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Masayuki Kyomoto - One of the best experts on this subject based on the ideXlab platform.
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clinical safety and wear resistance of the phospholipid polymer grafted highly cross linked Polyethylene liner
2017Co-Authors: Toru Moro, Takashige Umeyama, Yoshio Takatori, Kazuhiko Ishihara, Sakae Tanaka, Hiromi Oda, Yoon Taek Kim, Eisei Fukatani, Hideya Ito, Masayuki KyomotoAbstract:To reduce the production of wear particles and subsequent aseptic loosening, we created a human articular cartilage-mimicked surface for a highly Cross-Linked Polyethylene liner, whose surface grafted layer consisted of a biocompatible phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine). Although our previous in vitro findings showed that poly(2-methacryloyloxyethyl phosphorylcholine)-grafted particles were biologically inert and caused no subsequent bone resorptive responses, and poly(2-methacryloyloxyethyl phosphorylcholine) grafting markedly decreased wear in hip joint simulator tests, the clinical safety, and in vivo wear resistance of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners remained open to question. Therefore, in the present study, we evaluated clinical and radiographic outcomes of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners 5 years subsequent to total hip replacement in 68 consecutive patients. No reoperation was required for any reason, and no adverse events were associated with the implanted liners. The average Harris Hip Score increased from 38.6 preoperatively to 96.5 5 years postoperatively, and health-related quality of life, as indicated by the Short Form 36 Health Survey, improved. Radiographic analyses showed no periprosthetic osteolysis or implant migration. Between 1 and 5 years postoperatively, the mean steady-state wear rate was 0.002 mm/year, which represented a marked reduction relative to other highly Cross-Linked Polyethylene liners, and appeared to be unaffected by patient-related or surgical factors. Although longer follow up is required, poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners improved mid-term clinical outcomes. The clinical safety and wear-resistance results are encouraging with respect to the improvement of long-term clinical outcomes with poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2007–2016, 2017.
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effects of material thickness and surface modification of cross linked Polyethylene with poly 2 methacryloyloxyethyl phosphorylcholine on its deformation behavior wear resistance and durability under repetitive impact to sliding motion
2017Co-Authors: Kenichi Saiga, Masayuki Kyomoto, Yoshio Takatori, Kenichi Watanabe, Shuji Taketomi, Yuho Kadono, Sakae TanakaAbstract:Abstract 1 Background Large femoral heads and thin Cross-Linked Polyethylene (CLPE) acetabular liners are required for preventing dislocation in total hip arthroplasty (THA). However, the wear resistance and durability of thin CLPE liners in severe physiological conditions has not been fully understood. Methods In this study, we investigated the wear and fatigue properties of untreated CLPE (50 kGy gamma-ray irradiated and annealed) and poly(2-methacryloyloxyethyl phosphorylcholine)-grafted CLPE (PMPC-grafted CLPE) disks that were 3 mm and 6 mm in thickness and subjected to a repetitive impact-to-wear test using a pin-on-disk testing machine. Results PMPC grafting reduced the gravimetric wear of 3 mm and 6 mm thick CLPE disks, but did not affect volumetric changes at the impact area. However, the volumetric change for 6 mm thick PMPC-grafted CLPE disks in areas subjected to high pressure was significantly less than that for CLPE. The thickness of CLPE did not affect its gravimetric wear, whereas volumetric changes at both bearing and backside surfaces of 3 mm thick disks were significantly larger than those of 6 mm thick disks. The results of finite element analysis indicated that the maximum von Mises stress of 3 mm thick CLPE disks near the backside hole was greater than its yield stress, which resulted in cold flow. Delamination and fracture did not occur for any disks. Discussion Under impact-to-wear conditions, PMPC grafting and CLPE substrate with sufficient thickness brought wear and fatigue resistance; those are favorable candidates for bearing material under the severe physiological conditions present in reconstructed hip joints.
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a hydrated phospholipid polymer grafted layer prevents lipid related oxidative degradation of cross linked Polyethylene
2017Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Kazuhiko IshiharaAbstract:The surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve resistance against oxidative degradation in the construction of hip joint replacements. In this study, we aimed to evaluate the oxidative degradation caused by lipid absorption of a highly hydrophilic nanometer-scaled thickness layer prepared by grafting a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer and a high-dose gamma-ray irradiated CLPE with vitamin E blending (HD-CLPE[VE]). The HD-CLPE(VE) and PMPC-grafted HD-CLPE(VE) exhibited extremely high oxidation resistance regardless of lipid absorption, even though residual-free radical levels were detectable. The water wettability of the PMPC-grafted CLPE and PMPC-grafted HD-CLPE(VE) surfaces was considerably greater than that of untreated surfaces. The hydrated PMPC-grafted layer also exhibited extremely low solubility for squalene. Lipids such as squalene and cholesterol esters diminished the oxidation resistance of CLPE despite the vitamin E improvement. Notably, the PMPC-grafted surface was resistant to lipid absorption and diffusion as well as subsequent lipid-related oxidative degradation, likely because of the presence of the hydrated PMPC-grafted layer. Together, these results provide preliminary evidence that the resistance against lipid absorption and diffusion of a hydrated PMPC-grafted layer might positively affect the extent of resistance to the in vivo oxidation of orthopedic implants.
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prevention of bacterial adhesion and biofilm formation on a vitamin e blended cross linked Polyethylene surface with a poly 2 methacryloyloxyethyl phosphorylcholine layer
2015Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Takeo Shobuike, Hiroshi Miyamoto, Kazuhiko IshiharaAbstract:Abstract In the construction of artificial hip joint replacements, the surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve high wear resistance and prevent infection by bacteria. In this study, we fabricated a highly hydrophilic and antibiofouling poly(2-methacryloyloxyethyl phosphorylcholine [MPC]) (PMPC)-graft layer on the vitamin E-blended CLPE (HD-CLPE(VE)) surface. The 100-nm-thick, smooth, and electrically neutral PMPC layer was successfully fabricated on the HD-CLPE(VE) surface using photoinduced graft polymerization. The PMPC-grafted HD-CLPE(VE) was found to prevent bacterial adherence and biofilm formation on the surface because of the formation of a highly hydrophilic polyzwitterionic layer on the surface of HD-CLPE(VE), which can serve as an extremely efficient antibiofouling layer. The number of bacterial adhered on the PMPC-grafted HD-CLPE(VE) surface was reduced by 100-fold or more by PMPC grafting, regardless of the biofilm-production characteristics of the strains. In contrast, vitamin E blending did not affect bacterial adhesion. Moreover, the number of planktonic bacteria did not differ significantly, regardless of PMPC grafting and vitamin E blending. In conclusion, the PMPC-grafted HD-CLPE(VE) provided bacteriostatic effects associated with smooth, highly hydrophilic surfaces with a neutral electrostatic charge owing to the zwitterionic structure of the MPC unit. Thus, this modification may prove useful for the production of artificial hip joint replacement materials. Statement of Significance Our preliminary in vitro findings suggest that improved bacteriostatic performance of the HD-CLPE(VE) surface in orthopedic implants is possible via PMPC grafting. The results also indicate that surface modifications affect the anti-infection properties of the orthopedic implants and demonstrate that the application of a PMPC-grafted HD-CLPE(VE) surface may be a promising approach to extend the longevity and clinical outcomes of total hip arthroplasty. Further research is needed to evaluate the resistance to infection of PMPC-grafted HD-CLPE(VE) in terms of the varieties of biofilm formation tests including fluid flow conditions and animal experiments, which may offer useful clues to the possible performance of these materials in vivo .
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clinical and radiographic outcomes of total hip replacement with poly 2 methacryloyloxyethyl phosphorylcholine grafted highly cross linked Polyethylene liners three year results of a prospective consecutive series
2015Co-Authors: Yoshio Takatori, Takashige Umeyama, Hiroshi Kawaguchi, Masayuki Kyomoto, Toru Moro, Kazuhiko Ishihara, Masashi Kamogawa, Takeyuki Tanaka, Sakae TanakaAbstract:AbstractObjectives. This study aimed to evaluate the clinical safety and wear-resistance of the novel highly Cross-Linked Polyethylene (HXLPE) acetabular liner with surface grafting of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) at 3 years after total hip replacement (THR).Methods. Eighty consecutive patients underwent cementless THR using a 26-mm diameter cobalt–chromium–molybdenum alloy femoral head and a PMPC-grafted HXLPE liner for the bearing couplings. We evaluated the clinical and radiographic outcomes of 76 patients at 3 years after the index surgery.Results. The clinical results at 3 years were equivalent to a Harris hip score of 95.6 points. No adverse events were associated with the implanted PMPC-grafted HXLPE liner, and no periprosthetic osteolysis was detected. The mean femoral head penetration rate was 0.002 mm/year, representing marked reduction compared with other HXLPE liners.Conclusions. A PMPC-grafted HXLPE liner is a safe option in THR and probably reduces the generation of ...
Yoshio Takatori - One of the best experts on this subject based on the ideXlab platform.
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clinical safety and wear resistance of the phospholipid polymer grafted highly cross linked Polyethylene liner
2017Co-Authors: Toru Moro, Takashige Umeyama, Yoshio Takatori, Kazuhiko Ishihara, Sakae Tanaka, Hiromi Oda, Yoon Taek Kim, Eisei Fukatani, Hideya Ito, Masayuki KyomotoAbstract:To reduce the production of wear particles and subsequent aseptic loosening, we created a human articular cartilage-mimicked surface for a highly Cross-Linked Polyethylene liner, whose surface grafted layer consisted of a biocompatible phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine). Although our previous in vitro findings showed that poly(2-methacryloyloxyethyl phosphorylcholine)-grafted particles were biologically inert and caused no subsequent bone resorptive responses, and poly(2-methacryloyloxyethyl phosphorylcholine) grafting markedly decreased wear in hip joint simulator tests, the clinical safety, and in vivo wear resistance of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners remained open to question. Therefore, in the present study, we evaluated clinical and radiographic outcomes of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners 5 years subsequent to total hip replacement in 68 consecutive patients. No reoperation was required for any reason, and no adverse events were associated with the implanted liners. The average Harris Hip Score increased from 38.6 preoperatively to 96.5 5 years postoperatively, and health-related quality of life, as indicated by the Short Form 36 Health Survey, improved. Radiographic analyses showed no periprosthetic osteolysis or implant migration. Between 1 and 5 years postoperatively, the mean steady-state wear rate was 0.002 mm/year, which represented a marked reduction relative to other highly Cross-Linked Polyethylene liners, and appeared to be unaffected by patient-related or surgical factors. Although longer follow up is required, poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners improved mid-term clinical outcomes. The clinical safety and wear-resistance results are encouraging with respect to the improvement of long-term clinical outcomes with poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2007–2016, 2017.
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effects of material thickness and surface modification of cross linked Polyethylene with poly 2 methacryloyloxyethyl phosphorylcholine on its deformation behavior wear resistance and durability under repetitive impact to sliding motion
2017Co-Authors: Kenichi Saiga, Masayuki Kyomoto, Yoshio Takatori, Kenichi Watanabe, Shuji Taketomi, Yuho Kadono, Sakae TanakaAbstract:Abstract 1 Background Large femoral heads and thin Cross-Linked Polyethylene (CLPE) acetabular liners are required for preventing dislocation in total hip arthroplasty (THA). However, the wear resistance and durability of thin CLPE liners in severe physiological conditions has not been fully understood. Methods In this study, we investigated the wear and fatigue properties of untreated CLPE (50 kGy gamma-ray irradiated and annealed) and poly(2-methacryloyloxyethyl phosphorylcholine)-grafted CLPE (PMPC-grafted CLPE) disks that were 3 mm and 6 mm in thickness and subjected to a repetitive impact-to-wear test using a pin-on-disk testing machine. Results PMPC grafting reduced the gravimetric wear of 3 mm and 6 mm thick CLPE disks, but did not affect volumetric changes at the impact area. However, the volumetric change for 6 mm thick PMPC-grafted CLPE disks in areas subjected to high pressure was significantly less than that for CLPE. The thickness of CLPE did not affect its gravimetric wear, whereas volumetric changes at both bearing and backside surfaces of 3 mm thick disks were significantly larger than those of 6 mm thick disks. The results of finite element analysis indicated that the maximum von Mises stress of 3 mm thick CLPE disks near the backside hole was greater than its yield stress, which resulted in cold flow. Delamination and fracture did not occur for any disks. Discussion Under impact-to-wear conditions, PMPC grafting and CLPE substrate with sufficient thickness brought wear and fatigue resistance; those are favorable candidates for bearing material under the severe physiological conditions present in reconstructed hip joints.
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a hydrated phospholipid polymer grafted layer prevents lipid related oxidative degradation of cross linked Polyethylene
2017Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Kazuhiko IshiharaAbstract:The surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve resistance against oxidative degradation in the construction of hip joint replacements. In this study, we aimed to evaluate the oxidative degradation caused by lipid absorption of a highly hydrophilic nanometer-scaled thickness layer prepared by grafting a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer and a high-dose gamma-ray irradiated CLPE with vitamin E blending (HD-CLPE[VE]). The HD-CLPE(VE) and PMPC-grafted HD-CLPE(VE) exhibited extremely high oxidation resistance regardless of lipid absorption, even though residual-free radical levels were detectable. The water wettability of the PMPC-grafted CLPE and PMPC-grafted HD-CLPE(VE) surfaces was considerably greater than that of untreated surfaces. The hydrated PMPC-grafted layer also exhibited extremely low solubility for squalene. Lipids such as squalene and cholesterol esters diminished the oxidation resistance of CLPE despite the vitamin E improvement. Notably, the PMPC-grafted surface was resistant to lipid absorption and diffusion as well as subsequent lipid-related oxidative degradation, likely because of the presence of the hydrated PMPC-grafted layer. Together, these results provide preliminary evidence that the resistance against lipid absorption and diffusion of a hydrated PMPC-grafted layer might positively affect the extent of resistance to the in vivo oxidation of orthopedic implants.
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prevention of bacterial adhesion and biofilm formation on a vitamin e blended cross linked Polyethylene surface with a poly 2 methacryloyloxyethyl phosphorylcholine layer
2015Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Takeo Shobuike, Hiroshi Miyamoto, Kazuhiko IshiharaAbstract:Abstract In the construction of artificial hip joint replacements, the surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve high wear resistance and prevent infection by bacteria. In this study, we fabricated a highly hydrophilic and antibiofouling poly(2-methacryloyloxyethyl phosphorylcholine [MPC]) (PMPC)-graft layer on the vitamin E-blended CLPE (HD-CLPE(VE)) surface. The 100-nm-thick, smooth, and electrically neutral PMPC layer was successfully fabricated on the HD-CLPE(VE) surface using photoinduced graft polymerization. The PMPC-grafted HD-CLPE(VE) was found to prevent bacterial adherence and biofilm formation on the surface because of the formation of a highly hydrophilic polyzwitterionic layer on the surface of HD-CLPE(VE), which can serve as an extremely efficient antibiofouling layer. The number of bacterial adhered on the PMPC-grafted HD-CLPE(VE) surface was reduced by 100-fold or more by PMPC grafting, regardless of the biofilm-production characteristics of the strains. In contrast, vitamin E blending did not affect bacterial adhesion. Moreover, the number of planktonic bacteria did not differ significantly, regardless of PMPC grafting and vitamin E blending. In conclusion, the PMPC-grafted HD-CLPE(VE) provided bacteriostatic effects associated with smooth, highly hydrophilic surfaces with a neutral electrostatic charge owing to the zwitterionic structure of the MPC unit. Thus, this modification may prove useful for the production of artificial hip joint replacement materials. Statement of Significance Our preliminary in vitro findings suggest that improved bacteriostatic performance of the HD-CLPE(VE) surface in orthopedic implants is possible via PMPC grafting. The results also indicate that surface modifications affect the anti-infection properties of the orthopedic implants and demonstrate that the application of a PMPC-grafted HD-CLPE(VE) surface may be a promising approach to extend the longevity and clinical outcomes of total hip arthroplasty. Further research is needed to evaluate the resistance to infection of PMPC-grafted HD-CLPE(VE) in terms of the varieties of biofilm formation tests including fluid flow conditions and animal experiments, which may offer useful clues to the possible performance of these materials in vivo .
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clinical and radiographic outcomes of total hip replacement with poly 2 methacryloyloxyethyl phosphorylcholine grafted highly cross linked Polyethylene liners three year results of a prospective consecutive series
2015Co-Authors: Yoshio Takatori, Takashige Umeyama, Hiroshi Kawaguchi, Masayuki Kyomoto, Toru Moro, Kazuhiko Ishihara, Masashi Kamogawa, Takeyuki Tanaka, Sakae TanakaAbstract:AbstractObjectives. This study aimed to evaluate the clinical safety and wear-resistance of the novel highly Cross-Linked Polyethylene (HXLPE) acetabular liner with surface grafting of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) at 3 years after total hip replacement (THR).Methods. Eighty consecutive patients underwent cementless THR using a 26-mm diameter cobalt–chromium–molybdenum alloy femoral head and a PMPC-grafted HXLPE liner for the bearing couplings. We evaluated the clinical and radiographic outcomes of 76 patients at 3 years after the index surgery.Results. The clinical results at 3 years were equivalent to a Harris hip score of 95.6 points. No adverse events were associated with the implanted PMPC-grafted HXLPE liner, and no periprosthetic osteolysis was detected. The mean femoral head penetration rate was 0.002 mm/year, representing marked reduction compared with other HXLPE liners.Conclusions. A PMPC-grafted HXLPE liner is a safe option in THR and probably reduces the generation of ...
Kazuhiko Ishihara - One of the best experts on this subject based on the ideXlab platform.
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clinical safety and wear resistance of the phospholipid polymer grafted highly cross linked Polyethylene liner
2017Co-Authors: Toru Moro, Takashige Umeyama, Yoshio Takatori, Kazuhiko Ishihara, Sakae Tanaka, Hiromi Oda, Yoon Taek Kim, Eisei Fukatani, Hideya Ito, Masayuki KyomotoAbstract:To reduce the production of wear particles and subsequent aseptic loosening, we created a human articular cartilage-mimicked surface for a highly Cross-Linked Polyethylene liner, whose surface grafted layer consisted of a biocompatible phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine). Although our previous in vitro findings showed that poly(2-methacryloyloxyethyl phosphorylcholine)-grafted particles were biologically inert and caused no subsequent bone resorptive responses, and poly(2-methacryloyloxyethyl phosphorylcholine) grafting markedly decreased wear in hip joint simulator tests, the clinical safety, and in vivo wear resistance of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners remained open to question. Therefore, in the present study, we evaluated clinical and radiographic outcomes of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners 5 years subsequent to total hip replacement in 68 consecutive patients. No reoperation was required for any reason, and no adverse events were associated with the implanted liners. The average Harris Hip Score increased from 38.6 preoperatively to 96.5 5 years postoperatively, and health-related quality of life, as indicated by the Short Form 36 Health Survey, improved. Radiographic analyses showed no periprosthetic osteolysis or implant migration. Between 1 and 5 years postoperatively, the mean steady-state wear rate was 0.002 mm/year, which represented a marked reduction relative to other highly Cross-Linked Polyethylene liners, and appeared to be unaffected by patient-related or surgical factors. Although longer follow up is required, poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners improved mid-term clinical outcomes. The clinical safety and wear-resistance results are encouraging with respect to the improvement of long-term clinical outcomes with poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2007–2016, 2017.
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a hydrated phospholipid polymer grafted layer prevents lipid related oxidative degradation of cross linked Polyethylene
2017Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Kazuhiko IshiharaAbstract:The surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve resistance against oxidative degradation in the construction of hip joint replacements. In this study, we aimed to evaluate the oxidative degradation caused by lipid absorption of a highly hydrophilic nanometer-scaled thickness layer prepared by grafting a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer and a high-dose gamma-ray irradiated CLPE with vitamin E blending (HD-CLPE[VE]). The HD-CLPE(VE) and PMPC-grafted HD-CLPE(VE) exhibited extremely high oxidation resistance regardless of lipid absorption, even though residual-free radical levels were detectable. The water wettability of the PMPC-grafted CLPE and PMPC-grafted HD-CLPE(VE) surfaces was considerably greater than that of untreated surfaces. The hydrated PMPC-grafted layer also exhibited extremely low solubility for squalene. Lipids such as squalene and cholesterol esters diminished the oxidation resistance of CLPE despite the vitamin E improvement. Notably, the PMPC-grafted surface was resistant to lipid absorption and diffusion as well as subsequent lipid-related oxidative degradation, likely because of the presence of the hydrated PMPC-grafted layer. Together, these results provide preliminary evidence that the resistance against lipid absorption and diffusion of a hydrated PMPC-grafted layer might positively affect the extent of resistance to the in vivo oxidation of orthopedic implants.
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prevention of bacterial adhesion and biofilm formation on a vitamin e blended cross linked Polyethylene surface with a poly 2 methacryloyloxyethyl phosphorylcholine layer
2015Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Takeo Shobuike, Hiroshi Miyamoto, Kazuhiko IshiharaAbstract:Abstract In the construction of artificial hip joint replacements, the surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve high wear resistance and prevent infection by bacteria. In this study, we fabricated a highly hydrophilic and antibiofouling poly(2-methacryloyloxyethyl phosphorylcholine [MPC]) (PMPC)-graft layer on the vitamin E-blended CLPE (HD-CLPE(VE)) surface. The 100-nm-thick, smooth, and electrically neutral PMPC layer was successfully fabricated on the HD-CLPE(VE) surface using photoinduced graft polymerization. The PMPC-grafted HD-CLPE(VE) was found to prevent bacterial adherence and biofilm formation on the surface because of the formation of a highly hydrophilic polyzwitterionic layer on the surface of HD-CLPE(VE), which can serve as an extremely efficient antibiofouling layer. The number of bacterial adhered on the PMPC-grafted HD-CLPE(VE) surface was reduced by 100-fold or more by PMPC grafting, regardless of the biofilm-production characteristics of the strains. In contrast, vitamin E blending did not affect bacterial adhesion. Moreover, the number of planktonic bacteria did not differ significantly, regardless of PMPC grafting and vitamin E blending. In conclusion, the PMPC-grafted HD-CLPE(VE) provided bacteriostatic effects associated with smooth, highly hydrophilic surfaces with a neutral electrostatic charge owing to the zwitterionic structure of the MPC unit. Thus, this modification may prove useful for the production of artificial hip joint replacement materials. Statement of Significance Our preliminary in vitro findings suggest that improved bacteriostatic performance of the HD-CLPE(VE) surface in orthopedic implants is possible via PMPC grafting. The results also indicate that surface modifications affect the anti-infection properties of the orthopedic implants and demonstrate that the application of a PMPC-grafted HD-CLPE(VE) surface may be a promising approach to extend the longevity and clinical outcomes of total hip arthroplasty. Further research is needed to evaluate the resistance to infection of PMPC-grafted HD-CLPE(VE) in terms of the varieties of biofilm formation tests including fluid flow conditions and animal experiments, which may offer useful clues to the possible performance of these materials in vivo .
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clinical and radiographic outcomes of total hip replacement with poly 2 methacryloyloxyethyl phosphorylcholine grafted highly cross linked Polyethylene liners three year results of a prospective consecutive series
2015Co-Authors: Yoshio Takatori, Takashige Umeyama, Hiroshi Kawaguchi, Masayuki Kyomoto, Toru Moro, Kazuhiko Ishihara, Masashi Kamogawa, Takeyuki Tanaka, Sakae TanakaAbstract:AbstractObjectives. This study aimed to evaluate the clinical safety and wear-resistance of the novel highly Cross-Linked Polyethylene (HXLPE) acetabular liner with surface grafting of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) at 3 years after total hip replacement (THR).Methods. Eighty consecutive patients underwent cementless THR using a 26-mm diameter cobalt–chromium–molybdenum alloy femoral head and a PMPC-grafted HXLPE liner for the bearing couplings. We evaluated the clinical and radiographic outcomes of 76 patients at 3 years after the index surgery.Results. The clinical results at 3 years were equivalent to a Harris hip score of 95.6 points. No adverse events were associated with the implanted PMPC-grafted HXLPE liner, and no periprosthetic osteolysis was detected. The mean femoral head penetration rate was 0.002 mm/year, representing marked reduction compared with other HXLPE liners.Conclusions. A PMPC-grafted HXLPE liner is a safe option in THR and probably reduces the generation of ...
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Biomimetic hydration lubrication with various polyelectrolyte layers on Cross-Linked Polyethylene orthopedic bearing materials
2012Co-Authors: Masayuki Kyomoto, Kenichi Saiga, Hiroshi Kawaguchi, Toru Moro, Masami Hashimoto, Yoshio Takatori, Kazuhiko IshiharaAbstract:Abstract Natural joints rely on fluid thin-film lubrication by the hydrated polyelectrolyte layer of cartilage. However, current artificial joints with Polyethylene (PE) surfaces have considerably less efficient lubrication and thus much greater wear, leading to osteolysis and aseptic loosening. This is considered a common factor limiting prosthetic longevity in total hip arthroplasty (THA). However, such wear could be mitigated by surface modification to mimic the role of cartilage. Here we report the development of nanometer-scale hydrophilic layers with varying charge (nonionic, cationic, anionic, or zwitterionic) on Cross-Linked PE (CLPE) surfaces, which could fully mimic the hydrophilicity and lubricity of the natural joint surface. We present evidence to support two lubrication mechanisms: the primary mechanism is due to the high level of hydration in the grafted layer, where water molecules act as very efficient lubricants; and the secondary mechanism is repulsion of protein molecules and positively charged inorganic ions by the grafted polyelectrolyte layer. Thus, such nanometer-scaled hydrophilic polymers or polyelectrolyte layers on the CLPE surface of acetabular cup bearings could confer high durability to THA prosthetics.
Toru Moro - One of the best experts on this subject based on the ideXlab platform.
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clinical safety and wear resistance of the phospholipid polymer grafted highly cross linked Polyethylene liner
2017Co-Authors: Toru Moro, Takashige Umeyama, Yoshio Takatori, Kazuhiko Ishihara, Sakae Tanaka, Hiromi Oda, Yoon Taek Kim, Eisei Fukatani, Hideya Ito, Masayuki KyomotoAbstract:To reduce the production of wear particles and subsequent aseptic loosening, we created a human articular cartilage-mimicked surface for a highly Cross-Linked Polyethylene liner, whose surface grafted layer consisted of a biocompatible phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine). Although our previous in vitro findings showed that poly(2-methacryloyloxyethyl phosphorylcholine)-grafted particles were biologically inert and caused no subsequent bone resorptive responses, and poly(2-methacryloyloxyethyl phosphorylcholine) grafting markedly decreased wear in hip joint simulator tests, the clinical safety, and in vivo wear resistance of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners remained open to question. Therefore, in the present study, we evaluated clinical and radiographic outcomes of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners 5 years subsequent to total hip replacement in 68 consecutive patients. No reoperation was required for any reason, and no adverse events were associated with the implanted liners. The average Harris Hip Score increased from 38.6 preoperatively to 96.5 5 years postoperatively, and health-related quality of life, as indicated by the Short Form 36 Health Survey, improved. Radiographic analyses showed no periprosthetic osteolysis or implant migration. Between 1 and 5 years postoperatively, the mean steady-state wear rate was 0.002 mm/year, which represented a marked reduction relative to other highly Cross-Linked Polyethylene liners, and appeared to be unaffected by patient-related or surgical factors. Although longer follow up is required, poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners improved mid-term clinical outcomes. The clinical safety and wear-resistance results are encouraging with respect to the improvement of long-term clinical outcomes with poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2007–2016, 2017.
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a hydrated phospholipid polymer grafted layer prevents lipid related oxidative degradation of cross linked Polyethylene
2017Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Kazuhiko IshiharaAbstract:The surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve resistance against oxidative degradation in the construction of hip joint replacements. In this study, we aimed to evaluate the oxidative degradation caused by lipid absorption of a highly hydrophilic nanometer-scaled thickness layer prepared by grafting a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer and a high-dose gamma-ray irradiated CLPE with vitamin E blending (HD-CLPE[VE]). The HD-CLPE(VE) and PMPC-grafted HD-CLPE(VE) exhibited extremely high oxidation resistance regardless of lipid absorption, even though residual-free radical levels were detectable. The water wettability of the PMPC-grafted CLPE and PMPC-grafted HD-CLPE(VE) surfaces was considerably greater than that of untreated surfaces. The hydrated PMPC-grafted layer also exhibited extremely low solubility for squalene. Lipids such as squalene and cholesterol esters diminished the oxidation resistance of CLPE despite the vitamin E improvement. Notably, the PMPC-grafted surface was resistant to lipid absorption and diffusion as well as subsequent lipid-related oxidative degradation, likely because of the presence of the hydrated PMPC-grafted layer. Together, these results provide preliminary evidence that the resistance against lipid absorption and diffusion of a hydrated PMPC-grafted layer might positively affect the extent of resistance to the in vivo oxidation of orthopedic implants.
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prevention of bacterial adhesion and biofilm formation on a vitamin e blended cross linked Polyethylene surface with a poly 2 methacryloyloxyethyl phosphorylcholine layer
2015Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Takeo Shobuike, Hiroshi Miyamoto, Kazuhiko IshiharaAbstract:Abstract In the construction of artificial hip joint replacements, the surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve high wear resistance and prevent infection by bacteria. In this study, we fabricated a highly hydrophilic and antibiofouling poly(2-methacryloyloxyethyl phosphorylcholine [MPC]) (PMPC)-graft layer on the vitamin E-blended CLPE (HD-CLPE(VE)) surface. The 100-nm-thick, smooth, and electrically neutral PMPC layer was successfully fabricated on the HD-CLPE(VE) surface using photoinduced graft polymerization. The PMPC-grafted HD-CLPE(VE) was found to prevent bacterial adherence and biofilm formation on the surface because of the formation of a highly hydrophilic polyzwitterionic layer on the surface of HD-CLPE(VE), which can serve as an extremely efficient antibiofouling layer. The number of bacterial adhered on the PMPC-grafted HD-CLPE(VE) surface was reduced by 100-fold or more by PMPC grafting, regardless of the biofilm-production characteristics of the strains. In contrast, vitamin E blending did not affect bacterial adhesion. Moreover, the number of planktonic bacteria did not differ significantly, regardless of PMPC grafting and vitamin E blending. In conclusion, the PMPC-grafted HD-CLPE(VE) provided bacteriostatic effects associated with smooth, highly hydrophilic surfaces with a neutral electrostatic charge owing to the zwitterionic structure of the MPC unit. Thus, this modification may prove useful for the production of artificial hip joint replacement materials. Statement of Significance Our preliminary in vitro findings suggest that improved bacteriostatic performance of the HD-CLPE(VE) surface in orthopedic implants is possible via PMPC grafting. The results also indicate that surface modifications affect the anti-infection properties of the orthopedic implants and demonstrate that the application of a PMPC-grafted HD-CLPE(VE) surface may be a promising approach to extend the longevity and clinical outcomes of total hip arthroplasty. Further research is needed to evaluate the resistance to infection of PMPC-grafted HD-CLPE(VE) in terms of the varieties of biofilm formation tests including fluid flow conditions and animal experiments, which may offer useful clues to the possible performance of these materials in vivo .
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clinical and radiographic outcomes of total hip replacement with poly 2 methacryloyloxyethyl phosphorylcholine grafted highly cross linked Polyethylene liners three year results of a prospective consecutive series
2015Co-Authors: Yoshio Takatori, Takashige Umeyama, Hiroshi Kawaguchi, Masayuki Kyomoto, Toru Moro, Kazuhiko Ishihara, Masashi Kamogawa, Takeyuki Tanaka, Sakae TanakaAbstract:AbstractObjectives. This study aimed to evaluate the clinical safety and wear-resistance of the novel highly Cross-Linked Polyethylene (HXLPE) acetabular liner with surface grafting of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) at 3 years after total hip replacement (THR).Methods. Eighty consecutive patients underwent cementless THR using a 26-mm diameter cobalt–chromium–molybdenum alloy femoral head and a PMPC-grafted HXLPE liner for the bearing couplings. We evaluated the clinical and radiographic outcomes of 76 patients at 3 years after the index surgery.Results. The clinical results at 3 years were equivalent to a Harris hip score of 95.6 points. No adverse events were associated with the implanted PMPC-grafted HXLPE liner, and no periprosthetic osteolysis was detected. The mean femoral head penetration rate was 0.002 mm/year, representing marked reduction compared with other HXLPE liners.Conclusions. A PMPC-grafted HXLPE liner is a safe option in THR and probably reduces the generation of ...
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poly 2 methacryloyloxyethyl phosphorylcholine grafted highly cross linked Polyethylene liner in primary total hip replacement one year results of a prospective cohort study
2013Co-Authors: Yoshio Takatori, Tatsuro Karita, Shuhei Morimoto, Takashige Umeyama, Manabu Minami, Hideharu Sugimoto, Shigeru Nakamura, Toru Moro, Masashi Kamogawa, Yurie KoyamaAbstract:To control particle-induced osteolysis in total hip replacement (THR), we developed a new technique to graft poly(2-methacryloyloxyethyl phosphorylcholine) onto the surface of Polyethylene liners. A prospective cohort study was conducted to investigate the clinical safety of this novel bearing surface. Between April 2007 and September 2008, we recruited a prospective consecutive series of 80 patients in five participating hospitals. These patients received a cementless THR; a 26-mm-diameter cobalt–chromium–molybdenum alloy ball and a poly(2-methacryloyloxyethyl phosphorylcholine)-grafted Cross-Linked Polyethylene liner were used for the bearing couplings. These individuals were followed a year postoperatively. An evaluation of clinical performance was conducted through an assessment of hip joint function based on the evaluation chart authorized by the Japanese Orthopaedic Association. No patients were lost to follow-up. No adverse events were found to be correlated with the implanted liners. The average hip joint function score improved from 43.2 preoperatively to 91.7 postoperatively at 1 year. There was no implant migration nor periprosthetic osteolysis detected on radiographic analysis. On the basis of our results, we conclude that poly(2-methacryloyloxyethyl phosphorylcholine)-grafted Cross-Linked Polyethylene liners are a safe implant option for hip replacement surgery for short-term clinical use.
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clinical safety and wear resistance of the phospholipid polymer grafted highly cross linked Polyethylene liner
2017Co-Authors: Toru Moro, Takashige Umeyama, Yoshio Takatori, Kazuhiko Ishihara, Sakae Tanaka, Hiromi Oda, Yoon Taek Kim, Eisei Fukatani, Hideya Ito, Masayuki KyomotoAbstract:To reduce the production of wear particles and subsequent aseptic loosening, we created a human articular cartilage-mimicked surface for a highly Cross-Linked Polyethylene liner, whose surface grafted layer consisted of a biocompatible phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine). Although our previous in vitro findings showed that poly(2-methacryloyloxyethyl phosphorylcholine)-grafted particles were biologically inert and caused no subsequent bone resorptive responses, and poly(2-methacryloyloxyethyl phosphorylcholine) grafting markedly decreased wear in hip joint simulator tests, the clinical safety, and in vivo wear resistance of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners remained open to question. Therefore, in the present study, we evaluated clinical and radiographic outcomes of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners 5 years subsequent to total hip replacement in 68 consecutive patients. No reoperation was required for any reason, and no adverse events were associated with the implanted liners. The average Harris Hip Score increased from 38.6 preoperatively to 96.5 5 years postoperatively, and health-related quality of life, as indicated by the Short Form 36 Health Survey, improved. Radiographic analyses showed no periprosthetic osteolysis or implant migration. Between 1 and 5 years postoperatively, the mean steady-state wear rate was 0.002 mm/year, which represented a marked reduction relative to other highly Cross-Linked Polyethylene liners, and appeared to be unaffected by patient-related or surgical factors. Although longer follow up is required, poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners improved mid-term clinical outcomes. The clinical safety and wear-resistance results are encouraging with respect to the improvement of long-term clinical outcomes with poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly Cross-Linked Polyethylene liners. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2007–2016, 2017.
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effects of material thickness and surface modification of cross linked Polyethylene with poly 2 methacryloyloxyethyl phosphorylcholine on its deformation behavior wear resistance and durability under repetitive impact to sliding motion
2017Co-Authors: Kenichi Saiga, Masayuki Kyomoto, Yoshio Takatori, Kenichi Watanabe, Shuji Taketomi, Yuho Kadono, Sakae TanakaAbstract:Abstract 1 Background Large femoral heads and thin Cross-Linked Polyethylene (CLPE) acetabular liners are required for preventing dislocation in total hip arthroplasty (THA). However, the wear resistance and durability of thin CLPE liners in severe physiological conditions has not been fully understood. Methods In this study, we investigated the wear and fatigue properties of untreated CLPE (50 kGy gamma-ray irradiated and annealed) and poly(2-methacryloyloxyethyl phosphorylcholine)-grafted CLPE (PMPC-grafted CLPE) disks that were 3 mm and 6 mm in thickness and subjected to a repetitive impact-to-wear test using a pin-on-disk testing machine. Results PMPC grafting reduced the gravimetric wear of 3 mm and 6 mm thick CLPE disks, but did not affect volumetric changes at the impact area. However, the volumetric change for 6 mm thick PMPC-grafted CLPE disks in areas subjected to high pressure was significantly less than that for CLPE. The thickness of CLPE did not affect its gravimetric wear, whereas volumetric changes at both bearing and backside surfaces of 3 mm thick disks were significantly larger than those of 6 mm thick disks. The results of finite element analysis indicated that the maximum von Mises stress of 3 mm thick CLPE disks near the backside hole was greater than its yield stress, which resulted in cold flow. Delamination and fracture did not occur for any disks. Discussion Under impact-to-wear conditions, PMPC grafting and CLPE substrate with sufficient thickness brought wear and fatigue resistance; those are favorable candidates for bearing material under the severe physiological conditions present in reconstructed hip joints.
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a hydrated phospholipid polymer grafted layer prevents lipid related oxidative degradation of cross linked Polyethylene
2017Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Kazuhiko IshiharaAbstract:The surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve resistance against oxidative degradation in the construction of hip joint replacements. In this study, we aimed to evaluate the oxidative degradation caused by lipid absorption of a highly hydrophilic nanometer-scaled thickness layer prepared by grafting a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer and a high-dose gamma-ray irradiated CLPE with vitamin E blending (HD-CLPE[VE]). The HD-CLPE(VE) and PMPC-grafted HD-CLPE(VE) exhibited extremely high oxidation resistance regardless of lipid absorption, even though residual-free radical levels were detectable. The water wettability of the PMPC-grafted CLPE and PMPC-grafted HD-CLPE(VE) surfaces was considerably greater than that of untreated surfaces. The hydrated PMPC-grafted layer also exhibited extremely low solubility for squalene. Lipids such as squalene and cholesterol esters diminished the oxidation resistance of CLPE despite the vitamin E improvement. Notably, the PMPC-grafted surface was resistant to lipid absorption and diffusion as well as subsequent lipid-related oxidative degradation, likely because of the presence of the hydrated PMPC-grafted layer. Together, these results provide preliminary evidence that the resistance against lipid absorption and diffusion of a hydrated PMPC-grafted layer might positively affect the extent of resistance to the in vivo oxidation of orthopedic implants.
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prevention of bacterial adhesion and biofilm formation on a vitamin e blended cross linked Polyethylene surface with a poly 2 methacryloyloxyethyl phosphorylcholine layer
2015Co-Authors: Masayuki Kyomoto, Toru Moro, Yoshio Takatori, Sakae Tanaka, Shihori Yamane, Takeo Shobuike, Hiroshi Miyamoto, Kazuhiko IshiharaAbstract:Abstract In the construction of artificial hip joint replacements, the surface and substrate of a Cross-Linked Polyethylene (CLPE) liner are designed to achieve high wear resistance and prevent infection by bacteria. In this study, we fabricated a highly hydrophilic and antibiofouling poly(2-methacryloyloxyethyl phosphorylcholine [MPC]) (PMPC)-graft layer on the vitamin E-blended CLPE (HD-CLPE(VE)) surface. The 100-nm-thick, smooth, and electrically neutral PMPC layer was successfully fabricated on the HD-CLPE(VE) surface using photoinduced graft polymerization. The PMPC-grafted HD-CLPE(VE) was found to prevent bacterial adherence and biofilm formation on the surface because of the formation of a highly hydrophilic polyzwitterionic layer on the surface of HD-CLPE(VE), which can serve as an extremely efficient antibiofouling layer. The number of bacterial adhered on the PMPC-grafted HD-CLPE(VE) surface was reduced by 100-fold or more by PMPC grafting, regardless of the biofilm-production characteristics of the strains. In contrast, vitamin E blending did not affect bacterial adhesion. Moreover, the number of planktonic bacteria did not differ significantly, regardless of PMPC grafting and vitamin E blending. In conclusion, the PMPC-grafted HD-CLPE(VE) provided bacteriostatic effects associated with smooth, highly hydrophilic surfaces with a neutral electrostatic charge owing to the zwitterionic structure of the MPC unit. Thus, this modification may prove useful for the production of artificial hip joint replacement materials. Statement of Significance Our preliminary in vitro findings suggest that improved bacteriostatic performance of the HD-CLPE(VE) surface in orthopedic implants is possible via PMPC grafting. The results also indicate that surface modifications affect the anti-infection properties of the orthopedic implants and demonstrate that the application of a PMPC-grafted HD-CLPE(VE) surface may be a promising approach to extend the longevity and clinical outcomes of total hip arthroplasty. Further research is needed to evaluate the resistance to infection of PMPC-grafted HD-CLPE(VE) in terms of the varieties of biofilm formation tests including fluid flow conditions and animal experiments, which may offer useful clues to the possible performance of these materials in vivo .
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clinical and radiographic outcomes of total hip replacement with poly 2 methacryloyloxyethyl phosphorylcholine grafted highly cross linked Polyethylene liners three year results of a prospective consecutive series
2015Co-Authors: Yoshio Takatori, Takashige Umeyama, Hiroshi Kawaguchi, Masayuki Kyomoto, Toru Moro, Kazuhiko Ishihara, Masashi Kamogawa, Takeyuki Tanaka, Sakae TanakaAbstract:AbstractObjectives. This study aimed to evaluate the clinical safety and wear-resistance of the novel highly Cross-Linked Polyethylene (HXLPE) acetabular liner with surface grafting of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) at 3 years after total hip replacement (THR).Methods. Eighty consecutive patients underwent cementless THR using a 26-mm diameter cobalt–chromium–molybdenum alloy femoral head and a PMPC-grafted HXLPE liner for the bearing couplings. We evaluated the clinical and radiographic outcomes of 76 patients at 3 years after the index surgery.Results. The clinical results at 3 years were equivalent to a Harris hip score of 95.6 points. No adverse events were associated with the implanted PMPC-grafted HXLPE liner, and no periprosthetic osteolysis was detected. The mean femoral head penetration rate was 0.002 mm/year, representing marked reduction compared with other HXLPE liners.Conclusions. A PMPC-grafted HXLPE liner is a safe option in THR and probably reduces the generation of ...