Design and Manufacture of Bionic Porous Titanium Alloy Spinal Implant Based on Selective Laser Melting(SLM)

In order to meet the clinical requirements of spine surgery,this paper proposed the exploratory research of computer-aided design and selective laser melting(SLM)fabrication of a bionic porous titanium spine implant.The structural design of the spinal implant is based on CT scanning data to ensure correct matching,and the mechanical properties of the implant are verified by simulation analysis and laser selective melting experiment.The surface roughness of the spinal implant manufactured by SLM without post-processing is Ra 15μm,and the implant is precisely jointed with the photosensitive resin model of the upper and lower spine.The surface micro-hardness of the implant is HV 373,tensile strengthσ_(b)=1238.7 MPa,yield strengthσ_(0.2)=1043.9 MPa,the elongation is 6.43%,and the compressive strength of porous structure under 84.60%porosity is 184.09 MPa,which can meet the requirements of the reconstruction of stable spines.Compared with the traditional implant and intervertebral fusion cage,the bionic porous spinal implant has the advantages of accurate fit,porous bionic structure and recovery of patients,and the ion release experiment proved that implants manufactured by SLM are more suitable for clinical application after certain treatments.The elastic modulus of the sample is improved after heat treatment,mainly because the microstructure of the sample changes fromα’phase toα+βdual-phase after heat treatment.In addition,the design of high-quality bionic porous spinal implants still needs to be optimized for the actual needs of doctors.

Anterior vertebral body tethering for idiopathic scoliosis in growing children:A systematic review

BACKGROUND The management of idiopathic scoliosis(IS)in skeletally immature patients should aim at three-dimensional deformity correction,without compromising spinal and chest growth.In 2019,the US Food and Drug Administration approved the first instrumentation system for anterior vertebral body tethering(AVBT),under a Humanitarian Device Exception,for skeletally immature patients with curves having a Cobb angle between 35°and 65°.AIM To summarize current evidence about the efficacy and safety of AVBT in the management of IS in skeletally immature patients.METHODS From January 2014 to January 2021,Ovid Medline,Embase,Cochrane Library,Scopus,Web of Science,Google Scholar and PubMed were searched to identify relevant studies.The methodological quality of the studies was evaluated and relevant data were extracted.RESULTS Seven clinical trials recruiting 163 patients were included in the present review.Five studies out of seven were classified as high quality,whereas the remaining two studies were classified as moderate quality.A total of 151 of 163 AVBT procedures were performed in the thoracic spine,and the remaining 12 tethering in the lumbar spine.Only 117 of 163(71.8%)patients had a nonprogressive curve at skeletal maturity.Twenty-three of 163(14.11%)patients required unplanned revision surgery within the follow-up period.Conversion to posterior spinal fusion(PSF)was performed in 18 of 163(11%)patients.CONCLUSION AVBT is a promising growth-friendly technique for treatment of IS in growing patients.However,it has moderate success and perioperative complications,revision and conversion to PSF.

In vitro and in vivo evaluation of bone morphogenetic protein- 2 （BMP-2） immobilized collagen-coated polyetheretherketone （PEEK）

Polyetheretherketone （PEEK） is regarded as one of the most potential candidates of biomaterials in spinal implant applications. However, as a bioinert material, PEEK plays a limited role in osteoconduction and osseointegration. In this study, recombinant human bone morphogenetic protein-2 （rhBMP-2） was immobilized onto the surface of collagen-coated PEEK in order to prepare a multi-functional material. After adsorbed onto the PEEK surface by hydroph（bic interaction, collagen was cross-linked with N-（3-dimethylaminopropyl）-N＇-ethyl carbodiimide hydrochloride （EDC） and N-hydro xysuccinimide （NHS）. EDCINHS system also contributed to the immobilization of rhBMP- 2. Water contact angle tests, XPS and SEM clearly demonstrated the surface changes. ELISA tests quantified the amount of rhBMP-2 immobilized and the release over a period of 30 d. In vitro evaluation proved that the osteogenesis differentiation rate was higher when cells were cultured on modified PEEK discs than on regular ones. In vivo tests were conducted and positive changes of major parameters were presented. This report demonstrates that the rhBMP-2 immobilized method for PEEK modification increase bioactivity in vitro and in vivo, suggesting its practicability in orthopedic and spinal clinical applications.