace element quantification in blood.

A central finding across multiple case series is that implant wear generates particles of varying composition (polymer, metal, ceramic), which accumulate in surrounding tissue and trigger a chronic inflammatory response characterized by macrophage activation, multinucleated giant cells, and lymphocyte involvement. Particle load, size distribution, and composition reflect implant-specific failure pathways and contribute to osteolysis. 

Advanced analytical techniques—including SEM-EDS, TEM, ICP-MS, and histopathology—enable detailed characterization of wear debris and systemic exposure. Blood metal ion levels (e.g. Ti, Co, Cr and Zr) show significant correlation with implant wear and mechanical damage, supporting their role as potential biomarkers.

Retrieval case studies highlight how implant design factors, such as surface roughness and material combinations, influence wear and failure rates. The findings emphasize that no single method is sufficient; instead, a multimodal approach linking mechanical, biological, and systemic data is essential to fully understand implant failure and improve patient safety and future implant design." (Source: Paul Johan Høl)

Title:

"In vitro bone models based on primary human cells – challenges and potential"

Summary:

"In vitro bone models have become essential tools for drug development and regenerative medicine approaches. To mimic the situation in native bone tissue, in vitro bone models should involve not only osteoblasts and osteoclasts, but also osteocytes. However, primary human OCY are hard to isolate from bone tissue and cannot be further expanded in vitro due to their post-mitotic state. Moreover, the simultaneous cultivation and differentiation of cells with discrete requirements concerning media composition is challenging. Another challenge is the separation of the different (human) cell species for analysis. We have been working a couple of years on the formation of osteocyte-containing in vitro bone models comprising solely primary human cells. Starting with co-cultures of osteocytes and other bone cells, we went further to basic and advanced triple cultures of bone cells. After having created a functional in vitro triple culture model, human endothelial cells were implemented to perform quadruple cultures, since vascularization is crucial for bone regeneration. Finally, an in vitro bone model of four cells types with stable expression of all specific markers was established." (Source: Anne Bernhardt)