Degradation behavior of ZE21C magnesium alloy suture anchors and their effect on ligament-bone junction repair

Hard-Soft Dual-State Coatings Regulate Degradation Rate and Biocompatibility of Orthopedic Magnesium Implants

The biomechanical similarity of magnesium to cortical bone, along with its biocompatibility and biodegradability, makes it promising for orthopedic implants. However, rapid degradation compromises the structural integrity and fixation, causing failure. To address this issue, we developed a hard-soft dual-state coating to regulate degradation and improve performance. A dense magnesium hydroxide hard coating was formed by sodium hydroxide treatment, and the hydrogel soft coating formed by freeze-drying was 44.5 μm thick. The dual coating significantly improved the corrosion resistance and mechanical properties. Mg-OH-Hy implants exhibited a reduced corrosion rate of 0.61 mm/year (±0.02), an ultimate fracture force of 750 N (±10), and a pullout force of 350 N (±10). Electrochemical testing revealed an Ecorr of -1.08 V and an Icorr of 10-3·8 mA/cm2. This dual coating approach improves mechanical stability, controls degradation, and promotes bone integration, providing personalized solutions for diverse clinical applications.

Degradation behavior of porous magnesium alloy scaffold under the low-intensity pulsed ultrasound intervention and their effect on bone defects repair

Biodegradable porous magnesium alloy (pMg) scaffolds hold significant potential for repair of bone defects owing to favorable mechanical properties and biocompatibility. However, a critical challenge remains in matching the degradation rate of pMg scaffolds with the pace of bone regeneration. Low-intensity pulsed ultrasound (LIPUS) has emerged as a promising therapeutic strategy to enhance bone repair. In this study, femoral bone defects in Sprague-Dawley rats were implanted with pMg scaffolds, and LIPUS was applied to the defect sites post-operatively. This study primarily investigated the degradation behavior of pMg scaffolds in vivo experiments, as well as their reparative effects on bone defects under LIPUS intervention. In vivo analysis revealed that LIPUS intervention accelerated the degradation of pMg scaffolds by loosening the degradation layer, making it more susceptible to erosion. Concurrently, LIPUS enhanced the accumulation of beneficial calcium and phosphorus compounds on the surface of the pMg scaffolds. Furthermore, the pMg + LIPUS group exhibited enhanced bone formation and mineralization around the degradation site compared to the pMg group alone, attributed to the increasing osteocalcin (OCN) and type I collagen (COL-I) as well as reduction in osteolysis by pMg and LIPUS-induced osteogenesis effect. At the 24-week post-surgery, the hardness value (HV) of regeneration bone in the pMg + LIPUS group had a 15% increase compared to the pMg group and approached the HV of healthy bone. In conclusion, the promotion of bone tissue growth rate under the intervention of LIPUS in conjunction with the degradation rate of pMg scaffolds offers a novel clinical strategy for the repair of bone defects.

3D printed porous magnesium metal scaffolds with bioactive coating for bone defect repair: enhancing angiogenesis and osteogenesis

In orthopedics, the effective treatment of bone defects remains a major challenge. Magnesium (Mg) metals, with their excellent biocompatibility and favorable osteoconductivity, osteoinductivity, and osseointegration properties, hold great promise for addressing this issue. However, the rapid degradation rate of magnesium restricts its clinical application. In this study, a triply periodic minimal surface (TPMS)-structured porous magnesium alloy (Mg-Nd-Zn-Zr, JDBM) was fabricated using the laser powder bed fusion (LPBF) process. Strontium-doped octacalcium phosphate (SrOCP) and strontium hydrogen phosphate biphasic composite coatings were applied to the surface of the scaffolds. The results showed that the TPMS structure exhibited porous biomimetic characteristics that resemble cancellous bone, promoting vascular ingrowth and new bone formation. Additionally, the SrOCP coating significantly increased the surface roughness and hydrophilicity of the scaffold, which enhanced cell adhesion and osteogenic differentiation. The SrOCP coating also markedly reduced the degradation rate of the JDBM scaffolds while ensuring the sustained release of bioactive ions (Mg²⁺, Zn²⁺, Sr²⁺, and Ca²⁺), thus maintaining the scaffolds' biofunctional activity. Compared to JDBM scaffolds, JDBM/SrOCP scaffolds exhibited better biocompatibility and stronger vascularization and bone regeneration capabilities both in vitro and in vivo. Overall, this study presents a novel strategy for the repair of bone defects using magnesium-based biomaterials, providing new insights for future clinical applications.

Advances in biodegradable materials: Degradation mechanisms, mechanical properties, and biocompatibility for orthopedic applications

Mg-based and Zn-based biodegradable materials have the potential to become the next-generation implant materials to treat bone diseases, because of their desired degradation and mechanical properties. This article reviews the status of these implant materials. The required properties of biodegradable materials such as biodegradability, mechanical properties, and biocompatibility for performance evaluation were briefly discussed. The influence of fabrication techniques, microstructure, alloying elements, and post-processing techniques on the properties of Mg and Zn-based materials was addressed. The degradation mechanism by dissolution, oxidation, and interaction with human body cells was discussed. The biocompatibility of Mg and Zn-based biodegradable materials was analyzed. The significance of in vitro and in vivo biocompatibility testing was highlighted, emphasizing the superiority of in vivo results over cell line studies. This article identifies the many Mg and Zn-based biodegradable materials and summarizes the key findings.

Mg alloys with antitumor and anticorrosion properties for orthopedic oncology: A review from mechanisms to application strategies

As a primary malignant bone cancer, osteosarcoma (OS) poses a great threat to human health and is still a huge challenge for clinicians. At present, surgical resection is the main treatment strategy for OS. However, surgical intervention will result in a large bone defect, and some tumor cells remaining around the excised bone tissue often lead to the recurrence and metastasis of OS. Biomedical Mg-based materials have been widely employed as orthopedic implants in bone defect reconstruction, and, especially, they can eradicate the residual OS cells due to the antitumor activities of their degradation products. Nevertheless, the fast corrosion rate of Mg alloys has greatly limited their application scope in the biomedical field, and the improvement of the corrosion resistance will impair the antitumor effects, which mainly arise from their rapid corrosion. Hence, it is vital to balance the corrosion resistance and the antitumor activities of Mg alloys. The presented review systematically discussed the potential antitumor mechanisms of three corrosion products of Mg alloys. Moreover, several strategies to simultaneously enhance the anticorrosion properties and antitumor effects of Mg alloys were also proposed.

[Research progress of magnesium and magnesium alloy implants in sports medicine]

Objective

To review the research progress of magnesium and magnesium alloy implants in the repair and reconstruction of sports injury.

Methods

Relevant literature of magnesium and magnesium alloys for sports injury repair and reconstruction was extensively reviewed. The characteristics of magnesium and its alloys and their applications in the repair and reconstruction of sports injuries across various anatomical sites were thoroughly discussed and summarized.

Results

Magnesium and magnesium alloys have advantages in mechanical properties, biosafety, and promoting tendon-bone interface healing. Many preclinical studies on magnesium and magnesium alloy implants for repairing and reconstructing sports injuries have yielded promising results. However, successful clinical translation still requires addressing issues related to mechanical strength and degradation behavior, where alloying and surface treatments offer feasible solutions.

Conclusion

The clinical translation of magnesium and magnesium alloy implants for repairing and reconstructing sports injuries holds promise. Subsequent efforts should focus on optimizing the mechanical strength and degradation behavior of magnesium and magnesium alloy implants. Conducting larger-scale biocompatibility testing and developing novel magnesium-containing implants represent new directions for future research.

Stability, biomechanics and biocompatibility analysis following different preparation strategies of hierarchical zeolite coatings on titanium alloy surfaces

Traditional titanium alloy implant surfaces are inherently smooth and often lack effective osteoinductive properties. To overcome these limitations, coating technologies are frequently employed to enhance the efficiency of bone integration at the implant-host bone interface. Hierarchical zeolites, characterized by their chemical stability, can be applied to 3D-printed porous titanium alloy (pTi) surfaces as coating. The resulting novel implants with a "microporous-mesoporous-macroporous" spatial gradient structure can influence the behavior of adjacent cells; thereby, promoting the integration of bone at the implant interface. Consequently, a thorough exploration of various preparation methods is warranted for hierarchical zeolite coatings with respect to biocompatibility, coating stability, and osteogenesis. In this study, we employed three methods: in situ crystal growth, secondary growth, and layer-by-layer assembly, to construct hierarchical zeolite coatings on pTi, resulting in the development of a gradient structure. The findings of this investigation unequivocally demonstrated that the LBL-coating method consistently produced coatings characterized by superior uniformity, heightened surface roughness, and increased hydrophilicity, as well as increased biomechanical properties. These advantages considerably amplified cell adhesion, spreading, osteogenic differentiation, and mineralization of MC3T3-E1 cells, presenting superior biological functionality when compared to alternative coating methods. The outcomes of this research provide a solid theoretical basis for the clinical translation of hierarchical zeolite coatings in surface modifications for orthopedic implants.

Anchored sutures for fixation of the anterolateral thigh flap and prevention of orocutaneous fistula in oral and oropharyngeal cancer reconstruction

OBJECTIVE

This study aims to assess the efficacy of anchored sutures (AS) in securing the anterolateral thigh (ALT) flap during oral and oropharyngeal reconstructions, and its impact on the occurrence of orocutaneous fistula (OCF).

MATERIALS AND METHODS

A retrospective study was performed on patients who underwent ALT flap reconstruction in our department in the year 2022. The patients were divided into two groups based on whether the AS technique was used. The incidence of OCF was compared between the two groups, and AS-related complications were reported. Fisher's exact test was employed to assess the differences in baseline characteristics and the incidence of OCF between the two groups.

RESULTS

The study included 214 patients, with 156 in the conventional suture (CS) group and 58 in the AS group. The incidence of OCF in the AS group was significantly lower compared to that in the CS group (P = 0.039). However, there was a weak correlation between OCF and the AS technique (φ = -0.149). Among the 58 cases in the AS group, three (5.17%) experienced AS-related granuloma (ASRG) as complications.

CONCLUSION

The use of ALT flap reconstruction with the AS technique reduces the incidence of OCF; however, ASRG may be a potential complication.

CLINICAL RELEVANCE

This study demonstrates the effectiveness of AS technique in securing ALT flaps, leading to a decreased risk of OCF in oral and oropharyngeal defect reconstruction.