Effect of surface modification of graphene oxide with a reactive silane coupling agent on the mechanical properties and biocompatibility of acrylic bone cements.

Carbon allotrope materials (i.e. carbon nanotubes (CNTs), graphene, graphene oxide (GO)), have been used to reinforce acrylic bone cement. Nevertheless, the intrinsic incompatibility among the above materials produces a deficient interphase. Thus, in this work, the effect of the content of functionalized graphene oxide with a reactive silane on the mechanical properties and cell adhesion of acrylic bone cement was studied. GO was obtained by an oxidative process on natural graphite; subsequently, GO was functionalized with 3-methacryloxypropyltrimethoxysilane (MPS) to enhance the interphase between the graphenic material and acrylic polymeric matrix. Pristine GO and functionalized graphene oxide (GO-MPS) were characterized physicochemically (XPS, XRD, FTIR, and Raman) and morphologically (SEM and TEM). Silanized GO was added into the acrylic bone cement at different concentrations; the resulting materials were characterized mechanically, and their biocompatibility was also evaluated. The physicochemical characterization results showed that graphite was successfully oxidized, and the obtained GO was successfully functionalized with the silane coupling agent (MPS). SEM and TEM images showed that the GO is composed of few stacked layers. Compression testing results indicated a tendency of increasing stiffness and toughness of the acrylic bone cements at low concentration of functionalized GO. Additionally, the bending testing results showed a slightly increase in bone cement strain with the incorporation of GO-MPS. Finally, all samples exhibited cell viability higher than 70%, which means that materials are considered non-cytotoxic, according to the ISO 10993-5 standard.

Temporary arthrodesis through static spacer implantation in two-stage treatment of periprosthetic joint infections of the knee.

OBJECTIVE: Treatment of chronic periprosthetic joint infection of the knee requires the removal of the implant and thorough debridement, with reimplantation in a second stage surgery. Intramedullary spacers can be helpful during the interval between explantation and reimplantation and provide a temporary arthrodesis which fixes the knee in extension preserving leg length and administers local antibiotic therapy. INDICATIONS: Periprosthetic joint infection of the knee with large bony defects and severe infection of the native joint with advanced destruction/infiltration of the cartilage and bone and/or ligament insufficiency. CONTRAINDICATIONS: Suspected antibiotic resistance of the microbiological pathogen to local antibiotic drugs, incompliant patient, and known allergy to bone cement or antibiotic. SURGICAL TECHNIQUE: After implant removal, suitable metal rods are coated with antibiotic-loaded bone cement and inserted into the cleaned intramedullary canals of femur and tibia. Rods are joined at the joint line with a connector and joint space is filled with more bone cement to achieve temporary and very stable arthrodesis. POSTOPERATIVE MANAGEMENT: Partial weight-bearing and no flexion/extension while spacer is in place; second stage reimplantation as soon as infection is controlled. RESULTS: Complications related to the spacer were rare (5.3%). Reimplantation of an implant was possible in 95 of 113 patients (84%), of those, 23 (20%) received an arthrodesis. Of the 95 patients that were reimplanted, 14 showed signs of recurrent infection. Mean time to last follow-up was 15.6 months post reimplantation. Mean knee pain was 2.9/10; overall function was good; 6 patients had an extension lag; mean total range of motion was 88°.

Acrylic bone cement with Tutopatch for frontal sinus obliteration.

OBJECTIVE: To evaluate the use of acrylic bone cement with a Tutopatch collagen implant for frontal sinus obliteration after mucocele excision using a subjective assessment of patient satisfaction. METHODS: Patients with a recurrent frontal sinus mucocele with posterior table erosion, for whom an endoscopic approach was not feasible, and who underwent osteoplastic frontal sinus obliteration, were included. The post-operative outcomes were evaluated using a non-standardised questionnaire, comparing pre- and post-operative scores. RESULTS: All patients expressed post-operative satisfaction. Except for hyposmia, significant improvements were observed in all symptom scores. No major complications were observed during the post-operative course. CONCLUSION: Acrylic bone cement with Tutopatch can be effectively used in frontal sinus reconstruction in cases where an endoscopic approach is not feasible.

Primary stability of cement augmentation in locking plate fixation for proximal humeral fractures: A comparison of absorbable versus non-absorbable cement.

BACKGROUND: Cement augmentation has been suggested to increase the stability of screw anchoring in osteoporotic humeral fractures. Initial results are promising but may be jeopardized by cement leakage into the joint and difficult implant removal. Absorbable cement might have advantages in this regard, but it is unclear if the primary stability of both techniques is equivalent to each other. Therefore, this study aimed to compare its primary stability with that of non-absorbable cement augmentation. METHODS: Nineteen cadaveric humeri with two-part fracture models were treated with locking plate osteosynthesis and cement augmentation using either absorbable calcium phosphate cement (group 1) or polymethylmethacrylate (group 2). Fracture movement, stiffness, failure mode, and ultimate load under cyclic compressive loading were examined and compared between the groups. FINDINGS: The absolute and relative stiffness values in group 1 were significantly smaller than those in group 2 after 50 cycles (group 1: 114 ± 38 N/mm and 94 ± 8% vs. group 2: 188 ± 71 N/mm and 106 ± 9%; p50 = 0.022), 2000 cycles (group 1: 97 ± 34 N/mm and 81 ± 15% vs. group 2: 153 ± 47 N/mm and 88 ± 15%; p2000 = 0.028), and 5000 cycles (group 1: 98 ± 40 N/mm and 81 ± 22% vs. group 2: 158 ± 40 N/mm and 92 ± 16%; p5000 = 0.028). The failure load was not statistically significantly different between the groups. INTERPRETATION: Although the PMAA group showed higher values for absolute and relative stiffness, no statistically significant difference was found in the primary stability between absorbable and non-absorbable cement augmentation supporting plate osteosynthesis in proximal humeral fractures. In view of the potential advantages of bio-absorbable cement during the healing process, its use should be considered for the augmentation and stabilization of osteoporotic fractures.

Preparation of antibacterial acrylic bone cement with methacrylate derived from benzothiazole.

Methacrylate derived from benzothiazole (BTTMA) was incorporated into acrylic bone cement with a series of mass ratio (5 wt%, 10 wt%, and 15 wt%) with the aim to endow antibacterial activity. Properties such as dough time (tdough), setting time (tset), maximum temperature (Tpeak), fluid uptake, water solubility, mechanical properties, and biocompatibility of BTTMA containing bone cements were all investigated. Bone cement without BTTMA was used as control and named as plain cement. The results showed that, after incorporating BTTMA, tdough, flexural modulus, compressive strength of bone cements could be increased, while tset, Tpeak, fluid uptake, water solubility, and flexural strength would be reduced. All of BTTMA containing bone cements did not show hemolytic activity and cell toxicity, but only bone cement with 15 wt% of BTTMA showed antibacterial activity against Staphylococcus aureus (S. aureus).

The Role of Chitosan and Graphene Oxide in Bioactive and Antibacterial Properties of Acrylic Bone Cements.

Acrylic bone cements (ABC) are widely used in orthopedics for joint fixation, antibiotic release, and bone defect filling, among others. However, most commercially available ABCs exhibit a lack of bioactivity and are susceptible to infection after implantation. These disadvantages generate long-term loosening of the prosthesis, high morbidity, and prolonged and expensive treatments. Due to the great importance of acrylic bone cements in orthopedics, the scientific community has advanced several efforts to develop bioactive ABCs with antibacterial activity through several strategies, including the use of biodegradable materials such as chitosan (CS) and nanostructures such as graphene oxide (GO), with promising results. This paper reviews several studies reporting advantages in bioactivity and antibacterial properties after incorporating CS and GO in bone cements. Detailed information on the possible mechanisms by which these fillers confer bioactive and antibacterial properties to cements, resulting in formulations with great potential for use in orthopedics, are also a focus in the manuscript. To the best of our knowledge, this is the first systematic review that presents the improvement in biological properties with CS and GO addition in cements that we believe will contribute to the biomedical field.

Acrylic Bone Cements Modified with Graphene Oxide: Mechanical, Physical, and Antibacterial Properties.

Bacterial infections are a common complication after total joint replacements (TJRs), the treatment of which is usually based on the application of antibiotic-loaded cements; however, owing to the increase in antibiotic-resistant microorganisms, the possibility of studying new antibacterial agents in acrylic bone cements (ABCs) is open. In this study, the antibacterial effect of formulations of ABCs loaded with graphene oxide (GO) between 0 and 0.5 wt.% was evaluated against Gram-positive bacteria: Bacillus cereus and Staphylococcus aureus, and Gram-negative ones: Salmonella enterica and Escherichia coli. It was found that the effect of GO was dependent on the concentration and type of bacteria: GO loadings ≥0.2 wt.% presented total inhibition of Gram-negative bacteria, while GO loadings ≥0.3 wt.% was necessary to achieve the same effect with Gram-positives bacteria. Additionally, the evaluation of some physical and mechanical properties showed that the presence of GO in cement formulations increased wettability by 17%, reduced maximum temperature during polymerization by 19%, increased setting time by 40%, and increased compressive and flexural mechanical properties by up to 17%, all of which are desirable behaviors in ABCs. The formulation of ABC loading with 0.3 wt.% GO showed great potential for use as a bone cement with antibacterial properties.

Acrylic Bone Cement Incorporated with Low Chitosan Loadings.

Despite the potential of acrylic bone cement (ABC) loaded with chitosan (CS) for orthopedic applications, there are only a few in vitro studies of this composite with CS loading ≤ 15 wt.% evaluated in bioactivity tests in simulated body fluid (SBF) for duration > 30 days. The purpose of the present work was to address this shortcoming of the literature. In addition to bioactivity, a wide range of cement properties were determined for composites with CS loading ranging from 0 to 20 wt.%. These properties included maximum exotherm temperature (Tmax), setting time (tset), water contact angle, residual monomer content, flexural strength, bending modulus, glass transition temperature, and water uptake. For cement with CS loading ≥ 15 wt.%, there was an increase in bioactivity, increase in biocompatibility, decrease in Tmax, increase in tset, all of which are desirable trends, but increase in residual monomer content and decrease in each of the mechanical properties, with each of these trends, were undesirable. Thus, a composite with CS loading of 15 wt.% should be further characterized to explore its suitability for use in low-weight-bearing applications, such as bone void filler and balloon kyphoplasty.

Release behavior, mechanical properties, and antibacterial activity of ciprofloxacin-loaded acrylic bone cement: a mechanistic study.

OBJECTIVE: To evaluate the effect of ciprofloxacin concentration and cement geometry on release, mechanical, and antibacterial properties of PMMA bone cement. Significance: Cements are used in different geometries and drug concentrations. These can affect cement strength, drug release behavior, and its antibacterial activity. METHODS: Antibiotic-loaded bone cement (ALBC) containing 2.5, 5.0, and 10.0 wt% ciprofloxacin were prepared as slab, rectangular prism and short cylinder. Drug release and compression strength of the cements were investigated for 28 days at 37 °C. The ALBC efficacies against prevalent bone infection bacteria, S. aureus, E. coli, and P. aeruginosa, were investigated. Drug determination was by HPLC. RESULTS: A two-stage behavior of fast release through dissolution/diffusion (stage A; <96 h) and 2-5 times slower Fickian diffusion (stage B; 96-672 h) was observed. Significant differences for release rate were observed among different geometries in the order of cylinder > prism > slab, in correlation with systems' thickness, indicating lower drug depletion in thicker systems. Release rates were proportional to concentration for 2.5 and 5% systems. At 10.0% loading, however, apparently interconnected channels and higher porosity reduced the diffusional resistance and provided higher release rates than what expected from concentration increment. Growth of Gram-negative bacteria and S. aureus was inhibited at the lowest dose of drug over 1 and 48 h, respectively. ALBCs with 5.0 and 10.0% ciprofloxacin showed decrease of compression strength to below ISO standard. CONCLUSIONS: Different properties of acrylic cements are affected by geometry and drug concentration and should be considered for optimized drug therapy.

Fracture toughness and crack resistance curves of acrylic bone cements.

The fracture toughness KIc of 11 clinically used acrylic bone cements was studied in air at room temperature with single edge V-notched beam specimens. By driving the crack step-wise through the specimens, crack resistance curves ("R-curves") were recorded. One group of bone cements showed an increase of the fracture toughness with increasing crack length (including CMW1+G and several Palacos bone cements) whereas another group (including Simplex, SmartSet, Copal and some Palacos bone cements) did not exhibit an R-curve behavior. The plateau values for KIc ranged from 0.93 MPa√m (Simplex P) to 1.98 MPa√m (Palacos R+G). The observation of the crack growth with an optical microscope revealed some mechanisms influencing the crack growth like the formation of microcracks in the extended damage zone of the crack tip, the attraction of the crack by inclusions or the shielding of the crack tip by bridges in the wake of the crack. Furthermore, bone cements could be distinguished by the pattern of the path the crack followed during propagation. The crack pattern of CMW1+G provides a possible explanation of the distinct R-curve behavior of this cement.

A review of calcium phosphate cements and acrylic bone cements as injectable materials for bone repair and implant fixation.

Treatment of bone defects caused by trauma or disease is a major burden on human healthcare systems. Although autologous bone grafts are considered as the gold standard, they are limited in availability and are associated with post-operative complications. Minimally invasive alternatives using injectable bone cements are currently used in certain clinical procedures, such as vertebroplasty and balloon kyphoplasty. Nevertheless, given the high incidence of fractures and pathologies that result in bone voids, there is an unmet need for injectable materials with desired properties for minimally invasive procedures. This paper provides an overview of the most common injectable bone cement materials for clinical use. The emphasis has been placed on calcium phosphate cements and acrylic bone cements, while enabling the readers to compare the opportunities and challenges for these two classes of bone cements. This paper also briefly reviews antibiotic-loaded bone cements used in bone repair and implant fixation, including their efficacy and cost for healthcare systems. A summary of the current challenges and recommendations for future directions has been brought in the concluding section of this paper.

Novel Bioactive and Antibacterial Acrylic Bone Cement Nanocomposites Modified with Graphene Oxide and Chitosan.

Acrylic bone cements (ABCs) have played a key role in orthopedic surgery mainly in arthroplasties, but their use is increasingly extending to other applications, such as remodeling of cancerous bones, cranioplasties, and vertebroplasties. However, these materials present some limitations related to their inert behavior and the risk of infection after implantation, which leads to a lack of attachment and makes necessary new surgical interventions. In this research, the physicochemical, thermal, mechanical, and biological properties of ABCs modified with chitosan (CS) and graphene oxide (GO) were studied. Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H-NMR) scanning electron microscopy (SEM), Raman mapping, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), compression resistance, mechanical dynamic analysis (DMA), hydrolytic degradation, cell viability, alkaline phosphatase (ALP) activity with human osteoblasts (HOb), and antibacterial activity against Gram-negative bacteria Escherichia coli were used to characterize the ABCs. The results revealed good dispersion of GO nanosheets in the ABCs. GO provided an increase in antibacterial activity, roughness, and flexural behavior, while CS generated porosity, increased the rate of degradation, and decreased compression properties. All ABCs were not cytotoxic and support good cell viability of HOb. The novel formulation of ABCs containing GO and CS simultaneously, increased the thermal stability, flexural modulus, antibacterial behavior, and osteogenic activity, which gives it a high potential for its uses in orthopedic applications.

Bone cement modeling for percutaneous vertebroplasty.

Vertebroplasty procedures provide a significant benefit for patients suffering from vertebral fractures. In order to address current issues of vertebroplasty procedures, an injection device able to control the bone cement viscosity has been developed. In addition, this device allows to protect the practitioner by removing him/her from the X-rays area. In this context, a study is first proposed to quantify the bone cement viscosity during its polymerization reaction on a rotational rheometer. These experimental measurements have led to the identification of a complete behavior law that takes into account the simultaneous effects of shear rate, time, and temperature. Based on this preliminary study, this article finally aims to prove the ability of estimating the viscosity of the flowing bone cement on the developed injection system. A final set of experiments validates that the injection device dedicated to vertebroplasty procedures can control the flowing bone cement viscosity by acting on the temperature. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1504-1515, 2019.

Mechanical Properties and Porosity of Acrylic Cement Bone Loaded with Alendronate Powder.

Aseptic loosening is the most common complication of joint replacement. Previous studies showed that acrylic bone cement loaded with a commercially-available alendronate powder (APAC) had good promise against wear debris-mediated osteolysis for prevention of aseptic loosening. The purpose of the present study was to investigate the effect of adding alendronate powder to an acrylic bone cement on quasi-static mechanical properties (namely, compressive strength, compressive modulus, tensile strength, and flexural strength), fatigue life, porosity, and microstructure of the cement. The results showed that adding up to 1 wt./wt.% alendronate powder exerted no detrimental effect on any of the quasi-static mechanical properties. However, the fatigue life of APAC decreased by between ~17% and ~27 % and its porosity increased by between ~ 5-7 times compared with corresponding values for the control cement (no alendronate powder added). Fatigue life was negatively and significantly correlated with porosity. Considering that fatigue life of the cement plays a significant role in joint replacement survival, clinical use of APAC cannot be recommended.

Effect of polymerizable quaternary ammonium monomer MEIM-x's alkyl chain length and content on bone cement's antibacterial activity and physicochemical properties.

Quaternary ammonium monomers with N-alkyl chain length varied from 6 to 18, namely MEIM-x(x = 6-18), were incorporated into acrylic bone cements to prepare antibacterial bone cements. With the increasing of MEIM-x's alkyl chain length, the MEIM-x monomers' minimum inhibitory concentrations (MIC) decreased to 8 µg/mL and 2 µg/mL (MEIM-14, for E. coli and S. aureus, respectively) at first and then increased. The 50% hemolytic concentrations (HC50) decreased monotonously with the increasing of alkyl chain length. The bone cements contained 2% and 5% of long-chain MEIM-x (x ≥ 10) showed significant antibacterial activity against E. coli and S. aureus, while the bone cements contained short-chain MEIM-x(x < 10) showed a weaker activity. Overall, adding 2% of MEIM-x had acceptable influences on the bone cements' properties in terms of doughing time, setting time, peak temperature, solubility, fluid uptake, compressive strength, flexural strength, flexural modulus, hemolysis and cytotoxicity, but adding 5% of MEIM-x impaired the bone cements' mechanical properties and hemolysis significantly.

Compressive fatigue properties of commercially available standard and low-modulus acrylic bone cements intended for vertebroplasty.

Vertebroplasty (VP) is a minimally invasive surgical procedure commonly used to relieve severe back pain associated with vertebral compression fractures. The poly(methyl methacrylate) bone cement used during this procedure is however presumed to facilitate the occurrence of additional fractures next to the treated vertebrae. A reason for this is believed to be the difference in stiffness between the bone cement and the surrounding trabecular bone. The use of bone cements with lower mechanical properties could therefore reduce the risk of complications post-surgery. While intensive research has been performed on the quasi-static mechanical properties of these cements, there is no data on their long-term mechanical properties. In the present study, the in vitro compressive fatigue performance as well as quasi-static mechanical properties of two commercially available acrylic bone cements - a low-modulus cement (Resilience®) and a standard cement (F20) from the same manufacturer - were determined. The quasi-static mechanical properties of the low-modulus and standard cements after 24 h of setting were in the range of other vertebroplastic cements (σ = 70-75 MPa; E= 1600-1900 MPa). F20 displayed similar mechanical properties over time in 37 °C phosphate buffered saline solution, while the mechanical properties of the Resilience® cement decreased gradually due to an increased porosity in the polymeric matrix. The standard cement exhibited a fatigue limit of approx. 47 MPa, whereas the low-modulus cement showed a fatigue limit of approx. 31 MPa. In summary, the low-modulus bone cement had a lower fatigue limit than the standard cement, as expected. However, this fatigue limit is still substantially higher than the stresses experienced by vertebral trabecular bone.

Synthesis of imidazolium-containing mono-methacrylates as polymerizable antibacterial agents for acrylic bone cements.

With the aim to prepare antibacterial acrylic bone cements, a series of imidazolium-containg mono-methacrylates with N-alkyl chain length varied from 10 to 18 (MEIM-x) were synthesized as polymerizable antibacterial agents through a two-step reaction. The structures of the monomers were confirmed by 1H NMR. Methyl methacrylate in the liquid compoent of cements was partially replaced by MEIM-x to prepare bone cements with 5wt% of MEIM-x. Properties of prepared cements like antibacterial activity, doughing time, curing parameters including maximum temperature (Tmax) and setting time (tset), flexual strength (FS) and modulus (FM), compressive strength (CS) and fluid uptake (FU) in Ringer's solution were investigated. Acrylic bone cement without any MEIM-x was used as control. Compared with the control cement, MEIM-x-containing cements had shorter doughing time, lower Tmax, same or longer tset, and higher FU. Though MEIM-x could endow cements with strong antibacterial activity, it could reduce mechanical properties of bone cements. Therefore, further study should be taken to optimize the content of MEIM-x in cement which could supply sufficient antibacterial activity and maintain mechanical performance.

Development of advanced biantibiotic loaded bone cement spacers for arthroplasty associated infections.

The incidence increase of infections in patients with hip or knee implants with resistant pathogens (mainly some S. coagulase-negative and gram positive bacteria) demands advanced antibiotic loaded formulations. In this paper, we report the design of new biantibiotic acrylic bone cements for in situ delivery. They include a last generation antibiotic (daptomycin or linezolid) in combination with vancomycin and are performed based on a novel modification of the Palacos R® acrylic bone cement, which is based on two components, a liquid (methyl methacrylate) and a solid (polymeric phase). Hence, the solid component of the experimental formulations include 45wt% of microparticles of poly(D,L-lactic-co-glycolic) acid, 55wt% of poly(methyl methacrylate) beads and supplements (10wt-% each) of antibiotics. These formulations provide a selective and excellent control of the local release of antibiotics during a long time period (up to 2 months), avoiding systemic dissemination. The antimicrobial activity of the advanced spacers tested against S. aureus shows that single doses would be enough for the control of the infection. In vitro biocompatibility of cements on human osteoblasts is ensured. This paper is mainly focused on the preparation and characterization of cements and the studies of elution kinetics and bactericidal effects. Developed formulations are proposed as spacers for the treatment of infected arthroplasties, but also, they could be applied in other antibiotic devices to treat relevant bone-related infection diseases.

Morphological and mechanical characterization of composite bone cement containing polymethylmethacrylate matrix functionalized with trimethoxysilyl and bioactive glass.

Medical polymers of biostable nature (e.g. polymethylmetacrylate, PMMA) are widely used in various clinical applications. In this study, novel PMMA-based composite bone cement was prepared. Bioactive glass (BAG) particulate filler (30wt%) was added to enhance potentially the integration of bone to the cement. The polymer matrix was functionalized with trimethoxysilyl to achieve an interfacial bond between the matrix and the fillers of BAG. The amount of trimethoxysilyl in the monomer system varied from 0 to 75wt%. The effects of dry and wet (simulated body fluid, SBF at +37°C for 5 weeks) conditions were investigated. In total, 20 groups of specimens were prepared. The specimens were subjected to a destructive mechanical test in compression. Scanning electron microscopy (SEM) and micro-computed tomography (micro-CT) were used to study the surface and the three-dimensional morphology of the specimens. The results of the study indicated that the addition of trimethoxysilyl groups led to the formation of a hybrid polymer matrix which, in lower amounts (<10wt% of total weight), did not significantly affect the compression properties. However, when the specimens stored in dry and wet conditions were compared, the water sorption increased the compression strength (~5-10MPa per test group). At the same time, the water sorption also caused an evident porous structure formation for the specimens containing BAG and siloxane formation in the hybrid polymer matrix.

The feasibility of producing patient-specific acrylic cranioplasty implants with a low-cost 3D printer.

OBJECT Commercially available, preformed patient-specific cranioplasty implants are anatomically accurate but costly. Acrylic bone cement is a commonly used alternative. However, the manual shaping of the bone cement is difficult and may not lead to a satisfactory implant in some cases. The object of this study was to determine the feasibility of fabricating molds using a commercial low-cost 3D printer for the purpose of producing patient-specific acrylic cranioplasty implants. METHODS Using data from a high-resolution brain CT scan of a patient with a calvarial defect posthemicraniectomy, a skull phantom and a mold were generated with computer software and fabricated with the 3D printer using the fused deposition modeling method. The mold was used as a template to shape the acrylic implant, which was formed via a polymerization reaction. The resulting implant was fitted to the skull phantom and the cranial index of symmetry was determined. RESULTS The skull phantom and mold were successfully fabricated with the 3D printer. The application of acrylic bone cement to the mold was simple and straightforward. The resulting implant did not require further adjustment or drilling prior to being fitted to the skull phantom. The cranial index of symmetry was 96.2% (the cranial index of symmetry is 100% for a perfectly symmetrical skull). CONCLUSIONS This study showed that it is feasible to produce patient-specific acrylic cranioplasty implants with a low-cost 3D printer. Further studies are required to determine applicability in the clinical setting. This promising technique has the potential to bring personalized medicine to more patients around the world.