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Currently available focal knee resurfacing implants (FKRIs) are fully or partially composed of metals, which show a large disparity in elastic modulus relative to bone and cartilage tissue. Although titanium is known for its excellent osseointegration, the application in FKRIs can lead to potential stress‐shielding and metal implants can cause degeneration of the opposing articulating cartilage due to the high resulting contact stresses. Furthermore, metal implants do not allow for follow‐up using magnetic resonance imaging (MRI).To overcome the drawbacks of using metal based FKRIs, a biomimetic and MRI compatible bi‐layered non‐resorbable thermoplastic polycarbonate‐urethane (PCU)‐based FKRI was developed. The objective of this preclinical study was to evaluate the mechanical properties, biocompatibility and osteoconduction of a novel Bionate® 75D ‐ zirconium oxide (B75D‐ZrO2) composite material in vitro and the osseointegration of a B75D‐ZrO2 composite stem PCU implant in a caprine animal model. The tensile strength and elastic modulus of the B75D‐ZrO2 composite were characterized through in vitro mechanical tests under ambient and physiological conditions. In vitro biocompatibility and osteoconductivity were evaluated by exposing human mesenchymal stem cells to the B75D‐ZrO2 composite and culturing the cells under osteogenic conditions. Cell activity and mineralization were assessed and compared to Bionate® 75D (B75D) and titanium disks. The in vivo osseointegration of implants containing a B75D‐ZrO2 stem was compared to implants with a B75D stem and titanium stem in a caprine large animal model. After a follow‐up of 6 months, bone histomorphometry was performed to assess the bone‐to‐implant contact area (BIC). Mechanical testing showed that the B75D‐ZrO2 composite material possesses an elastic modulus in the range of the elastic modulus reported for trabecular bone. The B75D‐ZrO2 composite material facilitated cell mediated mineralization to a comparable extent as titanium. A significantly higher bone‐to‐implant contact (BIC) score was observed in the B75D‐ZrO2 implants compared to the B75D implants. The BIC of B75D‐ZrO2 implants was not significantly different compared to titanium implants. A biocompatible B75D‐ZrO2 composite approximating the elastic modulus of trabecular bone was developed by compounding B75D with zirconium oxide. In vivo evaluation showed an significant increase of osseointegration for B75D‐ZrO2 composite stem implants compared to B75D polymer stem PCU implants. The osseointegration of B75D‐ZrO2 composite stem PCU implants was not significantly different in comparison to analogous titanium stem metal implants. [ABSTRACT FROM AUTHOR]

Cartilage defects in the knee are often seen in young and active patients. There is a need for effective joint preserving treatments in patients suffering from cartilage defects, as untreated defects often lead to osteoarthritis. Within the last two decades, tissue engineering based techniques using a wide variety of polymers, cell sources, and signaling molecules have been evaluated. We start this review with basic background information on cartilage structure, its intrinsic repair, and an overview of the cartilage repair treatments from a historical perspective. Next, we thoroughly discuss polymer construct components and their current use in commercially available constructs. Finally, we provide an in-depth discussion about construct considerations such as degradation rates, cell sources, mechanical properties, joint homeostasis, and non-degradable/hybrid resurfacing techniques. As future prospects in cartilage repair, we foresee developments in three areas: first, further optimization of degradable scaffolds towards more biomimetic grafts and improved joint environment. Second, we predict that patient-specific non-degradable resurfacing implants will become increasingly applied and will provide a feasible treatment for older patients or failed regenerative treatments. Third, we foresee an increase of interest in hybrid construct, which combines degradable with non-degradable materials. [ABSTRACT FROM AUTHOR]

Middle-aged patients with early onset arthritis or cartilage defects are difficult to treat. These patients are relatively young for joint replacement and relatively old for regenerative therapies, i.e.: a treatment gap. Therefore, the concept of joint preservation has emerged with the main goal to delay of even prevent joint replacement. Several novel surgical techniques and treatment algorithms for cartilage repair are developed. New insights show that knee joint preservation is best achieved by combining treatments, for instance cartilage repair and mechanical (alignment) correction. Since combining different surgeries introduces more complexity, a guideline has been drafted, which states that (part of) this care is perhaps best centralised. It is therefore important, to treat patients eligible for joint preservation in collaboration with expert centres. This brief clinical lesson provides the latest insights in the Dutch knee joint preservation care supported by the latest guideline.

Goats or sheep are the preferred animal model for the preclinical evaluation of cartilage repair techniques due to the similarity of the goat stifle joint to the human knee. The medial femoral condyle of the stifle joint is the preferred site for the assessment of articular cartilage repair, as this is the primary location for this type of lesion in the human knee. Proper surgical exposure of the medial femoral condyle is paramount to obtain reproducible results without surgical error. When applying the standard human medial arthrotomy technique on the goat stifle joint, there are some key aspects to consider in order to prevent destabilization of the extensor apparatus and subsequent postoperative patellar dislocations with associated animal discomfort. This paper describes a modified surgical technique to approach the medial femoral condyle of the caprine stifle joint. The modified technique led to satisfactory exposure without postoperative incidence of patellar luxations and no long-term adverse effects on the joint., Competing Interests: The authors declare they have neither relevant material nor financial interests that relate to the research described in this paper., (© 2021 The Authors. Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal Sciences.)

A 57 year old woman with a history of liver cirrhosis and ascites presented with serous exudate spontaneously leaking from a ruptured umbilical hernia, also known as Flood syndrome. This syndrome is a rare complication of decompensated liver cirrhosis and is associated with high mortality. In this specific case, there was also omentum protruding through the umbilical hernia which limited the outflow of ascites. Patient was successfully treated with antibiotics and consecutive open primary hernia repair without mesh implantation.