Objective:To synthesize hydroxyapatite/poly (lactic-co-glycolic acid)(HA/PLGA) composites by substituting calcium ions in HA with Cu and Gd ions, characterize their physicochemical properties, and evaluate their feasibility for orbital bone defect repair.Methods:Different ratios of Cu-, Gd-, and Cu/Gd-substituted HA nanoparticles (Cu@HA, Gd@HA and Cu/Gd@HA) were synthesized via hydrothermal synthesis using copper nitrate, gadolinium nitrate, calcium chloride, and ammonium hydrogen phosphate.HA/PLGA, Cu@HA/PLGA, Gd@HA/PLGA, and Cu/Gd@HA/PLGA composites were prepared.HA/PLGA was prepared by co-preparing different ratios of nanoparticles with PLGA via phase inversion and solvent evaporation.The nanoparticles and composites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), environmental scanning electron microscope (ESEM) and micro-computed tomography (Micro-CT). Composite homogeneity was assessed by elemental analysis and the contact angle was measured to evaluate hydrophilicity.Imaging capability of composites was assessed by magnetic resonance imaging (MRI) and T1-weighted.CCK-8 method was used to detect the cytotoxicity of nanoparticles and their extract.Orbital bone defects model was established in 20 rats, which were randomly divided into 4 groups, and implanted with respective composites.Eight weeks after transplantation, the implants were evaluated using Micro-CT and MRI, and osteogenesis, collagen distribution and biocompatibility were assessed by hematoxylin-eosin staining, Masson, and Sirius red staining.All animal experiments complied with the regulations of the Laboratory Animal Ethics Committee of Dalian Medical University and were approved (No.AEE23104).Results:XRD and ESEM results showed that co-doping with Cu/Gd induced less HA lattice distortion than single doping.FT-IR results showed that the nanoparticles doped with Cu and Gd ions were consistent with the HA infrared absorption spectrum.ICP results revealed a higher Ca content in 0.5Cu/Gd@HA and 0.5Cu@HA samples than in 0.5Gd@HA sample.There was a statistically significant overall difference in contact angles among different groups of composites ( F=5.040, P<0.05), among which the 0.5Cu/Gd@HA/PLGA composite exhibited the smallest contact angle and the best hydrophilicity.There was no statistically significant difference in porosity among different groups of composites ( F=0.004, P>0.05). MRI results showed that Gd-doped composites displayed enhanced development and that the signal intensity of the 0.5Gd@HA/PLGA group was the highest.Micro-CT scanning results showed that the composition of the composite material doped with Cu and Gd was better than that of the pure HA/PLGA group, indicating that the metal ions Cu and Gd could promote bone growth.CCK-8 results showed that the nanoparticles and their extracts had no obvious cytotoxic effects.Eight weeks after modelling, Micro-CT showed that the 0.5Cu/Gd@HA/PLGA material degraded well in vivo and the staining results of bone tissue sections in the bone defect area suggested that tissues around the implanted material and rat organs in different groups did not show biological toxicity.In addition, the Gd-doped composites showed good magnetic imaging characteristics when implanted in animals. Conclusions:Cu/Gd@HA/PLGA composites exhibit favorable physicochemical properties, biosafety, osteogenic potential, and MRI contrast and have good clinical application prospects for orbital bone repair.

Objective:To synthesize hydroxyapatite/poly (lactic-co-glycolic acid)(HA/PLGA) composites by substituting calcium ions in HA with Cu and Gd ions, characterize their physicochemical properties, and evaluate their feasibility for orbital bone defect repair.Methods:Different ratios of Cu-, Gd-, and Cu/Gd-substituted HA nanoparticles (Cu@HA, Gd@HA and Cu/Gd@HA) were synthesized via hydrothermal synthesis using copper nitrate, gadolinium nitrate, calcium chloride, and ammonium hydrogen phosphate.HA/PLGA, Cu@HA/PLGA, Gd@HA/PLGA, and Cu/Gd@HA/PLGA composites were prepared.HA/PLGA was prepared by co-preparing different ratios of nanoparticles with PLGA via phase inversion and solvent evaporation.The nanoparticles and composites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), environmental scanning electron microscope (ESEM) and micro-computed tomography (Micro-CT). Composite homogeneity was assessed by elemental analysis and the contact angle was measured to evaluate hydrophilicity.Imaging capability of composites was assessed by magnetic resonance imaging (MRI) and T1-weighted.CCK-8 method was used to detect the cytotoxicity of nanoparticles and their extract.Orbital bone defects model was established in 20 rats, which were randomly divided into 4 groups, and implanted with respective composites.Eight weeks after transplantation, the implants were evaluated using Micro-CT and MRI, and osteogenesis, collagen distribution and biocompatibility were assessed by hematoxylin-eosin staining, Masson, and Sirius red staining.All animal experiments complied with the regulations of the Laboratory Animal Ethics Committee of Dalian Medical University and were approved (No.AEE23104).Results:XRD and ESEM results showed that co-doping with Cu/Gd induced less HA lattice distortion than single doping.FT-IR results showed that the nanoparticles doped with Cu and Gd ions were consistent with the HA infrared absorption spectrum.ICP results revealed a higher Ca content in 0.5Cu/Gd@HA and 0.5Cu@HA samples than in 0.5Gd@HA sample.There was a statistically significant overall difference in contact angles among different groups of composites ( F=5.040, P<0.05), among which the 0.5Cu/Gd@HA/PLGA composite exhibited the smallest contact angle and the best hydrophilicity.There was no statistically significant difference in porosity among different groups of composites ( F=0.004, P>0.05). MRI results showed that Gd-doped composites displayed enhanced development and that the signal intensity of the 0.5Gd@HA/PLGA group was the highest.Micro-CT scanning results showed that the composition of the composite material doped with Cu and Gd was better than that of the pure HA/PLGA group, indicating that the metal ions Cu and Gd could promote bone growth.CCK-8 results showed that the nanoparticles and their extracts had no obvious cytotoxic effects.Eight weeks after modelling, Micro-CT showed that the 0.5Cu/Gd@HA/PLGA material degraded well in vivo and the staining results of bone tissue sections in the bone defect area suggested that tissues around the implanted material and rat organs in different groups did not show biological toxicity.In addition, the Gd-doped composites showed good magnetic imaging characteristics when implanted in animals. Conclusions:Cu/Gd@HA/PLGA composites exhibit favorable physicochemical properties, biosafety, osteogenic potential, and MRI contrast and have good clinical application prospects for orbital bone repair.

Objective:To analyze the stability of different internal fixation methods for zygomaticomaxillary complex fracture using finite element biomechanical analysis and to provide a quantitative basis for the option of optimal internal fixation methods.Methods:One patient with zygomaticomaxillary complex ZMC fracture (Zingg B type) was enrolled from the Second Hospital of Dalian Medical University in October 2016.The zygomaticofrontal suture and the inferior orbital rim were fixed during the surgery, and the postoperative function was well recovered with no mouth opening restriction, diplopia or implant displacement, and had a symmetrical facial appearance.The preoperative orbital CT images were collected.The normal craniofacial bones finite element model (FEM/intact) was reconstructed through Mimics, Geomagic, Solidworks and Abaqus softwares based on the non-fractured side and verified.Based on the verified model, the segmentation and assembling was performed according to the fracture location, and the internal fixation models were established according to the methods of surgery, including fixed zygomaticofrontal suture model (FEM/ZFS), fixed inferior orbital rim model(FEM/IOR), fixed zygomaticofrontal suture and inferior orbital rim model (FEM/ZFS+ IOR), fixed ZFS and IOR and zygomaticomaxillary suture model (FEM/ZFS+ IOR+ ZMS). The masseter muscle strength was applied to the model.The stress and displacement were analyzed and the rotation angle of zygoma was calculated to compare the stability of different operative methods.The postoperative model (FEM/post) was established according to the actual operative method and was compared with FEM/ZFS+ IOR.This study protocol was approved by the Ethic Committee of The Second Hospital of Dalian Medical University (2020-33), and written informed consent was obtained from the subject before entering the study.Results:The established FEM/intact had a realistic appearance and good geometric similarity, and the validity and accuracy of model was verified.In the FEM/ZFS+ IOR and FEM/ZFS+ IOR+ ZMS, the maximal stress of the titanium plate was 396 MPa and 426 MPa, respectively, which was lower than the yield strength 483 MPa of pure titanium, and the maximal displacement of the fracture line was 0.10 mm and 0.06 mm, respectively, which was both≤0.1 mm, and the rotation angle of zygoma was both<2°.In the FEM/ZFS and FEM/IOR, the maximal stress of the titanium plate was 730 MPa and 501 MPa, respectively, which was higher than the yield strength of pure titanium; the maximal displacement of fracture line was 0.27 mm and 0.15 mm, respectively, which was >0.1 mm, and the rotation angle of zygoma was <2°.The results of FEM/post were consistent with those of FEM/ZFS+ IOR.Conclusions:The finite element analysis can perform digital analysis and evaluation of the stability of different internal fixation methods before surgery, which is available for the selecting of the optimal fixation methods.Finite element analysis can provide an objective quantitative basis for the precise treatment of zygomaticomaxillary complex fractures.