Hypovitaminosis D and K due to malnutrition or sunlight deprivation,increased bone resorption due to immobilization,low bone mineral density(BMD)and an increased risk of falls may contribute to an increased risk of hi...Hypovitaminosis D and K due to malnutrition or sunlight deprivation,increased bone resorption due to immobilization,low bone mineral density(BMD)and an increased risk of falls may contribute to an increased risk of hip fractures in patients with Parkinson’s disease.The purpose of the present study was to clarify the efficacy of interventions intended to prevent hip fractures in elderly patients with Parkinson’s disease.Pub Med was used to search the literature for randomized controlled trials(RCTs)regarding Parkinson’s disease and hip fractures.The inclusion criteria were 50 or more subjects per group and a study period of 1 year or longer.Five RCTs were identified and the relative risk and95%confidence interval were calculated for individual RCTs.Sunlight exposure increased serum hydroxyvitamin D[25(OH)D]concentration,improved motor function,decreased bone resorption and increased BMD.Alendronate or risedronate with vitamin D supplementation increased serum 25(OH)D concentration,strongly decreased bone resorption and increased BMD.Menatetrenone(vitamin K2)decreased serum undercarboxylated osteocalcin concentration,decreased bone resorption and increased BMD.Sunlight exposure(men and women),menatetrenone(women),alendronate and risedronate with vitamin D supplementation(women)significantly reduced the incidence of hip fractures.The respective RRs(95%confidence intervals)according to the intention-to-treat analysis were 0.27(0.08,0.96),0.13(0.02,0.97),0.29(0.10,0.85)and 0.20(0.06,0.68).Interventions,including sunlight exposure,menatetrenone and oral bisphosphonates with vitamin D supplementation,have a protective effect against hip fractures elderly patients with Parkinson’s disease.展开更多
BACKGROUND: The present study aimed to compare outcome of primary and secondary Illizarov's fi xator application as a treatment method for type III open tibial fractures in terms of nonunion and wound infection.ME...BACKGROUND: The present study aimed to compare outcome of primary and secondary Illizarov's fi xator application as a treatment method for type III open tibial fractures in terms of nonunion and wound infection.METHODS: This prospective study was done in a tertiary care center. Forty-eight type III tibial fractures were treated with Illizarov's apparatus between 2008 and 2011. The patients were divided into two groups depending on the treatment protocol, timing of wound closure and Illizarov's application, primary(n=28) and secondary(n=20).RESULTS: In the primary group, healing was achieved in all 28 patients. The median time to recovery was 24 weeks, and the median number of operations was 3. There were 6 patients with a bone defect. In the secondary group, complete recovery was achieved in 18 out of 20 patients. The median time to recovery was 30 weeks, and the median number of operations 5. There were 9 patients with a bone defect. The median time to recovery and the number of operations were signifi cantly smaller in patients undergoing primary operation. Union was 100% in the primary group and more than 95% in the secondary group. Chronic osteomyelitis persisted in one patient and below amputation was done in one patient in the secondary group.CONCLUSION: Primary wound closure and Illizarov's fixation required a smaller number of operations and shorter time to recovery than secondary wound closure and Illizarov's fi xation, mostly due to a signifi cantly less number of patients with a bone defect in the primary group.展开更多
Parkinson’s disease is a neurodegenerative disorder that is common in older people and is highly associated with depression, anxiety, apathy, psychosis, cognitive impairment, imbalance and sleep disturbances. These p...Parkinson’s disease is a neurodegenerative disorder that is common in older people and is highly associated with depression, anxiety, apathy, psychosis, cognitive impairment, imbalance and sleep disturbances. These patients have an increased risk of fracture compared to the general population. Comprehensive searches of databases are performed to identify reviews about the risk of fractures in this disease. Parkinson’s patients are at increased risk for low bone mineral density due to the effect of drugs, Parkinson’s disease and age factor, leading to an increased risk of falling down and fractures, especially in the hip. So, improved and innovative treatments with the focus on minimizing inadvertent bone resorption with anti-Parkinson’s disease medication will be highly effective in reducing fear of the disease and providing the patient with a better quality of life.展开更多
Background:Unfavorable fractures are among the most common complications of bilateral sagittal split ramus osteotomy(BSSRO).This study aimed to evaluate unfavorable fracture patterns during BSSRO and assess the relate...Background:Unfavorable fractures are among the most common complications of bilateral sagittal split ramus osteotomy(BSSRO).This study aimed to evaluate unfavorable fracture patterns during BSSRO and assess the related risk factors and treatment measures.Methods:The clinical records and radiographs of 679 patients(1358 sides)who underwent BSSRO at Shanghai Ninth People’s Hospital between September 2013 and December 2021 were examined.Results:Patients with unfavorable fractures who underwent surgical restoration were studied.The incidence of unfavorable fractures was 0.8%(n¼11),with the highest rate in the third year.The unfavorable fractures were divided into three types by location and clinical treatment:(1)SSRO could still be completed after buccal/lingual plate unfavorable fracture(0.6%,n=8);(2)condylar/coronoid process fractures/intermaxillary fixation needed(0.1%,n=2);(3)additional osteotomy required(0.07%,n=1).Conclusion:These results suggest that as a surgeon’s experience increases,the rate of unfavorable fractures may decrease.The novel classification of unfavorable fractures for SSRO might be useful for surgeons to make appropriate treatment choices during orthognathic surgery.展开更多
Introduction: Proximal humerus fractures are common, however, there is no consensus on a decision-making algorithm for the therapeutic management of these fractures, the aim of this study is to evaluate and compare fu...Introduction: Proximal humerus fractures are common, however, there is no consensus on a decision-making algorithm for the therapeutic management of these fractures, the aim of this study is to evaluate and compare functional results between two surgical techniques and to deduce the satisfactory results of the Kapandji’s pinning which, compared to the screw plate, should keep its place in the therapeutic arsenal. Patients and Methods: It’s a retrospective study, including two groups: The first of 18 patients treated with palm-tree pinning using kapandji’s technique, the second of 16 patients treated with anatomical screw plate at the orthopedic trauma service of the Mohamed VI university hospital between July 2013 and July 2018. We compared the results of the two techniques by studying three parameters which are the healing time, the anatomical reduction, and the functional outcomes. The average age was 46 years, and the sex ratio (M/F) was 2.3. Results: The statistical analysis of functional and radiological results showed no significant difference between the two techniques, indeed the average healing time was 56.3 days in the group treated by screw plate and 55.2 days in the group treated by Kapandji’s pinning (p = 0.46), Constant’s score was 73.18 and 79.05 respectively (p = 0.27) and the average cephalodiaphyseal angle was 49.03° and 52.07°, respectively (p = 0.35). Discussion: This study has clearly shown, as reported in the literature, that there is no conclusive evidence to suggest superiority of os-teosynthesis by anatomical plate versus kapandji’s pinning. However, the simple achievement of pinning according to kapandji’s technique, the preservation of soft tissues and the low cost make us prefer this technique. Furthermore, despite the progress noted in the development of osteosynthesis means of the proximal humerus, percutaneous pinning should always keep its place.展开更多
To evaluate the clinical significance of Baumann’s angle in the closed reduction and percutaneous pinning fixation for supracondylar fractures of the humerus in children.Methods There were 97 children (male 59,female...To evaluate the clinical significance of Baumann’s angle in the closed reduction and percutaneous pinning fixation for supracondylar fractures of the humerus in children.Methods There were 97 children (male 59,female 38,mean age of 6.8 years) with displaced supracondylar fracrtures of the humerus were treated in this hospital.Under fluoroscopy guidance,three-dimensional displacement of fractures was corrected by closed reduction.The percutaneous Kirschner wire pinning was applied only if the radiographs demonstrated that Baumann’s angle was less than 4 degree compared to that on the normal side.All of them were followed up for 34.5 months (range,12 to 48 months).Results There was one case with ulnar nerve palsy associated with the pinning.There were no Volkmann’s contracture in this group.X-ray examinations revealed an average 73.7 degrees of Baumann angle on the injured and 72.8 on uninjured side.An average 7.6 degrees of the carrying angle on the injured and 9.7 on uninjured side were also demonstrated by radiography.Five patients developed slight cubitus varus deformity.The result according to Flynn criteria were excellent in 85 patients (87.6%),good in 12 patients (12.4%).Conclusion The satisfactory results can be gained in children with displaced supracondylar fractures of the humerus by restoration of the normal Baumann angle and percutaneous pinning fixation.18 refs,2 figs.展开更多
Thoracolumbar fractures are usually treated by open posterior pedicle screw fixation.However,this procedure involves massive paraspinal muscle stripping,inflicting surgical trauma,and prolonged X-ray exposure.In this ...Thoracolumbar fractures are usually treated by open posterior pedicle screw fixation.However,this procedure involves massive paraspinal muscle stripping,inflicting surgical trauma,and prolonged X-ray exposure.In this study,we observed 127 patients with single-segment injury thoracolumbar fractures.Thirty-six patients were treated by the modified Wiltse’s paraspinal approach with minimally invasive channel system,while 91 patients were treated via traditional posterior approach.Operation time,intraoperative blood loss,intraoperative fluoroscopy frequency,screw placement accuracy,visual analogue scale score,and Cobb’s angle of two groups were compared.The X-ray exposure times were notably reduced(4.2±1.6) in the new approach group(P<0.05).The pedicle screw placement accuracy and Cobb’s angle after surgery were similar in the two groups.We conclude that modified Wiltse’s paraspinal approach w ith spinal minimally invasive channel system surgery can significantly reduce the X-ray exposure times and is an alternative therapy for the thoracolumbar fracture.展开更多
In fractured reservoir beds, fracture characteristics affect seismic wave response. Fractured models based on the Hudson＇s fractured medium theory were constructed in our laboratory by a backfilling technique. For th...In fractured reservoir beds, fracture characteristics affect seismic wave response. Fractured models based on the Hudson＇s fractured medium theory were constructed in our laboratory by a backfilling technique. For the same fracture density, the variations of the velocity and amplitude of the primary wave and shear wave parallel and perpendicular to the fracture were observed by altering the diameter （scale） of the penny-shaped fracture disk. The model test indicated that an increase of fracture scale increased the velocity and amplitude of the primary wave by about 2%. When the shear wave propagated parallel to the fracture, the velocity of the fast shear wave hardly changed, while the velocity of slow shear wave increased by 2.6% with increasing fracture scale. The results indicated that an increase of fracture scale would reduce the degree of anisotropy of the shear wave. The amplitudes of slow shear waves propagating parallel and perpendicular to fractures decreased with increasing fracture scale.展开更多
Association of fracture of trapezium with Bennett'sfracture is very rare and makes reduction and stabilisation more difficult. We are reporting a rare case of Bennett's fracture with fracture of the trapezium ...Association of fracture of trapezium with Bennett'sfracture is very rare and makes reduction and stabilisation more difficult. We are reporting a rare case of Bennett's fracture with fracture of the trapezium and subluxation of the carpo-metacarpal joint(CMC) joint. The patient was a 47-year-old school teacher who fell from his motorbike on his outstretched right dominant hand. Radiographs and computed tomography showed fracture of the trapezium with subluxation of the CMC joint, associated with Bennett's fracture. Open reduction and internal fixation was carried out. Trapezium was reduced first and secured with a 2 mm diameter screw. Bennett's fracture was then reduced and fixed with two per-cutaneously placed Kirchner's wires. CMC was stabilised with percutaneous Kirchner's wires. Latest follow up at 12 mo showed a healed fracture with good reduction of the CMC joint. Clinically patient had no pain and normal extension, abduction and opposition of the thumb. QuickD ASH score was 3.9/100. Thus, fracture of trapezium associated with a Bennett's fracture is a rare injury and if ignored it may lead to poor results. This injury is more challenging to manage than an isolated Bennett's fracture as anatomical reduction of the trapezium with reduction of the first CMC is needed. Fracture of the trapezium should be fixed first as this will provide a stable base for reduction of the Bennett's fracture.展开更多
The effects of plastic deformation and H2 S on fracture toughness of high strength casing steel（C110 steel） were investigated. The studied casing specimens are as follows： original casing, plastic deformation（PD）...The effects of plastic deformation and H2 S on fracture toughness of high strength casing steel（C110 steel） were investigated. The studied casing specimens are as follows： original casing, plastic deformation（PD） casing and PD casing after being immersed in NACE A solution saturated with H2S（PD＋H2S）. Instrumented impact method was employed to evaluate the impact behaviors of the specimens, meanwhile, dynamic fracture toughness（JId） was calculated by using Rice model and Schindler model. The experimental results show that dynamic fracture toughness of the casing decreases after plastic deformation. Compared with that of the original casing and PD casing, the dynamic fracture toughness decreases further when the PD casing immersed in H2 S, moreover, there are ridge-shaped feature and many secondary cracks present on the fracture surface of the specimens. Impact fracture mechanism of the casing is proposed as follows： the plastic deformation results in the increase of defect density of materials where the atomic hydrogen can accumulate in reversible or irreversible traps and even recombine to form molecular hydrogen, subsequently, the casing material toughness decreases greatly.展开更多
The fatigue fracture behavior of four ultrahigh strength steels with different melting processes and therefore different inclusion sizes were studied by using a rotating bar two-point bending fatigue machine in the hi...The fatigue fracture behavior of four ultrahigh strength steels with different melting processes and therefore different inclusion sizes were studied by using a rotating bar two-point bending fatigue machine in the high-cycle regime up to 107 cycles of loading. The fracture surfaces were observed by field emission scanning electron microscopy （FESEM）. It was found that the size of inclusion has significant effect on the fatigue behavior. For AtSI 4340 steel in which the inclusion size is smaller than 5.5 μm, all the fatigue cracks except one did not initiated from inclusion but from specimen surface and conventional S-N curve exists. For 65Si2MnWE and Aermet 100 steels in which the average inclusion sizes are 12.2 and 14.9 μm, respectively, fatigue cracks initiated from inclusions at lower stress amplitudes and stepwise S-N curves were observed. The S-N curve displays a continuous decline and fatigue failures originated from large oxide inclusion for 60Si2CrVA steel in which the average inclusion size is 44.4 pro. In the case of internal inclusion-induced fractures at cycles beyond about 1×10^6 for 65Si2MnWE and 60Si2CrVA steels, inclusion was always found inside the fish-eye and a granular bright facet （GBF） was observed in the vicinity around the inclusion. The GBF sizes increase with increasing the number of cycles to failure Nf in the long-life regime. The values of stress intensity factor range at crack initiation site for the GBF are almost constant with Nf, and are almost equal to that for the surface inclusion and the internal inclusion at cycles lower than about 1×10^6. Neither fish-eye nor GBF was observed for Aermet 100 steel in the present study.展开更多
文摘Hypovitaminosis D and K due to malnutrition or sunlight deprivation,increased bone resorption due to immobilization,low bone mineral density(BMD)and an increased risk of falls may contribute to an increased risk of hip fractures in patients with Parkinson’s disease.The purpose of the present study was to clarify the efficacy of interventions intended to prevent hip fractures in elderly patients with Parkinson’s disease.Pub Med was used to search the literature for randomized controlled trials(RCTs)regarding Parkinson’s disease and hip fractures.The inclusion criteria were 50 or more subjects per group and a study period of 1 year or longer.Five RCTs were identified and the relative risk and95%confidence interval were calculated for individual RCTs.Sunlight exposure increased serum hydroxyvitamin D[25(OH)D]concentration,improved motor function,decreased bone resorption and increased BMD.Alendronate or risedronate with vitamin D supplementation increased serum 25(OH)D concentration,strongly decreased bone resorption and increased BMD.Menatetrenone(vitamin K2)decreased serum undercarboxylated osteocalcin concentration,decreased bone resorption and increased BMD.Sunlight exposure(men and women),menatetrenone(women),alendronate and risedronate with vitamin D supplementation(women)significantly reduced the incidence of hip fractures.The respective RRs(95%confidence intervals)according to the intention-to-treat analysis were 0.27(0.08,0.96),0.13(0.02,0.97),0.29(0.10,0.85)and 0.20(0.06,0.68).Interventions,including sunlight exposure,menatetrenone and oral bisphosphonates with vitamin D supplementation,have a protective effect against hip fractures elderly patients with Parkinson’s disease.
文摘BACKGROUND: The present study aimed to compare outcome of primary and secondary Illizarov's fi xator application as a treatment method for type III open tibial fractures in terms of nonunion and wound infection.METHODS: This prospective study was done in a tertiary care center. Forty-eight type III tibial fractures were treated with Illizarov's apparatus between 2008 and 2011. The patients were divided into two groups depending on the treatment protocol, timing of wound closure and Illizarov's application, primary(n=28) and secondary(n=20).RESULTS: In the primary group, healing was achieved in all 28 patients. The median time to recovery was 24 weeks, and the median number of operations was 3. There were 6 patients with a bone defect. In the secondary group, complete recovery was achieved in 18 out of 20 patients. The median time to recovery was 30 weeks, and the median number of operations 5. There were 9 patients with a bone defect. The median time to recovery and the number of operations were signifi cantly smaller in patients undergoing primary operation. Union was 100% in the primary group and more than 95% in the secondary group. Chronic osteomyelitis persisted in one patient and below amputation was done in one patient in the secondary group.CONCLUSION: Primary wound closure and Illizarov's fixation required a smaller number of operations and shorter time to recovery than secondary wound closure and Illizarov's fi xation, mostly due to a signifi cantly less number of patients with a bone defect in the primary group.
文摘Parkinson’s disease is a neurodegenerative disorder that is common in older people and is highly associated with depression, anxiety, apathy, psychosis, cognitive impairment, imbalance and sleep disturbances. These patients have an increased risk of fracture compared to the general population. Comprehensive searches of databases are performed to identify reviews about the risk of fractures in this disease. Parkinson’s patients are at increased risk for low bone mineral density due to the effect of drugs, Parkinson’s disease and age factor, leading to an increased risk of falling down and fractures, especially in the hip. So, improved and innovative treatments with the focus on minimizing inadvertent bone resorption with anti-Parkinson’s disease medication will be highly effective in reducing fear of the disease and providing the patient with a better quality of life.
基金the University-Industry Collaborative Education Program of the Ministry of Education of China(grant no.201801301030).
文摘Background:Unfavorable fractures are among the most common complications of bilateral sagittal split ramus osteotomy(BSSRO).This study aimed to evaluate unfavorable fracture patterns during BSSRO and assess the related risk factors and treatment measures.Methods:The clinical records and radiographs of 679 patients(1358 sides)who underwent BSSRO at Shanghai Ninth People’s Hospital between September 2013 and December 2021 were examined.Results:Patients with unfavorable fractures who underwent surgical restoration were studied.The incidence of unfavorable fractures was 0.8%(n¼11),with the highest rate in the third year.The unfavorable fractures were divided into three types by location and clinical treatment:(1)SSRO could still be completed after buccal/lingual plate unfavorable fracture(0.6%,n=8);(2)condylar/coronoid process fractures/intermaxillary fixation needed(0.1%,n=2);(3)additional osteotomy required(0.07%,n=1).Conclusion:These results suggest that as a surgeon’s experience increases,the rate of unfavorable fractures may decrease.The novel classification of unfavorable fractures for SSRO might be useful for surgeons to make appropriate treatment choices during orthognathic surgery.
文摘Introduction: Proximal humerus fractures are common, however, there is no consensus on a decision-making algorithm for the therapeutic management of these fractures, the aim of this study is to evaluate and compare functional results between two surgical techniques and to deduce the satisfactory results of the Kapandji’s pinning which, compared to the screw plate, should keep its place in the therapeutic arsenal. Patients and Methods: It’s a retrospective study, including two groups: The first of 18 patients treated with palm-tree pinning using kapandji’s technique, the second of 16 patients treated with anatomical screw plate at the orthopedic trauma service of the Mohamed VI university hospital between July 2013 and July 2018. We compared the results of the two techniques by studying three parameters which are the healing time, the anatomical reduction, and the functional outcomes. The average age was 46 years, and the sex ratio (M/F) was 2.3. Results: The statistical analysis of functional and radiological results showed no significant difference between the two techniques, indeed the average healing time was 56.3 days in the group treated by screw plate and 55.2 days in the group treated by Kapandji’s pinning (p = 0.46), Constant’s score was 73.18 and 79.05 respectively (p = 0.27) and the average cephalodiaphyseal angle was 49.03° and 52.07°, respectively (p = 0.35). Discussion: This study has clearly shown, as reported in the literature, that there is no conclusive evidence to suggest superiority of os-teosynthesis by anatomical plate versus kapandji’s pinning. However, the simple achievement of pinning according to kapandji’s technique, the preservation of soft tissues and the low cost make us prefer this technique. Furthermore, despite the progress noted in the development of osteosynthesis means of the proximal humerus, percutaneous pinning should always keep its place.
文摘To evaluate the clinical significance of Baumann’s angle in the closed reduction and percutaneous pinning fixation for supracondylar fractures of the humerus in children.Methods There were 97 children (male 59,female 38,mean age of 6.8 years) with displaced supracondylar fracrtures of the humerus were treated in this hospital.Under fluoroscopy guidance,three-dimensional displacement of fractures was corrected by closed reduction.The percutaneous Kirschner wire pinning was applied only if the radiographs demonstrated that Baumann’s angle was less than 4 degree compared to that on the normal side.All of them were followed up for 34.5 months (range,12 to 48 months).Results There was one case with ulnar nerve palsy associated with the pinning.There were no Volkmann’s contracture in this group.X-ray examinations revealed an average 73.7 degrees of Baumann angle on the injured and 72.8 on uninjured side.An average 7.6 degrees of the carrying angle on the injured and 9.7 on uninjured side were also demonstrated by radiography.Five patients developed slight cubitus varus deformity.The result according to Flynn criteria were excellent in 85 patients (87.6%),good in 12 patients (12.4%).Conclusion The satisfactory results can be gained in children with displaced supracondylar fractures of the humerus by restoration of the normal Baumann angle and percutaneous pinning fixation.18 refs,2 figs.
基金financially supported by the National Natural Science Foundation of China(Grant No.81672152 and No.81871773)the Jiangsu Natural Science Foundation(Grant No.BE2018132)。
文摘Thoracolumbar fractures are usually treated by open posterior pedicle screw fixation.However,this procedure involves massive paraspinal muscle stripping,inflicting surgical trauma,and prolonged X-ray exposure.In this study,we observed 127 patients with single-segment injury thoracolumbar fractures.Thirty-six patients were treated by the modified Wiltse’s paraspinal approach with minimally invasive channel system,while 91 patients were treated via traditional posterior approach.Operation time,intraoperative blood loss,intraoperative fluoroscopy frequency,screw placement accuracy,visual analogue scale score,and Cobb’s angle of two groups were compared.The X-ray exposure times were notably reduced(4.2±1.6) in the new approach group(P<0.05).The pedicle screw placement accuracy and Cobb’s angle after surgery were similar in the two groups.We conclude that modified Wiltse’s paraspinal approach w ith spinal minimally invasive channel system surgery can significantly reduce the X-ray exposure times and is an alternative therapy for the thoracolumbar fracture.
文摘In fractured reservoir beds, fracture characteristics affect seismic wave response. Fractured models based on the Hudson＇s fractured medium theory were constructed in our laboratory by a backfilling technique. For the same fracture density, the variations of the velocity and amplitude of the primary wave and shear wave parallel and perpendicular to the fracture were observed by altering the diameter （scale） of the penny-shaped fracture disk. The model test indicated that an increase of fracture scale increased the velocity and amplitude of the primary wave by about 2%. When the shear wave propagated parallel to the fracture, the velocity of the fast shear wave hardly changed, while the velocity of slow shear wave increased by 2.6% with increasing fracture scale. The results indicated that an increase of fracture scale would reduce the degree of anisotropy of the shear wave. The amplitudes of slow shear waves propagating parallel and perpendicular to fractures decreased with increasing fracture scale.
文摘Association of fracture of trapezium with Bennett'sfracture is very rare and makes reduction and stabilisation more difficult. We are reporting a rare case of Bennett's fracture with fracture of the trapezium and subluxation of the carpo-metacarpal joint(CMC) joint. The patient was a 47-year-old school teacher who fell from his motorbike on his outstretched right dominant hand. Radiographs and computed tomography showed fracture of the trapezium with subluxation of the CMC joint, associated with Bennett's fracture. Open reduction and internal fixation was carried out. Trapezium was reduced first and secured with a 2 mm diameter screw. Bennett's fracture was then reduced and fixed with two per-cutaneously placed Kirchner's wires. CMC was stabilised with percutaneous Kirchner's wires. Latest follow up at 12 mo showed a healed fracture with good reduction of the CMC joint. Clinically patient had no pain and normal extension, abduction and opposition of the thumb. QuickD ASH score was 3.9/100. Thus, fracture of trapezium associated with a Bennett's fracture is a rare injury and if ignored it may lead to poor results. This injury is more challenging to manage than an isolated Bennett's fracture as anatomical reduction of the trapezium with reduction of the first CMC is needed. Fracture of the trapezium should be fixed first as this will provide a stable base for reduction of the Bennett's fracture.
基金Funded by the Construction of Key Disciplines for Young Teacher Science Foundation of the Southwest Petroleum University(No.P209)the Research Fund for the Doctoral Program of Higher Education(No.20105121120002)the National Natural Science Foundation of China(Nos.51004084 and 51374177)
文摘The effects of plastic deformation and H2 S on fracture toughness of high strength casing steel（C110 steel） were investigated. The studied casing specimens are as follows： original casing, plastic deformation（PD） casing and PD casing after being immersed in NACE A solution saturated with H2S（PD＋H2S）. Instrumented impact method was employed to evaluate the impact behaviors of the specimens, meanwhile, dynamic fracture toughness（JId） was calculated by using Rice model and Schindler model. The experimental results show that dynamic fracture toughness of the casing decreases after plastic deformation. Compared with that of the original casing and PD casing, the dynamic fracture toughness decreases further when the PD casing immersed in H2 S, moreover, there are ridge-shaped feature and many secondary cracks present on the fracture surface of the specimens. Impact fracture mechanism of the casing is proposed as follows： the plastic deformation results in the increase of defect density of materials where the atomic hydrogen can accumulate in reversible or irreversible traps and even recombine to form molecular hydrogen, subsequently, the casing material toughness decreases greatly.
基金the National Key Basic Research and Development Program of China under grant No.2004CB619104.
文摘The fatigue fracture behavior of four ultrahigh strength steels with different melting processes and therefore different inclusion sizes were studied by using a rotating bar two-point bending fatigue machine in the high-cycle regime up to 107 cycles of loading. The fracture surfaces were observed by field emission scanning electron microscopy （FESEM）. It was found that the size of inclusion has significant effect on the fatigue behavior. For AtSI 4340 steel in which the inclusion size is smaller than 5.5 μm, all the fatigue cracks except one did not initiated from inclusion but from specimen surface and conventional S-N curve exists. For 65Si2MnWE and Aermet 100 steels in which the average inclusion sizes are 12.2 and 14.9 μm, respectively, fatigue cracks initiated from inclusions at lower stress amplitudes and stepwise S-N curves were observed. The S-N curve displays a continuous decline and fatigue failures originated from large oxide inclusion for 60Si2CrVA steel in which the average inclusion size is 44.4 pro. In the case of internal inclusion-induced fractures at cycles beyond about 1×10^6 for 65Si2MnWE and 60Si2CrVA steels, inclusion was always found inside the fish-eye and a granular bright facet （GBF） was observed in the vicinity around the inclusion. The GBF sizes increase with increasing the number of cycles to failure Nf in the long-life regime. The values of stress intensity factor range at crack initiation site for the GBF are almost constant with Nf, and are almost equal to that for the surface inclusion and the internal inclusion at cycles lower than about 1×10^6. Neither fish-eye nor GBF was observed for Aermet 100 steel in the present study.
