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O Bostman - One of the best experts on this subject based on the ideXlab platform.
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Tissue restoration after Implantation of polyglycolide polydioxanone polylevolactide and metallic pins in cortical bone an experimental study in rabbits
2010Co-Authors: Harri Pihlajamaki, O Bostman, Sari Salminen, Olli Tynninen, Outi LaitinenAbstract:We performed qualitative and histoquantitative investigations of Tissue restoration after Implanting polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins in the intramedullary canal of rabbit femurs. The effect of bioabsorbable devices on healing of a cortical bone defect was also assessed. The cortical bone defect was created in the right femur of 80 rabbits. Bioabsorbable and metallic pins in 60 and two metallic pins alone were Implanted in 20 intramedullary canals; 80 left femurs served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. At all time points, collagenous connective Tissue, including bone trabeculae, surrounded the Implant at the Tissue–Implant interface, replacing hematopoiesis and fat of the intramedullary canal. The groups did not differ in the area and trabecular bone area fraction of the resulting callus. Residual fragments of PGA and PDS were observed at 24 weeks, and complete degradation occurred within 52 weeks. PGA, PDS, PLLA, and metallic Implants induced a bony and fibrous walling-off response in the intramedullary cavity. No inflammation was observed. Complete Tissue restoration did not occur within the follow-up, even after complete degradation of PGA and PDS, which had shorter degradation times than PLLA. The cortical bone healing effect was not different between bioabsorbable pins and metallic wires. Thus, these polymers had no specific osteostimulatory or osteoinhibitory properties compared to stainless steel. Within the follow-up period, there were no significant differences in biocompatibility between the Implants and no adverse inflammatory foreign-body reactions.
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Tissue response to polyglycolide polydioxanone polylevolactide and metallic pins in cancellous bone an experimental study on rabbits
2006Co-Authors: Harri Pihlajamaki, Sari Salminen, Outi Laitinen, Olli Tynninen, O BostmanAbstract:The purpose of this study was to investigate, qualitatively and histoquantitatively, the Tissue response of rabbit femur cancellous bone to polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins under identical conditions. Eighty knees in 50 rabbits were operated on by inserting bioabsorbable pins (PGA, PDS, or PLLA) together with metallic Kirschner wire in 60, and two metallic Kirschner wires alone in 20 knees, while 20 knees served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. Cancellous bone Tissue response to Implants was studied using histological, histomorphometrical, microradiographical, and oxytetracycline fluorescence methods. Residual fragments of PGA and PDS were seen at 24 weeks. Complete degradation of these polymers had taken place before 52 weeks. No signs of degradation of the PLLA pins were observed within the entire follow-up period. The osteoid formation surfaces at Tissue Implant-interface were statistically larger in all test groups as compared to intact controls. The number of macrophages at Tissue Implant-interfaces increased in all bioabsorbable Implant specimens until 6 weeks, and with PGA until 12 weeks. No differences in the osseous response emerged when comparing groups of bioabsorbable Implants with each other or with stainless steel group. Bioabsorbable pins and metallic Kirschner wires evoked an osteoconductive response in the cancellous bone surrounding Implant, but the response intensity between Implants displayed no differences. This suggests a simple, nonspecific walling-off new-bone front type of response. Consequently, the polymers possessed no specific osteostimulatory or osteoinhibitory properties. Within the follow-up, no significant differences in biocompatibility between the Implants appeared, and no frank inflammatory foreign-body reactions occurred. The small-volume pins obviously did not exceed the local Tissue tolerance and clearing capacity of the bone.
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transmission electron microscopic visualization of the degradation and phagocytosis of a poly l lactide screw in cancellous bone a long term experimental study
2002Co-Authors: Outi Laitinen, Harri Pihlajamaki, Antti Sukura, O BostmanAbstract:The increasing clinical use of biodegradable Implants in orthopedic surgery makes it necessary to determine their long-term behavior in Tissues. In this study, a biodegradable screw made of poly-L-lactide (PLLA) was inserted axially into the right distal femur in 18 rabbits. The degradation and phagocytosis process of PLLA was assessed histologically and by transmission electron microscopy (TEM). The follow-up times were 3 and 4.5 years for groups of nine and eight animals, respectively. Abundant birefringent polymeric material was still present in the center of the Implant channel in all specimens in both follow-up groups. The PLLA material studied appeared to be a biologically relatively inert material, with only sparse reactive cellular activity at the Tissue–Implant boundary. In the TEM specimens, polymeric particles of an average area of 2 μm2 were seen to be located intracellularly within phagocytic cells. The spheric and polygonal particles were membrane-bound and to a great extent filled up each phagocyte. In the 4.5-year specimens, the size of the polymeric particles, measured as area and perimeter, was significantly smaller (p < 0.02) than that of the 3-year specimens. The findings indicate that the ultimate degradation process of PLLA is much longer than it previously was thought to be. Complete degradation probably still would have taken years after the 4.5-year span of this study. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 33–39, 2002
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Tissue Implant interface at an absorbable fracture fixation plug made of polylactide in cancellous bone of distal rabbit femur
1994Co-Authors: Harri Pihlajamaki, O Bostman, M Manninen, Unto Paivarinta, P RokkanenAbstract:The Tissue-Implant interface at a self-reinforced poly-l-lactide (SR-PLLA) expansion plug Implanted in distal rabbit femoral cancellous bone was studied histologically, histomorphometrically, and microradiographically in 35 rabbits during consolidation of a transverse transcondylar osteotomy fixed with the SR-PLLA expansion plug. The absorbable plug for internal fixation of fractures and osteotomies measured 4.5 mm in diameter and 30 mm in length and had an expandable distal locking blade system. The femoral specimens were harvested in groups of 5–10 rabbits after a follow-up time of 3, 6, 12, and 24 weeks. The intact controlateral femur served as a control. Vigorous osteogenic response to the Implant was already observed at 3 weeks postoperatively, and the osteoid surface fraction at 24 weeks was still significantly higher than in the unoperated contralateral femur. Incomplete union of the osteotomy seemed to result in increased fibrous Tissue formation at the Tissue-Implant boundary. No signs of degradation of the SR-PLLA was observed within the entire follow-up period. The number of inflammatory cells at the Tissue-Implant interface was low. Consequently, the short-term biocompatibility of the Implant was deemed acceptable. Clinical application of the expansion plug is being planned.
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the Tissue Implant interface during degradation of absorbable polyglycolide fracture fixation screws in the rabbit femur
1992Co-Authors: O Bostman, M Manninen, Unto Paivarinta, E K Partio, Jarkko Vasenius, A Majola, P RokkanenAbstract:A transverse transcondylar osteotomy of the distal femur was fixed with an axially placed absorbable fracture fixation screw made of polyglycolide (PGA) in 25 rabbits. Changes at the Tissue-Implant interface accompanying degradation of the screw were examined histologically, histomorphometrically, and microradiographically seven, 20, 40, 80, and 250 days after Implantation. At seven days postImplantation, a layer of fibroblasts was seen surrounding the Implant, and new bone formation was discernible in the host Tissues adjacent to this membranous structure. At 20 days postImplantation, the geometry of the screw was still intact and the Tissue-Implant boundary was distinct. The first signs of invasion of vascular granulation Tissue into the Implant were observed 40 days after Implantation, at which time the osteotomies were united. The apparent walling-off response by formation of new trabecular bone outlining the PGA profile continued, with the greatest mean trabecular bone volume fraction at the interface, 23.9%, measured at 40 days. A significant decrease in the new bone volume occurred between 40 and 80 days postImplantation. The intensity of the foreign-body reaction seen was histologically moderate. The giant cell count was highest at 80 days postImplantation, when the migratory activity of phagocytic cells had transported intracellular particulate polymeric debris 400-800 microns away from the original Tissue-Implant boundary. At 250 days postImplantation, no birefringent polymeric material could be seen in the specimens. No contraindications for the clinical application of PGA Implants emerged in this study.
Steven M Van Gaalen - One of the best experts on this subject based on the ideXlab platform.
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comparison of polyetheretherketone versus silicon nitride intervertebral spinal spacers in a caprine model
2019Co-Authors: Roel F M R Kersten, Behdad Pouran, Arthur De Gast, Cumhur F Oner, Albert J. Van De Veen, Harrie Weinans, Gang Wu, Steven M Van GaalenAbstract:Polyetheretherketone (PEEK) is commonly used as a spinal spacer for intervertebral fusion surgery. Unfortunately, PEEK is bioinert and does not effectively osseointegrate into living bone. In contrast, comparable spacers made of silicon nitride (Si3 N4 ) possess a surface nanostructure and chemistry that encourage appositional bone healing. This observational study was designed to compare the outcomes of these two biomaterials when Implanted as spacers in an adult caprine model. Lumbar interbody fusion surgeries were performed at two adjacent levels in eight adult goats using Implants of PEEK and Si3 N4 . At six-months after surgery, the operative and adjacent spinal segments were extracted and measured for bone fusion, bone volume, bone-Implant contact (BIC) and soft-Tissue Implant contact (SIC) ratios, and biodynamic stability. The null hypothesis was that no differences in these parameters would be apparent between the two groups. Fusion was observed in seven of eight Implants in each group with greater bone formation in the Si3 N4 group (52.6%) versus PEEK (27.9%; p = 0.2). There were no significant differences in BIC ratios between PEEK and Si3 N4 , and the biodynamic stability of the two groups was also comparable. The results suggest that Si3 N4 spacers are not inferior to PEEK and they may be more effective in promoting arthrodesis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 688-699, 2019.
Harri Pihlajamaki - One of the best experts on this subject based on the ideXlab platform.
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Tissue restoration after Implantation of polyglycolide polydioxanone polylevolactide and metallic pins in cortical bone an experimental study in rabbits
2010Co-Authors: Harri Pihlajamaki, O Bostman, Sari Salminen, Olli Tynninen, Outi LaitinenAbstract:We performed qualitative and histoquantitative investigations of Tissue restoration after Implanting polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins in the intramedullary canal of rabbit femurs. The effect of bioabsorbable devices on healing of a cortical bone defect was also assessed. The cortical bone defect was created in the right femur of 80 rabbits. Bioabsorbable and metallic pins in 60 and two metallic pins alone were Implanted in 20 intramedullary canals; 80 left femurs served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. At all time points, collagenous connective Tissue, including bone trabeculae, surrounded the Implant at the Tissue–Implant interface, replacing hematopoiesis and fat of the intramedullary canal. The groups did not differ in the area and trabecular bone area fraction of the resulting callus. Residual fragments of PGA and PDS were observed at 24 weeks, and complete degradation occurred within 52 weeks. PGA, PDS, PLLA, and metallic Implants induced a bony and fibrous walling-off response in the intramedullary cavity. No inflammation was observed. Complete Tissue restoration did not occur within the follow-up, even after complete degradation of PGA and PDS, which had shorter degradation times than PLLA. The cortical bone healing effect was not different between bioabsorbable pins and metallic wires. Thus, these polymers had no specific osteostimulatory or osteoinhibitory properties compared to stainless steel. Within the follow-up period, there were no significant differences in biocompatibility between the Implants and no adverse inflammatory foreign-body reactions.
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Tissue response to polyglycolide polydioxanone polylevolactide and metallic pins in cancellous bone an experimental study on rabbits
2006Co-Authors: Harri Pihlajamaki, Sari Salminen, Outi Laitinen, Olli Tynninen, O BostmanAbstract:The purpose of this study was to investigate, qualitatively and histoquantitatively, the Tissue response of rabbit femur cancellous bone to polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins under identical conditions. Eighty knees in 50 rabbits were operated on by inserting bioabsorbable pins (PGA, PDS, or PLLA) together with metallic Kirschner wire in 60, and two metallic Kirschner wires alone in 20 knees, while 20 knees served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. Cancellous bone Tissue response to Implants was studied using histological, histomorphometrical, microradiographical, and oxytetracycline fluorescence methods. Residual fragments of PGA and PDS were seen at 24 weeks. Complete degradation of these polymers had taken place before 52 weeks. No signs of degradation of the PLLA pins were observed within the entire follow-up period. The osteoid formation surfaces at Tissue Implant-interface were statistically larger in all test groups as compared to intact controls. The number of macrophages at Tissue Implant-interfaces increased in all bioabsorbable Implant specimens until 6 weeks, and with PGA until 12 weeks. No differences in the osseous response emerged when comparing groups of bioabsorbable Implants with each other or with stainless steel group. Bioabsorbable pins and metallic Kirschner wires evoked an osteoconductive response in the cancellous bone surrounding Implant, but the response intensity between Implants displayed no differences. This suggests a simple, nonspecific walling-off new-bone front type of response. Consequently, the polymers possessed no specific osteostimulatory or osteoinhibitory properties. Within the follow-up, no significant differences in biocompatibility between the Implants appeared, and no frank inflammatory foreign-body reactions occurred. The small-volume pins obviously did not exceed the local Tissue tolerance and clearing capacity of the bone.
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transmission electron microscopic visualization of the degradation and phagocytosis of a poly l lactide screw in cancellous bone a long term experimental study
2002Co-Authors: Outi Laitinen, Harri Pihlajamaki, Antti Sukura, O BostmanAbstract:The increasing clinical use of biodegradable Implants in orthopedic surgery makes it necessary to determine their long-term behavior in Tissues. In this study, a biodegradable screw made of poly-L-lactide (PLLA) was inserted axially into the right distal femur in 18 rabbits. The degradation and phagocytosis process of PLLA was assessed histologically and by transmission electron microscopy (TEM). The follow-up times were 3 and 4.5 years for groups of nine and eight animals, respectively. Abundant birefringent polymeric material was still present in the center of the Implant channel in all specimens in both follow-up groups. The PLLA material studied appeared to be a biologically relatively inert material, with only sparse reactive cellular activity at the Tissue–Implant boundary. In the TEM specimens, polymeric particles of an average area of 2 μm2 were seen to be located intracellularly within phagocytic cells. The spheric and polygonal particles were membrane-bound and to a great extent filled up each phagocyte. In the 4.5-year specimens, the size of the polymeric particles, measured as area and perimeter, was significantly smaller (p < 0.02) than that of the 3-year specimens. The findings indicate that the ultimate degradation process of PLLA is much longer than it previously was thought to be. Complete degradation probably still would have taken years after the 4.5-year span of this study. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 33–39, 2002
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Tissue Implant interface at an absorbable fracture fixation plug made of polylactide in cancellous bone of distal rabbit femur
1994Co-Authors: Harri Pihlajamaki, O Bostman, M Manninen, Unto Paivarinta, P RokkanenAbstract:The Tissue-Implant interface at a self-reinforced poly-l-lactide (SR-PLLA) expansion plug Implanted in distal rabbit femoral cancellous bone was studied histologically, histomorphometrically, and microradiographically in 35 rabbits during consolidation of a transverse transcondylar osteotomy fixed with the SR-PLLA expansion plug. The absorbable plug for internal fixation of fractures and osteotomies measured 4.5 mm in diameter and 30 mm in length and had an expandable distal locking blade system. The femoral specimens were harvested in groups of 5–10 rabbits after a follow-up time of 3, 6, 12, and 24 weeks. The intact controlateral femur served as a control. Vigorous osteogenic response to the Implant was already observed at 3 weeks postoperatively, and the osteoid surface fraction at 24 weeks was still significantly higher than in the unoperated contralateral femur. Incomplete union of the osteotomy seemed to result in increased fibrous Tissue formation at the Tissue-Implant boundary. No signs of degradation of the SR-PLLA was observed within the entire follow-up period. The number of inflammatory cells at the Tissue-Implant interface was low. Consequently, the short-term biocompatibility of the Implant was deemed acceptable. Clinical application of the expansion plug is being planned.
Outi Laitinen - One of the best experts on this subject based on the ideXlab platform.
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Tissue restoration after Implantation of polyglycolide polydioxanone polylevolactide and metallic pins in cortical bone an experimental study in rabbits
2010Co-Authors: Harri Pihlajamaki, O Bostman, Sari Salminen, Olli Tynninen, Outi LaitinenAbstract:We performed qualitative and histoquantitative investigations of Tissue restoration after Implanting polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins in the intramedullary canal of rabbit femurs. The effect of bioabsorbable devices on healing of a cortical bone defect was also assessed. The cortical bone defect was created in the right femur of 80 rabbits. Bioabsorbable and metallic pins in 60 and two metallic pins alone were Implanted in 20 intramedullary canals; 80 left femurs served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. At all time points, collagenous connective Tissue, including bone trabeculae, surrounded the Implant at the Tissue–Implant interface, replacing hematopoiesis and fat of the intramedullary canal. The groups did not differ in the area and trabecular bone area fraction of the resulting callus. Residual fragments of PGA and PDS were observed at 24 weeks, and complete degradation occurred within 52 weeks. PGA, PDS, PLLA, and metallic Implants induced a bony and fibrous walling-off response in the intramedullary cavity. No inflammation was observed. Complete Tissue restoration did not occur within the follow-up, even after complete degradation of PGA and PDS, which had shorter degradation times than PLLA. The cortical bone healing effect was not different between bioabsorbable pins and metallic wires. Thus, these polymers had no specific osteostimulatory or osteoinhibitory properties compared to stainless steel. Within the follow-up period, there were no significant differences in biocompatibility between the Implants and no adverse inflammatory foreign-body reactions.
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Tissue response to polyglycolide polydioxanone polylevolactide and metallic pins in cancellous bone an experimental study on rabbits
2006Co-Authors: Harri Pihlajamaki, Sari Salminen, Outi Laitinen, Olli Tynninen, O BostmanAbstract:The purpose of this study was to investigate, qualitatively and histoquantitatively, the Tissue response of rabbit femur cancellous bone to polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins under identical conditions. Eighty knees in 50 rabbits were operated on by inserting bioabsorbable pins (PGA, PDS, or PLLA) together with metallic Kirschner wire in 60, and two metallic Kirschner wires alone in 20 knees, while 20 knees served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. Cancellous bone Tissue response to Implants was studied using histological, histomorphometrical, microradiographical, and oxytetracycline fluorescence methods. Residual fragments of PGA and PDS were seen at 24 weeks. Complete degradation of these polymers had taken place before 52 weeks. No signs of degradation of the PLLA pins were observed within the entire follow-up period. The osteoid formation surfaces at Tissue Implant-interface were statistically larger in all test groups as compared to intact controls. The number of macrophages at Tissue Implant-interfaces increased in all bioabsorbable Implant specimens until 6 weeks, and with PGA until 12 weeks. No differences in the osseous response emerged when comparing groups of bioabsorbable Implants with each other or with stainless steel group. Bioabsorbable pins and metallic Kirschner wires evoked an osteoconductive response in the cancellous bone surrounding Implant, but the response intensity between Implants displayed no differences. This suggests a simple, nonspecific walling-off new-bone front type of response. Consequently, the polymers possessed no specific osteostimulatory or osteoinhibitory properties. Within the follow-up, no significant differences in biocompatibility between the Implants appeared, and no frank inflammatory foreign-body reactions occurred. The small-volume pins obviously did not exceed the local Tissue tolerance and clearing capacity of the bone.
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transmission electron microscopic visualization of the degradation and phagocytosis of a poly l lactide screw in cancellous bone a long term experimental study
2002Co-Authors: Outi Laitinen, Harri Pihlajamaki, Antti Sukura, O BostmanAbstract:The increasing clinical use of biodegradable Implants in orthopedic surgery makes it necessary to determine their long-term behavior in Tissues. In this study, a biodegradable screw made of poly-L-lactide (PLLA) was inserted axially into the right distal femur in 18 rabbits. The degradation and phagocytosis process of PLLA was assessed histologically and by transmission electron microscopy (TEM). The follow-up times were 3 and 4.5 years for groups of nine and eight animals, respectively. Abundant birefringent polymeric material was still present in the center of the Implant channel in all specimens in both follow-up groups. The PLLA material studied appeared to be a biologically relatively inert material, with only sparse reactive cellular activity at the Tissue–Implant boundary. In the TEM specimens, polymeric particles of an average area of 2 μm2 were seen to be located intracellularly within phagocytic cells. The spheric and polygonal particles were membrane-bound and to a great extent filled up each phagocyte. In the 4.5-year specimens, the size of the polymeric particles, measured as area and perimeter, was significantly smaller (p < 0.02) than that of the 3-year specimens. The findings indicate that the ultimate degradation process of PLLA is much longer than it previously was thought to be. Complete degradation probably still would have taken years after the 4.5-year span of this study. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 33–39, 2002
Roel F M R Kersten - One of the best experts on this subject based on the ideXlab platform.
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comparison of polyetheretherketone versus silicon nitride intervertebral spinal spacers in a caprine model
2019Co-Authors: Roel F M R Kersten, Behdad Pouran, Arthur De Gast, Cumhur F Oner, Albert J. Van De Veen, Harrie Weinans, Gang Wu, Steven M Van GaalenAbstract:Polyetheretherketone (PEEK) is commonly used as a spinal spacer for intervertebral fusion surgery. Unfortunately, PEEK is bioinert and does not effectively osseointegrate into living bone. In contrast, comparable spacers made of silicon nitride (Si3 N4 ) possess a surface nanostructure and chemistry that encourage appositional bone healing. This observational study was designed to compare the outcomes of these two biomaterials when Implanted as spacers in an adult caprine model. Lumbar interbody fusion surgeries were performed at two adjacent levels in eight adult goats using Implants of PEEK and Si3 N4 . At six-months after surgery, the operative and adjacent spinal segments were extracted and measured for bone fusion, bone volume, bone-Implant contact (BIC) and soft-Tissue Implant contact (SIC) ratios, and biodynamic stability. The null hypothesis was that no differences in these parameters would be apparent between the two groups. Fusion was observed in seven of eight Implants in each group with greater bone formation in the Si3 N4 group (52.6%) versus PEEK (27.9%; p = 0.2). There were no significant differences in BIC ratios between PEEK and Si3 N4 , and the biodynamic stability of the two groups was also comparable. The results suggest that Si3 N4 spacers are not inferior to PEEK and they may be more effective in promoting arthrodesis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 688-699, 2019.