Application Research Of 3D Printing Technology In Bone Tissue Engineering And Spinal Surgery

Objective:To investigate the osteogenesis response of polydopamine modified 3D printing porous polycaprolactone scaffolds combined with BMP 2 microsphereMethods:Four sets of scaffolds(bare PCL scaffolds,PCL+PDA scaffolds,PCL+PDA+BMP2 scaffolds,PCL+PDA+BMP2 microsphere scaffolds)with diameters of 4mm and high of 4mm were prepared by 3D printing.In vitro,the scaffolds were observed by morphology and scanning electron microscope(SEM).Bone marrow mesenchymal stem cells were seeded on four groups of scaffolds to detect cell proliferation.The release of BMP2 from two groups of scaffolds(PCL+PDA+BMP2 scaffolds and PCL+PDA+BMP2 microsphere scaffolds)was detected.Bone marrow mesenchymal stem cells were seeded on four groups of scaffolds(PCL bare scaffolds;PCL+PDA scaffolds;PCL+PDA+BMP2 scaffolds;PCL+PDA+BMP2 microsphere scaffolds)to detect osteogenic and chondrogenic genes.In vivo,30 New Zealand white rabbits were randomly divided into five groups.After anesthesia,defects of 4mm in diameter were made on the left distal femur.No scaffold were implanted in control group.Four groups of scaffolds(PCL bare scaffolds,PCL+PDA scaffolds,PCL+PDA+BMP2 scaffolds and PCL+PDA+BMP2 microsphere scaffolds)were implanted into the bone defects according to the grouping.The animals were killed 3 months after the operation.The distal femur of the left knee was taken for morphology,Micro-CT and histological staining(HE and Safranin O staining).Results:In vitro,the PCL bare scaffolds were white and the PCL scaffolds modified with PDA were black.SEM showed that surface of PCL scaffolds were smooth while particles were formed on the surface of PDA modified PCL scaffolds.The proliferation of PCL+PDA scaffolds,PCL+PDA+BMP2 scaffolds and PCL+PDA+BMP2 microsphere scaffolds increased significantly,and the proliferation of PCL+PDA+BMP2 microspheres were more higher.The BMP2 of PCL+PDA+BMP2 scaffolds and PCL+PDA+BMP2 microsphere scaffolds could be released stably after 14 days.In vivo,the PCL scaffolds and the PCL+PDA scaffolds revealed poor regeneration in the bone defects,while the PCL+PDA+BMP2 scaffolds and the PCL+PDA+BMP2 microsphere scaffolds showed better regeneration,especially the PCL+PDA+BMP2 microsphere scaffolds with nearly 100%recovery by morphology,Micro-CT and histological staining(HE and Safranin O staining).Conclusion:Poly dopamine modified 3D printing porous polycaprolactone scaffolds combined with BMP 2 microsphere can stably release the BMP2,and can better promote osteogenesis.Objective:To investigate the application of 3D printing(3DP)rapid prototyping(RP)technique assisted the posterior segment pedicle nail bar system in the treatment of thoracolumbar vertebral fracture patients.Methods:42 thoracolumbar vertebral fracture patients were devided into two groups.Patients in 3D printing group were examined using CT scanning.Anatomical data of.Dicom was reconstructed to.STL data through M3D software.3DP-RP was performed using fused deposition modeling(FDM)technique.The length and diameter of pedicle screws,angle of pedicle screws and the distance of entry point and midline were measured based on the 3D printing prototyping.Operation time of pedicle screw(min),exposure time of X-ray(min),and JOA scores after operation were recorded.Results:No significant difference of pedicle screw size was found between the implants used and preoperative planned.3D printing group has a shorter time of operation of pedicle screw and exposure time of X-ray,compared to the non-3D printing group.After 6 months follow-up observation,no internal fixation displacement happened in 3DP surgery.JOA score with 3DP procedure after 1 week,2 weeks and 1 month is better than with non-3D printing procedureConclusions:3DP technique improved efficiency and accuracy of the posterior segment pedicle nail bar system in the treatment of thoracolumbar vertebral fracture patients.