Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 22
Filter
Add filters








Year range
1.
Chinese Journal of Trauma ; (12): 545-550, 2023.
Article in Chinese | WPRIM | ID: wpr-992633

ABSTRACT

Objective:To compare the predictive performance of different machine learning models using pre-hospital data to predict adverse inhospital outcome in patients with severe trauma.Methods:A retrospective cohort study was conducted to analyze the clinical data of 100 135 patients with severe trauma from the National Trauma Data Bank (NTDB) from January 2017 to December 2018. There were 69 644 males and 30 480 females apart from 11 patients with missing gender information, with the range age of 16-89 years [(50.1±21.1)years]. Clinical characteristics included demographic information (sex and age), trauma type (blunt or penetrating trauma), pre-hospital time [emergency medical services (EMS) response time, EMS scene time, and EMS transport time], pre-hospital vital signs (systolic blood pressure, pulse rate, respiratory rate, and oxygen saturation), trauma score [Glasgow coma score (GCS) and injury severity score (ISS)]. The original data were divided into the training set (in the year 2017) and the testing set (in the year 2018) according to the year of admission, including 50 429 patients in the training set and 49 706 patients in the testing set. The patients were classified into non-adverse outcome group ( n=94 526) and adverse outcome group ( n=5 609), according to whether they had an adverse outcome or not. There were 2 808 patients with adverse outcome in the training set and 2 801 patients with adverse outcome in the testing set. All models were built based on the training set. Eight machine learning algorithms consisting of neural network (NNET), naive Bayes (NB), gradient boosting machine (GBM), adaptive boosting (Ada), random forest (RF), bagging tree (BT), categorical boosting (CatBoost) and extreme gradient boosting (XGB) were used to construct prediction models for clinical outcomes among patients with severe trauma based on their clinical features. Models were evaluated according to the sensitivity, specificity, area under the receiver operating characteristic (ROC) curve (AUC) and Hosmer-Lemeshow goodness-of-fit test. Results:Of the NNET, NB, GBM, Ada, RF, BT, CatBoost and XGB models in the testing set, the sensitivity was 0.84, 0.83, 0.27, 0.79, 0.83, 0.81, 0.62 and 0.78, respectively; the specificity was 0.79, 0.76, 0.81, 0.79, 0.79, 0.74, 0.83 and 0.79, respectively; the AUC was 0.89 (95% CI 0.88, 0.90), 0.86 (95% CI 0.85, 0.87), 0.54 (95% CI 0.53, 0.55), 0.86 (95% CI 0.85, 0.87), 0.88 (95% CI 0.88, 0.90), 0.83 (95% CI 0.82, 0.85), 0.77 (95% CI 0.76, 0.79) and 0.86 (95% CI 0.85, 0.87), respectively. The NNET model had the best differentiation. In terms of calibration degree, both NNET and NB showed good performance ( P>0.05 for Hosmer-Lemeshow goodness-of-fit test). Conclusion:The NNET model has a favorable predictive performance for adverse inhospital outcome in patients with severe trauma, which may provide a reference for the rapid prediction of prognosis in patients with severe trauma.

2.
Chinese Journal of Trauma ; (12): 11-22, 2022.
Article in Chinese | WPRIM | ID: wpr-932205

ABSTRACT

Blast injury of the chest injury is the most common wound in modern war trauma and terrorist attacks, and is also the most fatal type of whole body explosion injury. Most patients with severe blast injury of the chest die in the early stage before hospitalization or during transportation, so first aid is critically important. At present, there exist widespread problems such as non-standard treatment and large difference in curative effect, while there lacks clinical treatment standards for blast injury of the chest. According to the principles of scientificity, practicality and advancement, the Trauma Society of Chinese Medical Association has formulated the guidance of classification, pre-hospital first aid, in-hospital treatment and major injury management strategies for blast injury of the chest, aiming to provide reference for clinical diagnosis and treatment.

3.
Chinese Journal of Medical Instrumentation ; (6): 38-41, 2022.
Article in Chinese | WPRIM | ID: wpr-928854

ABSTRACT

Cannulated Screw is a common internal fixation for the treatment of femoral neck fractures. However, the traditional implantation method has disadvantages such as inaccuracy and large radiation exposure. Based on the anatomical characteristics of the femoral neck and geometric principles, we develop a novel guide device for cannulated screws insertion. The cadaver experiment showed that it can improve the accuracy of cannulated screws implantation, reduce puncture attempts and the radiation exposure of doctors and patients.


Subject(s)
Humans , Bone Screws , Femoral Neck Fractures/surgery , Fracture Fixation, Internal , Robotic Surgical Procedures
4.
Chinese Journal of Pancreatology ; (6): 230-232, 2016.
Article in Chinese | WPRIM | ID: wpr-501977

ABSTRACT

Objective To investigate functional role and clinical significance of the methylation in the promoter of TPAP gene in the development and progression of pancreatic cancer.Methods Surgically resected specimen from 68 patients who were pathologically diagnosed as pancreatic cancer in Changhai Hospital from July 2006 to August 2009 were collected.The methylation in the promoter of TPAP gene in tumor and nontumor adjacent tissue was detected by methylation specific PCR.Results The methylation rate of tumor and non-tumor adjacent tissue was (0.214 ± 0.057) % and (0.084 ± 0.096) %,respectively,and pancreatic cancer tissue had significantly higher methylation rate than the adjacent tissue.Hypermethylation of TPAP gene was not correlated with age,gender,tumor differentiation,lymphatic metastasis,serum CEA and CA19-9,but was positively correlated with distant metastasis.Conclusions Hypermethylation in the promoter of TPAP gene may participate in the invasion and metastasis of pancreatic cancer and the hypermethylation of the promoter is closely associated with the tumorigenesis and development of pancreatic cancer.

5.
Chinese Journal of Orthopaedic Trauma ; (12): 758-761, 2011.
Article in Chinese | WPRIM | ID: wpr-421126

ABSTRACT

Objective To explore the effect of persistent stress on the ultrastructure of cancellous bone in the process of fracture healing.Method A transverse osteotomy on both sides of the femoral tuberositas was performed in 20 adult dogs. One side was fixed with a self-designed tuberositas memofy-pressure connector (TMC) which was made of NiTi shape memory alloy, and the other with compressive steel-wire (SW) cerclage.Five animals in each group were sacrificed at 2, 4, 8, 12 weeks after operation and observed under transmission electron microscope.Results The fracture healing was accelerated in the TMC group.The osteoblasts, chondroblasts and collagen fibers at the fracture sites showed significantly different morphology between the 2 groups at every observation time.Most cells and collagen fibers in the TMC group grew along the same direction as the stress, but those in the SW group grew in disorder.Both the number and functional activity of the osteoblasts and chondroblasts were higher in the TMC group than in the SW group.Conclusion Persistent stress can enhance healing and bone reconstruction following a cancellous bone fracture.

6.
Chinese Journal of Trauma ; (12): 9-14, 2009.
Article in Chinese | WPRIM | ID: wpr-396841

ABSTRACT

Objective To design a new method of posterior wall reconstruction for severely corn-minuted and obsolete fracture of the posterior wall of the aeetabulum. Methods (1) Biomechanical study (from two perspectives: the stability and the stress distribution on the femoral head and the acetabu-lure) : six fresh adult' s pelvis and femur specimens were collected and divided into experimental group ( consisted of the left sides) and control group ( consisted of the right sides). After the defects of the pos-terior wall were made, the defects were anatomically reconstructed with the harvested ilium by acetabular tridimentional memory fixation system (ATMFS) in the experimental group, whereas the acetabular frag-ments were repositioned to the defect sites and fixated by the plates and screws in the control group. Lon-gitudinal and latitudinal displacement, stability of the anatomically reconstructed posterior wall of the ace-tabulum, the fitness of femoral head to the acetabulum after anatomical reconstruction and mean and maxi-mum pressure of anterior wall, posterior and cupuh of the acetabuhm were analysed and compared. (2) Cinical study: The posterior wall defect on the harvested ilium piece was repaired with 3-directional loc-king of ATMFS in 10 male patients (at age of 16-50 years, mean 36.4 years) from January 2000 to June 2002. There were seven patients with flesh acetabular fractures and three with old acetabular fractures.The period from fracture to reconstruction for the patients with old fractures was 58-251 days ( 137.7 days an average). The patients were foUowed up for 5.8 years (average 5.2-7.1 years). Results (1) Biomechanical study showed no statistical difference upon stability and fitness of femoral head to acetabu-lum after reconstruction in experimental and control groups. (2) Clinical study: postoperative X-ray film showed no repeated displacement of the fracture and the patients began out-of-bed movement with weight bearing after 1.6 months (1.2-2.1 months). Heterotopic ossification was found in two patients, with no influence on the joint function. According to the elinieal ranking standard of Modified d' Aubigne and Postal, the excellence rate was 93%. Conclusions Anatomical reconstruction of posterior wall of the acetabulum by using serf ilium with ATMS has good stability and stress distribution of the femoral head and the reconstructed acetabulum in clinical application and offers a new method for treatment of severely comminuted and obsolete fracture of posterior wall of acetabulum.

7.
Chinese Journal of Tissue Engineering Research ; (53): 7647-7650, 2009.
Article in Chinese | WPRIM | ID: wpr-405779

ABSTRACT

OBJECTIVE: To compare the clinical effect between Gamma nail and proximal femoral nail (PFN) on the treatment for femoral intertrochanteric fractures in the elderly.METHODS: A total of 131 cases (39 males and 92 females; aged 70?81 years, mean age of 76 years) with femoral intertrochanteric fractures were collected from the Department of Orthopaedics, the Affiliated Changhai Hospital of the Second Military Medical University of Chinese PLA from January 2005 to January 2008. Femoral intertrochanteric fractures were classified based on AO system, including type A1 (n=56) and type A2 (n=75). All cases were randomly divided into Gamma nail group (n=65) and PFN group (n=66). Pre- and post-operative blood loss, blood transfusion volume, operating time, and length of stay were recorded, while the complications were detected following nail implantation. Functional changes of injured limbs were detected after 9 months.RESULTS: At 9 months after following up, there was no significant difference in blood loss, blood transfusion volume, operating time, and length of stay between the two groups before and after implantation (P> 0.05). Furthermore, complications did not occur during or after implantation. Six cases in the PFN group had infection in which of them had diabetes mellitus. There were no complications such as cutting out of femoral head, femoral shaft fractures, breakage of internal device or pushing out phenomenon. All cases got bone union at the final follow-up of nine months and did not get nonunion, delayed union of fractures or shortening of injured extremity.CONCLUSION: Gamma nail and PFN have equal effect on the treatment of femoral intertrochanteric fractures in the elderly.

8.
Chinese Journal of Trauma ; (12): 602-604, 2008.
Article in Chinese | WPRIM | ID: wpr-399171

ABSTRACT

Objective To retrospectively analyse the anterior and posterior surgical approaches in treatment of unstable burst thoracolumbar fractures and compare radiographic measurement parameters of beth surgical techniques so as to provide references for surgical treatment of such kind of fracture. Methods The study selected 41 patients with unstable thoracolumbar fracture treated with either anterior neurodecomprossion and fixation (n=19) or posterior reposition and internal fixation by pedicle screw (n=22) from January 2003 to December 2005. All patients were followed up for 24-48 months ( mean 38 months) and divided into anterior approach group and posterior approach group. Sagittal alignment was assessed by the Cobb angle depending on lateral radiographs. Results The Cobb angle of the anterior approach group was average 27.3°on admission but 3.1°postoperatively and 4.6° at follow-up; while the Cobb angle of posterior approach was average 26.1° on admission, 3.0°postoperatively and 12.5°at follow-up. There was no statistical difference between Cobb angle on admission and postoperative one (P>0.05) but showed significant differences between them at follow-up ( P<0.01). Conclusion The anterior surgical approach can consistently yield better maintenance of kyphotic correction compared with the posterior surgical approach.

9.
Chinese Journal of Tissue Engineering Research ; (53): 10397-10400, 2008.
Article in Chinese | WPRIM | ID: wpr-406796

ABSTRACT

BACKGROUND:Swan-like memory connector (SMC) can form a three-dimensional fixation on long bone shaft,ensure the stability of fracture ends,and produce a continuous dynamic compressive stress on the fracture ends.Insulin-like growth factorⅠ (IGF-Ⅰ) regulates bone development and metabolism,cell differentiation,as well as mitosis.During the union process of fracture,IGF-I is effective to promote cellular proliferation,stimulate bone formation and result in chondrogenesis.OBJECTIVE:To quantitatively determine the effect of SMC and conventional dynamic compression plate (DCP) on the concentration of local IGF-Ⅰ in the union duration of rabbit humerus fracture.DESIGN,TIME AND SETTING:A controlled observational animal study was performed in the laboratory,Department of Orthopaedics,Changhai Hospital,the Second Military Medical University of Chinese PLA from January to May in 2007.MATERIALS:SMC was Ni-Ti alloy panel,comprising 50%-53% Ni,was customized by Lanzhou Seemine Shape Memory Alloy Co.,Ltd.The temperature of shape recovery was (33±2) ℃.METHODS:Thirty adult New Zealand rabbits were used in this study and were processed into osteotomy.The experiment sides of rabbit humerus were cut and fixed with SMC at random,serving as SMC group,and the other sides were cut at the same position and fixed with DCP,serving as DCP group.Each five animals were put to death at the time points of 2,3,4,6,8,and 12 weeks after internal fixation.Specimens were obtained from the areas that were 0.5 cm besides the fracture line.MAIN OUTCOME MEASURES:Following internal fixation,the contents of local IGF-Ⅰ in the specimens of different time points (2,3,4,6,8,and 12 weeks) were determined in both SMC group and DCP group.RESULTS:In the SMC-treated group,the contents of IGF-I increased 2 weeks after internal fixation,reached the maximum at 6 weeks,and then decreased at 8-12 weeks.In the DCP-treated group,the contents of IGF-Ⅰincreased 2 weeks after internal fixation,reached the maximum at 8 weeks,and then decreased at 12 weeks.No significant differences were found between the SMC group and the DCP group at 2,8,12 weeks after internal fixation (P > 0.05).Compared with the DCP group,the SMC group had a remarkably higher content of IGF-Ⅰ at the time points of 3,4 and 6 weeks (P < 0.05).The difference was the most statistically significant at 4 weeks.CONCLUSION:Compared with conventional DCP,the SMC could better promote the secretion of IGF-Ⅰin fracture and facilitate the fracture union due to the continuous dynamic compressive stress and three-dimensional fixation.

10.
Chinese Journal of Tissue Engineering Research ; (53): 161-163, 2006.
Article in Chinese | WPRIM | ID: wpr-408693

ABSTRACT

BACKGROUND: It is often found in the clinic that apart from oppression and instability, there is much difference in sensibility and motion function recovery in patients who have similar imageological changes. Studies show that adhesion in the dura mater of spinal cord, traction of fibrous strip,traumatic scar, malacosis and cyst are the main causes.OBJECTIVE: To investigate the clinical effects of spinal decompression and nerve tissue implantation for obsolete incomplete paralysis.DESIGN: Self-control observation.SETTING: Department of Orthopaedics, Changhai Hospital of Second Military Medical University of Chinese PLA.PARTICIPANTS: We selected 28 patients with traumatic obsolete incom plete paralysis from the Department of Orthopaedics, Changhai Hospital of Second Military Medical University of Chinese PLA, from June 1994 to August 2002. Injured vertebral segments were T7-T9 (5 cases), T10-T12 (12 cases), and L1-2(11 cases). Sixteen patients had undergone decompression, fusion and internal fixation. Thirteen cases of them had undergone posterior decompression and pedicle screw internal fixation. The internal fixation devices had been removed in 7 patients before this procedure. Six cases of traumatic obsolete incomplete paralysis had been treated by hyperbaric oxygen. According to the classification of Frankel, 16 cases were degree B and 12 cases were degree C.METHODS: The dura mater of spinal cord was opened, and the fibrous bands adhering to the spinal cord from arachnoid, pia mater spinalis, ligamenta denticulatum, initial part of nerve root were complete relieved. Then the spinal cord with scar fibers contracted was opened by 3-6 incisions,which were 0.1-0.2 mm deep and longer than the scar part. Cyst found in the spinal cord in 6 cases was opened and the liquid in it was sucked. After that, we denuded spineurium and perineurium of the autogenous sural nerve graft, making the texture and appearance of the nerve look like cauda equine. The nerve was lined in several strips and longitudinally implanted into the incised spinal cord and cyst, and then it was sutured with pia mater spinalis with 9-0 scatheless wire. Finally the endorachis was sutured or covered by sacrospinal muscle.RESULTS: Sixteen cases were followed up for an average of 2.5 years, and all the patients entered the result analysis. The sensibility and motion func tion increased above one grade. Eleven patients who had suffered gatism had obvious progress. The strength of main muscle was increased by 2 grades and reached grade 4 in 16 cases, and walking capability was recovered. In 10 cases it was increased by 1 grade Only sensation had progress in 2 cases.CONCLUSION: Relieving adhesion in the endorhachis, incising the cicatricial spinal cord and bridging the autogenous peripheral nerve have good therapeutic results for gatism and recovering the muscle power of the ex-tremities for the patients with traumatic obsolete incomplete paralysis.

11.
International Journal of Biomedical Engineering ; (6)2006.
Article in Chinese | WPRIM | ID: wpr-558254

ABSTRACT

Nickel titanium shape memory alloys(NiTi-SMA) are thought to be the promising biomaterials of biological osteosynthesis(BO) with regard to biomedical applications. However, a critical concern is the release of harmful Ni ions from the implants into the living tissues. And little is known about the influences of surface modifications on the biocompatibility of these alloys. The emphasis was focused on the recent developments, the related questions, surface treatments, future directionsin.

12.
Chinese Journal of Orthopaedic Trauma ; (12)2004.
Article in Chinese | WPRIM | ID: wpr-585483

ABSTRACT

Objective To discuss the therapy for acetabular comminuted fractur e combined with compressive defects. Methods From July 1997 to February 2005, 43 cases of comminuted acetabular fracture combined with compressive defect were t reated. 25 cases were obsolete, 16 fresh, and 2 malformed (90 days after injury) . 34 cases were complicated fractures with defects, and 9 simple fractures with defects. The defect volumes ranged from 3 to 9 cm3, averaging 4.5 cm3. They were treated with ATMFS (acetabular tridimensional memory fixation system) to fixate the comminuted bone fragments tridimensionally. The modified acetabular approac h, reduction of acetabular comminuted articular face, anatomical reconstruction of posterior wall of acetabulum with autogenous ilium, autogenous and artificial bone implantation and bone wax isolation were used. The follow-ups lasted from 5 to 86 months, averaging 15.7 months. Results 31 cases achieved anatomical red uction by filling up the compressive defects. 12 cases were treated by anatomica l reconstruction of posterior wall. On average, 5.3 months after operation, the injured hip joint was as good as the healthy one in 40 cases. Ischemia necrosis of femoral head occurred in 1 case, and 2 cases experienced heterotopic ossifica tion with ischemia necrosis of femoral head which led to osseous fusion of hip j oint. Conclusion The new methods for treatment of acetabular fractures with comp ressive defects elevate the reduction rate of acetabulum and femoral head, and a re effective for the functional recovery of hip joint.

13.
Chinese Journal of Trauma ; (12)2003.
Article in Chinese | WPRIM | ID: wpr-675490

ABSTRACT

Objective To discuss the biomechanical factors in the nonunion of femoral fractures and raise corresponding measures. Methods Sixty eight cases with nonunion of femoral shaft fractures were treated with interlocking intramedullary nailing and 13 with nonunion of distal femoral fractures fixated with dynamic condylar screw (DCS). Inner and outer intramedullary bone graft was performed simultaneously. Results The follow up time was 8 24 months with an average of 14 months in all cases. Sixty eight cases got bone healing except for five cases with breakage of nail or lock nail, which were all cured with again interlocking intramedullary nailing combined with bone graft. Thirteen cases with nonunion of distal femoral fractures were healed after DCS internal fixation treatment. The healing time averaged 6.5 months in 81 cases. According to synthetic standards including bone healing and function recovery, 54 cases won excellent bone healing, 21 good and 6 poor, with an excellence rate of 92.6%. Conclusions The failed femoral fracture operation is mainly due to the failed internal fixation caused by the biomechanical factor of the abductor muscles. Therefore, intramedullary nailing system should be the first choice for internal fixation of femoral shaft fractures and nonunion; and DCS should be used for condylar fractures and nonunion.

14.
Chinese Journal of Orthopaedic Trauma ; (12)2002.
Article in Chinese | WPRIM | ID: wpr-586329

ABSTRACT

Objective To develop a new method of treating fractures and nonunion of radial and ulnar diaphyses. Methods We designed a kind of radius-ulna shape memory connector (RSMC) on the basis of the shape memory property of nitinol alloy and the anatomic characteristics of radial and ulnar diaphyses. It is capable of providing 3-D fixation and exerting continually longitudinal compression upon fracture sites. It was used in 31 cases (57 bones) of fresh fractures and 39 cases (53 bones) of nonunion, totaling 70 cases (110 bones). Results The mean follow-up time was 1.5 years(from 7 months to 2 years). In the fresh fracture group, no delayed union or nonunion was observed, and the solid bone healing time averaged 2.3 months. In the nonunion group, all the cases were cured at one time and the solid bone healing time averaged 3.5 months, but two cases were complicated with slight skin infection which had little influence on the internal fixation and bone healing. Conclusion RSMC can provide a new and efficacious method for the treatment of fracture and nonunion of radial and ulnar diaphyses.

15.
Chinese Journal of Orthopaedic Trauma ; (12)2002.
Article in Chinese | WPRIM | ID: wpr-684428

ABSTRACT

Objective To analyze the causes of postoperative step off of the tibial plateau fracture and to suggest strategies to cope with them. Methods 57 cases of tibial plateau fracture who had been treated operatively in our department from January 2001 to June 2003 with satisfactory reduction of the articular surface were reviewed. Their radiograms were analyzed. Results The follow ups lasted 6 to 30 months (average 15 months). Postoperative step off rate was 28.1%in all the cases according to radiological step off criteria. (A depression of the articular surface more than 3 millimeters or malalignment of the extremity more than 5 degrees is considered as step off.). Six causes of loss of reduction were: 1) more than sixty years of age, 2) severe osteoporosis, 3) preoperative displacement and fracture fragmentation, 4) poor anti shearing strength of screw and plate, 5) loose bonegraft, and 6) premature weight bearing. Conclusions The key points to enhance the outcome include precise judgment of the type of fracture, sufficient amount of bonegraft, rigid internal fixation after anatomic reduction and an appropriate plan for performing early, loadless, functional exercise. The traumatic osteoarthritis may be avoided or deferred if the above mentioned six causes can be taken into full consideration or preventive measures can be taken.

16.
Chinese Journal of Orthopaedic Trauma ; (12)2002.
Article in Chinese | WPRIM | ID: wpr-684427

ABSTRACT

Objective To explore the incidence of tibial plateau fracture with ligament injuries and the early diagnosis and management of the condition. Methods Fifty seven cases of tibial plateau fractures which had been treated operatively from Jan. 2001 to Jun.2003 and had satisfactory reduction of the articular surface were reviewed. The stability of their knee joints was analyzed. Results The follow up lasted 6 to 30 months with an average of 15 months. The incidence of knee unstability was low. The four potential reasons for the postoperative knee stability were found to be: 1) the low prevalence of ligament injury with displaced fractures of tibial plateau; 2) incomplete ligament disruption or mild ligament injury; 3) anatomic reduction and rigid internal fixation; 4) fine and detailed plan for immobilization and functional exercise. Conclusion The prevalence of complete ligament disruption is low, and nonoperative management can result in satisfactory outcomes for tibial plateau fracture with incomplete ligament injury.

17.
Chinese Journal of Orthopaedic Trauma ; (12)2002.
Article in Chinese | WPRIM | ID: wpr-684277

ABSTRACT

Objective To research on the new technique and method of bone grafting for nonunion of four limbs. Methods A new method of bone grafting was developed to take advantage of Nitinol Shape Memory Connector. It included splinting mode, padding mode and seeding mode. 148 cases of bone nonunion in 134 patients were treated with the modified method. Results The patients were followed up for 5.5 months to 6 years, with an average period of 2.25 years. On the average, the nonunion healed with lamellar bone 3.5 months after the operation. The healing rate was 99.3% . Conclusion The author s modified bone grafting provides a new and efficacious method for treatment of the limb nonunion.

18.
Academic Journal of Second Military Medical University ; (12)2001.
Article in Chinese | WPRIM | ID: wpr-552242

ABSTRACT

Objective: To analyze the design of Nitinol Patellar Concentrator (NT-PC) and its biomechanic characteristics for treating comminuted patellar fractures.Methods:NT-PC and patellar was analyzed by ANSYS software,the finite element was three dimension brick unit with 20 nodes, 8 faces, and the degree of freedom was 6.In NT-PC,10 483 units were divided and the number of nodes was 17 959;In Patellar,8 775 units were divided and the number of nodes was 15 847.The patellar model was loaded according to the 5 converging directions of NT-PC.Results:NT-PC had tension force on its internal face and pressure force in its external face.The maximum value was 195.8 MPa and -18 MPa,which was far from its utmost stress and fatigue limit.The memory converging force of NT-PC was 134 N.The stress (0.8 MPa) was evenly distributed on the patellar surface.Stress calculation of every node indicated that positive stress was the main stress.Conclusion: The design of NT-PC is reasonable and has good reusing character.After fixation, exercise is allowed immediately after operation.The continual positive stress is good for the stability of fracture end and fracture healing.

19.
Academic Journal of Second Military Medical University ; (12)2000.
Article in Chinese | WPRIM | ID: wpr-677551

ABSTRACT

Objective:To study the biomechanical basis of swan like memory compressive connector (SMC) for treating fractures and nonunions, and the facilitating effects of dynamic memorial stress of SMC for bone healing. Methods:By computer emulation and three dimensional (3D) finite element analysis, the biomechanical behavior of humeral type connector for fixing humerus was emulated and analyzed. The finite element model of humeral type connector was divided into 3 487 units. The number of nodes was 5 397. The element was a unit with 20 nodes, 4 faces. The finite element model of humerus was divided into 5 783 units, the number of nodes was 9 863. And the finite element was a 3D unit with 10 nodes, 4 faces.Results:When the connector fixated humerus, it came in for tension stress in its inner surface, and compressing stress in its outer surface. The maximum first structural major stress of metamorphosed compressive part was 224.5 MPa and -34 MPa, far less than its utmost stress and fatigue limit. The initiative memorial bone holding force for maintaining axial stability was 125.05 N, and the longitudinal initiative memorial compression force was 196 N. The stress distribution in fixed humerus was even, the stress in most nodes was positive stress. Conclusion:The SMC has good anti fatigue and reuse characters. The dynamic memorial compressive stress field is good for the stability of fixation and enhancement of bone healing.

20.
Academic Journal of Second Military Medical University ; (12)2000.
Article in Chinese | WPRIM | ID: wpr-677550

ABSTRACT

Objective:To study the biomechanical basis of swan like memory compressive connector (SMC) for treating fractures and nonunions of humerus. Methods:The study was performed by electrometric, two and three dimensional (3D) photoelasticity techniques. By gauging and multiple time standardization, load strain curve was got, then the dynamic memory force of SMC was calculated. The dynamically compressive force of swan neck compressive part was calculated by 2D photoelasticity. By precision moulding, the epoxy resin 3D photoelasticity humeral model was established, then it was fixated by SMC, meanwhile, an epoxy resin cirque was used to share the continuously memorial compress. The 3D stress distribution of humeral model was got, and 6 space component stress of the inspected node was divided by Leize polarizing microscope. Results:The continuously memory force of SMC was 110.35 N. The longitudinal dynamical compressive memory force was 163.88 N. 3D photoelasticity method showed that the swan neck compressive part of SMC, swan body connecting part of SMC and swan wing holding part of SMC were in consistent with each other, memorably holding bone, 3D fixation style was formed, and overall stress distribution was produced.. Conclusion:The stress field produced by 3D memory fixation of SMC is good for the treatment of fractures and nonunions. Early function exercises are allowed, and the fracture healing is prompted.

SELECTION OF CITATIONS
SEARCH DETAIL