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Michailidis N, Petousis M, Saltas V, Papadakis V, Spiridaki M, Mountakis N, Argyros A, Valsamos J, Nasikas NK, Vidakis N. Investigation of the Effectiveness of Silicon Nitride as a Reinforcement Agent for Polyethylene Terephthalate Glycol in Material Extrusion 3D Printing. Polymers (Basel) 2024; 16:1043. [PMID: 38674964 PMCID: PMC11054951 DOI: 10.3390/polym16081043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 04/07/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Polyethylene terephthalate glycol (PETG) and silicon nitride (Si3N4) were combined to create five composite materials with Si3N4 loadings ranging from 2.0 wt.% to 10.0 wt.%. The goal was to improve the mechanical properties of PETG in material extrusion (MEX) additive manufacturing (AM) and assess the effectiveness of Si3N4 as a reinforcing agent for this particular polymer. The process began with the production of filaments, which were subsequently fed into a 3D printer to create various specimens. The specimens were manufactured according to international standards to ensure their suitability for various tests. The thermal, rheological, mechanical, electrical, and morphological properties of the prepared samples were evaluated. The mechanical performance investigations performed included tensile, flexural, Charpy impact, and microhardness tests. Scanning electron microscopy and energy-dispersive X-ray spectroscopy mapping were performed to investigate the structures and morphologies of the samples, respectively. Among all the composites tested, the PETG/6.0 wt.% Si3N4 showed the greatest improvement in mechanical properties (with a 24.5% increase in tensile strength compared to unfilled PETG polymer), indicating its potential for use in MEX 3D printing when enhanced mechanical performance is required from the PETG polymer.
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Affiliation(s)
- Nikolaos Michailidis
- Physical Metallurgy Laboratory, Mechanical Engineering Department, School of Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (N.M.); (A.A.)
- Centre for Research & Development of Advanced Materials (CERDAM), Centre for Interdisciplinary Research and Innovation, Balkan Centre, Building B’, 10th Km Thessaloniki-Thermi Road, 57001 Thessaloniki, Greece
| | - Markos Petousis
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece; (M.P.); (M.S.); (N.M.); (J.V.)
| | - Vassilis Saltas
- Department of Electronic Engineering, Hellenic Mediterranean University, 73133 Chania, Greece;
| | - Vassilis Papadakis
- Institute of Electronic Structure and Laser of the Foundation for Research and Technology-Hellas (IESL-FORTH)—Hellas, N. Plastira 100m, 70013 Heraklion, Greece;
- Department of Industrial Design and Production Engineering, University of West Attica, 12243 Athens, Greece
| | - Mariza Spiridaki
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece; (M.P.); (M.S.); (N.M.); (J.V.)
| | - Nikolaos Mountakis
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece; (M.P.); (M.S.); (N.M.); (J.V.)
| | - Apostolos Argyros
- Physical Metallurgy Laboratory, Mechanical Engineering Department, School of Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (N.M.); (A.A.)
- Centre for Research & Development of Advanced Materials (CERDAM), Centre for Interdisciplinary Research and Innovation, Balkan Centre, Building B’, 10th Km Thessaloniki-Thermi Road, 57001 Thessaloniki, Greece
| | - John Valsamos
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece; (M.P.); (M.S.); (N.M.); (J.V.)
| | - Nektarios K. Nasikas
- Division of Mathematics and Engineering Sciences, Department of Military Sciences, Hellenic Army Academy, 16673 Vari, Greece;
| | - Nectarios Vidakis
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece; (M.P.); (M.S.); (N.M.); (J.V.)
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Petousis M, Michailidis N, Papadakis VM, Korlos A, Mountakis N, Argyros A, Dimitriou E, Charou C, Moutsopoulou A, Vidakis N. Optimizing the Rheological and Thermomechanical Response of Acrylonitrile Butadiene Styrene/Silicon Nitride Nanocomposites in Material Extrusion Additive Manufacturing. Nanomaterials (Basel) 2023; 13:nano13101588. [PMID: 37242004 DOI: 10.3390/nano13101588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 05/03/2023] [Accepted: 05/06/2023] [Indexed: 05/28/2023]
Abstract
The current research aimed to examine the thermomechanical properties of new nanocomposites in additive manufacturing (AM). Material extrusion (MEX) 3D printing was utilized to evolve acrylonitrile butadiene styrene (ABS) nanocomposites with silicon nitride nano-inclusions. Regarding the mechanical and thermal response, the fabricated 3D-printed samples were subjected to a course of standard tests, in view to evaluate the influence of the Si3N4 nanofiller content in the polymer matrix. The morphology and fractography of the fabricated filaments and samples were examined using scanning electron microscopy and atomic force microscopy. Moreover, Raman and energy dispersive spectroscopy tests were accomplished to evaluate the composition of the matrix polymer and nanomaterials. Silicon nitride nanoparticles were proved to induce a significant mechanical reinforcement in comparison with the polymer matrix without any additives or fillers. The optimal mechanical response was depicted to the grade ABS/Si3N4 4 wt. %. An impressive increase in flexural strength (30.3%) and flexural toughness (47.2%) was found. The results validate that these novel ABS nanocomposites with improved mechanical properties can be promising materials.
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Affiliation(s)
- Markos Petousis
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece
| | - Nikolaos Michailidis
- Physical Metallurgy Laboratory, Mechanical Engineering Department, School of Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Centre for Research & Development of Advanced Materials (CERDAM), Center for Interdisciplinary Research and Innovation, Balkan Centre, Building B', 10th km Thessaloniki-Thermi Road, 57001 Thessaloniki, Greece
| | - Vassilis M Papadakis
- Institute of Electronic Structure and Laser of the Foundation for Research and Technology-Hellas (IESL-FORTH), N. Plastira 100m, 70013 Heraklion, Greece
- Department of Industrial Design and Production Engineering, University of West Attica, 12243 Athens, Greece
| | - Apostolos Korlos
- Department of Industrial Engineering and Management, International Hellenic University, 14th km Thessaloniki-N. Moudania, 57001 Thermi, Greece
| | - Nikolaos Mountakis
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece
| | - Apostolos Argyros
- Physical Metallurgy Laboratory, Mechanical Engineering Department, School of Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Centre for Research & Development of Advanced Materials (CERDAM), Center for Interdisciplinary Research and Innovation, Balkan Centre, Building B', 10th km Thessaloniki-Thermi Road, 57001 Thessaloniki, Greece
| | - Evgenia Dimitriou
- Physical Metallurgy Laboratory, Mechanical Engineering Department, School of Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Centre for Research & Development of Advanced Materials (CERDAM), Center for Interdisciplinary Research and Innovation, Balkan Centre, Building B', 10th km Thessaloniki-Thermi Road, 57001 Thessaloniki, Greece
| | - Chrysa Charou
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece
| | - Amalia Moutsopoulou
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece
| | - Nectarios Vidakis
- Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece
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Kersten RFMR, Öner FC, Arts MP, Mitroiu M, Roes KCB, de Gast A, van Gaalen SM. The SNAP Trial: 2-Year Results of a Double-Blind Multicenter Randomized Controlled Trial of a Silicon Nitride Versus a PEEK Cage in Patients After Lumbar Fusion Surgery. Global Spine J 2022; 12:1687-1695. [PMID: 33406905 PMCID: PMC9609539 DOI: 10.1177/2192568220985472] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
STUDY DESIGN Randomized controlled trial. OBJECTIVES Lumbar interbody fusion with cages is performed to provide vertebral stability, restore alignment, and maintain disc and foraminal height. Polyetheretherketone (PEEK) is commonly used. Silicon nitride (Si3N4) is an alternative material with good osteointegrative properties. This study was designed to assess if Si3N4 cages perform similar to PEEK. METHODS A non-inferiority double-blind multicenter RCT was designed. Patients presenting with chronic low-back pain with or without leg pain were included. Single- or double-level instrumented transforaminal lumbar interbody fusion (TLIF) using an oblique PEEK or Si3N4 cage was performed. The primary outcome was the Roland-Morris Disability Questionnaire (RMDQ). The non-inferiority margin for the RMDQ was 2.6 points on a scale of 24. Secondary outcomes included the Oswestry Disability Questionnaire (ODI), Visual Analogue Scales (VAS), SF-36 Physical Function, patient and surgeon Likert scores, radiographic evaluations for subsidence, segmental motion, and fusion. Follow-up was planned at 3, 6, 12, and 24-months. RESULTS Ninety-two patients were randomized (i.e. 48 to PEEK and 44 to Si3N4). Both groups showed good clinical improvements on the RMDQ scores of up to 5-8 points during follow-up. No statistically significant differences were observed in clinical and radiographic outcomes. Mean operative time and blood loss were statistically significantly higher for the Si3N4 cohort. Although not statistically significant, there was a higher incidence of complications and revisions associated with the Si3N4 cage. CONCLUSIONS There was insufficient evidence to conclude that Si3N4 was non-inferior to PEEK.
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Affiliation(s)
- R. F. M. R. Kersten
- Department of Orthopedics, Clinical
Orthopedic Research Center–midden Nederland (CORC-mN), Diakonessenhuis
Utrecht/Zeist, The Netherlands,Department of Orthopedics, University Medical Center
Utrecht, Utrecht University, The Netherlands,R. F. M. R. Kersten, Department of
Orthopedics, University Medical Center Utrecht, Heidelberglaan 100, 3584CX,
Utrecht, the Netherlands.
| | - F. C. Öner
- Department of Orthopedics, University Medical Center
Utrecht, Utrecht University, The Netherlands
| | - M. P. Arts
- Department of Neurosurgery, Haaglanden Medical Center, the Hague, The Netherlands
| | - M. Mitroiu
- Department of Biostatistics and Research
Support, Clinical Trial Methodology, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, The
Netherlands
| | - K. C. B. Roes
- Department of Health Evidence, Section
Biostatistics, Radboud University Medical Center, Radboud University, The
Netherlands
| | - A. de Gast
- Department of Orthopedics, Clinical
Orthopedic Research Center–midden Nederland (CORC-mN), Diakonessenhuis
Utrecht/Zeist, The Netherlands
| | - S. M. van Gaalen
- Department of Orthopedics, Clinical
Orthopedic Research Center–midden Nederland (CORC-mN), Diakonessenhuis
Utrecht/Zeist, The Netherlands,Spinecenter.Amsterdam, Acibadem
International Medical Center, Amsterdam, the Netherlands
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Gray MT, Davis KP, McEntire BJ, Bal BS, Smith MW. Transforaminal lumbar interbody fusion with a silicon nitride cage demonstrates early radiographic fusion. J Spine Surg 2022; 8:29-43. [PMID: 35441113 PMCID: PMC8990392 DOI: 10.21037/jss-21-115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/14/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Degeneration of the lumbar spine is common in aging adults and reflects a significant morbidity burden in this population. In selected patients that prove unresponsive to non-surgical treatment, posterior lumbar fusion (PLF) surgery, with or without adjunctive transforaminal lumbar interbody fusion (TLIF) can relieve pain and improve function. We describe here the radiographic fusion rates for PLF versus TLIF, using an intervertebral spinal cage made of silicon nitride ceramic (chemical formula Si3N4). METHODS This retrospective cohort analysis enrolled 99 patients from August 2013 to January 2017; 17 had undergone PLF at 24 levels, while 82 had undergone TLIF at 104 levels. All operations were performed by a single surgeon at one institution. Radiographic and clinical outcomes were compared between PLF and TLIF at 2 and 6 weeks and then at 3, 6, 12, and 24 months. RESULTS TLIF patients fused at higher rates compared to PLF at the 3-month (38.5% vs. 8.3%, P=0.006), 6-month (78.7% vs. 35.0%, P<0.001) and 12-month time periods (97.9% vs. 81.3%, P=0.018), with no difference at 24 months (100% vs. 94.4%, P=0.102). Index level segmental motion was significantly less and intervertebral disc height was improved in TLIF over PLF at all follow up intervals. Foraminal height was only greater in early follow up periods (2 weeks, 6 weeks and 3 months). TLIF patients experienced lover rates of PI-LL mismatch which was maintained across long term follow-up. Pelvic tilt was lower following TLIF compared to PLF, with no differences in complication rates between study groups. CONCLUSIONS Our retrospective series demonstrated that TLIF performed with silicon nitride interbody cages led to earlier radiographic fusion, greater restoration of disc and foraminal height, increased segmental rigidity and improved sagittal alignment when compared to PLF alone.
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Affiliation(s)
| | - Kyle P. Davis
- Indiana University School of Medicine, Indianapolis, IN, USA
| | | | - B. Sonny Bal
- SINTX Technologies Corporation, Salt Lake City, UT, USA
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Min SR, Cho MS, Lee SH, Park J, An HD, Kim GU, Yoon YJ, Seo JH, Jang JW, Bae JH, Lee SH, Kang IM. Analysis for DC and RF Characteristics Recessed-Gate GaN MOSFET Using Stacked TiO 2/Si 3N 4 Dual-Layer Insulator. Materials (Basel) 2022; 15:ma15030819. [PMID: 35160771 PMCID: PMC8836490 DOI: 10.3390/ma15030819] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/12/2022] [Accepted: 01/19/2022] [Indexed: 02/04/2023]
Abstract
The self-heating effects (SHEs) on the electrical characteristics of the GaN MOSFETs with a stacked TiO2/Si3N4 dual-layer insulator are investigated by using rigorous TCAD simulations. To accurately analyze them, the GaN MOSFETs with Si3N4 single-layer insulator are conducted to the simulation works together. The stacked TiO2/Si3N4 GaN MOSFET has a maximum on-state current of 743.8 mA/mm, which is the improved value due to the larger oxide capacitance of TiO2/Si3N4 than that of a Si3N4 single-layer insulator. However, the electrical field and current density increased by the stacked TiO2/Si3N4 layers make the device’s temperature higher. That results in the degradation of the device’s performance. We simulated and analyzed the operation mechanisms of the GaN MOSFETs modulated by the SHEs in view of high-power and high-frequency characteristics. The maximum temperature inside the device was increased to 409.89 K by the SHEs. In this case, the stacked TiO2/Si3N4-based GaN MOSFETs had 25%-lower values for both the maximum on-state current and the maximum transconductance compared with the device where SHEs did not occur; Ron increased from 1.41 mΩ·cm2 to 2.56 mΩ·cm2, and the cut-off frequency was reduced by 26% from 5.45 GHz. Although the performance of the stacked TiO2/Si3N4-based GaN MOSFET is degraded by SHEs, it shows superior electrical performance than GaN MOSFETs with Si3N4 single-layer insulator.
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Affiliation(s)
- So-Ra Min
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - Min-Su Cho
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - Sang-Ho Lee
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - Jin Park
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - Hee-Dae An
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - Geon-Uk Kim
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - Young-Jun Yoon
- Korea Multi-Purpose Accelerator Complex, Korea Atomic Energy Research Institute, Gyeongju 38180, Korea;
| | - Jae-Hwa Seo
- Power Semiconductor Research Center, Korea Electrotechnology Research Institute, Changwon 51543, Korea;
| | - Jae-Won Jang
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - Jin-Hyuk Bae
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - Sin-Hyung Lee
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
| | - In-Man Kang
- School of Electronic and Electrical Engineering, Kyungpook National University, Daegu 41566, Korea; (S.-R.M.); (M.-S.C.); (S.-H.L.); (J.P.); (H.-D.A.); (G.-U.K.); (J.-W.J.); (J.-H.B.); (S.-H.L.)
- Correspondence:
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McEntire BJ, Maslin G, Bal BS. Two-year results of a double-blind multicenter randomized controlled non-inferiority trial of polyetheretherketone (PEEK) versus silicon nitride spinal fusion cages in patients with symptomatic degenerative lumbar disc disorders. J Spine Surg 2020; 6:523-540. [PMID: 33102889 DOI: 10.21037/jss-20-588] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background During lumbar spinal fusion, spacer cages are implanted to provide vertebral stability, restore sagittal alignment, and maintain disc and foraminal height. Polyetheretherketone (PEEK) is commonly used by most spine surgeons. Silicon nitride (Si3N4) is a less well-known alternative although it was first used as a spacer in lumbar fusion over 30 years ago. The present study was designed to see if Si3N4 cages would perform similarly to PEEK in a randomized controlled trial. Methods A non-inferiority multicenter 100-patient study was designed where both the observer and patient were blinded. Single- or double-level transforaminal lumbar interbody fusion with pedicle screw fixation using an oblique PEEK or Si3N4 cage was performed. The primary non-inferiority outcome was the Roland-Morris Disability Questionnaire (RMDQ). Secondary measures included the Oswestry Disability Questionnaire, Visual Analogue Scales (VAS) for back and leg pain, SF-36 Physical and Mental Function indices, patient and surgeon Likert scores on perceived recovery, and X-ray and CT radiological evaluations for subsidence, segmental motion, and fusion. Follow-up evaluations occurred at 3, 6, 12, and 24 months. Results After exclusions for protocol violations and canceled surgeries, 92 patients were randomized (i.e., 48 for PEEK and 44 for Si3N4). There were no differences in baseline demographics, pre-operative disabilities, or pain scores between the groups. Both treatment arms showed significant improvements in disability, pain, and recovery scores. No significant differences were observed for subsidence, segmental motion, or fusion. For the primary outcome (i.e., RMDQ scores), the non-inferiority of Si3N4 compared to PEEK could not be established using the original protocol criteria. However, the comparison was undermined by larger than anticipated patient fallout coupled with higher than expected RMDQ score standard deviations. A post hoc analysis coupled with a more extensive review of the literature was conducted which resulted in the selection of a revised clinically justified non-inferiority margin; and using this method, the non-inferiority of Si3N4 was affirmed. Conclusions This study demonstrated that the use of either PEEK or Si3N4 cages is safe and effective for patients undergoing lumbar spine fusion for chronic degenerative disc disease.
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Affiliation(s)
| | - Greg Maslin
- Biomedical Statistical Consulting, Wynnewood, PA, USA
| | - B Sonny Bal
- SINTX Technologies, Inc., Salt Lake City, UT, USA
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Calvert GC, VanBuren Huffmon G, Rambo WM, Smith MW, McEntire BJ, Bal BS. Clinical outcomes for lumbar fusion using silicon nitride versus other biomaterials. J Spine Surg 2020; 6:33-48. [PMID: 32309644 PMCID: PMC7154368 DOI: 10.21037/jss.2019.12.11] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 11/12/2019] [Indexed: 12/18/2022]
Abstract
BACKGROUND In lumbar fusion surgery, intervertebral spacer cages made of silicon nitride (Si3N4) ceramic are an available option among other biomaterials. While the surface chemistry of Si3N4 is known to favor bone fusion, large-scale clinical studies attesting to its efficacy are lacking. This multicenter retrospective study compared lumbar fusion outcomes for Si3N4 cages to previously reported data for other cage materials. METHODS Pre-operative patient demographics, comorbidities, changes in visual analog scale (ΔVAS) pain scores, complications, adverse events, and secondary surgical interventions (SSI) were compiled from the records of 450 patients who underwent Si3N4 lumbar spinal fusion at four separate U.S. surgical centers. For comparison, MEDLINE/PubMed and Google Scholar searches identified studies reporting similar outcomes for other biomaterials. A total of 1,025 patients from 26 cohorts reported in 14 publications met inclusion criteria for this control group. RESULTS Overall, the mean last-follow-up for all patients was 341±293 days (11.4±9.8 months), with the longest follow-up being 6.4 years. Patients with Si3N4 implants were similar in gender and age distribution to the control group but had higher BMI values (30.9±6.1 vs. 25.8±4.1, P<0.01) and lower tobacco use (15.8% vs. 30.0%, P<0.01). Both the Si3N4 and control groups showed significant improvements in VAS pain scores from preoperative to last follow-up. For the Si3N4 group, ΔVAS was 36.8±35.4 points compared to 37.6±22.5 points (P=0.63) for the metadata group. Complications and reoperations for the Si3N4 and the control groups were similar (i.e., 9.8% and 3.1% versus 12.4% and 2.9%, P=0.16 and P=0.84, respectively). CONCLUSIONS Lumbar fusion with Si3N4 spacers compared favorably with the improvements reported with other commonly used biomaterial cages.
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