AIM：To describe a novel technique of creating a landing strip within the trabecular meshwork to guide trabecular micro-bypass stent（iStent） implantation in patients who underwent phacoemulsification.METHODS：Thirty...AIM：To describe a novel technique of creating a landing strip within the trabecular meshwork to guide trabecular micro-bypass stent（iStent） implantation in patients who underwent phacoemulsification.METHODS：Thirty-four eyes from 30 patients who underwent i Stent implantation after phacoemulsification from May 2014 to February 2015 were included in our retrospective study. All iStents were implanted via the ＂landing strip＂ technique. A 25-gauge microvitreoretinal blade was used to bisect the trabecular meshwork to less than 1 clock-hour, effectively creating a landing strip. The iStent applicator was pressed along the landing strip and then the stent was released into the trabecular meshwork. RESULTS：Of the 34 eyes with iStent implantation, 27（79.4%） eyes had primary open-angle glaucoma, 6（17.6%） eyes had pseudoexfoliation glaucoma, and 1（2.9%） eye had ocular hypertension. At 6-month follow-up（n=17）, the mean number of hypotensive medications decreased from 2.2±1.2 at baseline to 0.8±1.3（P=0.05） and mean intraocular pressure decreased from 19.7±4.1 mm Hg at baseline to 16.7±2.1 mm Hg（P=0.58）. Two eyes（5.9%） required subsequent trabeculectomy. CONCLUSION：The ＂landing strip＂ technique appears to be an effective way to assist with iS tent implantation.展开更多
Background:The study aimed to investigate the 24-month safety and efficacy of implantation of two secondgeneration iStent inject trabecular micro-bypass stents with concomitant cataract surgery.Methods:This consecutiv...Background:The study aimed to investigate the 24-month safety and efficacy of implantation of two secondgeneration iStent inject trabecular micro-bypass stents with concomitant cataract surgery.Methods:This consecutive case series included 164 eyes of 109 patients implanted with the iStent inject®device with concomitant cataract surgery.The series was comprised of eyes with primary open-angle glaucoma(n=84),pseudoexfoliation glaucoma(n=42),normal-tension glaucoma(n=18),and ocular hypertension(n=20).All 164 eyes reached 9–14 months of follow-up(“12-month consistent cohort”),with a subset of 88 eyes reaching 21–26 months of follow-up(“24-month consistent cohort”).Performance outcome measures included intraocular pressure(IOP)and number of glaucoma medications.Safety outcomes included intra-or postoperative complications,the need for secondary procedures and corrected distance visual acuity.Comparisons of change in continuous(e.g.,IOP)and categorical(e.g.,proportions of eyes on zero medications)measures between baseline and postoperative times were made with the paired t-test and McNemar’s chi-squared test,respectively.Results:At 12 months postoperatively,IOP was reduced by 25.5%(from 20.0±5.5 mmHg to 14.9±2.0 mmHg;p<0.001);at 24 months postoperatively,IOP was reduced by 26.6%(from 20.3±6.1 mmHg to 14.9±1.9 mmHg;p<0.001).At 12 months postoperatively,mean number of glaucoma medications was reduced by 85.0%(from 2.0±1.0 to 0.3±0.8 medications;p<0.001);at 24 months postoperatively,mean number of medications was reduced by 81.0%(from 2.1±1.1 to 0.4±0.8 medications;p<0.001).After 12 months,96.3%of eyes had an IOP≤18 mmHg and 58.5%of eyes had an IOP≤15 mmHg,with 81.1%of eyes free of any medication,compared to 1.8%of eyes medication-free in the 12-month cohort at baseline.After 24 months,98.9%of eyes had an IOP≤18 mmHg and 53.4%of eyes had an IOP≤15 mmHg,with 72.7%free of medication compared to 1.1%of eyes medication-free in the 24-month cohort at baseline.Overall,a high safety profile was observed with no significant postoperative complications.Conclusions:The insertion of iStent inject(comprised of two second-generation trabecular micro-bypass stents)with cataract surgery effectively provides a sustained reduction in IOP with a markedly improved medication burden up to 24 months postoperatively.展开更多
Background With advance of age, alterations in bone quality, quantity and microarchitecture render osteoporotic trabecular bone become more sensitive to local failure. The aims of the present study were to clarify the...Background With advance of age, alterations in bone quality, quantity and microarchitecture render osteoporotic trabecular bone become more sensitive to local failure. The aims of the present study were to clarify the extent to which the distribution of tissue-level stresses and strains was affected by structural changes and the extent to which osteoporotic acetabular trabecular bone was damaged at small strains. Methods Using a DAWING 4000A supercomputer, nonlinear micro-finite element （μFE） analyses were performed to calculate the tissue-level strains and stresses for each element in the trabecular bone of one osteoporotic acetabulum at small strains to quantify the tissue-level damage accumulation and mechanical properties. Results In contour plots of the tissue, maximum principal logarithmic strains, high tissue-level strains, both compressive and tensile, were observed in the osteoporotic trabecular bone at small apparent strains from 0.2% to 0.5% strain. The compressive apparent stress-strain curve showed typical nonlinear behavior and tangent modulus reduction with increasing strains. The microdamage curve suggested that microdamage began at 0.2% apparent strain in the osteoporotic trabecular bone and increased sharply, although very few microfractures occurred. The quartiles of the maximum principal logarithmic strains, minimum principal logarithmic strains and Von Mises stresses increased nonlinearly. For the inter-quartile range of the Von Mises stresses, a leap occurred at small strains ranging from 0.2% to 0.3% while microdamage commenced. Conclusions Extensive microdamage was primarily responsible for the large loss in apparent mechanical properties that occurred in the trabecular bone of the osteoporotic acetabulum at small strains. With increasing apparent strains, continuous nonlinear increments of tissue-level strains and stresses resulted in microdamage that propagated throughout the specimen with very few microfractures. Chin Med J 2009; 122（17）：2041-204 7展开更多
The objective of this study was to study the age-related adaptation of lumbar vertebral trabecular bone at the apparent level, as well as the tissue level in three orthogonal directions. Ninety trabecular specimens we...The objective of this study was to study the age-related adaptation of lumbar vertebral trabecular bone at the apparent level, as well as the tissue level in three orthogonal directions. Ninety trabecular specimens were obtained from six normal L4 vertebral bodies of six male cadavers in two age groups, three aged 62 years and three aged 69 years, and were scanned using a high-resolution micro-computed tomography （micro-CT） system, then converted to micro- finite element models to do micro-finite element analyses. The relationship between apparent stiffness and bone volume fraction, and the tissue level yon Mises stress distribution for each trabecular specimen when compressed separately in the longitudinal direction, medial-lateral and anterior-posterior directions （transverse directions） were derived and compared between two age groups. The results showed that at the apparent level, trabecular bones from 69-year group had stiffer bone structure relative to their volume fractions in all three directions, and in both age groups, changes in bone volume fraction could explain more variations in apparent stiffness in the longitudinal direction than the transverse directions; at the tissue level, aging had little effect on the tissue von Mises stress distributions for the compressions in all the three directions. The novelty of the present study was that it provided quantitative assessments on the age and direction- related adaptation of Chinese male lumbar vertebral trabecular bone from two different levels： stiffness at the apparent level and stress distribution at the tissue level. It may help to understand the failure mechanisms and fracture risks of vertebral body associated with aging and direction for the prevention of fracture risks in elder individuals.展开更多
This study aims to investigate the regional variations of trabecular morphological parameters and mechanical parameters of the femoral head,as well as to determine the relationship between trabecular morphological and...This study aims to investigate the regional variations of trabecular morphological parameters and mechanical parameters of the femoral head,as well as to determine the relationship between trabecular morphological and mechanical parameters.Seven femoral heads from patients with fractured proximal femur were scanned using a micro-CT system.Each femoral head was divided into 12 sub-regions according to the trabecular orientation.One 125 mm^3 trabecular cubic model was reconstructed from each sub-region.A total of 81 trabecular models were reconstructed,except three destroyed sub-regions from two femoral heads during the surgery.Trabecular morphological parameters,i.e.trabecular separation（Tb.Sp）,trabecular thickness（Tb.Th）,specific bone surface（BS/B V）,bone volume fraction（BV/TV）,structural model index（SMI）,and degree of anisotropy（DA） were measured.Micro-finite element analyses were performed for each cube to obtain the apparent Young＇s modulus and tissue level von Mises stress distribution under 1%compressive strain along three orthogonal directions,respectively.Results revealed significant regional variations in the morphological parameters（P〈0.05）.Young＇s moduli along the trabecular orientation were significantly higher than those along the other two directions.In general,trabecular mechanical properties in the medial region were lower than those in the lateral region.Trabecular mechanical parameters along the trabecular orientation were significantly correlated with BS/BV,BV/TV,Tb.Th,and DA.In this study,regional variations of microstructural features and mechanical properties in the femoral head of patients with proximal femur fracture were thoroughly investigated at the tissue level.The results of this study will help to elucidate the mechanism of femoral head fracture for reducing fracture risk and developing treatment strategies for the elderly.展开更多
In order to study the microstructure characteristics of normal lunate bones, eight fresh cadaver normal lunates were scanned with micro-computed tomography. High-resolution images of the micro-structure of normal luna...In order to study the microstructure characteristics of normal lunate bones, eight fresh cadaver normal lunates were scanned with micro-computed tomography. High-resolution images of the micro-structure of normal lunates were obtained and we analyzed the nutrient foramina. Then nine regions of interest(ROI) were chosen in the central sagittal plane so that we could obtain the parameters of trabecular bones of ROIs. The distal lamellar-like compact structure had statistically significant differences when it was compared with the ROIs in the volar and dorsal ends of the distal cortex. The difference of diameter between the volar and dorsal foramina was significant(P<0.05). However, there was no significant difference regarding the number. The trabecular bones of the volar and dorsal distal ends had lower intensity than those of the distal central subchondral bone plate. The diameters of the nutrient foramina on the volar cortex were larger than those on the dorsal. This research provided more detailed information about microstructure of normal lunate and the nutrient foramina on cortex, and a reference for further study about diseased lunate.展开更多
文摘AIM：To describe a novel technique of creating a landing strip within the trabecular meshwork to guide trabecular micro-bypass stent（iStent） implantation in patients who underwent phacoemulsification.METHODS：Thirty-four eyes from 30 patients who underwent i Stent implantation after phacoemulsification from May 2014 to February 2015 were included in our retrospective study. All iStents were implanted via the ＂landing strip＂ technique. A 25-gauge microvitreoretinal blade was used to bisect the trabecular meshwork to less than 1 clock-hour, effectively creating a landing strip. The iStent applicator was pressed along the landing strip and then the stent was released into the trabecular meshwork. RESULTS：Of the 34 eyes with iStent implantation, 27（79.4%） eyes had primary open-angle glaucoma, 6（17.6%） eyes had pseudoexfoliation glaucoma, and 1（2.9%） eye had ocular hypertension. At 6-month follow-up（n=17）, the mean number of hypotensive medications decreased from 2.2±1.2 at baseline to 0.8±1.3（P=0.05） and mean intraocular pressure decreased from 19.7±4.1 mm Hg at baseline to 16.7±2.1 mm Hg（P=0.58）. Two eyes（5.9%） required subsequent trabeculectomy. CONCLUSION：The ＂landing strip＂ technique appears to be an effective way to assist with iS tent implantation.
文摘Background:The study aimed to investigate the 24-month safety and efficacy of implantation of two secondgeneration iStent inject trabecular micro-bypass stents with concomitant cataract surgery.Methods:This consecutive case series included 164 eyes of 109 patients implanted with the iStent inject®device with concomitant cataract surgery.The series was comprised of eyes with primary open-angle glaucoma(n=84),pseudoexfoliation glaucoma(n=42),normal-tension glaucoma(n=18),and ocular hypertension(n=20).All 164 eyes reached 9–14 months of follow-up(“12-month consistent cohort”),with a subset of 88 eyes reaching 21–26 months of follow-up(“24-month consistent cohort”).Performance outcome measures included intraocular pressure(IOP)and number of glaucoma medications.Safety outcomes included intra-or postoperative complications,the need for secondary procedures and corrected distance visual acuity.Comparisons of change in continuous(e.g.,IOP)and categorical(e.g.,proportions of eyes on zero medications)measures between baseline and postoperative times were made with the paired t-test and McNemar’s chi-squared test,respectively.Results:At 12 months postoperatively,IOP was reduced by 25.5%(from 20.0±5.5 mmHg to 14.9±2.0 mmHg;p<0.001);at 24 months postoperatively,IOP was reduced by 26.6%(from 20.3±6.1 mmHg to 14.9±1.9 mmHg;p<0.001).At 12 months postoperatively,mean number of glaucoma medications was reduced by 85.0%(from 2.0±1.0 to 0.3±0.8 medications;p<0.001);at 24 months postoperatively,mean number of medications was reduced by 81.0%(from 2.1±1.1 to 0.4±0.8 medications;p<0.001).After 12 months,96.3%of eyes had an IOP≤18 mmHg and 58.5%of eyes had an IOP≤15 mmHg,with 81.1%of eyes free of any medication,compared to 1.8%of eyes medication-free in the 12-month cohort at baseline.After 24 months,98.9%of eyes had an IOP≤18 mmHg and 53.4%of eyes had an IOP≤15 mmHg,with 72.7%free of medication compared to 1.1%of eyes medication-free in the 24-month cohort at baseline.Overall,a high safety profile was observed with no significant postoperative complications.Conclusions:The insertion of iStent inject(comprised of two second-generation trabecular micro-bypass stents)with cataract surgery effectively provides a sustained reduction in IOP with a markedly improved medication burden up to 24 months postoperatively.
文摘Background With advance of age, alterations in bone quality, quantity and microarchitecture render osteoporotic trabecular bone become more sensitive to local failure. The aims of the present study were to clarify the extent to which the distribution of tissue-level stresses and strains was affected by structural changes and the extent to which osteoporotic acetabular trabecular bone was damaged at small strains. Methods Using a DAWING 4000A supercomputer, nonlinear micro-finite element （μFE） analyses were performed to calculate the tissue-level strains and stresses for each element in the trabecular bone of one osteoporotic acetabulum at small strains to quantify the tissue-level damage accumulation and mechanical properties. Results In contour plots of the tissue, maximum principal logarithmic strains, high tissue-level strains, both compressive and tensile, were observed in the osteoporotic trabecular bone at small apparent strains from 0.2% to 0.5% strain. The compressive apparent stress-strain curve showed typical nonlinear behavior and tangent modulus reduction with increasing strains. The microdamage curve suggested that microdamage began at 0.2% apparent strain in the osteoporotic trabecular bone and increased sharply, although very few microfractures occurred. The quartiles of the maximum principal logarithmic strains, minimum principal logarithmic strains and Von Mises stresses increased nonlinearly. For the inter-quartile range of the Von Mises stresses, a leap occurred at small strains ranging from 0.2% to 0.3% while microdamage commenced. Conclusions Extensive microdamage was primarily responsible for the large loss in apparent mechanical properties that occurred in the trabecular bone of the osteoporotic acetabulum at small strains. With increasing apparent strains, continuous nonlinear increments of tissue-level strains and stresses resulted in microdamage that propagated throughout the specimen with very few microfractures. Chin Med J 2009; 122（17）：2041-204 7
基金The project supported by the Hong Kong Polytechnic University Research Grants(G-U273) the National Natural Science Foundation of China(10502021 and 10529202)
文摘The objective of this study was to study the age-related adaptation of lumbar vertebral trabecular bone at the apparent level, as well as the tissue level in three orthogonal directions. Ninety trabecular specimens were obtained from six normal L4 vertebral bodies of six male cadavers in two age groups, three aged 62 years and three aged 69 years, and were scanned using a high-resolution micro-computed tomography （micro-CT） system, then converted to micro- finite element models to do micro-finite element analyses. The relationship between apparent stiffness and bone volume fraction, and the tissue level yon Mises stress distribution for each trabecular specimen when compressed separately in the longitudinal direction, medial-lateral and anterior-posterior directions （transverse directions） were derived and compared between two age groups. The results showed that at the apparent level, trabecular bones from 69-year group had stiffer bone structure relative to their volume fractions in all three directions, and in both age groups, changes in bone volume fraction could explain more variations in apparent stiffness in the longitudinal direction than the transverse directions; at the tissue level, aging had little effect on the tissue von Mises stress distributions for the compressions in all the three directions. The novelty of the present study was that it provided quantitative assessments on the age and direction- related adaptation of Chinese male lumbar vertebral trabecular bone from two different levels： stiffness at the apparent level and stress distribution at the tissue level. It may help to understand the failure mechanisms and fracture risks of vertebral body associated with aging and direction for the prevention of fracture risks in elder individuals.
基金supported by the National Natural Science Foundation of China(Nos.11322223,11432016,81471753 and 11272134)the 973 Program(No.2012CB821202)
文摘This study aims to investigate the regional variations of trabecular morphological parameters and mechanical parameters of the femoral head,as well as to determine the relationship between trabecular morphological and mechanical parameters.Seven femoral heads from patients with fractured proximal femur were scanned using a micro-CT system.Each femoral head was divided into 12 sub-regions according to the trabecular orientation.One 125 mm^3 trabecular cubic model was reconstructed from each sub-region.A total of 81 trabecular models were reconstructed,except three destroyed sub-regions from two femoral heads during the surgery.Trabecular morphological parameters,i.e.trabecular separation（Tb.Sp）,trabecular thickness（Tb.Th）,specific bone surface（BS/B V）,bone volume fraction（BV/TV）,structural model index（SMI）,and degree of anisotropy（DA） were measured.Micro-finite element analyses were performed for each cube to obtain the apparent Young＇s modulus and tissue level von Mises stress distribution under 1%compressive strain along three orthogonal directions,respectively.Results revealed significant regional variations in the morphological parameters（P〈0.05）.Young＇s moduli along the trabecular orientation were significantly higher than those along the other two directions.In general,trabecular mechanical properties in the medial region were lower than those in the lateral region.Trabecular mechanical parameters along the trabecular orientation were significantly correlated with BS/BV,BV/TV,Tb.Th,and DA.In this study,regional variations of microstructural features and mechanical properties in the femoral head of patients with proximal femur fracture were thoroughly investigated at the tissue level.The results of this study will help to elucidate the mechanism of femoral head fracture for reducing fracture risk and developing treatment strategies for the elderly.
文摘In order to study the microstructure characteristics of normal lunate bones, eight fresh cadaver normal lunates were scanned with micro-computed tomography. High-resolution images of the micro-structure of normal lunates were obtained and we analyzed the nutrient foramina. Then nine regions of interest(ROI) were chosen in the central sagittal plane so that we could obtain the parameters of trabecular bones of ROIs. The distal lamellar-like compact structure had statistically significant differences when it was compared with the ROIs in the volar and dorsal ends of the distal cortex. The difference of diameter between the volar and dorsal foramina was significant(P<0.05). However, there was no significant difference regarding the number. The trabecular bones of the volar and dorsal distal ends had lower intensity than those of the distal central subchondral bone plate. The diameters of the nutrient foramina on the volar cortex were larger than those on the dorsal. This research provided more detailed information about microstructure of normal lunate and the nutrient foramina on cortex, and a reference for further study about diseased lunate.
