Infections associated with orthopaedic implants are currently one of the major concerns of orthopaedic surgeons. Metallic antimicrobial nanocoatings have demonstrated great potential in preventing implant infections due to their excellent antimicrobial properties and biocompatibility. However, there are potential risks associated with these metal nanoparticles, such as cytotoxicity of silver and copper, and rapid dissolution of zinc and magnesium which affects implant stability. Therefore, the clinical application of nanometallic coatings still faces challenges in how to better enhance biosafety, regulate degradation rate, and enhance osseointegration. This paper reviews the progress and challenges in the application of antimicrobial nanometallic coatings on implants to provide a reference for related research.

Objective:To investigate the effects of dual vascularized tissue-engineered bone constructed by vascular bundles and endothelial progenitor cells (EPCs) on repair of large bone defects and vascular regeneration.Methods:EPCs were seeded on the demineralized bone matrix (DBM) scaffolds and cultured for 6 days. The attachment and morphology of EPCs on DBM scaffolds were observed by electron microscopy. Next, the radial artery was implanted into a vascular groove opened inside the DBM-EPCs composite scaffolds. Finally, models of a large segmental bone defect were constructed using the radii from 18 New Zealand white rabbits. The rabbits were randomly divided into 4 groups using a simple random sampling method: DBM group, DBM+EPCs group, DBM+vascular bundle group, and DBM+EPCs+vascular bundle group. The DBM group and DBM+EPCs group shared the same rabbits so that transplantations were conducted into the left and right forearms respectively; the DBM+vascular bundle group and DBM+EPCs+vascular bundle group also shared the same rabbits so that transplantations were conducted into the left and right forearms respectively. Consequently, there were 9 experimental sites in each group. X-ray examination and gross morphological observation were performed to evaluate the bone regeneration in the experimental rabbits in each group at 4, 8, and 12 weeks after surgery, and CD31 immunofluorescence staining was used to evaluate the vascular regeneration. Micro-CT was used to analyze bone tissue parameters and reconstruct the three-dimensional structures of the defects site at 12 weeks after surgery.Results:Compared with the DBM, DBM+EPCs and DBM+vascular bundle groups, the DBM+EPCs+vascular bundle group showed new bone tissue crawling on the scaffold surface at 4 weeks after surgery, almost complete healing of the bone defect area at 8 weeks, and forming of a complete and dense bone bridge and appearance of a bone marrow cavity at 12 weeks. Micro-CT data at 12 weeks after surgery showed regular arrangement of the trabeculae, significantly improved mineralization, and increased thickness of the bone cortex in the DBM+EPCs+vascular bundle group. Additionally, in the DBM+EPCs+vascular bundle group, the number of microvessels was significantly higher than that in the other groups at 4, 8, 12 weeks after surgery ( P<0.05), and the angiogenesis and bone tissue regeneration were particularly prominent at 12 weeks after surgery. The number of CD31 cells in the DBM+EPCs+vascular bundle group increased significantly more than that in the DBM, DBM+EPCs and DBM+vascular bundle groups ( P<0.05). Conclusion:As the dual vascularized tissue-engineered bone constructed by vascular bundles and EPCs can significantly promote bone tissue regeneration and angiogenesis, it may be a potential therapeutic strategy for repair of large bone defects.

Objective:To investigate the effects of dual vascularized tissue-engineered bone constructed by vascular bundles and endothelial progenitor cells (EPCs) on repair of large bone defects and vascular regeneration.Methods:EPCs were seeded on the demineralized bone matrix (DBM) scaffolds and cultured for 6 days. The attachment and morphology of EPCs on DBM scaffolds were observed by electron microscopy. Next, the radial artery was implanted into a vascular groove opened inside the DBM-EPCs composite scaffolds. Finally, models of a large segmental bone defect were constructed using the radii from 18 New Zealand white rabbits. The rabbits were randomly divided into 4 groups using a simple random sampling method: DBM group, DBM+EPCs group, DBM+vascular bundle group, and DBM+EPCs+vascular bundle group. The DBM group and DBM+EPCs group shared the same rabbits so that transplantations were conducted into the left and right forearms respectively; the DBM+vascular bundle group and DBM+EPCs+vascular bundle group also shared the same rabbits so that transplantations were conducted into the left and right forearms respectively. Consequently, there were 9 experimental sites in each group. X-ray examination and gross morphological observation were performed to evaluate the bone regeneration in the experimental rabbits in each group at 4, 8, and 12 weeks after surgery, and CD31 immunofluorescence staining was used to evaluate the vascular regeneration. Micro-CT was used to analyze bone tissue parameters and reconstruct the three-dimensional structures of the defects site at 12 weeks after surgery.Results:Compared with the DBM, DBM+EPCs and DBM+vascular bundle groups, the DBM+EPCs+vascular bundle group showed new bone tissue crawling on the scaffold surface at 4 weeks after surgery, almost complete healing of the bone defect area at 8 weeks, and forming of a complete and dense bone bridge and appearance of a bone marrow cavity at 12 weeks. Micro-CT data at 12 weeks after surgery showed regular arrangement of the trabeculae, significantly improved mineralization, and increased thickness of the bone cortex in the DBM+EPCs+vascular bundle group. Additionally, in the DBM+EPCs+vascular bundle group, the number of microvessels was significantly higher than that in the other groups at 4, 8, 12 weeks after surgery ( P<0.05), and the angiogenesis and bone tissue regeneration were particularly prominent at 12 weeks after surgery. The number of CD31 cells in the DBM+EPCs+vascular bundle group increased significantly more than that in the DBM, DBM+EPCs and DBM+vascular bundle groups ( P<0.05). Conclusion:As the dual vascularized tissue-engineered bone constructed by vascular bundles and EPCs can significantly promote bone tissue regeneration and angiogenesis, it may be a potential therapeutic strategy for repair of large bone defects.

Infections associated with orthopaedic implants are currently one of the major concerns of orthopaedic surgeons. Metallic antimicrobial nanocoatings have demonstrated great potential in preventing implant infections due to their excellent antimicrobial properties and biocompatibility. However, there are potential risks associated with these metal nanoparticles, such as cytotoxicity of silver and copper, and rapid dissolution of zinc and magnesium which affects implant stability. Therefore, the clinical application of nanometallic coatings still faces challenges in how to better enhance biosafety, regulate degradation rate, and enhance osseointegration. This paper reviews the progress and challenges in the application of antimicrobial nanometallic coatings on implants to provide a reference for related research.

Objective:To compare the mechanical properties between our self-designed axially controlled compression spinal rod (ACCSR) and conventional spinal rod (CSR) for lumbar spondylolysis (LS).Methods:This study selected 36 ACCSRs (the ACCSR group) and 36 CSRs (the CSR group), both of which were in a diameter of 6.0 mm and manufactured in the same batch. They were subjected respectively to biomechanical tests of spinal rod and pedicle screw-rod internal fixation system. In spinal rod tests: the stiffness and yield load of the spinal rods were calculated using four-point bending tests ( n=7) and comparisons were made between the 2 groups; spinal rod fatigue tests ( n=8) recorded the successful compression loads after 2.5 million cycles of loading and compared them with the maximum force at the isthmus of a normal adult's unilateral lumbar spine (198.72 N). In tests of the pedicle screw-rod internal fixation system, the axial compression tests ( n=7) measured the axial gripping capacity, the axial torsion tests ( n=7) the torsional gripping capacity, and the lateral compression tests ( n=7) the stiffness and yield load of pedicle screws in the 2 groups respectively. Results:The stiffness [(1,543.37±61.41) N/mm] and yield load [1,338.57 (1,282.00, 1,353.80) N] of ACCSR group were significantly smaller than those of CSR group [(3,797.63±156.15) N/mm and 4,059.95 (3,813.80, 4,090.89) N] ( P<0.05). The spinal rod fatigue tests showed that the respective loads of CSR and ACCSR passing the 2.5 million fatigue tests were 640.00 N and 320.00 N, both larger than the maximum force at the unilateral lumbar isthmus of a normal adult (198.72 N). There were no significant differences between the ACCSR group and the CSR group in the axial gripping capacity and torsional gripping capacity, as well as in stiffness and yield load of screws between the 2 groups ( P>0.05). Conclusions:In fixation of LS, although the yield load, stiffness and fatigue resistance of ACCSR are inferior to those of CSR, the biomechanical properties of the two sets of pedicle screw-rod internal fixation system are comparable. The fatigue resistance of ACCSR can meet the stress requirements of the normal human isthmus.

Tissue engineering bone technology, grounded in seed cells, cytokines, and scaffold supports, provides an effective solution for addressing extensive bone defects, demonstrating significant potentials in the field of bone repair. However, this technology still faces numerous challenges. Focusing on vascularization in engineered bones, this article reviews various methods to enhance vascularization within tissue-engineered bones, including multicellular co-culture, application of angiogenic factors, advanced 3D printing, and aid of surgical interventions. This article also analyses the latest research developments and the limitations of the methods, and speculates future research directions for tissue engineered bone.

Limb (digit) replantation is the primary treatment in salvage of severed traumatic limbs (digits). It is vital to improve the success rate of limb (digit) salvage and the function recovery. Once a human limb (digit) is separated from the body, blood circulation stops and normal physiological metabolism are disrupted, hence result in a series of physiological and pathological changes such as cell degeneration and tissue necrosis, which greatly affect the therapeutic effect of limb (digit) replantation. Therefore, how to scientifically minimise the metabolism of tissues in a severed limb (digit) and mitigate the subsequent ischaemia-reperfusion injury to improve the success rate of limb (digit) replantation is a hot issue in the field of limb (digit) replantation. In this article, a review of current status and progress of existing limb (digit) preservation methods are presented. Through an extensive search and analysis of literatures, the advantages and disadvantages of current limb (digit) preservation methods are summarised in the hope that it will provide a reference for clinical preservation of severed limbs (digit) .