Bioactive ceramic coating of cancellous screws improves the osseointegration in the cancellous bone

Humidity-Responsive Amorphous Calcium-Magnesium Pyrophosphate/Cassava Starch Scaffold for Enhanced Neurovascular Bone Regeneration

Developing a neurovascular bone repair scaffold with an appropriate mechanical strength remains a challenge. Calcium phosphate (CaP) is similar to human bone, but its scaffolds are inherently brittle and inactive, which require recombination with active ions and polymers for bioactivity and suitable strength. This work discussed the synthesis of amorphous magnesium-calcium pyrophosphate (AMCP) and the subsequent development of a humidity-responsive AMCP/cassava starch (CS) scaffold. The scaffold demonstrated enhanced mechanical properties by strengthening the intermolecular hydrogen bonds and ionic bonds between AMCP and CS during the gelatinization and freeze-thawing processes. The release of active ions was rapid initially and stabilized into a long-term stable release after 3 days, which is well-matched with new bone growth. The release of pyrophosphate ions endowed the scaffold with antibacterial properties. At the cellular level, the released active ions simultaneously promoted the proliferation and mineralization of osteoblasts, the proliferation and migration of endothelial cells, and the proliferation of Schwann cells. At the animal level, the scaffold was demonstrated to promote vascular growth and peripheral nerve regeneration in a rat skull defect experiment, ultimately resulting in the significant and rapid repair of bone defects. The construction of the AMCP/CS scaffold offers practical suggestions and references for neurovascular bone repair.

High Boron Content Enhances Bioactive Glass Biodegradation

Derived Hench bioactive glass (BaG) containing boron (B) is explored in this work as it plays an important role in bone development and regeneration. B was also found to enhance BaG dissociation. However, it is only possible to incorporate a limited amount of B. To increase the amount of B in BaG, bioactive borosilicate glasses (BaG-B_x) were fabricated based on the use of the solution-gelation process (sol-gel). In this work, a high B content (20 wt.%) in BaG, respecting the conditions of bioactivity and biodegradability required by Hench, was achieved for the first time. The capability of BaG-B_x to form an apatite phase was assessed in vitro by immersion in simulated body fluid (SBF). Then, the chemical structure and the morphological changes in the fabricated BaG-B_x (x = 0, 5, 10 and 20) were studied. The formation of hydroxyapatite (HAp) layer was observed with X-ray diffraction (XRD) and infrared (IR) spectroscopy. The presence of HAp layer was confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Enhanced bioactivity and chemical stability of BaG-B_x were evaluated with an ion exchange study based on Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and energy dispersive spectroscopy (EDS). Results indicate that by increasing the concentration of B in BaG-Bx, the crystallization rate and the quality of the newly formed HAp layer on BaG-B_x surfaces can be improved. The presence of B also leads to enhanced degradation of BaGs in SBF. Accordingly, BAG-B_x can be used for bone regeneration, especially in children, because of its faster degradation as compared to B-free glass.

Anterior Cervical Discectomy and Fusion Performed Using a CaO-SiO2-P2O5-B2O3 Bioactive Glass Ceramic or Polyetheretherketone Cage Filled with Hydroxyapatite/β-Tricalcium Phosphate: A Prospective Randomized Controlled Trial

A CaO-SiO₂-P₂O₅-B₂O₃ bioactive glass-ceramic (BGS-7) spacer provides high mechanical stability, produces a chemical bond to the adjacent endplate, and facilitates fusion after spine surgery. This prospective, randomized, single-blind, non-inferiority trial aimed to evaluate the radiographic outcomes and clinical efficacy of anterior cervical discectomy and fusion (ACDF) using a BGS-7 spacer for treating cervical degenerative disorders. Thirty-six patients underwent ACDF using a BGS-7 spacer (Group N), and 40 patients underwent ACDF using polyetheretherketone (PEEK) cages filled with a mixture of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) for the treatment of cervical degenerative disorders. The spinal fusion rate was assessed 12 months postoperatively using three-dimensional computed tomography (CT) and dynamic radiographs. Clinical outcomes included patient-reported outcome measures, visual analog scale scores for neck and arm pain, and scores from the neck disability index (NDI), European Quality of Life-5 Dimensions (EQ-5D), and 12-item Short Form Survey (SF-12v2). All participants were randomly assigned to undergo ACDF using either a BGS-7 spacer or PEEK cage filled with HA and β-TCP. The primary outcome was the fusion rate on CT scan image at 12 months after ACDF surgery based on a per-protocol strategy. Clinical outcomes and adverse events were also assessed. The 12-month fusion rates for the BGS-7 and PEEK groups based on CT scans were 81.8% and 74.4%, respectively, while those based on dynamic radiographs were 78.1% and 73.7%, respectively, with no significant difference between the groups. There were no significant differences in the clinical outcomes between the two groups. Neck pain, arm pain, NDI, EQ-5D, and SF-12v2 scores significantly improved postoperatively, with no significant differences between the groups. No adverse events were observed in either group. In ACDF surgery, the BGS-7 spacer showed similar fusion rates and clinical outcomes as PEEK cages filled with HA and β-TCP.

Feasibility and safety of a CaO-SiO2-P2O5-B2O3 bioactive glass ceramic spacer in posterior lumbar interbody fusion compared with polyetheretherketone cage: a prospective randomized controlled trial

PURPOSE

The CaO-SiO2-P2O5-B2O3 glass-ceramic (BGS-7) spacer is a recently developed spacer that shows chemical bonding to bone with high mechanical stability. Further, this spacer achieves similar results to those of titanium cages. However, evidence regarding the advantages of the BGS-7 spacer is weak compared to polyetheretherketone (PEEK) cage. A randomized controlled trial is therefore warranted. The purpose of this study was to compare the radiographic and clinical efficacies and safety of the BGS-7 spacer compared to those of the PEEK cage in patients who underwent posterior lumbar interbody fusion (PLIF).

METHODS

The 54 participants who required one- or two-level PLIF due to lumbar degenerative disorders were randomly assigned to receive a BGS-7 spacer or PEEK cage. Visual analog scale (VAS), Oswestry Disability Index (ODI), European Quality of Life-5 Dimensions (EQ-5D), and painDETECT score were evaluated before surgery and at 3, 6, and 12 months after surgery. The fusion rate, degree of osteolysis, cage migration, and subsidence around the cage (spacer) were evaluated on computer tomography (CT) images at 12 months after surgery.

RESULTS

The 12-month fusion rates were 77.8% in the BGS-7 spacer group and 81.0% in the PEEK cage group, with no significant difference (p = 0.807). The result regarding the non-inferiority of BGS-7 spacer was inconclusive. The linear mixed model showed no significant intervention effect in VAS, ODI, EQ-5D, and painDETECT score at the 3-, 6-, or 12-month follow-up. In addition, we found no significant between-group differences in the extent of osteolysis, spacer migration. However, the subsidence around the cage was significantly lower in the BGS-7 spacer group.

CONCLUSIONS

This trial found similar fusion rates, and clinicoradiographic outcomes between the BGS-7 spacer and PEEK cage for PLIF. However, the non-inferiority was inconclusive. Safety concerns regarding fracture and migration of the BGS-7 spacer must be considered. Thus, the BGS-7 spacer design for PLIF surgery should be modified before further clinical use.

Long-term results comparison after anterior cervical discectomy with BGS-7 spacer (NOVOMAX®-C) and allograft spacer: A prospective observational study

Introduction: In an anterior cervical discectomy and fusion (ACDF), various types of graft materials including autograft, allograft, and synthetic graft have been used to achieve adequate spinal fusion. Allograft spacer is mainly used in cervical fusion, especially in the anterior approach. The synthetic bone graft material BGS-7(CaO-SiO2-P2O5-B2O3, bioactive Glass-Ceramics) can bind with surrounding bone tissue by forming a hydroxyapatite layer bone bridge, leading to faster graft osseointegration. This study was conducted to compare long-term clinical outcome of BGS-7 spacer and allograft spacer for anterior cervical discectomy and fusion surgery. Materials and Methods: From September 2014 to December 2016, Consecutive anterior cervical discectomy and fusion surgeries using a BGS-7 spacer (N = 18) and Allograft spacer (N = 26) were compared for postoperative clinical outcomes. Radiologic assessments were performed, and Instrumental failure, including breakage, cage migration, subsidence were observed and Fusion status were analyzed. Finite element analysis was performed for simulating mechanical stress between the vertebral body and implant. Clinical outcomes were evaluated using neck VAS, NDI, and JOA on the patient's final follow-up visits. Results: Among the 44 patients who underwent an anterior cervical discectomy and fusion surgery using the BGS-7 spacer and Allograft spacer, there were 30 men and 14 women. The average age at the operation was 47.69 ± 10.49 in allograft spacer and 51.67 ± 11.03 in BGS-7 spacer. The mean follow-up period was 89.18 ± 5.44 months. Twenty three (88.46%) patients in allograft spacer and 20(100%) patients in BGS-7 spacer were demonstrated radiologic evidence of interbody fusion in last OPD, which accounts for fusion grade 4 or 5. Peak stresses were 343.85 MPa in allograft spacer, and 132.55 MPa in BGS-7 spacer. Long-term clinical outcomes including neck VAS, NDI, and JOA didn't show statistical differences between the two groups. There were no adverse events related to the BGS-7 spacer.10.3389/fbioe.2023.110046. Conclusion: The BGS-7 spacer demonstrated reliability as a spacer in anterior cervical discectomy and fusionF surgery without instrumental failure. Early stabilization with a bony bridge formation was observed at the intermediate follow-up period, and the long-term clinical outcome was favorable at more than 60 months after surgery without any adverse events. Thus, the BGS-7 spacer is a safe and effective alternative to the allograft spacer in anterior cervical discectomy and fusion surgery.

Nanodesigned coatings obtained by plasma electrolytic oxidation of titanium implant and their cytotoxicity

The titanium implant was treated with plasma electrolytic oxidation and subsequent ionic exchange and thermal treatment in order to obtain bioactive layer consisting of titanium oxide, calcium and sodium titanates and hydroxyapatite, as confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) revealed that the given method, besides corresponding phase composition, enables suitable nanotopology for cell attachment and proliferation. Cytotoxicity investigations by MTT, LDH and propidium iodide assays and light microscopy showed that these coatings were not toxic to L929 cells.

A Novel Screw Drive for Allogenic Headless Position Screws for Use in Osteosynthesis-A Finite-Element Analysis

Due to their osteoconductive properties, allogenic bone screws made of human cortical bone have advantages regarding rehabilitation compared to other materials such as stainless steel or titanium. Since conventional screw drives like hexagonal or hexalobular drives are difficult to manufacture in headless allogenic screws, an easy-to-manufacture screw drive is needed. In this paper, we present a simple drive for headless allogenic bone screws that allows the screw to be fully inserted. Since the screw drive is completely internal, no threads are removed. In order to prove the mechanical strength, we performed simulations of the new drive using the Finite-Element method (FEM), validated the simulations with a prototype screw, tested the novel screw drive experimentally and compared the simulations with conventional drives. The validation with the prototype showed that our simulations provided valid results. Furthermore, the simulations of the new screw drive showed good performance in terms of mechanical strength in allogenic screws compared to conventional screw drives. The presented screw drive is simple and easy to manufacture and is therefore suitable for headless allogenic bone screws where conventional drives are difficult to manufacture.

A Clinical Trial to Evaluate the Efficacy and Safety of 3D Printed Bioceramic Implants for the Reconstruction of Zygomatic Bone Defects

The purpose of this study was to evaluate the clinical efficacy and safety of patient-specific additive-manufactured CaOSiO₂-P₂O₅-B₂O₃ glass-ceramic (BGS-7) implants for reconstructing zygomatic bone defects at a 6-month follow-up. A prospective, single-arm, single-center, clinical trial was performed on patients with obvious zygoma defects who needed and wanted reconstruction. The primary outcome variable was a bone fusion between the implant and the bone evaluated by computed tomography (CT) at 6 months post surgery. Secondary outcomes, including implant immobilization, satisfaction assessment, osteolysis, subsidence of the BGS-7 implant, and safety, were assessed. A total of eight patients were enrolled in the study. Two patients underwent simultaneous reconstruction of the left and right malar defects using a BGS-7 3D printed implant. Cone beam CT analysis showed that bone fusion at 6 months after surgery was 100%. We observed that the average fusion rate was 76.97%. Osteolysis around 3D printed BGS-7 implants was not observed. The mean distance displacement of all 10 implants was 0.4149 mm. Our study showed no adverse event in any of the cases. The visual analog scale score for satisfaction was 9. All patients who enrolled in this trial were aesthetically and functionally satisfied with the surgical results. In conclusion, this study demonstrates the safety and promising value of patient-specific 3D printed BGS-7 implants as a novel facial bone reconstruction method.

A Long-Term Follow-up, Multicenter, Comparative Study of the Radiologic, and Clinical Results Between a CaO-SiO2-P2O5-B2O3 Bioactive Glass Ceramics (BGS-7) Intervertebral Spacer and Titanium Cage in 1-Level Posterior Lumbar Interbody Fusion

STUDY DESIGN

This is a prospective, stratified randomized, multicenter, 4-year follow-up study.

OBJECTIVE

The authors aimed to evaluate the long-term clinical efficacy and safety of CaO-SiO2-P2O5-B2O3 glass ceramics (BGS-7) spacers in 1-level posterior lumbar interbody fusion (PLIF) at a 4-year follow-up.

SUMMARY OF BACKGROUND DATA

According to 1-year follow-up results, BGS-7 spacer showed similar fusion rates and clinical outcomes compared with titanium cage. A long-term follow-up study beyond 2 years is necessary to investigate the status of intervertebral bone graft volumes. Moreover, longer follow-up is mandatory to also evaluate the safety and efficacy of BGS-7 spacers, because they remain in the intervertebral space for a long time.

MATERIALS AND METHODS

In this prospective, randomized, multicenter, 4-year follow-up study, we evaluated 62 of the 74 patients who underwent 1-level PLIF. During 1-level PLIF, titanium cages filled with autologous local bone were inserted into the control group patients and BGS-7 spacers were inserted to the experimental group patients. Bone fusion was evaluated by plain radiography and thin-section computed tomography. Visual Analog Scale (VAS), the Oswestry Disability Index (ODI), Short Form-36 Health Survey (SF-36), and evaluation of safety were conducted after 48 months.

RESULTS

Computed tomography scan showed a bone fusion rate of 90.6% in the BGS-7 spacer group and 93.3% in the control group, with no significant differences between groups. The BGS-7 spacer group showed a significantly larger area directly fused to the endplate than the control group (P<0.001). The BGS-7 spacer group showed a significant increase in the fused area compared with the titanium group at 1- and 4-year follow-up. The ODI, SF-36, back pain, and lower limb pain in both groups showed significant improvement after surgery, and no significant differences were observed between the groups. Both groups showed no additional adverse events.

CONCLUSIONS

The 4-year follow-up study showed similar fusion rates and clinical outcomes in both the BGS-7 spacer and autologous bone with a titanium cage in 1-level PLIF. However, the BGS-7 spacer implants showed a larger area of fusion with the endplates than that of autologous bone with a titanium cage. Therefore, the results demonstrated that the BGS-7 spacer can be considered as a novel intervertebral spacer to achieve successful spinal fusion without safety concerns for long-term use.

A programmable, fast-fixing, osteo-regenerative, biomechanically robust bone screw

The use of a screw for repairing defected bones is limited by the dilemma between stiffness, bioactivity and internal fixation ability in current products. For polymer bone screw, it is difficult to achieve the bone stiffness and osteo-induction. Polymer composites may enhance bioactivity and mechanical properties but sacrifice the shape memory properties enormously. Herein, we fabricated a programmable bone screw which is composed of shape memory polyurethane, hydroxyapatite and arginylglycylaspartic acid to resolve the above problem. This composite has significantly improved mechanical and shape-memory properties with a modulus of 250 MPa, a shape fixity ratio of ~90% and a shape recovery ratio of ~96%. Moreover, shape fixity and recovery ratios of the produced SMPC screw in the simulative biological condition were respectively ~80% and ~82%. The produced screw could quickly recover to its original shape in vitro within 20 s leading to easy internal fixation. Additionally, the composite could support mesenchymal stem cell survival, proliferation and osteogenic differentiation in vitro tests. It also promoted tissue growth and showed beneficial mechanical compatibility after implantation into a rabbit femoral intracondyle for 12 weeks with little inflammation. Such bone screw exhibited a fast-fixing, tightened fitting, enhanced supporting and boosted bioactivity simultaneously in the defective bone, which provides a solution to the long-standing problem for bone repairing. We envision that our composite material will provide valuable insights into the development of a new generation of bone screws with good fixation and osteogenic properties. STATEMENT OF SIGNIFICANCE: The main obstacles to a wider use of a bone screw are unsatisfied stiffness, inflammatory response and screw loosening issues. Herein, we report a programmable screw with mechanically robust, bioactive and fast-fixing performances. The shape memory polymer composite takes advantage of the component in the natural bone and possesses a stable bush-like structure inside through the covalent bonding, and thus achieve significantly improved mechanical and memory properties. Based on its shape memory effect, the produced screw was proved to offer a recovery force to surroundings and promote the bone regeneration effectively. Therefore, the composite realizes our expectations on functions through structure design and paves a practical and effective way for the development of a new generation of bone screws.

Nonstoichiometric wollastonite bioceramic scaffolds with core-shell pore struts and adjustable mechanical and biodegradable properties

Controllable mechanical strength and biodegradation of bioceramic scaffolds is a great challenge to treat the load-bearing bone defects. Herein a new strategy has been developed to fabricate porous bioceramic scaffolds with adjustable component distributions based on varying the core-shell-structured nozzles in three-dimensional (3D) direct ink writing platform. The porous bioceramic scaffolds composed of different nonstoichiometic calcium silicate (nCSi) with 0%, 4% or 10% of magnesium-substituting-calcium ratio (CSi, CSi-Mg4, CSi-Mg10) was fabricated. Beyond the mechanically mixed composite scaffolds, varying the different nCSi slurries through the coaxially aligned bilayer nozzle makes it easy to create core-shell bilayer bioceramic filaments and better control of the different nCSi distribution in pore strut after sintering. It was evident that the magnesium substitution in CSi contributed to the increase of compressive strength for the single-phasic scaffolds from 11.2 MPa (CSi), to 39.4 MPa (CSi-Mg4) and 80 MPa (CSi-Mg10). The nCSi distribution in pore struts in the series of core-shell-strut scaffolds could significantly adjust the strength [e.g. CSi@CSi-Mg10 (58.9 MPa) vs CSi-Mg10@CSi (30.4 MPa)] and biodegradation ratio in Tris buffer for a long time stage (6 weeks). These findings demonstrate that the nCSi components with different distributions in core or shell layer of pore struts lead to tunable strength and biodegradation inside their interconnected macropore architectures of the scaffolds. It is possibly helpful to develop new bioactive scaffolds for time-dependent tailoring mechanical and biological performances to significantly enhance bone regeneration and repair applications, especially in some load-bearing bone defects.

Comparison of fusion rate and clinical results between CaO-SiO2-P2O5-B2O3 bioactive glass ceramics spacer with titanium cages in posterior lumbar interbody fusion

BACKGROUND CONTEXT

The CaO-SiO₂-P₂O₅-B₂O₃ glass ceramics spacer generates chemical bonding to adjacent bones with high mechanical stability to produce a union with the end plate, and ultimately stability.

PURPOSE

The authors aimed to compare the clinical efficacy and safety of CaO-SiO₂-P₂O₅-B₂O₃ glass ceramics with a titanium cage that is widely used for posterior lumbar interbody fusion (PLIF) surgery in the clinical field.

STUDY DESIGN/SETTING

This is a prospective, stratified randomized, multicenter, single-blinded, comparator-controlled non-inferiority trial.

PATIENT SAMPLE

The present study was conducted in four hospitals and enrolled a total of 86 patients between 30 and 80 years of age who required one-level PLIF due to severe spinal stenosis, spondylolisthesis, or huge disc herniation.

OUTCOME MEASURES

The Oswestry Disability Index (ODI), Short Form-36 Health Survey (SF-36), and pain visual analog scale (VAS) were assessed before surgery and at 3, 6, and 12 months after surgery. The spinal fusion rate was assessed at 6 and 12 months after surgery.

METHODS

The spinal fusion rate and the area of fusion, subsidence of each CaO-SiO₂-P₂O₅-B₂O₃ glass ceramics and titanium cage, and the extent of osteolysis were evaluated using a dynamic plain radiography and a three-dimensional computed tomography at 12 months after surgery. The present study was supported by BioAlpha, and some authors (JHL, C-KL, and B-SC) have stock ownership (<10,000 US dollars).

RESULTS

From the plain radiography results, the 6-month fusion rates for the bioactive glass ceramics group and the titanium group were 89.7% and 91.4%, respectively. In addition, the 12-month fusion rates based on CT scan were 89.7% and 91.2%, respectively, showing no significant difference. However, the bone fusion area directly attached to the end plate of either bioactive glass ceramics or the titanium cage was significantly higher in the bioactive glass ceramics group than in the titanium group. The ODI, SF-36, back pain, and lower limb pain in both groups significantly improved after surgery, with no significant differences between the groups. No significant differences between the two groups were observed in the extent of subsidence and osteolysis.

CONCLUSIONS

In lumbar posterior interbody fusion surgery, CaO-SiO₂-P₂O₅-B₂O₃ glass ceramics spacer showed a similar fusion rates and clinical outcomes compared with titanium cage.

SPECT/CT demonstrates the osseointegrative response of a stemless shoulder prosthesis

BACKGROUND

This study evaluates bone remodeling processes in the proximal humerus induced by the implantation of a stemless shoulder prosthesis with regard to time of response and type and extent of bone turnover.

METHODS

Twenty-eight patients with primary osteoarthritis of the shoulder undergoing a stemless shoulder arthroplasty were prospectively evaluated. The local metabolic bone activity in 5 regions of interest (ROIs 1-5) around the implant and in 1 reference region (ROI ref.) in the humeral diaphysis was analyzed after the application of technetium Tc 99m DPD using single-photon emission computed tomography integrated with multidetector computed tomography (SPECT/CT). The study cohort was divided into 4 groups according to the timing of the most recent follow-up appointment to evaluate the primary osseointegrative response after surgery. The bone uptake values were expressed in target (ROIs 1-5) to nontarget (ROI ref.) ratios.

RESULTS

No difference within the 4 subgroups with respect to the time of local metabolic bone activity in the ROIs was found at 90 days after surgery. The highest initial metabolic activity and most temporal modifications were found in ROI 1, which was localized in the superior segment of the stem.

CONCLUSIONS

SPECT/CT data suggest that the primary osseointegration of a stemless shoulder prosthesis is almost completed 3 months after implantation. Variations in metabolic activity pattern in the ROIs during follow-up may be caused by different loading conditions of the bone.

Osteosynthesis-screw augmentation by ultrasound-activated biopolymer--an ovine in vivo study assessing biocompatibility and bone-to-implant contact

OBJECTIVES

Screw fixation and fragment anchoring in osteoporotic bones is often difficult. Problems like the cut out phenomenon and implant migration in osteoporotic bones have been reported. One possibility of improving the anchoring force of screws is augmentation of the screw. Cement-augmented screws in spinal surgery could exhibit a better anchoring in osteoporotic bones.

METHODS

The purpose of this study was to examine the effect of screw augmentation using a resorbable polymer. Ultrasound-activated biodegradable pins were used for the purpose of a resorbable augmentation technique. Cannulated screws were inserted into the femur of 12 sheep and augmented by an ultrasound-activated polylactic acid (PLDLA) pin. In a paired approach, four screws were implanted in each animal: 2× a 10-mm thread and 2× a 20-mm thread, both of which were augmented with polymer. Both screws, named A and B, were also applied without augmentation (control group) and implanted into the contralateral hind limb. After 4, 8, and 12 weeks, the sheep were euthanized and a macroscopical and histological examination followed.

RESULTS

The polymer spread well out of the screws into the cancellous lacunae. Around the polymer, the peripheral bone showed signs of healthy and active bone tissue. No evidence of inflammation or infection was observed. The boneto-implant contact was significantly higher in the augmented screws. Biocompatibility was proven in histopathological examination. After 12 weeks, no pathological changes were found.

CONCLUSION

Ultrasound-activated polymer augmentation of cannulated screws may improve the anchoring in osteoporotic bone.

ARTICLE FOCUS

Can screw augmentation using a resorbable polymer improve the bone-to-implant contact in case of screw osteosynthesis? Is there any effect on the surrounding tissue by the induced temperature and liquefied polymer? Can biocompatibility be proven by this new osteosynthesis?

KEY MESSAGES

Screw augmentation by ultrasound-activated biopolymer leads to a significant higher bone-to-implant contact than pure screw osteosynthesis. No tissue damage could be observed by the application of the SonicFusion™.

STRENGTH AND LIMITATIONS OF THIS STUDY

The ovine in vivo study concept can simulate physiological conditions. First examination of screw augmentation by ultrasound-activated biopolymer. No biomechanical testing of the higher bone-to-implant contact by now.

Regenerative nanomedicine: current perspectives and future directions

Nanotechnology has considerably accelerated the growth of regenerative medicine in recent years. Application of nanotechnology in regenerative medicine has revolutionized the designing of grafts and scaffolds which has resulted in new grafts/scaffold systems having significantly enhanced cellular and tissue regenerative properties. Since the cell–cell and cell-matrix interaction in biological systems takes place at the nanoscale level, the application of nanotechnology gives an edge in modifying the cellular function and/or matrix function in a more desired way to mimic the native tissue/organ. In this review, we focus on the nanotechnology-based recent advances and trends in regenerative medicine and discussed under individual organ systems including bone, cartilage, nerve, skin, teeth, myocardium, liver and eye. Recent studies that are related to the design of various types of nanostructured scaffolds and incorporation of nanomaterials into the matrices are reported. We have also documented reports where these materials and matrices have been compared for their better biocompatibility and efficacy in supporting the damaged tissue. In addition to the recent developments, future directions and possible challenges in translating the findings from bench to bedside are outlined.

Negative effect of rapidly resorbing properties of bioactive glass-ceramics as bone graft substitute in a rabbit lumbar fusion model

Background

Bioactive glass-ceramics have the ability to directly bind to bones and have been widely used as bone graft substitutes due to their high osteoconductivity and biocompatibility. CaO-SiO₂-P₂O₅-B₂O₃ glass-ceramics are known to have good osteoconductivity and are used as bone graft extenders.

Methods

This study aimed to evaluate the effects of the resorbing properties of glass-ceramics in bone fusion after producing and analyzing three types of CaO-SiO₂-P₂O₅-B₂O₃ glass-ceramics with high osteoconductivity that had enhanced resorption by having an increased B₂O₃ content. The three types of CaO-SiO₂-P₂O₅-B₂O₃ glass-ceramics with B₂O₃ contents of 8.0, 9.0, and 9.5 weight % were designated and grouped as P20B80, P10B90, and P5B95, respectively. Glass-ceramic types were tested for fusion rates and bone formation by employing the lumbar 5-6 intertransverse process fusion model in 51 New Zealand male rabbits. Bioactivity was assessed by soaking in simulated body fluid (SBF).

Results

In vitro study results showed sufficient hydroxycarbonate apatite layer formation occurred for P20B80 in1 day, for P10B90 in 3 days, and for P5B95 in 5 days after soaking in SBF. For the rabbit lumbar spine posterolateral fusion model, the autograft group recorded a 100% fusion rate with levels significantly higher than those of P20B80 (29.4%), P10B90 (0%), and P5B95 (14.3%), with high resorbing properties. Resorbing property differences among the three glass-ceramic groups were not significant. Histological results showed new bone formation confirming osteoconductivity in all three types of glass-ceramics. Radiomorphometric results also confirmed the resorbing properties of the three glass-ceramic types.

Conclusions

The high resorbing properties and osteoconductivity of porous glass-ceramics can be advantageous as no glass-ceramics remain in the body. However, their relatively fast rate of resorption in the body negatively affects their role as an osteoconductive scaffold as glass-ceramics are resorbed before bony fusion.

In vitro and in vivo evaluation of the bioactivity of hydroxyapatite-coated polyetheretherketone biocomposites created by cold spray technology

Polyetheretherketone (PEEK) is a material that is widely used in medicine because its mechanical properties show excellent similarity to those of human bone. However, because it is bioinert, PEEK shows limited ability to bind to natural bone tissue. Here, we applied a cold spray method to make a hydroxyapatite (HA)-coated PEEK hybrid material and evaluated its osteointegration in vitro and in vivo. With the cold spray method, the HA coating formed a homogeneous layer and adhered strongly to the PEEK disk implant. When the material was tested in vitro, early cell adhesion and viability improved. Alkaline phosphatase (ALP) activity and calcium concentration were also higher in cells cultured on HA-coated PEEK disks. In addition, the expression of osteoblast differentiation markers, such as ALP, bone sialoprotein and runt-related transcription factor 2, increased in these cells. For the in vivo test, we designed and implanted HA-coated PEEK cylinders into a rabbit ilium model by the press-fit method. The bone-implant contact ratio, trabecular number and trabecular thickness were determined using either three-dimensional microcomputed tomography or general two-dimensional histomorphometric analysis. This report demonstrates that the HA coating on the PEEK implant added with the cold spray method increased biocompatibility in vitro and promoted osteointegration in vivo, which suggests that the HA coating may improve the biofunctionality of various medical devices used in clinical applications.

Incorporation of bioactive glass in calcium phosphate cement: An evaluation

Bioactive glasses (BGs) are known for their unique ability to bond to living bone. Consequently, the incorporation of BGs into calcium phosphate cement (CPC) was hypothesized to be a feasible approach to improve the biological performance of CPC. Previously, it has been demonstrated that BGs can successfully be introduced into CPC, with or without poly(d,l-lactic-co-glycolic) acid (PLGA) microparticles. Although an in vitro physicochemical study on the introduction of BG into CPC was encouraging, the biocompatibility and in vivo bone response to these formulations are still unknown. Therefore, the present study aimed to evaluate the in vivo performance of BG supplemented CPC, either pure or supplemented with PLGA microparticles, via both ectopic and orthotopic implantation models in rats. Pre-set scaffolds in four different formulations (1: CPC; 2: CPC/BG; 3: CPC/PLGA; and 4: CPC/PLGA/BG) were implanted subcutaneously and into femoral condyle defects of rats for 2 and 6 weeks. Upon ectopic implantation, incorporation of BG into CPC improved the soft tissue response by improving capsule and interface quality. Additionally, the incorporation of BG into CPC and CPC/PLGA showed 1.8- and 4.7-fold higher degradation and 2.2- and 1.3-fold higher bone formation in a femoral condyle defect in rats compared to pure CPC and CPC/PLGA, respectively. Consequently, these results highlight the potential of BG to be used as an additive to CPC to improve the biological performance for bone regeneration applications. Nevertheless, further confirmation is necessary regarding long-term in vivo studies, which also have to be performed under compromised wound-healing conditions.