Rotator cuff repair with biodegradable high-purity magnesium suture anchor in sheep model

Versatile application of magnesium-related bone implants in the treatment of bone defects

Magnesium-related bone implants have garnered significant attention in the treatment of bone defects. The applications of magnesium in promoting bone repair mainly include degradable magnesium-based scaffolds owing to its special physical properties and composite materials modified by magnesium ions because of its biological activity. Although numerous studies have confirmed the unique application advantages and efficacy of magnesium in promoting bone repair, some obvious shortcomings persist, including the rapid degradation of magnesium-based scaffolds. In this review, the deficiencies of magnesium and its alloys in the construction of orthopedic implants and their key influencing factors were summarized; furthermore, some advanced improvement schemes were summarized and analyzed. Additionally, the application strategies of magnesium-modified bone implants are summarized and discussed. Lastly, this review incorporates the latest research and discoveries on magnesium in orthopedic science, comprehensively exploring the mechanism of magnesium's role in the complex microenvironment of bone defects from multiple dimensions. This paper provides a comprehensive summary and analysis of cutting-edge concepts in the design and development of magnesium-based bone implants, considering various perspectives such as the physical properties and biological functions of magnesium.

Multi-modal investigation of the bone micro- and ultrastructure, and elemental distribution in the presence of Mg-xGd screws at mid-term healing stages

Magnesium (Mg) - based alloys are becoming attractive materials for medical applications as temporary bone implants for support of fracture healing, e.g. as a suture anchor. Due to their mechanical properties and biocompatibility, they may replace titanium or stainless-steel implants, commonly used in orthopedic field. Nevertheless, patient safety has to be assured by finding a long-term balance between metal degradation, osseointegration, bone ultrastructure adaptation and element distribution in organs. In order to determine the implant behavior and its influence on bone and tissues, we investigated two Mg alloys with gadolinium contents of 5 and 10 wt percent in comparison to permanent materials titanium and polyether ether ketone. The implants were present in rat tibia for 10, 20 and 32 weeks before sacrifice of the animal. Synchrotron radiation-based micro computed tomography enables the distinction of features like residual metal, degradation layer and bone structure. Additionally, X-ray diffraction and X-ray fluorescence yield information on parameters describing the bone ultrastructure and elemental composition at the bone-to-implant interface. Finally, with element specific mass spectrometry, the elements and their accumulation in the main organs and tissues are traced. The results show that Mg-xGd implants degrade in vivo under the formation of a stable degradation layer with bone remodeling similar to that of Ti after 10 weeks. No accumulation of Mg and Gd was observed in selected organs, except for the interfacial bone after 8 months of healing. Thus, we confirm that Mg-5Gd and Mg-10Gd are suitable material choices for bone implants.

An overview of magnesium-based implants in orthopaedics and a prospect of its application in spine fusion

Due to matching biomechanical properties and significant biological activity, Mg-based implants present great potential in orthopedic applications. In recent years, the biocompatibility and therapeutic effect of magnesium-based implants have been widely investigated in trauma repair. In contrast, the R&D work of Mg-based implants in spinal fusion is still limited. This review firstly introduced the general background for Mg-based implants. Secondly, the mechanical properties and degradation behaviors of Mg and its traditional and novel alloys were reviewed. Then, different surface modification techniques of Mg-based implants were described. Thirdly, this review comprehensively summarized the biological pathways of Mg degradation to promote bone formation in neuro-musculoskeletal circuit, angiogenesis with H-type vessel formation, osteogenesis with osteoblasts activation and chondrocyte ossification as an integrated system. Fourthly, this review followed the translation process of Mg-based implants via updating the preclinical studies in fracture fixation, sports trauma repair and reconstruction, and bone distraction for large bone defect. Furthermore, the pilot clinical studies were involved to demonstrate the reliable clinical safety and satisfactory bioactive effects of Mg-based implants in bone formation. Finally, this review introduced the background of spine fusion surgeryand the challenges of biological matching cage development. At last, this review prospected the translation potential of a hybrid Mg-PEEK spine fusion cage design.

Advances in the application of hydrogel-based scaffolds for tendon repair

Tendon injuries often lead to joint dysfunction due to the limited self-regeneration capacity of tendons. Repairing tendons is a major challenge for surgeons and imposes a significant financial burden on society. Therefore, there is an urgent need to develop effective strategies for repairing injured tendons. Tendon tissue engineering using hydrogels has emerged as a promising approach that has attracted considerable interest. Hydrogels possess excellent biocompatibility and biodegradability, enabling them to create an extracellular matrix-like growth environment for cells. They can also serve as a carrier for cells or other substances to accelerate tendon repair. In the past decade, numerous studies have made significant progress in the preparation of hydrogel scaffolds for tendon healing. This review aims to provide an overview of recent research on the materials of hydrogel-based scaffolds used for tendon tissue engineering and discusses the delivery systems based on them.

Absorbable implants in sport medicine and arthroscopic surgery: A narrative review of recent development

Over the past two decades, advances in arthroscopic and minimally invasive surgical techniques have led to significant growth in sports medicine surgery. Implants such as suture anchors, interference screws, and endo-buttons are commonly used in these procedures. However, traditional implants made of metal or inert materials are not absorbable, leading to complications that affect treatment outcomes. To address this issue, absorbable materials with excellent mechanical properties, good biocompatibility, and controlled degradation rates have been developed and applied in clinical practice. These materials include absorbable polymers, absorbable bioceramics, and absorbable metals. In this paper, we will provide a comprehensive summary of these absorbable materials from the perspective of clinicians, and discuss their clinical applications and related research in sport medicine.

Biodegradable Implants for Internal Fixation of Fractures and Accelerated Bone Regeneration

Bone fractures have always been a burden to patients due to their common occurrence and severe complications. Traditionally, operative treatments have been widely used in the clinic for implanting, despite the fact that they can only achieve bone fixation with limited stability and pose no effect on promoting tissue growth. In addition, the nondegradable implants usually need a secondary surgery for implant removal, otherwise they may block the regeneration of bones resulting in bone nonunion. To overcome the low degradability of implants and avoid multiple surgeries, tissue engineers have investigated various biodegradable materials for bone regeneration, whereas the significance of stability of long-term bone fixation tends to be neglected during this process. Combining the traditional orthopedic implantation surgeries and emerging tissue engineering, we believe that both bone fixation and bone regeneration are indispensable factors for a successful bone repair. Herein, we define such a novel idea as bone regenerative fixation (BRF), which should be the main future development trend of biodegradable materials.

Polymer bilayer-Micro arc oxidation surface coating on pure magnesium for bone implantation

Background

Pure magnesium-based ortho-implants have a number of advantages. However, vital parameters like degradation rate and biocompatibility still call for significant improvement.

Methods

In this study, poly (1,3-trimethylene carbonate) (PTMC) and polydopamine (PDA) bilayer and micro arc oxidation composite coatings were prepared successively on magnesium surface by immersion method and microarc oxidation. Its corrosion resistance and biocompatibility were evaluated by in vitro corrosion tests, cellular compatibility experiments, and in vivo animal experiments.

Results

In vitro experiments demonstrated that the composite coating provides excellent corrosion protection and biocompatibility. Animal studies demonstrated that the composite coating slowed the degradation of the implant and was not toxic to animal viscera.

Conclusion

In conclusion, the inorganic-organic composite coating proposed in this study provided good corrosion resistance and enhanced biocompatibility for pure magnesium implants.

The translational potential of this article

The translational potential of this article is to develop an anti-corrosion composite coating on a pure magnesium surface and to verify the viability of its use in animal models. It is hoped to open up a new approach to the design of new degradable orthopedic magnesium-based implants.