Polylactic Acid Hydroxyapatite Research Articles

A polylactic acid/hydroxyapatite/scholzite composite scaffold for promoting healing of osteoporotic bone defects in rats

To investigate the release kinetics of Zn2+ from nZCP-loaded polylactic acid/hydroxyapatite (PLA/HA) composite scaffold (PHZ) and determine the optimal nZCP content in the scaffold. The particle size of nZCP was measured by DLS measurement, and PXRD, FTIR, and SEM were used to characterize the scaffolds and nZCP distribution; EDS was used to analyze element composition of the scaffold. Compression strength of the scaffold was determined, and ion release profile was investigated using ICP-MS. The biocompatibility of the materials was evaluated by CCK-8 assay and dead/alive staining of rat bone marrow stem cells (BMSCs) incubated with their aqueous extracts. ALP staining, alizarin red staining, RT-qPCR, and Western blotting were used to assess the osteogenic potential of the treated cells. In a rat model of bilateral ovariectomy (OVX) with femoral condylar bone defect, PHZ-1, PHZ-2, PHZ-3 or PLA/HA scaffold was implanted into the bone defect, and bone repair was observed using a microCT scanner and histological staining at 6 and 12 weeks. DLS, PXRD, SEM, FTIR, and EDS confirmed successful synthesis of 10-nm ZCP and efficient nZCP loading in the scaffold. PHZ-2 and PHZ-3 had significantly greater compression strength than PLA/HA. ICP-MS showed that Zn2+ release from PHZ-1, PHZ-2 and PHZ-3 were all optimal for promoting osteogenesis. In rat BMSCs, all the 4 scaffolds showed good biocompatibility, and their extracts enhanced ALP activity and extracellular matrix mineralization and promoted expressions of ALP, RUNX2, and OCN in the cells. In the rat models, nZCP in the implants improved bone graft integration at 6 weeks, and PHZ-2 and PHZ-3 more effectively induced new bone formation at 12 weeks (P < 0.05). PHZ scaffold is capable of stable Zn2+ release to promote osteoporotic bone defect healing, and PHZ-2 and PHZ-3 scaffolds with nZCP mass fraction of 4.5%-7.5% have better osteogenic activity.

The Use of Lactide Polymers in Bone Tissue Regeneration in Dentistry-A Systematic Review.

(1) Background: Different compositions of biodegradable materials are being investigated to successfully replace non-resorbable ones in bone tissue regeneration in dental surgery. The systematic review tried to address the question, "Can biodegradable polymers act as a replacement for conventional materials in dental surgery procedures?" (2) Methods: An electronic search of the PubMed and Scopus databases was conducted in October 2022. The following keywords were used: (lactide polymers) and (hydroxyapatite or fluorapatite) and (dentistry) and (regeneration). Initially, 59 studies were found. Forty-one studies met the inclusion criteria and were included in the review. (3) Results: These usually improved the properties and induced osteogenesis, tissue mineralisation and bone regeneration by inducing osteoblast proliferation. Five studies showed higher induction of osteogenesis in the case of biomaterials, UV-HAp/PLLA, ALBO-OS, bioresorbable raw particulate hydroxyapatite/poly-L-lactide and PLGA/Hap, compared to conventional materials such as titanium. Four studies confirmed improvement in tissue mineralisation with the usage of biomaterials: hydroxyapatite/polylactic acid (HA/PLA) loaded with dog's dental pulp stem cells (DPSCs), Coll/HAp/PLCL, PDLLA/VACNT-O:nHAp, incorporation of hydroxyapatite and simvastatin. Three studies showed an acceleration in proliferation of osteoblasts for the use of biomaterials with additional factors such as collagen and UV light. (4) Conclusions: Lactide polymers present higher osteointegration and cell proliferation rate than the materials compared. They are superior to non-biodegradable materials in terms of the biocompability, bone remodelling and healing time tests. Moreover, because there is no need of reoperation, as the material automatically degrades, the chance of scars and skin sclerosis is lower. However, more studies involving greater numbers of biomaterial types and mixes need to be performed in order to find a perfect biodegradable material.

Repair of Cranial Defects in Rabbits with 3D-Printed Hydroxyapatite/Polylactic Acid Composites.

The safety and efficacy of three-dimensional- (3D-) printed hydroxyapatite/polylactic acid (HA-PLA) composites in repairing cranial defects were evaluated in a rabbit experimental model. Twelve New Zealand rabbits were selected as experimental subjects. Two holes (A and B), each with a diameter of approximately 1 cm, were made in the cranium of each rabbit. Hole A served as the experimental manipulation, and hole B served as the control manipulation. A 3D-printed HA-PLA composite was used for placement onto hole A, whereas autologous bone powder was used for placement onto hole B. Samples from the experimental holes and the control holes were collected at 30 and 90 days after surgery. The obtained materials were examined in terms of their morphologies and histopathologies and were also subjected to simultaneous hardness tests. Both the 3D-printed HA-PLA composite and autologous bone powder were able to repair and fill the cranial defects at 30 days and 90 days after surgery. At 30 days after surgery, the microhardness of the area repaired by the HA-PLA composite was lower than that of the area repaired by autogenous bone powder (p < 0.01), but neither of these treatments reached the hardness of normal bone at this time (p < 0.01). At 90 days after surgery, there was no statistically significant difference in the microhardness of the repaired area from the 3D-printed HA-PLA composite compared with that of the repaired area from autologous bone powder (p > 0.05), and there was no statistically significant difference in the hardness of the two repaired areas compared with that of the normal bone (p > 0.05). Hematoxylin-eosin staining showed that bone cells in the HA-PLA material in the experimental group grew and were arranged in an orderly manner. Bone trabeculae and marrow cavities were formed on the pore surface and inside of the HA-PLA scaffold, and the arrangement of bone trabeculae was regular. 3D-printed HA-PLA composites can induce bone regeneration, are biocompatible, have the same strength as autologous bone powder, are able to degrade, and are ultimately safe and effective for repairing cranial defects in rabbits. However, further research is needed to determine the feasibility of 3D-printed HA-PLA composites in human cranioplasty.

Strontium doped electrospinning fiber membrane with antibacterial and osteogenic properties prepared by pulse electrochemical method

• Composite fibers were prepared by electrostatic spinning and pulse electrochemical deposition. • PPy controls the slow release of Sr 2+ and Cu 2+ for a long time. • Good physiological stability and long-term antibacterial effect. • Fiber has good osteogenic and angiogenic properties. The osteogenic differentiation and new bone formation are commonly delayed by bacterial infection of orthopedic implants, which is urgent to be resolved quickly in the clinic. The current paper prepared a strontium-doped electrospinning fiber membrane with antibacterial and osteogenic properties by pulse electrochemical method. Polylactic acid/hydroxyapatite (PLLA/HA) composite fiber substrate was fabricated by electrospinning technology, and strontium doped SrHA/Cu/Polypyrrole (PPy) composite coating was constructed with pulse electrodeposition method on its surface. The strontium doping technique, degradation of Sr 2+ and Cu 2+ , cellular compatibility, and the antibacterial activity of the fiber membrane were examined. The results revealed that the deposition of phosphorus and calcium on composite fiber was the highest, indicating good biological activity. The release of Sr 2+ and Cu 2+ was stable and gradual due to the modulation of PPy. The composite fiber presented excellent antibacterial performance and the antibacterial rate was close to 100% against Staphylococcus aureus and Escherichia coli. Furthermore, it is conducive to the adhesion, spread, and proliferation of vascular endothelial cells and osteoblasts, namely outstanding osteogenesis and angiogenesis abilities. In conclusion, the multifunctional PLLA/HA@SrHA/Cu/PPy composite fiber membrane with good antibacterial and osteogenic activity by electrospinning technology and pulsed electrochemical deposition method provides an effective strategy for the poor bone healing of infected bone defects. Strontium doped antibacterial osteogenic PLLA/HA@SrHA/Cu/PPy composite fiber was constructed by electrostatic spinning and pulsed electrochemical deposition technology, which showed good antibacterial properties and had the ability to promote bone induction and angiogenesis.

High porosity composite structures produced from poly(lactic acid)/hydroxyapatite microspheres using novel Dual Beam Laser Sintering method: Analysis of structural, mechanical and thermal properties

The paper discusses the applicability of the novel Dual Beam Laser Sintering (DBLS) method for processing of poly(lactic acid)/hydroxyapatite (PLA/HAp) composite powders. The composite microspheres were prepared using the solid-in-oil-in-water (S/O/W) emulsification technique. The three-dimensional structures made of composite microspheres with different filler content – 5 % and 10 % by weight of HAp were processed using DLBS that uses a new method of preheating the powder bed. The obtained results were compared to the case of pure PLA presented in our previous work.The quality of the powders was determined using Dry Laser Diffraction (DLS), X-Ray Computed Tomography (XCT), Revolution Powder Analysis (RPA) and Differential Scanning Calorimetry (DSC). The melt flow rate and the thermal conductivity of the microspheres were also determined. Conducted research shows that the morphology of the particle depends heavily on the HAp content which ultimately influences the powder flowability properties. Moreover, the properties of samples manufactured using DBLS were evaluated. The internal microstructure was reconstructed using XCT and the open porosity structures were revealed. The influence of both the porosity and the HAp reinforcement on the mechanical properties was observed. Additionally, a thermal DSC analysis was carried out, which allowed to assess how the filler and process parameters affect the degree of crystallinity of the obtained structures and the thermal degradation of the composite.In general, the presented study shows the possibility of designing part properties not only by means of the DBLS process parameters but also by influencing the powder material properties. Both raw material properties and process parameters affect the morphology of pores and therefore the mechanical properties of PBF processed material.

3D‐printing polylactic acid/hydroxyapatite fracture internal fixation plates for bone repair

AbstractFracture internal fixation plates are the most common implants in internal fixation and have been applied to fix fractures for over a hundred years. Plates of metal material remain the gold standard. However, they are not the ideal bone plate considering the stress shielding induced by the high elastic modulus and biomechanical mismatch with bone. PLA fracture internal fixation plates present the advantages of matching with the elastic modulus of the bone and absorbable properties but are limited by poor toughness and acidic degradation. Degradable bone plates composed of polylactic acid/hydroxyapatite (PLA/HA) composite were prepared by fused deposition modeling, which had higher bending strength and compressive strength than that of pure PLA. The hydrophilicity of PLA/HA composite was improved by the addition of HA, it was beneficial to the adhesion of cells on the surface of the composite. The results of in vitro degradability showed that the addition of HA can effectively neutralize the acidity generated by PLA degradation. Meanwhile, the addition of HA can improve the cell affinity to promote the adhesion and growth of MC3T3‐E1 cells on the surface of the composites. Consequently, the PLA/HA composite shows a good potential as a bone plate to fix bone fractures.

Development of beta-carotene-loaded poly(lactic acid)/hydroxyapatite core-shell nanoparticles for osteoblast differentiation

ABSTRACT Beta-carotene (BC) is a nutrient in vegetables and a precursor of vitamin A. BC has been reported to have anticarcinogenic, antiaging, and antioxidation properties and prevents heart diseases. Recently, BC has gained significant attention due to stimulating effect on osteoblast differentiation. Poly(lactic acid)/hydroxyapatite (PLA/HAp) core-shell nanoparticles have been reported earlier with a load capacity of 250% for water-insoluble substances, using a surfactant-free emulsification method. In this work, PLA/HAp core-shell nanoparticles loaded with BC were prepared, and osteoblast differentiation behavior was evaluated. BC was successfully loaded into PLA/HAp core-shell nanoparticles with diameters of approximately 30 nm. BC/loaded PLA/HAp core-shell nanoparticles stimulated osteoblast differentiation by upregulating collagen type I, osteopontin, and osteocalcin expression. In addition, the gene expression levels of these osteoblasts were significantly larger than those stimulated by PLA/HAp core-shell nanoparticles without BC and cultured in a differential medium (with ascorbic acid and β-glycerophosphate). PLA/HAp core-shell nanoparticles showed satisfactory cytocompatibility because they were attached to the osteoblasts. Consequently, BC was effectively delivered to osteoblasts by nanoparticles. These results suggested that BC-loaded PLA/HAp core-shell nanoparticles could enhance bone formation.

Enhanced tissue regeneration through immunomodulation of angiogenesis and osteogenesis with a multifaceted nanohybrid modified bioactive scaffold.

Major traumatic tissue defects are common clinical problems often complicated by infection and local vascular dysfunction, processes which hinder the healing process. Although local application of growth factors or stem cells through various tissue engineering techniques are promising methods for the repair of tissue defects, limitations in their clinical application exist. Herein, we synthesized multifaceted nanohybrids composed of Quaternized chitosan (QCS), Graphene oxide (GO), and Polydopamine (PDA; QCS-GO-PDA). Covalent grafting of QCS and GO at a mass ratio of 5:1 (5QCS-1GO) displayed excellent biocompatibility and enhanced osteogenic ability, while addition of PDA (5QCS-1GO-PDA) reduced the level of reactive oxygen species (ROS). 5QCS-1GO-PDA was able to achieve wound tissue regeneration by reducing the inflammatory response and enhancing angiogenesis. Furthermore, Polylactic acid/hydroxyapatite (PLA/HA) composite scaffolds were printed using Selective Laser Sintering (SLS) and the hybrid nanomaterial (5QCS-1GO-PDA) was used to coat the PLA/HA scaffold (5QCS-1GO-PDA@PLA/HA) to be used for rapid bone regeneration. 5QCS-1GO-PDA not only improved angiogenesis and osteogenic differentiation, but also induced M2-type polarization of macrophages and promoted bone regeneration via the BMP2/BMPRs/Smads/Runx2 signaling pathway. The bidirectional enhanced healing ability of the multifaceted nanohybrids 5QCS-1GO-PDA provides a promising method of effectively treating tissue defects.

PLA/Hydroxyapatite scaffolds exhibit in vitro immunological inertness and promote robust osteogenic differentiation of human mesenchymal stem cells without osteogenic stimuli

Bone defects stand out as one of the greatest challenges of reconstructive surgery. Fused deposition modelling (FDM) allows for the printing of 3D scaffolds tailored to the morphology and size of bone damage in a patient-specific and high-precision manner. However, FDM still suffers from the lack of materials capable of efficiently supporting osteogenesis. In this study, we developed 3D-printed porous scaffolds composed of polylactic acid/hydroxyapatite (PLA/HA) composites with high ceramic contents (above 20%, w/w) by FDM. The mechanical properties of the PLA/HA scaffolds were compatible with those of trabecular bone. In vitro degradation tests revealed that HA can neutralize the acidification effect caused by PLA degradation, while simultaneously releasing calcium and phosphate ions. Importantly, 3D-printed PLA/HA did not induce the upregulation of activation markers nor the expression of inflammatory cytokines in dendritic cells thus exhibiting no immune-stimulatory properties in vitro. Evaluations using human mesenchymal stem cells (MSC) showed that pure PLA scaffolds exerted an osteoconductive effect, whereas PLA/HA scaffolds efficiently induced osteogenic differentiation of MSC even in the absence of any classical osteogenic stimuli. Our findings indicate that 3D-printed PLA scaffolds loaded with high concentrations of HA are most suitable for future applications in bone tissue engineering.

Challenge Tooth Regeneration in Adult Dogs with Dental Pulp Stem Cells on 3D-Printed Hydroxyapatite/Polylactic Acid Scaffolds.

Tooth regeneration is an important issue. The purpose of this study was to explore the feasibility of using adult dental pulp stem cells on polylactic acid scaffolds for tooth regeneration. Three teeth were extracted from each side of the lower jaws of two adult dogs. In the experimental group, dental pulp stem cells were isolated and seeded in the 3D-printed hydroxyapatite/polylactic acid (HA/PLA) scaffolds for transplantation into left lower jaw of each dog. The right-side jaw of each dog was transplanted with cell-free scaffolds as the control group. Polychrome sequentially labeling was performed for observation of mineralization. Dental cone beam computed tomography (CBCT) irradiation was used for assessment. Nine months after surgery, dogs were euthanized, and the lower jaws of dogs were sectioned and fixed for histological observation with hematoxylin and eosin staining. The results showed that the degree of mineralization in the experimental group with cells seeded in the scaffolds was significantly higher than that of the control group transplanted with cell-free scaffolds. However, the HA/PLA scaffolds were not completely absorbed in both groups. It is concluded that dental pulp stem cells are important for the mineralization of tooth regeneration. A more rapid absorbable material was required for scaffold design for tooth regeneration.

Fabrication and resonance simulation of 3D-printed biocomposite mesoporous implants with different periodic cellular topologies

In order to achieve more efficient additive materials having precise desired porosities with excellent performance, advanced manufacturing techniques can be put to use. In the present study, 3D printing technology is employed to fabricate mesoporous bioceramic-based bony scaffolds made of various periodic cellular topologies including cubic, cylindrical and hexagonal porosity configurations. The samples are composed of polylactic acid-hydroxyapatite (PLA-HA) mesoporous bioceramic-based nanocomposites. Via the respective experiments, the mechanical properties of the fabricated bony scaffolds are extracted corresponding to each porosity configuration with different pore sizes. Moreover, by using the scanning electron microscopy (SEM), X-ray diffraction (XRD) and the permeability characteristics of the fabricated bio-composite samples after soaking in the simulated body fluid (SBF) are captured. Thereafter, based on the experimentally obtained mechanical properties, the multiple time-scales method is utilized to develop an analytical solution for the nonlinear secondary resonance of PLA-HA mesoporous beam-type implants under subharmonic and superharmonic excitations. The frequency-response and amplitude response associated with the both types of hard excitations are depicted corresponding to different periodic cellular topologies and pore sizes. It is observed that among various periodic cellular topologies, the gap between two branches of the subharmonic frequency-response associated with the cubic and hexagonal ones is maximum and minimum, respectively. In the case of superharmonic excitation, it is found that through reduction of the pore size, the peak of frequency-response and its associated value of the detuning parameter decrease.

Evaluation of Drug-Loading Ability of Poly(Lactic Acid)/Hydroxyapatite Core-Shell Particles.

Poly(lactic acid)/hydroxyapatite (PLA/HAp) core–shell particles are prepared using the emulsification method. These particles are safe for living organisms because they are composed of biodegradable polymers and biocompatible ceramics. These particles are approximately 50–100 nm in size, and their hydrophobic substance loading can be controlled. Hence, PLA/HAp core–shell particles are expected to be used as drug delivery carriers for hydrophobic drugs. In this work, PLA/HAp core–shell particles with a loading of vitamin K1 were prepared, and their drug-loading ability was evaluated. The particles were 40–80 nm in diameter with a PLA core and a HAp shell. The particle size increased with an increase in the vitamin K1 loading. The drug-loading capacity (LC) value of the particles, an indicator of their drug-loading ability, was approximately 250%, which is higher than the previously reported values. The amount of vitamin K1 released from the particles increased as the pH of the soaking solution decreased because the HAp shell easily dissolved under the acidic conditions. The PLA/HAp particles prepared in this work were found to be promising candidates for drug delivery carriers because of their excellent drug-loading ability and pH sensitivity.

3D printed bone tissue regenerative PLA/HA scaffolds with comprehensive performance optimizations

Polylactic acid/Hydroxyapatite (PLA/HA) composite was widely studied and applied in the field of biomaterials for its good processability, bioactivity, and mechanical properties. In addition to traditional preparation methods, additive manufacturing has also been adopted to prepare PLA/HA composites with customized geometries. This work combined the comprehensive optimized PLLA (L-polylactic acid)/nano-HA (nHA) composite with the low-cost and stable Fused deposition modeling (FDM) technology to successfully prepare PLLA/nHA porous bone repair scaffolds. The results showed that PLLA/nHA composite ink satisfied the smoothness of printing, and the accuracy also met the requirements of personalized bone repair application. The high loaded nHA scaffold had suitable compressive strength was significantly higher than those of pure HA ceramic scaffold and cancellous bone. Besides, in vitro bone-like apatite formation on the surface in the degradation process and in vivo evaluations further verified its good osteogenic property. Compared with other complex and cutting-edge 3D printing technologies, this study provides a low-cost, stable, simple and fast way to realize personalized printing of bone repair scaffolds, which is undoubtedly conductive to the improvement and rapid deployment of personalized biomaterials in clinical applications.

Effects of electromagnetic fields treatment on rat critical-sized calvarial defects with a 3D-printed composite scaffold

BackgroundCurrent strategies for craniofacial defect are faced with unmet outcome. Combining 3D-printing with safe, noninvasive magnetic therapy could be a promising breakthrough.MethodsIn this study, polylactic acid/hydroxyapatite (PLA/HA) composite scaffold was fabricated. After seeding rat bone marrow mesenchymal stem cells (BMSCs) on scaffolds, the effects of electromagnetic fields (EMF) on the proliferation and osteogenic differentiation capacity of BMSCs were investigated. Additionally, 6-mm critical-sized calvarial defect was created in rats. BMSC-laden scaffolds were implanted into the defects with or without EMF treatment.ResultsOur results showed that PLA/HA composite scaffolds exhibited uniform porous structure, high porosity (~ 70%), suitable compression strength (31.18 ± 4.86 MPa), modulus of elasticity (10.12 ± 1.24 GPa), and excellent cyto-compatibility. The proliferation and osteogenic differentiation capacity of BMSCs cultured on the scaffolds were enhanced with EMF treatment. Mechanistically, EMF exposure functioned partly by activating mitogen-activated protein kinase (MAPK) or MAPK-associated ERK and JNK pathways. In vivo, significantly higher new bone formation and vascularization were observed in groups involving scaffold, BMSCs, and EMF treatment, compared to scaffold alone. Furthermore, after 12 weeks of implanting, craniums in groups including scaffold, BMSCs, and EMF exposure showed the greatest biomechanical properties.ConclusionIn conclusion, EMF treatment combined with 3D-printed scaffold has great potential applications in craniofacial regeneration.

Preparation and characterization of a novel polylactic acid/hydroxyapatite composite scaffold with biomimetic micro-nanofibrous porous structure.

Combining synthetic polymer scaffolds with inorganic bioactive factors is widely used to promote the bioactivity and bone conductivity of bone tissue. However, except for the chemical composition of scaffold, the biomimetic structure also plays an important role in its application. In this study, we report the fabrication of polylactic acid/hydroxyapatite (PLA/HA) composite nanofibrous scaffolds via phase separation method to mimic the native extracellular matrix (ECM). The SEM analysis showed that the addition of HA dramatically impacted the morphology of the PLA matrix, which changed from 3D nanofibrous network structure to a disorderly micro-nanofibrous porous structure. At the same time, HA particles could be evenly dispersed at the end of the fiber. The FTIR and XRD demonstrated that there was not any chemical interaction between PLA and HA. Thermal analyses showed that HA could decrease the crystallization of PLA, but improve the thermal decomposition temperature of the composite scaffold. Moreover, water contact angle analysis of the PLA/HA composite scaffold demonstrated that the hydrophilicity increased with the addition of HA. Furthermore, apatite-formation ability tests confirmed that HA could not only more and faster induced the deposition of weak hydroxyapatite but also induced specific morphology of HA.

On 3D printed scaffolds for orthopedic tissue engineering applications

This paper outlines an in vitro evaluation of 3D printed scaffold of polylactic acid (PLA) blended with hydroxyapatite (HAp) and chitosan (CS) for orthopedic tissue engineering applications. In the first stage, selected composition/proportion of PLA–HAp–CS (based on melt flow-ability, mechanical and thermal properties) was 3D printed with fused deposition modeling (FDM) process. The 3D printed scaffolds were used for process capability analysis to ascertain the industrial usability of PLA–HAp–CS composite scaffold for batch production (especially in assembly applications). Further, in the second stage, an in vitro evaluation was performed to investigate the linkages of fibroblast cells for 3D printed scaffold. The results of study outline the rapid increase in growth of fibroblast cells for FDM-printed scaffolds of PLA–HAp–CS thus ensuring its capability of supporting cell adhesion and cell proliferation. Further, the dimensional variations and Shore D hardness of 3D printed scaffolds are under statistically control, with process capability indices (Cp and Cpk ≥ 1).

Multifactor Optimization for Development of Biocompatible and Biodegradable Feed Stock Filament of Fused Deposition Modeling

In this research work, multifactor optimization for the development of biocompatible and biodegradable composite material-based feed stock filament of fused deposition modeling (FDM) has been reported. The polylactic acid (PLA) has been selected as a polymer matrix with hydroxyapatite (HAp) and chitosan (CS) as filler for potential use in medical applications. The feedstock filament of PLA–HAp–CS can be used directly on FDM open-source 3D printer (without change in any hardware or software of system). The optimization results are supported by mechanical tensile testing, thermal analysis and scanning electron microscope-based photomicrographs. Finally, the feasibility of fabrication of functional prototypes for medical applications by using in-house prepared feedstock filament on the FDM has been ascertained.

Osteolysis is observed around both bioabsorbable and nonabsorbable anchors on serial magnetic resonance images of patients undergoing arthroscopic rotator cuff repair

ObjectivesThe objective of this study was to evaluate the incidence of osteolysis around the bioabsorbable and nonabsorbable anchors using serial magnetic resonance imaging (MRI) and to determine the relationship between osteolysis and the retear rate after arthroscopic rotator cuff repair. MethodsFrom July 2012 to July 2014, 50 patients [28 men and 22 women; mean age, 56.4 (range: 45–56) years] underwent arthroscopic rotator cuff repair for a medium-to large-size tear with double-row suture-bridge technique. The bioabsorbable anchors used in the medial row comprised hydroxyapatite-polylactic acid enantiomer, and the nonabsorbable anchors in the lateral row were polyetheretherketone (PEEK)-type anchors. All patients underwent MRI evaluation at 3, 6, and 12 months postoperatively to determine osteolysis and identify any retear. ResultsThe incidences of osteolysis at 3, 6, and 12 months postoperatively were 1%, 4%, and 6% with nonabsorbable anchors and 13%, 29%, and 39% with bioabsorbable anchors, respectively. The incidences of osteolysis were significantly higher with the bioabsorbable anchors than with the nonabsorbable anchors (P < 0.005 for all three follow-ups). There was no significant difference between osteolysis and non-osteolysis groups regarding the retear rate or retear size (P = 0.189 and 0.069, respectively). ConclusionsOsteolysis was common around bioabsorbable anchors used for arthroscopic rotator cuff repair, and it also occurred around the PEEK-type nonabsorbable anchors. The incidence of osteolysis of nonabsorbable anchors was significantly lower than that of bioabsorbable anchors. Osteolysis did not significantly affect rotator cuff retear after arthroscopic repair with either bioabsorbable or nonabsorbable anchors. Level of evidenceLevel III, Therapeutic Study.

Thermal expansivity and degradation properties of PLA/HA and PLA/βTCP in vitro conditioned composites

The objective of this study was to investigate the thermal expansivities and degradation properties for several in vitro conditioned biodegradable poly(lactic acid)/hydroxyapatite (PLA/HA) and poly(lactic acid)/β-tricalcium phosphate (PLA/βTCP) composites with different mass% of the particle reinforcements (i.e. 10, 20 and 30). The samples were prepared by extrusion followed by injection moulding and incubated in a customized simulated body fluid at 37 °C over 60, 90, 120, 150 and 180 days, respectively. Thermal expansion and degradation properties of in vitro conditioned samples, along with dynamic mechanical properties of unconditioned ones, were systematically investigated through coefficients of linear thermal expansion and thermal strain changes, decomposition temperatures, mass changes and per cent residues. The results indicated that PLA/βTCP composites performed better than PLA/HA composites, irrespective of their filler mass%, revealing high values of glass transition temperatures, around a mean value of 65 °C, both on dynamic mechanical analysis and on dilatation measurements but lower values on their degradation temperatures, such as 360 °C. The results suggest the feasibility of tailoring high-loaded osteoconductive fillers-reinforced PLA composites for various medical and engineering applications.

A porous polymeric-hydroxyapatite scaffold used for femur fractures treatment: fabrication, analysis, and simulation.

One of the most common fractures in the skeleton happens in the femur. One of the important reasons for this fracture is because it is the longest bone in the body and osteoporosis affect this part a lot. The geometric complexity and anisotropy properties of this bone have received a lot of attention in the orthopedic field. In this research, a femur designed using 3D printing machine using the middle part of the hip made of polylactic acid-hydroxyapatite (PLA-HA) nanocomposite containing 0, 5, 10, 15, and 25wt% of ceramic nanoparticle. Three different types of loadings, including centralized loading, full-scale, and partially loaded, were applied to the designed femur bone. The finite element analysis was used to analyze biomechanical components. The results of the analysis showed that it is possible to use the porous scaffold model for replacement in the femur having proper strength and mechanical stability. Stress-strain analysis on femoral implant with biometric HA and PLA after modeling was performed using the finite element method under static conditions in Abaqus software. Three scaffold structures, i.e., mono-, hybrid, and zonal structures, that can be fabricated using current bioprinting techniques are also discussed with respect to scaffold design.