Analyzing the behavior of a porous nano-hydroxyapatite/polyamide 66 (n-HA/PA66) composite for healing of bone defects

A comparison of anterior reconstruction of spinal defect using nano-hydroxyapatite/polyamide 66 cage and autologous iliac bone for thoracolumbar tuberculosis: a stepwise propensity score matching analysis

Purpose

Previous studies have confirmed the advantages and disadvantages of autogenous iliac bone and nano-hydroxyapatite/polyamide 66 (n-HA/PA66) cage. However, there is no conclusive comparison between the efficacy of the two implant materials in spinal tuberculosis bone graft fusion. The aim of this study was to analyze the mid-to long-term clinical and radiologic outcomes between n-HA/PA66 cage and autogenous iliac bone for anterior reconstruction application of spinal defect for thoracolumbar tuberculosis.

Methods

We retrospectively reviewed all patients who underwent anterior debridement and strut graft with n-HA/PA66 cage or iliac bone combined with anterior instrumentations between June 2009 and June 2014. One-to-one nearest-neighbor propensity score matching (PSM) was used to match patients who underwent n-HA/PA66 cage to those who underwent iliac bone. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) and visual analogue score (VAS). Radiographic evaluations included cage subsidence and segmental angle.

Results

At the end of the PSM analysis, 16 patients from n-HA/PA66 cage group were matched to 16 patients in Iliac bone group. The C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) values in the n-HA/PA66 group decreased significantly from 33.19 ± 10.89 and 46.63 ± 15.65 preoperatively, to 6.56 ± 2.48 and 9.31 ± 3.34 at the final follow-up, respectively (p < 0.001). There were no significant differences in the CRP and ESR values between the two groups at the final follow-up. The VAS and JOA scores in the iliac bone and n-HA/PA66 group were significantly improved at the 3-month follow-up postoperatively (both p < 0.001). Then, improvements of VAS and JOA scores continue long at final follow-up. However, there were no significant differences in the VAS and JOA scores at any time point between the two groups (p > 0.05). Although the segmental angle (SA) significantly increased after surgery in both groups, there was no significant difference at any time point after surgery (p > 0.05). There were no significant differences in the cage subsidence and fusion time between the two groups.

Conclusion

Overall, our data suggest that the n-HA/PA66 cage outcomes are comparable to those in the autogenous iliac bone, with a similar high fusion rate as autogenous iliac bone.

Comparison of Long-term Follow-Up of n-HA PA66 Cage and PEEK Cage of Lumbar Interbody Fusion in Multi-level Degenerative Lumbar Diseases: A Stepwise Propensity Score Matching Analysis

OBJECTIVE

Previous studies have confirmed that the nanohydroxyapatite/polyamide-66 (n-HA/PA66) cage is an ideal alternative material for degenerative lumbar disease (DLD) comparable to the polyether ether ketone (PEEK) cage due to its similar radiographic fusion, subsidence rate, and clinical results. However, these studies were restricted to one-level surgery. The aim of this study was to analyze the long-term clinical and radiologic outcomes between n-HA PA66 cage and PEEK cage for patients with multi-level degenerative lumbar diseases (DLDs).

METHODS

We retrospectively reviewed all patients who underwent multi-level transforaminal lumbar interbody fusion (TLIF) from June 2010 to December 2016 with a minimum 6-year follow-up. Matched-pair analysis was performed using a 1-to-1 closest neighbor approach to match patients who received an n-HA PA66 cage with those who received a PEEK cage. Clinical outcomes and radiographic evaluations were compared between the two groups. The independent student's t-test and χ2 -test were applied to compare the differences between groups.

RESULTS

At the end of the propensity score matching (PSM) analysis, 48 patients from n-HA/PA66 group were matched to 48 patients in the PEEK group. No significant difference was observed in cage subsidence and bony fusion except for adjacent segment degeneration (ASD). The occurrence of ASD was 14.58% (7/48) in the n-HA/PA 66 group, which was significantly less than that in the PEEK group (33.33% [16/48]) (p = 0.031). Although the intervertebral space height (IH), segmental angle (SA) and lumbar lordosis (LL) significantly increased after surgery in both groups, there was no significant difference at any time point after surgery (p > 0.05). The visual analogue scale (VAS) and Oswestry disability index (ODI) scores significantly improved in both groups at 3m postoperative, 1y postoperative and at final follow-up. However, there were no significant differences in the VAS and ODI score at any time point (p > 0.05). The total complications and re-admission rate were not different between the two groups.

CONCLUSION

Overall, our data suggest that the outcomes of n-HA/PA66 cage group are comparable to those of the PEEK cage group, with a similar high fusion rate and low cage subsidence rate as PEEK cages, except its lower rate of ASD occurrence.

Clinical and radiological outcomes of n-HA/PA66 cages in anterior spine reconstruction following total en bloc spondylectomy for tumors

Objective

This retrospective monocentric study was conducted to evaluate the clinical and radiological outcomes of the nano-hydroxyapatite/polyamide66 (n-HA/PA66) cage in reconstructing the anterior column of the spine following total en bloc spondylectomy (TES).

Methods

A cohort of 24 patients, 20 diagnosed with primary malignant tumors and 4 with metastatic malignancies, was selected based on specific inclusion criteria. All were subjected to TES and anterior column reconstruction with the n-HA/PA66 cage from January 2013 to July 2023 at a single institution. Pre-operative embolization was performed on all patients. Documented factors included operation duration, intraoperative blood loss, length of hospital stay, treatment history, and involved level. Mechanical complications and radiological parameters such as the local kyphotic angle (LKA), anterior vertebral height (AVH), posterior vertebral height (PVH), cage subsidence, and bone fusion time were evaluated. Quality of life and neurological function were gauged using tools like the Visual Analog Scale (VAS), Eastern Cooperative Oncology Group (ECOG) performance score, Karnofsky Performance Score (KPS) scale, and American Spinal Injury Association (ASIA) grading.

Results

All patients were followed up for 12-127 months, with an average period of 39.71 months. An average operation time of approximately 8.57 h and a blood loss volume of about 1,384 ml were recorded. No instances of tumor recurrence or multiple organ metastases were reported, though recurrence was detected in 2 living patients. Solid fusion was achieved in all patients at a mean time of 6.76 ± 0.69 months. Cage breakage or migration was not observed. Subsidence into the adjacent vertebral bodies was identified in 3 patients but was deemed clinically irrelevant. Significant improvements in VAS, ECOG performance score, KPS scale, and ASIA scores were noted from pre- to post-surgery (P < 0.05). A marked enhancement in the AVH was observed from before surgery to immediately after (P < 0.05). LKA, AVH, and PVH values between postoperative and final follow-up showed no significant variance (P > 0.05).

Conclusion

The integration of TES and the n-HA/PA66 cage was found to yield promising clinical and radiological outcomes in anterior column spine reconstruction. The use of this material did not hinder oncological care, including the provision of adjuvant treatments (chemo/radiotherapy), ultimately contributing to the enhanced long-term quality of life for spinal tumor patients.

Does Preoperative Modic Changes Influence the Short-term Fusion Rate of Single Level Transforaminal Lumbar Interbody Fusion?-a Matched-pair Case Control Study

OBJECTIVE

At present, the influence of Modic changes (MCs) on postoperative fusion rate of lumbar interbody fusion (LIF) is mainly focused on the medium- and long-term fusion rate, while the short-term fusion rate has not been reported. The aim of this study was to compare the short-term fusion rate of lumbar degenerative disease patients with and without MCs after single level transforaminal lumbar interbody fusion (TLIF).

METHODS

In this retrospective and matched-pair case control study, we included 100 patients who underwent TLIF from January 2017 to January 2020 and had at least two follow-up visits over a two-year period. Fifty patients with MCs (MCs group) were matched with 50 patients without MCs (non MCs group) for age, sex, surgical level, diagnosis, operative time, and intraoperative blood loss. We collected the X-ray and computed tomography (CT) data of patients from 3 months to 2 years after the operation to assess bony fusion and the cage union ratio. According to the type of cage, the MCs group was further divided into the nano-hydroxyapatite/polyamide 66 (n-HA/PA66) group and polyetheretherketone (PEEK) group, and the fusion performance between the two groups was compared. Finally, age, sex, body mass index (BMI), smoking and cage type were included in the logistic regression model for risk factor analysis.

RESULTS

The bony fusion rates in the MCs group at 3 months, 6 months, 1 year and 2 years after surgery were significantly lower than those in the non MCs group (P < 0.05) (23.8% vs 62.5%, 52.6% vs 78.9%, 61.1% vs 83.3%, 74.0% vs 90.0%). The average coronal cage union ratios of the upper and lower endplates in the MCs group were significantly lower than those in the non MCs group (54.3% ± 17.5% vs 75.0% ± 17.2%, P < 0.05; 73.3% ± 12.0% vs 84.9% ± 8.0%, P < 0.05). Similarly, analogous results were obtained by comparing the MCs and non MCs groups' three-dimensional CT sagittal plane images (62.5% ± 16.5% vs 76.1% ± 12.4%, P < 0.05; 67.0% ± 13.9% vs 79.8% ± 11.5%, P < 0.05).

CONCLUSION

Short-term fusion rates were lower in the MCs group than in the non MCs group. The coronal and sagittal cage union ratio in the MCs group was lower than that in the non MCs group. The fusion performance of n-HA/PA66 and PEEK cages in the MCs group was comparable.

Macrophage fusion event as one prerequisite for inorganic nanoparticle-induced antitumor response

While most nanomaterials are designed to assist tumor therapy, some inorganic nanoparticles have been reported to impede cancer development. We assume that the immune response elicited by these foreign nanoparticles might be associated with the remodeling of immune landscape in the tumor microenvironment (TME). We studied representative inorganic nanoparticles widely used in the biomedical field and first demonstrated that needle-shaped hydroxyapatite (n-nHA), granule-shaped hydroxyapatite, and silicon dioxide can effectively impair tumor progression in vivo. Substantial multinucleated giant cells (MNGCs) were formed around these antitumor nanoparticles, while the ratio of monocytes and macrophages was decreased in the TME. We found that high expression of the STXBP6 protein induced by n-nHA-treated macrophages triggers autophagy, which markedly promotes macrophage fusion into MNGCs. In this way, extensive depletion of tumor-associated macrophages in the TME was achieved, which suppressed tumor growth and metastasis. This intrinsic antitumor immunity of inorganic nanoparticles should not be neglected when designing future nanomedicines to treat cancer.

The effects of nano-hydroxyapatite/polyamide 66 scaffold on dog femoral head osteonecrosis model: a preclinical study

The lack of mechanical support in the bone tunnel formed after CD often results in a poor therapeutic effect in ONFH. The n-HA/P66 has excellent biocompatibility and mechanical properties and has been widely used in bone regeneration. The present study aimed to evaluate the effects of n-HA/P66 scaffold treatment in a dog model of ONFH. A FEA was performed to analyze the mechanical changes in the femoral head after CD and n-HA/P66 scaffold or tantalum rod implantation. Fifteen male beagles were selected to establish the model of ONFH by liquid nitrogen freezing method, and the models were identified by x-ray and MRI 4 weeks after modeling and randomly divided into three groups. Nine weeks later, femoral head samples were taken for morphology, micro-CT, and histological examination. The FEA showed that the n-HA/P66 scaffold proved the structural support in the bone tunnel, similar to the tantalum rod. The morphology showed that the femoral head with n-HA/P66 implantation is intact, while the femoral heads in the model group and CD group are collapsing. Moreover, the micro-CT results of the n-HA/P66 scaffold group were better than the model group and the CD group, and the interface between the n-HA/P66 scaffold and bone tissue is blurred. Furthermore, the histological result also verifies the alterations in micro-CT, and bone tissue grows in the bone tunnel with n-HA/P66 scaffold implanted while few in the CD group. The CD results in a lack of mechanical support in the femoral head subchondral bone and bone tunnel high stress. The n-HA/P66 scaffold implantation can provide mechanical support and relieve high stress induced by CD. The n-HA/P66 scaffold can treat femoral head necrosis and provide the bone tissue growth scaffold for the femoral head after CD to promote bone tissue regeneration.

The improved bioactive n-HA/PA66 cage versus the PEEK cage in anterior cervical fusion: results from a 6-year follow-up and a case-matched study

BACKGROUND

The nanohydroxyapatite/polyamide 66 (n-HA/PA66) cage, a bioactive nonmetal cage, is fabricated in a hollow cylindrical shape and has been widely used for decades with good clinical outcomes for anterior cervical fusion. However, there remain some radiological complications, such as a slightly high subsidence rate. To improve the clinical outcomes, the improved n-HA/PA66 cage now has been developed into a trapezoidal and wedge shape, a better biomechanical shape matching the cervical spine that is similar to that of the PEEK cage. However, there have been no long-term comparisons of the improved n-HA/PA66 cage and PEEK cage in anterior cervical reconstruction.

METHODS

Fifty-eight patients who underwent single-level anterior cervical decompression and fusion (ACDF) with the improved n-HA/PA66 cage (n-HA/PA66 group) were matched with patients with the PEEK cage (PEEK group) by clinical presentation, segment, age and sex. All patients underwent a minimum of 6 years of follow-up. The radiographic parameters (cage subsidence, fusion status, cervical lordosis, and segmental sagittal alignment) and clinical parameters (10-point visual analogue scale, Neck Disability Index and Japanese Orthopedic Association scores) from patients were evaluated before surgery, immediately after surgery, and at the latest follow-up.

RESULTS

The n-HA/PA66 and PEEK groups were well matched in terms of clinical presentation, segment, age, and sex at surgery. The n-HA/PA66 and PEEK cages had similar fusion rates at 6 months postoperatively (n-HA/PA66: 58.6% vs. PEEK: 51.7%, P = 0.455) and at the last follow-up (n-HA/PA66: 96.6% vs. PEEK: 93.1%, P = 0.402). The respective cage subsidence rates in the n-HA/PA66 and PEEK groups were 6.9 and 12.1% (P = 0.342). The correction of SA was similar between the groups at the final follow-up (n-HA/PA66: 4.29 ± 1.99 vs. PEEK: 3.99 ± 2.59 P = 0.464). There were no significant differences between the two groups in mean cervical lordosis, visual analogue scale scores of the neck and arm, NDI scores, JOA scores or patients' overall satisfaction at the final follow-up.

CONCLUSION

After single-level ACDF, the improved n-HA/PA66 cage had similar excellent results in both radiological and clinical outcomes compared with the PEEK cage over 6 years of follow-up. According to these results, the improved n-HA/PA66 cage and the PEEK cage could be comparable for ACDF.

[Comparison of nano-hydroxyapatite/polyamide 66 bioactive support and autologous iliac bone in bone grafting and fusion for elderly patients with lumbar tuberculosis]

Objective

To investigate the safety of nano-hydroxyapatite/polyamide 66 (n-HA/PA66) bioactive support in bone grafting and fusion for elderly patients with lumbar tuberculosis, and to analyze its effectiveness and advantages by comparing with autologous iliac bone grafting.

Methods

A retrospective analysis was performed on 48 elderly patients with lumbar tuberculosis who met the selection criteria between January 2017 and January 2020. The patients all underwent one-stage posterior pedicle screw internal fixation combined with anterior lesion removal and bone grafting and fusion, of which 23 cases applied n-HA/PA66 bioactive support+allogeneic bone graft (n-HA/PA66 group) and 25 cases applied autologous iliac bone graft (autologous iliac bone group). There was no significant difference between the two groups in gender, age, bone density, disease duration, lesion segment, and preoperative pain visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score, and Cobb angle ( P>0.05). The operation time, intraoperative blood loss, and postoperative complications, as well as the VAS score, JOA score, American Spinal Injury Association (ASIA) spinal cord injury grading, Cobb angle, and bone fusion were recorded and compared between the two groups.

Results

The operations were completed successfully in both groups. n-HA/PA66 group had significantly less operation time and intraoperative blood loss than the autologous iliac bone group ( P<0.05). All patients were followed up 12-24 months, with an average of 15.7 months. And the difference in follow-up time between the two groups was not significant ( P>0.05). Postoperative complications occurred in 3 cases (13%) in the n-HA/PA66 group and 10 cases (40%) in the autologous iliac group, and the difference in the incidence of complications between the two groups was significant ( χ 2=4.408, P=0.036). The postoperative VAS scores and JOA scores significantly improved when compared with the preoperative scores in both groups ( P<0.05), and the difference was significant ( P<0.05) between 2 weeks after operation and the last follow-up. The difference in VAS score at 2 weeks after operation was significant between the two groups ( P<0.05), and there was no significant difference ( P>0.05) at the other time points. At last follow-up, according to the ASIA grading, the effective improvement rate was 86% (18/21) in the n-HA/PA66 group and 90% (18/20) in the autologous iliac group, with no significant difference ( χ 2=0.176, P=0.675). Imaging review showed that grade Ⅰ bony fusion was obtained in both groups, and the fusion time of bone graft in the n-HA/PA66 group was significantly longer than that in the autologous iliac bone group ( P<0.05). There was no significant difference in the Cobb angle at each time point between the two groups ( P>0.05). No recurrence of tuberculosis, loosening or fracture of the internal fixator, or displacement of the bone graft was observed during follow-up.

Conclusion

In elderly patients with lumbar spine tuberculosis, the n-HA/PA66 bioactive support combined with allogeneic bone graft can effectively restore and maintain the fusion segment height and physiological curvature of the lumbar spine, and the fusion rate of bone graft is similar to that of autologous iliac bone, which can achieve better effectiveness.

Arg-Gly-Asp peptide functionalized poly-amino acid/ poly (p-benzamide) copolymer with enhanced mechanical properties and osteogenicity

Poly-amino acid (PAA) is a promising biomaterial in biomedical engineering due to its similar amide bond structure to collagen and excellent biocompatibility, but the lack of osteogenic activity and inferior mechanical strength limit its long-term application in orthopedics. In this study, a poly-amino acid/poly (p-benzamide) (PAA-PBA) copolymer with high mechanical strength was designed and fabricated by the method of solution polymerization. The chain structures, thermal properties and mechanical properties of these polymers were evaluated and results showed that PBA greatly promoted the mechanical properties of PAA, and the copolymer performed the maximum mechanical strengths with compressive strength, bending strength and tensile strength of 123 MPa, 107 MPa and, 95 MPa, respectively. To increase the bioactivity of surface, a bioactive coating that consists of poly-(dopamine) (PDA) nanolayers and tripeptide Arginine-Glycine-Aspartic acid (RGD) on sulfonated PAA-PBA copolymer was created. A porous structure appeared on the surface after modification, the surface roughness and hydrophilicity of copolymer has been improved obviously after introducing PDA and RGD peptide coating. The in vitro bioactivity evaluation demonstrated that the RGD-functionalized sample showed a significantly improved ability to promote bone apatite mineralization, cell adhesion, proliferation and osteogenic differentiation. In a word, such a strategy of material synthesis and surface modification method shows a great potential for broadening the use of PAA in the application of load-bearing bone substitute biomaterials.

Application of Solution Blow Spinning for Rapid Fabrication of Gelatin/Nylon 66 Nanofibrous Film

Gelatin (GA) is a natural protein widely used in food packaging, but its fabricated fibrous film has the defects of a high tendency to swell and inferior mechanical properties. In this work, a novel spinning technique, solution blow spinning (SBS), was used for the rapid fabrication of nanofiber materials; meanwhile, nylon 66 (PA66) was used to improve the mechanical properties and the ability to resist dissolution of gelatin films. Morphology observations show that GA/PA66 composite films had nano-diameter from 172.3 to 322.1 nm. Fourier transform infrared spectroscopy and X-ray indicate that GA and PA66 had strong interaction by hydrogen bonding. Mechanical tests show the elongation at break of the composite film increased substantially from 7.98% to 30.36%, and the tensile strength of the composite film increased from 0.03 MPa up to 1.42 MPa, which indicate that the composite films had the highest mechanical strength. Water vapor permeability analysis shows lower water vapor permeability of 9.93 g mm/m2 h kPa, indicates that GA/PA66 film's water vapor barrier performance was improved. Solvent resistance analysis indicates that PA66 could effectively improve the ability of GA to resist dissolution. This work indicates that SBS has great promise for rapid preparation of nanofibrous film for food packaging, and PA66 can be applied to the modification of gelatin film.

Porous copper- and lithium-doped nano-hydroxyapatite composite scaffold promotes angiogenesis and bone regeneration in the repair of glucocorticoids-induced osteonecrosis of the femoral head

Glucocorticoids-induced osteonecrosis of the femoral head (GIONFH) is a common refractory disease. In the present study, we aimed to synthesize the nano-hydroxyapatite-copper-lithium (Cu-Li-nHA) composite porous scaffold to promote osteogenesis and angiogenesis functions to repair GIONFH by regulating the Wnt/β-catenin and HIF-1α/VEGF pathways. The physicochemical property of the scaffold was characterized and their osteogenic and angiogenic effects were tested through a serial of experimentsin vitroandin vivo. Results showed that 0.25% Cu-Li-nHA scaffolds possessed the highest mechanical and biocompatibilityin vitro. Then the 0.25% Cu-Li-nHA scaffolds significantly enhanced the new bone formation on defects in GIONFH rabbitsin vivo. Moreover, the scaffold could increase the expression of osteogenic and angiogenic factors along with the activation of factors in Wnt/β-catenin and HIF-1α/VEGF pathwaysin vitroandin vivo. In conclusion, the 0.25% Cu-Li-nHA scaffold could improve the osteogenesis and angiogenesis by upregulating the Wnt/β-catenin and HIF-1α/VEGF pathways which benefited to repair the GIONFH in rabbit models.

A Dual Peptide Sustained-Release System Based on Nanohydroxyapatite/Polyamide 66 Scaffold for Synergistic-Enhancing Diabetic Rats' Fracture Healing in Osteogenesis and Angiogenesis

Diabetes mellitus impairs fracture healing and function of stem cells related to bone regeneration; thus, effective bone tissue engineering therapies can intervene with those dysfunctions. Nanohydroxyapatite/polyamide 66 (n-HA/PA66) scaffold has been used in fracture healing, whereas the low bioactivity limits its further application. Herein, we developed a novel bone morphogenetic protein-2- (BMP-2) and vascular endothelial growth factor- (VEGF) derived peptides-decorated n-HA/PA66 (BVHP66) scaffold for diabetic fracture. The n-HA/PA66 scaffold was functionalized by covalent grafting of BMP-2 and VEGF peptides to construct a dual peptide sustained-release system. The structural characteristics and peptide release profiles of BVHP66 scaffold were tested by scanning electron microscopy, Fourier transform infrared spectroscopy, and fluorescence microscope. Under high glucose (HG) condition, the effect of BVHP66 scaffold on rat bone marrow mesenchymal stem cells’ (rBMSCs) adherent, proliferative, and differentiate capacities and human umbilical vein endothelial cells’ (HUVECs) proliferative and tube formation capacities was assessed. Finally, the BVHP66 scaffold was applied to fracture of diabetic rats, and its effect on osteogenesis and angiogenesis was evaluated. In vitro, the peptide loaded on the BVHP66 scaffold was in a sustained-release mode of 14 days. The BVHP66 scaffold significantly promoted rBMSCs’ and HUVECs’ proliferation and improved osteogenic differentiation of rBMSCs and tube formation of HUVECs in HG environment. In vivo, the BVHP66 scaffold enhanced osteogenesis and angiogenesis, rescuing the poor fracture healing in diabetic rats. Comparing with single peptide modification, the dual peptide-modified scaffold had a synergetic effect on bone regeneration in vivo. Overall, this study reported a novel BVHP66 scaffold with excellent biocompatibility and bioactive property and its application in diabetic fracture.

Electrospun polyamide-6/chitosan nanofibers reinforced nano-hydroxyapatite/polyamide-6 composite bilayered membranes for guided bone regeneration

Periodontal defect poses a significant challenge in orthopedics. Guided Bone Regeneration (GBR) membrane is considered as one of the most successful methods applied to reconstruct alveolar bone and then to achieve periodontal defect repair/regeneration. In this paper, a novel polyamide-6/chitosan@nano-hydroxyapatite/polyamide-6 (PA6/CS@n-HA/PA6) bilayered tissue guided membranes by combining a solvent casting and an electrospinning technique was designed. The developed PA6/CS@n-HA/PA6 composites were characterized by a series of tests. The results show that n-HA/PA6 and electrospun PA6/CS layers are tightly bound by molecular interaction and chemical bonding, which enhances the bonding strength between two distinct layers. The porosity and adsorption average pore diameter of the PA6/CS@n-HA/PA6 membranes are 36.90 % and 22.61 nm, respectively. The tensile strength and elastic modulus of PA6/CS@n-HA/PA6 composites are 1.41 ± 0.18 MPa and 7.15 ± 1.09 MPa, respectively. In vitro cell culture studies demonstrate that PA6/CS@n-HA/PA6 bilayered scaffolds have biological safety, good bioactivity, biocompatibility and osteoconductivity.

Clinical observation of mineralized collagen bone grafting after curettage of benign bone tumors

Curettage of benign bone tumor is a common cause for bone defect. For such bone defect repair, autogenous bone, allogeneic bone and traditional artificial bone graft substitutes have many disadvantages. In recent years, a biomimetic mineralized collagen (MC) with similar composition and microstructures to the natural bone matrix was developed and used for treating various bone defects. In this work, a retrospective study analyzed clinical outcomes of patients treated with curettage of benign bone tumors and bone grafting with MC, in comparison to another group treated with the same surgical method and autogenous bone. Lane–Sandhu X-ray score of the autogenous bone group was superior to the MC group at 1 month after the operation, but the two groups had no statistical difference at 6 and 12 months. The MC group was better in Musculoskeletal Tumor Society scoring at 1 and 6 months after the operation, and the two groups had no statistical difference at 12 month. Therefore, the MC performed not as good as autogenous bone in early stage of bone healing but achieved comparable outcomes in long-term follow-ups. Moreover, the MC has advantages in function recovery and avoided potential complications induced by harvesting autogenous bone.

Bone regenerative medicine: metatarsus defects in sheep to evaluate new therapeutic strategies for human long bone defect. A systematic review

INTRODUCTION

Large bone defects in long bone are not able to repair themselves and require grafts. Although autograft is the gold standard, it is associated with some disadvantages. Consequently, the application of tissue engineering (TE) techniques help with the use of allogenic biological and artificial scaffolds, cells and growth factors (GFs). Following 3Rs and in vitro testing strategies, animal models are required in preclinical in vivo studies to evaluate the therapeutic effects of the most promising TE techniques.

MATERIALS AND METHODS

A systematic review was performed from 2000 to 2019 to evaluate bone regeneration sheep metatarsus defects.

RESULTS

Eleven in vivo studies on sheep metatarsus defect were retrieved. The mid-diaphysis of metatarsus was the region most employed to perform critical size defects. Natural, synthetic and hybrid scaffolds were implanted, combined with bone marrow mesenchymal stem cells (BMSCs), GFs such as osteogenic protein 1 (OP1) and platelet rich plasma (PRP). The maximum follow-up period was 4 and 6 months in which radiography, histology, histomorphometry, computed tomography (CT) and biomechanics were performed to evaluate the healing status.

CONCLUSIONS

the sheep metatarsus defect model seems to be a suitable environment with a good marriage of biological and biomechanical properties. Defects of 3 cm are treated with natural scaffolds (homologous graft or allografts), those of 2.5 cm with natural, synthetic or composite scaffolds, while little defects (0.5 × 0.5 cm) with composite scaffolds. No difference in results is found regardless of the defect size.

In vivo evaluation of porous nanohydroxyapatite/polyamide 66 struts in a goat cervical fusion model

The hollow cylindrical nanohydroxyapatite/polyamide 66 strut (n-HA/PA66) has been used clinically for anterior cervical reconstruction. However, rates of occurrence of a “radiolucent gap” between the dense strut and adjacent endplates were reported. The aim of this in vivo study was to evaluate the viability and advantages of the novel porous n-HA/PA66 strut. The goat C3/4 partial discectomy and fusion model was built, and two groups of n-HA/PA66 struts were implanted into C3/4: group 1, porous n-HA/PA66 strut; and group 2, hollow cylindrical n-HA/PA66 strut filled with autogenous cancellous bone. CT evaluation was performed to assess the fusion status after 12 and 24 weeks. The cervical spines were harvested. Histomorphological analysis was performed to determine new bone formation. Biomechanical testing was performed to determine range of motion (ROM). CT confirmed the disappearance of the boundary of the porous strut and host bone, while the radiolucent gap remained clearly discernible in the dense strut group. The mean CT fusion scores of the porous group were significantly higher. Histologic evaluation showed that the porous struts promoted better osteointegration. Calcein fluorochrome labelling indicated faster bone ingrowth in the porous struts. Biomechanical tests revealed that the porous struts had significantly reduced micromotion. The porous n-HA/PA66 strut could offer interesting potential for cervical reconstruction after corpectomy.

Single approach to double-channel core decompression and bone grafting with structural bone support for treating osteonecrosis of the femoral head in different stages

BACKGROUND

We created a novel method-single approach to double-channel core decompression and bone grafting with structural bone support (SDBS)-to treat early-stage osteonecrosis of the femoral head (ONFH) by improving the Phemister technique. This study aimed to evaluate the results of SDBS for early-stage ONFH.

METHODS

Altogether, 53 patients (73 hips) were treated using SDBS during 2016-2018. Bilateral (20 patients) and unilateral (33 patients = 18 left hips, 15 right hips) ONFH was diagnosed. According to the Association Research Circulation Osseous classification stages, the femoral heads were staged as IIB (n = 15), IIC (n = 19), IIIA (n = 34), IIIB (n = 4), and IIIC (n = 1). The Harris hip score was used to evaluate the hips' clinical function, computed tomography to evaluate subchondral fractures, and plain radiography to assess the extent of femoral head collapse.

RESULTS

The average follow-up was 20.71 ± 6.65 months (6-36 months). At the patients' last follow-up, 4 hips were found to require arthroplasty. Thus, the overall femoral head survival rate was 94.52% (69/73). Also, the overall Harris score (84.44 ± 14.57) was significantly higher than that preoperatively (77.67 ± 14.37) (P = 0.000). The combined excellent and good rate (76.71%) was significantly higher than that preoperatively (38.36%) (P = 0.000). Imaging showed that 16 femoral heads had some ONFH progression. The average length of stay was 6.15 ± 0.86 days. The average incision measured 2.69 ± 0.30 cm. Intraoperative blood loss was 61.20 ± 4.81 ml. There were no complications during or after the operation.

CONCLUSION

SDBS is an effective method for treating early-stage ONFH. It is a hip-preserving surgical approach to slow/prevent ONFH progression.

In vitro and in vivo evaluations of nano-hydroxyapatite/polyamide 66/yttria-stabilized zirconia as a novel bioactive material for bone screws: Biocompatibility and bioactivity

Zirconia and its derivatives have been receiving increased levels of attention with regard to their potential application in bone tissue engineering. These materials are of particular interest because of their excellent characteristics, such as superior biological and mechanical properties. In this study, yttria-stabilized tetragonal zirconia (YTZ)-reinforced nanohydroxyapatite/polyamide 66 (nHA/PA66) bone screws were prepared. The biocompatibility and bioactivity of nHA/PA66/YTZ were evaluated in vitro using MC3T3-E1 cells. Biocompatibility and bioactivity experiments (cell counting kit-8 tests, cell immunofluorescence analysis, and polymerase chain reaction) showed that nHA/PA66/YTZ could facilitate the biological functions of MC3T3-E1 cells. The attachment, proliferation, spreading, and expression of genes associated with osteogenesis (collagen 1, osteopontin, and osteocalcin) in cells cultured with the nHA/PA66/YTZ composite were all superior compared with the control groups (P < 0.05). In addition, nHA/PA66/YTZ bone screws were implanted into the femoral condyles of rabbits, and titanium screws were employed as a control group; postoperative histology and blood analysis revealed no obvious damage to the liver, kidneys, or any other major organs in either of the experimental groups. Moreover, nHA/PA66/YTZ screws resulted in significantly better bone-implant contact interfaces and enhanced formation of trabecular bone (P < 0.05); these characteristics were markedly better than those in the group that received titanium screws. These observations indicate that YTZ-reinforced nHA/PA66 composites have significant potential for applications in bone tissue engineering.

Biomechanical analysis of a novel height-adjustable nano-hydroxyapatite/polyamide-66 vertebral body: a finite element study

Background

To compare the biomechanical properties of a novel height-adjustable nano-hydroxyapatite/polyamide-66 vertebral body (HAVB) with the titanium mesh cage (TMC) and artificial vertebral body (AVB), and evaluate its biomechanical efficacy in spinal stability reconstruction.

Methods

A 3D nonliner FE model of the intact L1-sacrum was established and validated. Three FE models which instrumented HAVB, TMC, and AVB were constructed for surgical simulation. A pure moment of 7.5 Nm and a 400-N preload were applied to the three FE models in 3D motion. The peak von Mises stress upon each prosthesis and the interfaced endplate was recorded for analysis. In addition, the overall and intersegmental range of motion (ROM) of each model was investigated to assess the efficacy of each model in spinal stability reconstruction.

Results

AVB had the greatest stress concentration compared with TMC and HAVB in all motions (25.6–101.8 times of HAVB, 0.8–8.1 times of TMC). The peak stress on HAVB was 3.1–10.3% of TMC and 1.6–3.9% of AVB. The maximum stress values on L2 caudal and L4 cranial endplates are different between the three FE models: 0.9–1.9, 1.3–12.1, and 31.3–117.9 times of the intact model on L2 caudal endplates and 0.9–3.5, 7.2–31.5, and 10.3–56.4 times of the intact model on L4 cranial endplates in HAVB, TMC, and AVB, respectively, while the overall and segmental ROM reduction was similar between the three models, with AVB providing a relatively higher ROM reduction in all loading conditions (88.1–84.7% of intact model for overall ROM and 69.5–82.1% for L1/2, 87.0–91.7% for L2/4, and 71.1–87.2% for L4/5, respectively).

Conclusions

HAVB had similar biomechanical efficacy in spinal stability reconstruction as compared with TMC and AVB. The material used and the anatomic design of HAVB can help avoid stress concentration and the stress shielding effect, thus greatly reducing the implant-associated complications. HAVB exhibited some advantageous biomechanical properties over TMC and AVB and may prove to be a potentially viable option for spinal stability reconstruction. Further in vivo and vitro studies are still required to validate our findings and conclusions.

Orthogonal test design for the optimization of superparamagnetic chitosan plasmid gelatin microspheres that promote vascularization of artificial bone

The optimal conditions for the preparation of superparamagnetic chitosan plasmid (pReceiver‐M29‐VEGF165/DH5a) gelatin microspheres (SPCPGMs) were determined. Then, the performance of the SPCPGMs during neovascularization was evaluated in vivo. The SPCPGMs were prepared through a cross‐linking curing method and then filled into the hollow scaffold of an artificial bone. Neovascularization at the bone defect position was histologically examined in samples collected 2, 4, 6, and 8 weeks after the operation. The cellular magnetofection rate of superparamagnetic chitosan nanoparticles/plasmid (pReceiver‐M29‐VEGF165/DH5a) complexes reached 1–3% under static magnetic field (SMF). Meanwhile, the optimal conditions for SPCPGM fabrication were 20% Fe₃O₄ (w/v), 4 mg of plasmid, 5.3 mg of glutaraldehyde, and 500 rpm of emulsification rotate speed. Under oscillating magnetic fields (OMFs), 4–6 μg of plasmids was released daily for 21 days. Under the combined application of SMF and OMF, evident neovascularization occurred at the bone defect position 6 weeks after the operation. This result is expected to provide a new type of angiogenesis strategy for the research of bone tissue engineering.

The protective role of CsNPs and CurNPs against DNA damage, oxidative stress, and histopathological and immunohistochemical alterations induced by hydroxyapatite nanoparticles in male rat kidney

Hydroxyapatite nanoparticles (HAP-NPs) are an inorganic component of natural bone and are mainly used in the tissue engineering field due to their bioactivity, osteoconductivity, biocompatibility, non-inflammatory, and non-toxicity properties. However, the current toxicity data for HAP-NPs regarding human health are limited, and only a few results from basic studies have been published. Therefore, the present study was designed to investigate the beneficial role of chitosan nanoparticles (CsNPs) and curcumin nanoparticles (CurNPs) in alleviating nephrotoxicity induced by HAP-NPs in male rats. The results showed that HAP-NPs caused a reduction in antioxidant enzymes and induced lipid peroxidation, nitric oxide production and DNA oxidation. Moreover, HAP-NP administration was associated with intense histologic changes in kidney architecture and immunoreactivity to proliferating cell nuclear antigen (PCNA). However, the presence of CsNPs and/or CurNPs along with HAP-NPs reduced the levels of oxidative stress through improving the activities of antioxidant enzymes. Also, the rats administered the nanoparticles showed a moderate improvement in glomerular damage which matched that of the control group and showed mild positive reactions to PCNA-ir in glomeruli and renal tubules in the cortical and medullary portions. These novel insights confirm that the presence of chitosan and curcumin in nanoforms has powerful biological effects with enhanced bioactivity and bioavailability phenomena compared to their microphase counterparts. Also, they were able to ameliorate the nephrotoxicity induced by HAP-NPs.

Application of hydroxyapatite nanoparticles in tumor-associated bone segmental defect

Hydroxyapatite (HA) has been widely applied in bone repair because of its superior biocompatibility. Recently, a proliferation-suppressive effect of HA nanoparticles (n-HA) against various cancer cells was reported. This study was aimed at assessing the translational value of n-HA both as a bone-regenerating material and as an antitumor agent. Inhibition of tumor growth, prevention of metastasis, and enhancement of the survival rate of tumor-bearing rabbits treated with n-HA were demonstrated. Activated mitochondrial-dependent apoptosis in vivo was confirmed, and we observed that a stimulated immune response was involved in the n-HA-induced antitumor effect. A porous titanium scaffold loaded with n-HA was fabricated and implanted into a critical-sized segmental bone defect in a rabbit tumor model. The n-HA-releasing scaffold not only showed a prominent effect in suppressing tumor growth and osteolytic lesion but also promoted bone regeneration. These findings provide a rationale for using n-HA in tumor-associated bone segmental defects.

[Effectiveness of nano-hydroxyapatite/polyamide-66 Cage in interbody fusion for degenerative lumbar scoliosis]

Objective

To explore the effectiveness of nano-hydroxyapatite/polyamide-66 (n-HA/PA66) Cage in interbody fusion for degenerative lumbar scoliosis.

Methods

A retrospective analysis was designed and conducted for 43 patients, who underwent posterior decompression and n-HA/PA66 Cage interbody fusion with correction of deformity between January 2013 and June 2016. Eighteen cases were single-level fusion (single-level group) and 25 cases were double-level fusion (double-level group). There was no significant difference in gender, age, body mass index, direction of convex, degree of apical rotation, fusion level, the number of osteoporotic patients, pre-operative intervertebral height of fusion segments, coronal Cobb angle, visual analogue score (VAS), and modified Oswestry Disability Index (ODI) between 2 groups ( P>0.05). The operation time, intraoperative blood loss, postoperative drainage, hospital stay, and complications of the operation were recorded. Modified ODI, VAS score, and MacNab criteria were adopted to assess clinical outcomes. Radiographic indexes, including intervertebral height of fusion segments, coronal Cobb angle, disc insertion depth, and the bone graft fusion rate, were also evaluated.

Results

There was no significant difference in operation time, intraoperative blood loss, postoperative drainage, and hospital stay between 2 groups ( P>0.05). All patients were followed up 18-62 months (mean, 30.9 months). Wound complications, postoperative delirium, and Cage retropulsion occurred in 4 cases (2 cases in single-level group, 2 cases in double-level group), 1 case of single-level group, and 1 case of double-level group, respectively. The intervertebral height of fusion segments after operation significantly improved compared with preoperative ones in both groups ( P<0.05). At last follow-up, the intervertebral height in double-level group was superior to which in single-level group ( P<0.05). The coronal Cobb angles after operation significantly improved compared with preoperative ones ( P<0.05), and no significant difference was found between 2 groups at each time point ( P>0.05). The disc insertion depth showed no significant difference between different time points after operation in 2 groups ( P>0.05) and between 2 groups at each time point after operation ( P>0.05). Bony fusion was obtained in all patients at last follow-up. The VAS score and modified ODI after operation in both groups were superior to those before operation ( P<0.05). The VAS score in double-level group was higher than that in single-level group ( P<0.05) at last follow-up, and no significant difference was found in VAS score and modified ODI between 2 groups at other time points ( P>0.05). According to the MacNab criteria, the excellent and good rates at last follow-up were 94.4% and 84.0% in single-level group and double-level group, respectively.

Conclusion

The n-HA/PA66 Cage can effectively restore and maintain the disc height of fusion segment, normal sequence, and biomechanical stability of the spine, and gain favorable effectivenss for degenerative lumbar scoliosis. And double-level fusion is superior to single-level fusion in maintaining disc height of fusion segment.

D-RADA16-RGD-Reinforced Nano-Hydroxyapatite/Polyamide 66 Ternary Biomaterial for Bone Formation

BACKGROUND

Nano-hydroxyapatite/polyamide 66 (nHA/PA66) is a composite used widely in the repair of bone defects. However, this material is insufficient bioactivity. In contrast, D-RADA16-RGD self-assembling peptide (D-RADA16-RGD sequence containing all D-amino acids is Ac-RADARADARADARADARGDS-CONH₂) shows admirable bioactivity for both cell culture and bone regeneration. Here, we describe the fabrication of a favorable biomaterial material (nHA/PA66/D-RADA16-RGD).

METHODS

Proteinase K and circular dichroism spectroscopy were employed to test the stability and secondary structural properties of peptide D-RADA16-RGD respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the surface of these materials. Confocal laser scanning (CLS), cell counting kit-8 tests (CCK-8), alizarin red S staining, cell immunofluorescence analysis and Western blotting were involved in vitro. Also biosafety and bioactivity of them have been evaluated in vivo.

RESULTS

Proteinase K and circular dichroism spectroscopy demonstrated that D-RADA16-RGD in nHA/PA66 was able to form stable-sheet secondary structure. SEM and TEM showed that the D-RADA16-RGD material was 7-33 nm in width and 130-600 nm in length, and the interwoven pore size ranged from 40 to 200 nm. CLS suggests that cells in nHA/PA66/D-RADA16-RGD group were linked to adjacent cells with more actin filaments. CCK-8 analysis showed that nHA/PA66/D-RADA16-RGD revealed good biocompatibility. The results of Alizarin-red S staining and Western blotting as well as vivo osteogenesis suggest nHA/PA66/D-RADA16-RGD exhibits better bioactivity.

CONCLUSION

This study demonstrates that our nHA/PA66/D-RADA16-RGD composite exhibits reasonable mechanical properties, biocompatibility and bioactivity with promotion of bone formation.

Improved osteoblast adhesion and osseointegration on TiO2 nanotubes surface with hydroxyapatite coating

To improve initial osteoblast adhesion and subsequent osseointegration, TiO₂ nanotubes layer was constructed on the titanium (Ti) surface by anodic oxidation (AO), with an additional hydroxyapatite (HA) coating to form the AO/HA surface. Tests on in vitro cellular activity displayed that the AO surface, especially the AO/HA surface, promoted initial adhesion, proliferation and differentiation of osteoblast cells. The modified AO and AO/HA surfaces further presented an up-regulated gene expression of osteogenic and adhesion markers collagen type 1 (COL), osteopontin (OPN), osteocalcin (OCN) and vinculin. In addition, in vivo experiments with a rat model demonstrated that the AO surface, particularly the AO/HA surface, achieved earlier osseointegration and a superior bone bonding ability compared with Ti. Our study shed light on a synergistic role played by nanotopography and HA in promoting osteoblast adhesion, proliferation, differentiation and osseointegration, thus suggesting a promising method for better modifying the implant surface.

A Novel Height-Adjustable Nano-Hydroxyapatite/Polyamide-66 Vertebral Body for Reconstruction of Thoracolumbar Structural Stability After Spinal Tumor Resection

BACKGROUND

Reconstruction of thoracolumbar structural stability is a formidable challenge for spine surgeons after vertebral body tumor resection. Various disadvantages of the currently used expandable or nonexpandable cages have limited their clinical applications. We sought to develop a novel prosthesis for clinical use and assess its preliminary clinical outcome in reconstruction of thoracolumbar structural stability after spinal tumor resection.

METHODS

Using data obtained from a retrospective analysis of the morphological characteristics of the thoracolumbar vertebrae and endplates in previously reported studies, we modified the nano-hydroxyapatite/polyamide-66 (n-HA/PA66) strut into a novel height-adjustable vertebral body. A retrospective study was performed of 7 patients who had undergone reconstruction of thoracolumbar structural stability with this novel prosthesis from August 2016 to January 2017.

RESULTS

A novel height-adjustable vertebral body (AHVB) composed of n-HA/PA66 with 2 separate components with a 163° contact surface at each end was manufactured. The height-adjustable range was 28-37 mm. No significant implant-related complications were observed in the process of operation. All patients experienced a significant reduction in pain, with the visual analog scale score decreasing from 7.9 to 4.0. Neurological improvement was assessed using the Frankel grading system after surgery. Postoperative radiographic and computed tomography/magnetic resonance imaging findings indicated that the operated segment was stable, the outcome of kyphosis correction was good, and no prosthesis subsidence or dislocation was observed.

CONCLUSION

This novel prosthesis has many advantages in the reconstruction of height, lordosis, and alignment after thoracolumbar spinal tumor resection and has a favorable prospect for clinical application.

Enhanced bone defect repairing effects in glucocorticoid-induced osteonecrosis of the femoral head using a porous nano-lithium-hydroxyapatite/gelatin microsphere/erythropoietin composite scaffold

Glucocorticoid-induced osteonecrosis of the femoral head (GIONFH) is a common debilitating disease that occurs in young and middle-aged adults. To treat early GIONFH, core decompression and bone graft are regarded as effective measures. However, the ideal bone graft should possess bioactivity as well as biomechanical properties. The most commonly used bone graft materials are currently unsatisfactory. In this study, we fabricated a composited scaffold using lithium (Li) to activate the Wnt signal pathway and erythrogenin (EPO) to upregulate the HIF-1/VEGF pathway to improve the osteogenic and angiogenic effects of the scaffold. We obtained the porous gelatin/nano-lithium-hydroxyapatite/gelatin microsphere/rhEPO (Li-nHA/GMs/rhEPO) composited scaffold and assessed its mechanical properties, release properties, and in vitro bioactivity. Then, we implanted the scaffold into the femoral heads of GIONFH rabbits after core decompression surgery and evaluated the osteogenic and angiogenic abilities of the scaffold in vivo as well as its bone defect repair efficacy. As the results show, the Li-nHA/GM/rhEPO scaffold possessed good mechanical compression strength and enabled continuous release of Li and rhEPO. Moreover, the scaffold improved the viability of glucocorticoid-treated BMMSCs and vascular endothelial cells and increased the expression of osteogenic and angiogenic factors. In the in vivo study, the composited scaffold improved new bone formation and exerted effects on repairing femoral head defects in GIONFH rabbits. Additionally, the osteogenic and angiogenic factors were increased along with the activation of factors in the Wnt signal pathway and the HIF-1/VEGF pathway. In conclusion, the Li-nHA/GM/rhEPO scaffold can upregulate the Wnt and HIF-1/VEGF pathways at same time and has effects on improving osteogenesis and angiogenesis, which benefits the repair of GIONFH.

[Treatment of proximal femoral benign lesions by proximal femoral nail anti-rotation combined with curettage and bone graft through the Watson-Jones approach]

Objective

To evaluate the feasibility and effectiveness of proximal femoral nail anti-rotation (PFNA) combined with curettage and bone graft through Watson-Jones approach in the treatment of proximal femur benign tumors and tumor like lesions.

Methods

The clinical data of 38 patients with benign tumors and tumor like lesions in the proximal femur who were treated through the Watson-Jones approach with PFNA combined with curettage and bone graft between January 2008 and January 2015 were retrospective analysed. There were 24 males and 14 females with an average age of 28 years (range, 15-57 years). Pathological types included 20 cases of fibrous dysplasia, 7 cases of bone cyst, 5 cases of aneurysmal bone cyst, 3 cases of giant cell tumor of bone, 2 cases of enchondroma, and 1 case of non-ossifying fibroma. Before operation, hip pain occurred in 19 patients, pathological fracture occurred in 12 patients, limb shortening and coxa varus deformity was found in 4 patients, and 3 patients received surgery for the local recurrence. The operation time, intraoperative blood loss, and full-weight bearing time after operation were recorded. Patients were followed up to observe union of bone graft and the position of internal fixator on X-ray films and CT images. Visual analogue scale (VAS) score was used to evaluate the level of pain. The Musculoskeletal Tumor Society (MSTS93) score was used to evaluate lower limb function. Harris hip score was used to evaluate hip joint function.

Results

The operation time was 130-280 minutes (mean, 182 minutes) and the intraoperative blood loss was 300-1 500 mL (mean, 764 mL). After operation, 3 cases of fat liquefaction of incision healed successfully by carefully dressing, and the rest incisions healed by first intention. All patients started partially weight-bearing exercise at 2-4 weeks after operation. The total weight-bearing time was 3-6 months (mean, 4.2 months). All the patients were followed up 24-108 months (median, 60 months). Imaging examination showed that the bone graft fused and the fusion time was 8-18 months (mean, 11.4 months). During the follow-up period, there was no complication such as pathological fracture, femoral head ischemic necrosis, hip joint dislocation, internal fixation loosening and fracture, and no tumor recurrence or distant metastasis occurred. At last follow-up, the VAS score, MSTS93 score, and Harris score were significantly improved when compared with preoperative ones ( P<0.05).

Conclusion

The treatment of proximal femoral benign lesions by PFNA combined with curettage and bone graft through the Watson-Jones approach is safe and effective, with advantages of better mechanical stability, less residual tumor, and less postoperative complications.

Oxidative stress and DNA damage in zebrafish liver due to hydroxyapatite nanoparticles-loaded cadmium

This study investigated the acute and sub-acute toxicity responses in zebrafish following their exposure to hydroxyapatite-loaded cadmium nanoparticles (nHAP-Cd). The results indicate that cadmium chloride (Cd²⁺), 20 nm nHAP-Cd (nHAP₂₀-Cd), and 40 nm nHAP-Cd (nHAP₄₀-Cd) caused toxicity in zebrafish; the toxicity levels were in the following order: Cd²⁺ > nHAP₂₀-Cd > nHAP₄₀-Cd. Furthermore, nHAP-Cd showed level II grade of acute toxicity in zebrafish; the gradation was done on the guidelines of the Organization for Economic Co-operation and Development 203. We also found that Cd²⁺ ions and nHAP-Cd affected the malondialdehyde (MDA) levels and membrane permeability of zebrafish livers; these effects were compliant with the changes in antioxidant levels. The results of enzyme assays indicate the following notion: following the exposure of zebrafish to 0.12-0.93 mg/L nHAP-Cd, the activities of peroxidase, superoxide dismutase, and catalase enzymes increased significantly. Moreover, the content of anti-superoxide anion also increased substantially. This increasing trend of enzymatic activity was observed until the concentration of nHAP-Cd reached 1.86 mg/L nHAP-Cd. By increasing the concentration of both Cd²⁺ and nHAP-Cd, we found that levels of DNA damage had increased substantially in zebrafish liver; this effect was visualized by performing comet assay.

Biofunctionalized peptide nanofiber-based composite scaffolds for bone regeneration

Bone tissue had moderate self-healing capabilities, but biomaterial scaffolds were required for the repair of some defects such as large bone defects. Peptide nanofiber scaffolds demonstrated important potential in regenerative medicine. Functional modification and controlled release of signal molecules were two significant approaches to increase the bioactivity of biofunctionalized peptide nanofiber scaffolds, but peptide scaffolds were limited by insufficient mechanical strength. Thus, it was necessary to combine peptide scaffolds with other materials including polymers, hydroxyapatite, demineralized bone matrix (DBM) and metal materials based on the requirement of different bone defects. As the development of peptide-based composite scaffolds continued to evolve, ultimate translation to the clinical environment may allow for improved therapeutic outcomes for bone repair.

Investigation of chronic toxicity of hydroxyapatite nanoparticles administered orally for one year in wistar rats

Although the toxicity/biocompatibility of hydroxyapatite nanoparticles (nano HA), a prospective nano biomaterial is extensively studied, its interaction on biological systems following chronic exposure is less exploited. In the present study, Wistar rats were given various concentrations of nano HA in the diet to determine the chronic toxicity and potential carcinogenicity. Altogether 140 rats were used for the study under various administration dosages along with control. The animals were sacrificed after 12months of controlled continuous dosing. All in-life parameters, including body weight, food consumption, clinical observations, survival, biochemical and hematology, were unaffected by the chronic exposure of nano HA orally. Similarly, gross and histopathological evaluation was also unchanged following exposure to nano HA. No evidence of nano HA-related lesions or Nano HA-induced neoplasia was suggested in this rodent bioassay study.

An effective treatment of experimental osteomyelitis using the antimicrobial titanium/silver-containing nHP66 (nano-hydroxyapatite/polyamide-66) nanoscaffold biomaterials

Effective treatment of osteomyelitis remains a formidable clinical challenge. The rapid emergence of multidrug-resistant bacteria has renewed interest in developing antimicrobial biomaterials using antiseptic silver ions to treat osteomyelitis. However, inadequate local retention and severe cytotoxic effects have limited the clinical use of ionic silver for bone grafts. We recently developed novel porous nano-hydroxyapatite/polyamide 66 (nHP66)-based nanoscaffold materials containing varied concentrations of silver ions (Ag⁺) (TA-nHAPA66) and oxidized titanium (TiO₂), which was added as a second binary element to enhance antibacterial activity and biocompatibility. In this study, we establish a large cohort of rabbit model of experimental osteomyelitis and investigate the in vivo antimicrobial and therapeutic effects of TA-nHP66 biomaterials and their in vivo silver release kinetics. We find the TA-nHP66 scaffolds exhibit potent antibacterial activities against E. coli and S. aureus, support cell adhesion and cell proliferation of pre-osteoblasts, and stimulate osteogenic regulator/marker expression. Moreover, the TA2-nHP66 scaffold exerts potent antibacterial/anti-inflammation effects in vivo and promotes bone formation at the lesion site of osteomyelitis. We further demonstrate that TA2-nHP66 exhibits excellent biosafety profile without apparent systemic toxicities. Therefore, the TA-nHP66 scaffold biomaterials may be further explored as an effective adjuvant therapy for infected bone defects and/or osteomyelitis debridement.

Self-assembled high-strength hydroxyapatite/graphene oxide/chitosan composite hydrogel for bone tissue engineering

Graphene hydrogel has shown greatly potentials in bone tissue engineering recently, but it is relatively weak in the practical use. Here we report a facile method to synthesize high strength composite graphene hydrogel. Graphene oxide (GO), hydroxyapatite (HA) nanoparticles (NPs) and chitosan (CS) self-assemble into a 3-dimensional hydrogel with the assistance of crosslinking agent genipin (GNP) for CS and reducing agent sodium ascorbate (NaVC) for GO simultaneously. The dense and oriented microstructure of the resulted composite gel endows it with high mechanical strength, high fixing capacity of HA and high porosity. These properties together with the good biocompatibility make the ternary composite gel a promising material for bone tissue engineering. Such a simultaneous crosslinking and reduction strategy can also be applied to produce a variety of 3D graphene-polymer based nanocomposites for biomaterials, energy storage materials and adsorbent materials.

In vitro and in vivo biocompatibility and osteogenesis of graphene-reinforced nanohydroxyapatite polyamide66 ternary biocomposite as orthopedic implant material

Graphene and its derivatives have been receiving increasing attention regarding their application in bone tissue engineering because of their excellent characteristics, such as a vast specific surface area and excellent mechanical properties. In this study, graphene-reinforced nanohydroxyapatite/polyamide66 (nHA/PA66) bone screws were prepared. The results of scanning electron microscopy observation and X-ray diffraction data showed that both graphene and nHA had good dispersion in the PA66 matrix. In addition, the tensile strength and elastic modulus of the composites were significantly improved by 49.14% and 21.2%, respectively. The murine bone marrow mesenchymal stem cell line C3H10T1/2 exhibited better adhesion and proliferation in graphene reinforced nHA/PA66 composite material compared to the nHA/PA66 composites. The cells developed more pseudopods, with greater cell density and a more distinguishable cytoskeletal structure. These results were confirmed by fluorescent staining and cell viability assays. After C3H10T1/2 cells were cultured in osteogenic differentiation medium for 7 and 14 days, the bone differentiation-related gene expression, alkaline phosphatase, and osteocalcin were significantly increased in the cells cocultured with graphene reinforced nHA/PA66. This result demonstrated the bone-inducing characteristics of this composite material, a finding that was further supported by alizarin red staining results. In addition, graphene reinforced nHA/PA66 bone screws were implanted in canine femoral condyles, and postoperative histology revealed no obvious damage to the liver, spleen, kidneys, brain, or other major organs. The bone tissue around the implant grew well and was directly connected to the implant. The soft tissues showed no obvious inflammatory reaction, which demonstrated the good biocompatibility of the screws. These observations indicate that graphene-reinforced nHA/PA66 composites have great potential for application in bone tissue engineering.

Clinical outcomes of two types of cages used in transforaminal lumbar interbody fusion for the treatment of degenerative lumbar diseases: n-HA/PA66 cages versus PEEK cages

This study reports the clinical effects of nano-hydroxyapatite/polyamide66 cages (n-HA/PA66 cages) and compares the clinical outcomes between n-HA/PA66 and polyetheretherketone cages (PEEK cages) for application in transforaminal lumbar interbody fusion (TLIF). A retrospective and case-control study involving 124 patients using n-HA/PA66 cages and 142 patients using PEEK cages was conducted. All patients underwent TLIF and had an average of 2-years of follow-up. The Oswestry Disability Index and Visual Analog Scale were selected to assess the pain of low back and leg, as well as neurological status. The intervertebral space height and segmental angle were also measured to estimate the radiological changes. At the 1-year and final follow-ups, the fusion and subsidence rates were evaluated. There was no significant difference between the two groups regarding clinical and radiological results. At the final follow-up, the bony fusion rate was 92.45 and 91.57 % for the n-HA/PA66 and PEEK groups, respectively, and the subsidence rate was 7.55 and 8.99 %, respectively. The study indicated that both n-HA/PA66 and PEEK cages could promote effective clinical and radiographic outcomes when used to treat degenerative lumbar diseases. The high fusion and low subsidence rates revealed that n-HA/PA66 cages could be an alternative ideal choice as the same to PEEK cages for lumbar reconstruction after TLIF.

Long-term results of anterior cervical corpectomy and fusion with nano-hydroxyapatite/polyamide 66 strut for cervical spondylotic myelopathy

To assess the long-term clinical and radiographic outcomes of anterior cervical corpectomy and fusion (ACCF) with a neotype nano-hydroxyapatite/polyamide 66 (n-HA/PA66) strut in the treatment of cervical spondylotic myelopathy (CSM). Fifty patients with CSM who underwent 1- or 2-level ACCF with n-HA/PA66 struts were retrospectively investigated. With a mean follow-up of 79.6 months, the overall mean JOA score, VAS and cervical alignment were improved significantly. At last follow-up, the fusion rate was 98%, and the subsidence rate of the n-HA/PA66 strut was 8%. The "radiolucent gap" at the interface between the n-HA/PA66 strut and the vertebra was further noted to evaluate the osteoconductivity and osseointegration of the strut, and the incidence of it was 62% at the last follow-up. Three patients suffered symptomatic adjacent segment degeneration (ASD). No significant difference was detected in the outcomes between 1- and 2-level corpectomy at follow-ups. In conclusion, the satisfactory outcomes in this study indicated that the n-HA/PA66 strut was an effective graft for cervical reconstruction. Moreover, the osteoconductivity and osseointegration of the strut is still need to be optimized for future clinical application owing to the notably presence of "radiolucent gap" in present study.

Poly(acrylic acid)-regulated Synthesis of Rod-Like Calcium Carbonate Nanoparticles for Inducing the Osteogenic Differentiation of MC3T3-E1 Cells

Calcium carbonate, especially with nanostructure, has been considered as a good candidate material for bone regeneration due to its excellent biodegradability and osteoconductivity. In this study, rod-like calcium carbonate nanoparticles (Rod-CC NPs) with desired water dispersibility were achieved with the regulation of poly (acrylic acid). Characterization results revealed that the Rod-CC NPs had an average length of 240 nm, a width of 90 nm with an average aspect ratio of 2.60 and a negative ζ-potential of −22.25 ± 0.35 mV. The degradation study illustrated the nanoparticles degraded 23% at pH 7.4 and 45% at pH 5.6 in phosphate-buffered saline (PBS) solution within three months. When cultured with MC3T3-E1 cells, the Rod-CC NPs exhibited a positive effect on the proliferation of osteoblast cells. Alkaline phosphatase (ALP) activity assays together with the osteocalcin (OCN) and bone sialoprotein (BSP) expression observations demonstrated the nanoparticles could induce the differentiation of MC3T3-E1 cells. Our study developed well-dispersed rod-like calcium carbonate nanoparticles which have great potential to be used in bone regeneration.

A Novel High Mechanical Property PLGA Composite Matrix Loaded with Nanodiamond-Phospholipid Compound for Bone Tissue Engineering

A potential bone tissue engineering material was produced from a biodegradable polymer, poly(lactic-co-glycolic acid) (PLGA), loaded with nanodiamond phospholipid compound (NDPC) via physical mixing. On the basis of hydrophobic effects and physical absorption, we modified the original hydrophilic surface of the nanodiamond (NDs) with phospholipids to be amphipathic, forming a typical core-shell structure. The ND-phospholipid weight ratio was optimized to generate sample NDPC50 (i.e., ND-phospholipid weight ratio of 100:50), and NDPC50 was able to be dispersed in a PLGA matrix at up to 20 wt %. Compared to a pure PLGA matrix, the introduction of 10 wt % of NDPC (i.e., sample NDPC50-PF10) resulted in a significant improvement in the material's mechanical and surface properties, including a decrease in the water contact angle from 80 to 55°, an approximately 100% increase in the Young's modulus, and an approximate 550% increase in hardness, thus closely resembling that of human cortical bone. As a novel matrix supporting human osteoblast (hFOB1.19) growth, NDPC50-PFs with different amounts of NDPC50 demonstrated no negative effects on cell proliferation and osteogenic differentiation. Furthermore, we focused on the behaviors of NDPC-PFs implanted into mice for 8 weeks and found that NDPC-PFs induced acceptable immune response and can reduce the rapid biodegradation of PLGA matrix. Our results represent the first in vivo research on ND (or NDPC) as nanofillers in a polymer matrix for bone tissue engineering. The high mechanical properties, good in vitro and in vivo biocompatibility, and increased mineralization capability suggest that biodegradable PLGA composite matrices loaded with NDPC may potentially be useful for a variety of biomedical applications, especially bone tissue engineering.

In vitro evaluation of an yttria-stabilized zirconia reinforced nano-hydroxyapatite/polyamide 66 ternary biomaterial: biomechanics, biocompatibility and bioactivity

The characterization of a novel ternary biomaterial composed of nano-hydroxyapatite/polyamide 66/yttria-stabilized tetragonal zirconia.

Safety of bioabsorbable implants in vitro

Background

The aim of the present study was to investigate the safety of bioabsorbable plates and screws in humans.

Methods

For this purpose, an implant system based on [poly(lactic-co-glycolic acids)(85:15)] was designed. The system was tested for pH, temperature, and swelling and then its surface morphology was analyzed for surface porosity using environmental electron microscopy. Then, the effects of this bioabsorbable system on the viability and profileration of osteocytes were examined on a molecular level via in vitro experiments. A [poly(lactic-co-glycolic acids)(90:10)] bioabsorbable implant, which is commercially available and used in orthopedic surgery, was used as control group. For the statistical evaluation of the data obtained in the present study, the groups were compared by Tukey HSD test following ANOVA. The significance level was set as p < 0.05.

Results

It was observed that the osteocytes cultivated on the PLGA system designed in the present study included more live cells and allowed more proliferation compared to the control.

Conclusion

One of the criteria in the selection of implants for orthopedic surgery is that a good implant should not need removal and thus a second surgery. In the present study, a bioabsorbable implant was designed considering this criterion. The present study is the first step to prove the safety of this new design by in vitro toxicity and viability experiments.