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Hepatitis E virus （HEV） infection is the most common cause of acute viral hepatitis worldwide， and over the past ten years， studies have shown that HEV can not only cause acute self-limiting hepatitis， but also lead to severe and chronic infection. Pregnant women or patients with underlying liver disease may progress to liver failure after HEV infection， resulting in a relatively high mortality rate， and patients receiving solid organ transplantation may progress to chronic hepatitis after HFV infection. This article introduces the diagnosis， clinical features， transmission， prevention， and treatment of severe and chronic HEV infection， discusses the features of immune response， inflammatory response， and the virus itself during the severe exacerbation and chronicity of HEV infection， and summarizes the mechanism in promoting the progression of HEV. Nevertheless， there are still large gaps between current studies and clinical application， and there is still a lack of effective diagnosis and treatment regimens for severe and chronic HEV infection. It is necessary for clinical researchers to conduct research on the pathogenesis of hepatitis E and systematic cohort studies and improve the level of clinical nursing， thereby achieving the goal of preventing hepatitis E and improving the prognosis of patients with hepatitis E.
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Objective:To investigate the effect of Budesonide (BUD) on pulmonary vascular development and the expression of vascular endothelial growth factor (VEGF) and nucleotide binding oligomerization domain-like receptor protein 3 (NLRP3) in newborn rats with bronchopulmonary dysplasia (BPD) caused by intrauterine infection.Methods:The 15-day-pregnant SD rats were divided into control group and infection group [intraperitoneal injection of 0.35 mg/(kg·d) lipopolysaccharide], and the newborn rats born by the above groups were divided into 3 groups: BUD group (0.5 mg of BUD suspension), normal control group (NC group, equal amount of 9 g/L saline), BPD group (equal amount of 9 g/L saline), with 40 rats in each group, all of them were inhaled twice a day for 14 days.Ten newborn rats were selected at birth, on the 3 rd, 7 th and 14 th day after administration.Pulmonary histopathological changes and radial alveolar counts (RAC) were observed after HE staining, and the thickness of alveolar respiratory membrane was measured; the platelet-endothelial cell adhesion molecule (PECAM-1/CD 31) in lung tissue was detected by immunohistochemistry, and the density of pulmonary microvessels was calculated; the expressions of VEGF, NLRP3 and Caspase-1 were detected by Western blot; and the levels of serum interleukin( IL)-1β and IL-18 were measured by enzyme-linked immunosorbent assay. Results:With the increase of day-old, the lung tissue of newborn rats in NC group was gradually developed and matured, the structure of alveoli was clear, the size was uniform, the count was significantly increased, and no obvious pathological changes were observed.In BPD group, the lung tissue structure was disordered, the alveoli were different in size and few in count, and inflammatory cells were exuded from the alveoli or the alveoli space.Compared with BPD group, the pathological changes of lung tissue in BUD group were significantly reduced.On the 3 rd, 7 th and 14 th day after administration, compared with NC group, the RAC, average integral optical density of CD 31 positive cells, density of pulmonary microvessel and level of VEGF protein in lung tissue of BPD group and BUD group were lower, and the differences were statistically significant (all P<0.05); while the thickness of respiratory membrane, level of NLRP3, Caspase-1 proteins in lung tissue and serum levels of IL-1β, IL-18 were significantly higher, and the differences were statistically significant(all P<0.05). Compared with BPD group, the RAC, average integral optical density of CD 31 positive cells, density of pulmonary microvessel and level of VEGF protein in lung tissue of BPD group and BUD group were significantly higher, and the differences were statistically significant (all P<0.05); while the thickness of respiratory membrane, level of NLRP3, Caspase-1 proteins in lung tissue and serum levels of IL-1β, IL-18 were significantly lower, and the differences were statistically significant (all P<0.05). Conclusions:The occurrence and development of pathological changes of BPD newborn rats caused by intrauterine infection can affect the development of pulmonary vessels through the inflammatory response of lung tissue.BUD can alleviate pathological changes in lung tissues of BPD newborn rats by reducing inflammatory reaction and up-regulating VEGF expression, promoting pulmonary vascular remodeling, and increasing pulmonary microvascular density.
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Objective To investigate the peripherally inserted central catheter (PICC) to improve the accuracy of three valve PICC head end position of the fortune with endocardial mapping method.Methods 204 patients with PICC were randomly divided into observation group and control group according to the digital table,102 cases in each group.The observation group used saline infusion method by three valve PICC guided endocardial mapping catheter tip location.The control group received conventional positioning surface positioning method.The accurate rate of end position of the two groups was compared.Results The head position accuracy of the observation group was significantly higher than that of the control group (100.00％ vs.93.14％,x2 =3.003,P =0.004).Conclusion The use of saline drip instillation to guide intracardiac electrogram during PICC catheter placement can reduce ectopia and improve the accuracy of the head end position of the catheter,and it is worthy of promotion.
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BACKGROUND:Dynamic hip screws have been considered as a classic method for intertrochanteric fracture. However, migration of the hip screw resulting in cut-out of the femoral head remains the most common mechanical failure, which requires secondary surgery. OBJECTIVE:On the basis of the traditional dynamic hip screw, we modified the lag screw, designed new internal fixation system as cemented dynamic hip screws to explore the feasibility and the biomechanical properties for the treatment of osteoporotic intertrochanteric fracture. METHODS:A total of 24 hip samples were harvested from fresh cadavers with osteoporosis. Bone density was measured. According to the standards, the specimens were made into intertrochanteric fracture models of AO31-A1 type. Of each specimen, one side implanted with cemented dynamic hip screws served as experimental group, and another side implanted with traditional dynamic hip screw served as control group. Axial compression, twisting and fatigue load biomechanics were tested. Their biomechanical functions were compared. RESULTS AND CONCLUSION:Stress intensity, axial stiffness and horizontal shear stiffness were higher in the experimental group than in the control group (P<0.05). At torsion angle of 3°, torsional moment was higher in the experimental group than in the control group (P<0.05). Fatigue load was higher in the experimental group than in the control group (P<0.05). Results suggested that cemented dynamic hip screw internal fixation system in the treatment of senile osteoporotic intertrochanteric fracture can effectively enhance the hip screw holding force and prevent femoral cutting. Biomechanical property, stiffness, endurance resistance and stability of cemented dynamic hip screw are better than traditional dynamic hip screw.
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BACKGROUND:There are currently various surgical methods of patel a fracture, and they have advantages and disadvantages, thus cannot wel meet the requirements of patients. OBJECTIVE:To evaluate biomechanical properties of internal fixation plate to treat patel ar fracture and to provide theoretical evidence for clinical application. METHODS:According to the statistics of patel a in the Chinese population, a titanium al oy spider internal fixation plate was designed and manufactured for the treatment of patel ar fractures. Knee joint specimens in six fresh cadavers were randomly divided into two groups and the comminuted fracture model of patel a were established. The models were fixed with internal fixation plate of patel a and NiTi patel ar concentrator. Biomechanical tests were carried out to compare the biomechanical properties. RESULTS AND CONCLUSION:Both the two fixation methods could meet the 1-kN quadriceps femoris contraction. The internal fixation plate of patel a was superior to NiTi patel ar concentrator in the patel ar isolation shift, muscle strength and joint strength, as wel as mechanical properties of patel a-point surface. There were significant differences between the two groups (P<0.05). The internal fixation plate of patel a is designed in accordance with the anatomical and biomechanical properties of the patel a, the fixation strength can completely meet clinical requirement and deserve further application.
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BACKGROUND:The traditional surgical method have large trauma in the treatment of tibiofibular syndesmosis injury, and cannot wel complete the repair of ligament. But the suture anchor has clear effect for ligament repair, ligament reconstruction and bone connection. OBJECTIVE:To investigate the biomechanical properties of the suture anchor in the treatment of tibiofibular syndesmotic injury, and to compare with lag screw internal fixation. METHODS:Eight ankle joint specimens were col ected, and the biomechanical experiment was performed for stress analysis. The suture anchor technology and lag screw internal fixation were used respectively to treat the tibiofibular syndesmotic injury. The biomechanical properties of the stress strength, stiffness and stability were compared. RESULTS AND CONCLUSION:The biomechanical properties of the stress strength, stiffness and stability of suture anchor technology for the treatment of tibiofibular syndesmotic injury were better than those of lag screw internal fixation, and there were significant differences in the strength and stiffness between two methods (P<0.05);the stress shielding rate of suture anchor technology was lower than that of lag screw internal fixation, and the difference was significant (P<0.05);the tibiofibular syndesmosis separated displacement of suture anchor technology was lower than that of lag screw internal fixation, and the difference was significant (P<0.05). The results indicate that the suture anchor technology is a minimal invasion and good method to realize physiological reconstruction and elastic fixation with stable fixation strength and less trauma, and without secondary operation.
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ObjectiveTo observe the effects of different angles between tibial tunnel and tibial platform on “killer turn” in posterior cruciate ligament (PCL) reconstruction,and primarily discuss a safe and reasonable tunnel technology. Methods Eighteen fresh tendon grafts were used to reconstruct the PCL on the tibial side of fresh cadavers.The tibial tunnels of all specimens were built via anteromedial approach.Based on the different angles between tibial tunnel and tibial platform,all specimens were divided into Group A (30°),Group B (40°) and Group C (50°),with six specimens in each group.Area of tibial tunnel exit,pressure of tibia tunnel exit and circulation characteristics of tendons under the cyclic load before and after biomechanical test were recorded.ResultsThe area of tibial tunnel exit had statistical difference among three groups after the test ( F =8.80,P ＜ 0.05 ).The pressure of tibial tunnel exit had statistical difference among three groups (F =3.91,P ＜ 0.05 ).The cyclic frequency and fatigue strength of the transplanted tendons had statistical difference among three groups under the same cyclic load ( 256 N ) and same frequency ( 126 Hz ) ( F =4.25,P ＜ 0.05 ).Conclusions The angle between tibial tunnel and tibial platform has negative correlation with the area and pressure of tibial tunnel exit,and has positive correlation with the cyclic frequency and fatigue strength of the transplanted tendons under cyclic load.The ideal anatomy position of the tibial tunnel is the anteromedial tunnel with the angle of 40° between the tibial tunnel and the tibial platform.
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ObjectiveTo develop an EZ screw remover for screwing out the skidded screws,discuss its design features and biomechanical characteristics and verify its extracting effect by clinical applications.MethodsFresh skeleton specimens were used in the study,including the femur (n =3),tibia ( n =3 ),radius and ulna ( n =3 ).The screws were fixed to the specimens according to clinical requirements and bone cement was filled into the medullary cavity.The specimens were randomized into three biomechanical test model groups,ie,Group A (measuring the skidded screws with the biggest torsion when the screws were taken out by screwdriver),Group B (measuring the skidded screws with the biggest torsion when the screws were taken out by one handle of EZ screw remover) and Group C ( measuring the skidded screws with the biggest torsion when the screws were taken out by two handles).The fixed screws were divided into two types of φ4.5 mm and φ3.5 mm.The experimental specimens were tested on the universal testing machines to measure the maximum torque,torsion angle,power consumption value and efficiency when drawing out the screws. The experimental data were compared between groups.The skidded screws encountered in clinical were taken out with EZ screw remover to verify the extracting effect.ResultsThe pullout torque in Groups A,B and C was 2.87-3.27 N · m,3.06-4.83N · m and 4.12-8.36 N · m respectively ( P ＜ 0.05 ).The average torsion angle value in each corresponding group was 0.77°,0.28°,0.16° respectively (P ＜ 0.05 ).When the screws were screwed out,the average power consumption was 21 J,32 J and 45 J in Groups A,B and C respectively and power ( mechanical efficiency) was 0.35 J/s,0.53 J/s and 0.75J/s in Groups A,B and C respectively,with significant differences ( P ＜ 0.05 ).Seventeen pieces of the cannulated skidded screws of φ7.3 mm in seven patients were successfully taken out by using the EZ screw remover.ConclusionEZ screw removerhas enough resistance strength and rigidity to torsion as well as powerful clamping force and hence is an ideal tool for screwing out the skidded screw in orthopedics.
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Objective To compare the biomechanical pull-out strength (POS) of three different fixations in upper thoracic vertebras using translaminar screws (TLS), translaminar facet screws (TLFS), and transpedicle screws (TPS), respectively. Methods Nine fresh human cadaveric cervicothoracic junction spines specimens which including T1-T3 vertebras were harvested. The vertebras specimens were scanned using dual-energy radiograph absorptiometry for bone mineral density. Both of screw insertion techniques at each vertebrae was randomized. All the screw insertions were based on direct observation and the CT scan on the pedicles. The peak of insertional torque (IT) was recorded and axial pull-out testing was performed to simulate intraoperative failure of fixation. Results The mean peak IT of the TFLS, TPS and TLS were (0.43±0.01), (0.40±0.01), (0.35±).01) N·m, respectively. There was no statistically significant difference between the TFLS and TPS, and between the TPS and TLS was same. But the TFLS generated statistically greater peak 1T in comparison with the TLS(t=-13.86, P＜0.05). The mean POS of TLFS was (771±106) N,which had no statistically significant difference in comparison with the TPS(733±65) N. And the TLS (663±86) N was same. But the TFLS generated statistically greater POS in comparison with the TLS (t=9.907, P＜0.05). The peak IT showed a strong positive correlation with POS in three screw techniques. Bone mineral density correlation with POS in all methods of fixation. Conclusion It was not a significant difference to compare POS of TLS and TLFS to that of TPS respectively. TLS and TLFS appear to be a biomechanically sound alternative in the upper thoracic spine, and appear to be a safe and effective technique for instrumenting the upper thoracic spine.
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Objective To investigate the biomechanical properties of the posterior tibial anatomic plate. Methods A total of 25 fresh frozen adult tibial top and matching femur specimens were randomly divided into four groups. One specimen was used as normal control ( N group), and the remaining 24specimens were with Schatzker Ⅵ tibial plateau fracture and accompanied by rear split and backward fracture displacement. The lateral margin of the tibia was fixed with a L-type plate, and the medial margin was fixed with the same plate after remodeling. The 24 specimens were divided into three groups, eight specimens per group. The posterior margin of the tibia was fixed by posterior tibial anatomic plate ( Group A), T-type plate ( Group B) or straight reconstruction plate ( Group C). The strength, stiffness, torsional biomechanics and failure load performance of the plates in each group were evaluated. Results The strength and stiffness of test groups was superior to that of Group N ( P ＞ 0.05 ), and the torsional biomechanics of test groups was close to that of Group N ( P ＞ 0.05 ). The posterior tibial anatomic plate was superior to T-type plate and straight reconstruction plate in aspects of strength, stiffness, torsional biomechanics and failure load performance ( P ＜ 0.05 ). Conclusions Posterior tibial anatomic plate has excellent biomechanical properties, and it is superior to other materials in treating posterior tibial plateau fracture and restoring the stability of the knee.
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Objective To observe curative effects of augmentation fixation technique injected with PMMA through lateral holes of dynamical hip screw (DHS) in treatment of unstable intertrochanteric fracture of senile osteoporotic patients. Methods From January 2006 to December 2007,15 senile osteoporotic inpatients with unstable femoral intertrochanteric fracture were treated with augmentation technique injected with PMMA to the femoral head through central channel and lateral holes of DHS. Clinical data about function of hip joint and complications early after operation were observed. All patients were followed up till fractures were healed, when the hip joint function was evaluated according to Harris standarch. Results Surgical trauma indices such as operation time and bleeding volume of augmentation technique were the same as those of merely DHS fixation. All the patients could safely do hip flexion and extension exercises in the bed and completely sit up by bedside 2-3 days after operation. Six patients could do walking exercise with aid one week after operation, with no complications relating to staying in bed or to PMMA during per-operation period. All fractures were healed 3-6 months after operation, without complications like fixation loosening, cut or destruction of femoral head during postoperative follow-up period. Six months after operation, 14 patients recovered viability to normal. According to Harris standards, the results were excellent in four patients, good in 10 and fair in one, with average Harris score of 83 points. Conclusions The augmentation fixation technique injected with PMMA through lateral holes of DHS has advantages of better DHS anchoring ability in femoral heads, less surgical trauma, reliable fixation and early functional exercise and is suitable for senile osteoporotic patients with unstable intertrochanteric fractures.
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Objective To compare the difference of therapeutic effect of surgical operation and non-operation for acute damnification of elbow ulnar collateral ligament in rabbits.Methods A total of 81 New Zealand rabbits were randomly and equally divided into three groups(27 rabbits per group),ie,Group A(control group):the ulnar collateral ligaments of right elbow joint were only enclosed;Group B:the ulnar collateral ligaments of right elbow joint were severed and sutured;Group C:the ulnar collateral ligaments of right elbow joint were severed,without suture.The biomechanics was detected at time intervals of 3 and 6 weeks.Results Twelve weeks after transplantation,the displacements of the ligaments in Groups B and C were(6.06±0.4)mm and(7.72±0.44)mm,with statistical difference(P ＜ 0.05).The displacement of the ligaments in Group A was(5.87±0.46)mm,which was similar to that of Group B(P＞0.05).The maximum loads of the ligaments of Groups B and C were(68.23±5.64)N and (42.45±3.66)N respectively,with statistical difference(P＜0.05).The maximum load of the ligaments of Group A was(72.86±2.99)N,which was similar to that of Group B(P ＞ 0.05).The rigidities of the ligaments of Groups B and C were(11.33±1.52)N/mm and(5.52±0.67)N/mm respectively,with significant difference(P ＜ 0.05).The rigidities of the ligaments of Group A was(12.49±1.44)N/mm,which was similar to that of Group B(P ＞ 0.05).The power consumption of the ligaments of Groups B and C were(0.206±0.017)J and(0.163±0.013)J respectively,with statistical difference(P＜0.05).The power consumption of the ligaments of Group A was(0.213±0.010)J,which was similar to that of Group B(P＞0.05).Conclusion Surgical operation is more effective than the non-operation in dealing with acute damnification of the ulnar collateral ligaments of elbow ulnar collateral ligament in rabbits.
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Objective To evaluate the biomechanism of three kinds of internal fixations in treatment of complex tibial plateau fractures. Methods Eighteen human antiseptic cadaver tibial plateau specimens were used to make models of complex tibial plateau fracture (type Ⅵ fractures of Schatzker classification). The models were fixated with a lateral Golf-buttress plate (GP), modified dual plate (a lateral Golf-buttress plate plus a medial five-hole one-third tubular antiglide plate) (DP) or a lateral locking compression plate (LCP) respectively to compare strength, rigidity and stability of different fixation methods. Results The biomechanical strength, rigidity and stability in DP group and LCP group were better than those in GP group (P<0.05), while there was no statistical difference between LCP group and DP group (P>0.05). Conclusions Locking compression plate and modified dual plate are fairly ideal internal fixators for treatment of complex tibial plateau fractures. In the meantime, locking compression plate emphasizes conservation of soft tissues and blood supply, can better meet the requirement of the biological fixation of fracture and is the most ideal internal fixator at present.
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BACKGROUND: The biomechanical studies about calcium sulfate cement vertebroplasty are only limited to the single fracture vertebra, not performed in spinal compression fracture unit with posterior transpedicular screw fixation. Furthermore, performing experimental study in the whole function spine unit (FSU) conforms to actual clinical situation. OBJECTIVE: To assess the biomechanical properties of calcium sulfate vertebroplasty combined with posterior transpedicular screw fixation in treatment of thoracolumbar compression fractures. DESIGN, TIME AND SETTING: A controlled experiment was performed at the Biomechanical Laboratory of Shanghai University in March 2009. MATERIALS: Fifteen fresh thoracolumbar spines were harvested from male calves and made into T_(11)-L_1 FSU, then divided into 3 groups randomly: normal control group, posterior transpedicular screw fixation group and transpedicular screw fixation plus vertebroplasty group. METHODS: T_(12) flexion-compression fracture models were made in all specimens of posterior transpedicular screw fixation group and transpedicular screw fixation plus vertebroplasty group, undergoing reduction and posterior transpedicular screw fixation, and calcium sulfate vertebroplasty combined with posterior transpedicular screw fixation respectively. MAIN OUTCOME MEASURES: All specimens were placed on the WE-10A universal testing machine for mechanical test. Load-straining, load-displacing, rigidity, strength and torsion of the FSU were performed in axial compression, flexion, extension and lateral bending states. The experimental outcomes were collected and compared by statistic analysis. RESULTS: The load-strain and loed-displacement showed a linear relationship. Straining values in vertebral body and intervertebral disc of calcium sulfate vertebroplasty plus posterior transpedicular screw fixation group were 14% and 12% less than that of posterior transpedicular screw fixation group, 21% and 13% less than that of normal control group. The thoracolumbar displacement in calcium sulfate vertebroplasty Plus posterior transpedicular screw fixation group decreased 25% and 37% as compared with other 2 groups respectively. Compared with normal control and posterior transpedicular screw fixation group, the thoracolumbar stiffness in calcium sulfate vertebroplasty plus posterior transpedicular screw fixation group increased 53% and 44% respectively. The strength in vertebral body and intervertebral disc of calcium sulfate vertebroplasty plus posterior transpedicular screw fixation group were 14% and 24% higher than that of posterior transpedicular screw fixation group, 13% and 20% higher than that of normal control group. The maximal twisting strength of FSU in calcium sulfate vertebroplasty plus posterior transpedicular screw fixation group were 18% and 30% higher than that of other 2 groups, the twisting stiffness were 30% and 40% higher than that of other 2 groups. The data above were significant differences statistically (P < 0.05). CONCLUSION: Posterior transpedicular screw fixation combined with calcium sulfate vertebroplasty show superior biomechanical properties for treatment of thoracolumbar compression fractures, which exhibits not only strong strength and stiffness, but also stable FSU, thus could decrease the stress loading of the internal fixation, the incidences of screw breakage and avoid the altitude loss of vertebral body.
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BACKGROUND: Absorbable materials for internal fixation have some advantages such as simple surgery, rapid recovery and no need to second surgery, and have been accepted in the circle of orthopaedics, and had been applied in the clinic. However, the system experiment evidences are not reliable.OBJECTIVE: To investigate whether the absorbable material (the absorbable tension band, absorbable stick or screw) is an acceptable alternative to stainless steel wire with Kirschner wire by comparing their biomechanical properties in the fixation of patella transverse fractures.DESIGN, TIME AND SETTING: The randomized controlled study of biomechanical analysis was performed at the Laboratory of Institute of Biomechanics, Shanghai University from March 2007 to January 2008.MATERIALS: Eight fresh patellae specimens were collected, with the complete patella, articular capsule and patellar ligament (3.0-4.0 cm) and quadriceps femoris (4.0-5.0 cm), and then divided into two groups at random, AO steel wire group (n = 2) and absorbable tension band group (n = 6).METHODS: Eight fresh patellae specimens were divided into two groups at random, AO steel wire group (n = 2) and absorbable tension band group (n = 6) to create models of transverse fractures, which were separately fixed by absorbable tension band,steel wire tension band + Kirschner wire to measure their biomechanics function. If fracture gap reached 1.0 mm, the fixation failed.MAIN OUTCOME MEASURES: The changes in patellar ligament tensile force, quadriceps femoris tensile force, patellar displacement, quadriceps femoris displacement, patellar ligament displacement and patella tensile strain were measured under external load.RESULTS: Under external load, no significant difference was determined in total displacement between the absorbable tension band group and AO steel wire group (9%-10% difference). No significant difference was detected in patellar strain between absorbable tension band group and AO steel wire group (9%-10% difference). The patellofemoral joint force was similar between the absorbable tension band group and AO steel wire group. When internal fixation displaced 1 mm, the load was 587 N in the absorbable tension band group, and 650 N in the AO steel wire group (P > 0.05).CONCLUSION: The absorbable material is an acceptable alternative to stainless steel wire with Kirschner wire in the fixation of patella transverse fractures, with the advantages of good biological function and good stability at the broken ends of fractured bone.
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BACKGROUND:Operative approaches of lumbar interbody fusion include anterior (ALIF),posterior (PLIF) and transforaminal lumbar interbody fusion (TLIF).The resected structures and cage implantation sites are different,and the initial stability of lumbar spine is varied.OBJECTIVE:To compare the initial stability of lumbar spine following ALIF,PLIF or TLIF in combination with bilateral pedicle screw fixation.DESIGN:Comparative observation.MATERIALS:Fifteen samples of fresh calf lumbar spine were used.METHODS:Models ofALIE PLIF and TLIF were simulated.After examination as normal group,the samples were randomly divided into three groups (n=5).Besides anterior,posterior and transforaminal lumbar interbody fusion include anterior,bilateral pedicle screw fixation was performed.MAIN OUTCOME MEASURES:Biomechanical characteristics of the lumbar spine before and after ALIF,PLIF or TLIF in combination with bilateral pedicle screw fixation.RESULTS:Following three approaches of lumbar interbody fusion,the stability of lumbar spine was significantly reduced,which was enhanced after bilateral pedicle screw fixation (torsion indexes were also increased).In addition,rigidity of the lumbar spine was enhanced.The stability indexes of lumbar spine following TLIF were significantly greater than the other approaches,indicating the initial stability of TLIF was the best.The rigidity,stress,and swain of lumbar spine following PLIF were greater than ALIE but torsion indexes were smaller than ALIE CONCLUSION:The stability of lumbar spine following lumbar interbody fusion was significantly reduced compared with normal sample.But bilateral pedicle screw fixation greatly increases the stability.Among three types of lumbar interbody fusion,the initial stability of lumbar spine following TLIF is the best.
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[Objective]To analyze the biomechanics of different positions of femoral head-and-neck nail in fixation of proximal femoral fracture.[Method]Stable and unstable fracture models were made from 24 fresh femur specimens,and fixed with r-nail and DHS.Head-and-neck nails were placed in different positions to test their mechanical properties of anti-compression,anti-bending,anti-shearing and anti-torsion,and compared with each other.[Result]Mechanical properties of the femoral strength,stiffness,stability and loading capacity were tested and compared.To the stable fracture group,head-and-neck nail should be placed in middle-lower and posterior 1/3 of femoral neck,which leads to the best loading capacity.To the unstable fracture group,it should be placed between femoral head and neck,which lead to strong obliquity mechanics and valuable for bone union.[Conclusion]Confirm of the best position of femoral head-and-neck nail could improve the effect of fixation and enhance the surgical treatment of proximal femoral fracture.
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[Objective]Ulnar fractures fixed by interlocking intramedullary nails or dynamic compression plates were tested to compare their biomechanical function,in order to provide the theoretical basis for clinical practice.[Method]In the experiment,12 pieces of fresh ulnars were used to produce middle-part transverse fracture models;which were fixed by interlocking intramedullary nails or six-hole 3.5 mm dynamic compression plates seperately.The diameter of intramedullary nail was 4mm,and the length was 200-230mm.The specimen was set on the MTS test machine.The rigidity and strength of ulnar fractures fixed by interlocking intramedullary nails were compared with those of ulnar fractures fixed by six-hole 3.5 mm dynamic compression plates in the anti-axial test,anti-bending test,anti-torsional test.[Result]In the anti-axial test,anti-bending test and anti-torsional test,the rigidity of ulnar fractures fixed by interlocking intramedullary nails was 450.00?38.42 N/mm,45.64?5.24 N?cm/Deg,11.42?1.21N?cm/Deg in sequence;while the rigidity fixed by dynamic compression plates was 405.40?29.26 N/mm,41.00?4.78 N.cm/Deg,10.05?1.32 N?cm/Deg accordingly.Burdened 1000N axial pressure,the displacement of interlocking intramedullay nail fixing specimen was 2.20?0.11 mm,and the compression plate fixing specimen was 2.48?0.15 mm.Given a 5 N?M bending burden,the maximum radial bending degree of interlocking intramedullay nailfixing specimen was 3.25?0.15 mm,which was 3.60?0.21 mm of compression plate fixing specimen.In the anti-torsional test,the interlocking intramedullay nail and compression plate fixing specimen could burden 2.40?0.13 N?M and 1.90?0.10 N?M respectively.The experimental data were analyzed by software SPSS.10,which came to a distinguished difference by t-test(P
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BACKGROUND: Conventional means in treatment of distal tibiofibular syndesmosis disruption include plaster cast or splint immobilization as external fixation and internal fixation using screws, and bone bolts or plates;however, some disadvantages such as unstable fixation and uncertain fixation exist.OBJECTIVE: To observe the primary clinical curative effect of newly self-developed fixation, Hook-plate fixation (HPF), for distal tibiofibular syndesmosis disruption and its biochemical characteristics of HPF.DESIGN: Self-control observation.PARTICIPANTS: We recruited 23 patients with sustaining abruption of lower tibiofibular ligament union with fibular fracture who received treatment in the Department of Orthopedics, Affiliated Hospital of Yangzhou University Medical College, between October 2001 and March 2004. According to the Lauge-Hansen classification system, there were 11 cases of supination-lateral rotations, 7 cases of pronation-lateral rotations and 5cases of pronation-abductions. Among them 14 had bimalleolar fractures and 9 had trimalleolar fractures.METHODS: HPF was used on the 23 patients with distal tibiofibular syndesmosis disruption. Radiographs were taken routinely. Talocrural joint function exercise was recommended at week 1 and partial weight bearing was allowed 2 months later. Functions were evaluated according to modified Mazur's criteria (excellent, good, fair and poor).MAIN OUTCOME MEASURES: ①Healing time and function ev aluation after operation for distal tibiofibular syndesmosis disruption. ② Adverse events and side effectsRESULTS: Totally 23 patients entered the result analysis, with the mean of 11 months' follow-up. ①Results of healing time and function evaluation in the patients after operation for distal tibiofibular syndesmosis disruption: The healing time of fracture ranged from 12 to 18 weeks: 16 cases were excellent, 5 good, and 2 fair. ② Adverse events and side effects:There was no separation of the tibiofibular space, the distance between medial malleolus or lateral malleolus and anklebone was symmetrical.There was no mobilization or rupture of the internal fixation after operation.CONCLUSION: HPF is applied in treating distal tibiofibular syndesmosis disruption. It causes no postoperative complications, and can recover the ankle joint function with stable internal fixation and good biomechanical features.
ABSTRACT
BACKGROUND: The anterior thoracolumbar internal fixation devices can be divided into two main categories: the stick system such as kaneda,and the plate system such as Z-plate. Both categories have satisfactory biomechanical properties, but the devices of these types are all imported and so expensive that they exceed the affordability of domestic patients:Based on various anterior throacolumbar internal fixation devices and the spinal characteristics of the Chinese people, the author designed a new brand of anterior thoracolumbar internal fixation device for Chinese people:New Ti-plate (NTP).OBJECTIVE: Biomechanical properties of three anterior thoracolumbar internal fixation devices were compared in an attempt to provide a scientific and theoretical basis for clinical applications.DESIGN: A sampling investigation.SETTING: The Department of Orthopaedics of the Second Affiliated Hospital of Soochow University and Department of Radiology of Nantong Hongqiao Hospital.PARTICIPANTS: This study was carried out at the Biomechanical Engineering Research Institute of Shanghai University between May and August 2003. Fifteen fresh spinal samples from the healthy adults (T12-S1) were used in this study.METHODS: Fifteen spinal (T12-S1) specimens were obtained from fresh bodies to induce injuries to anterior and middle columns, which were fixed with Dunn Ⅲ, NTP and Z-plate respectively to compare the strength, rigidity, and the stability of the spine.MAIN OUTCOME MEASURES: Changes of load-straining and loaddisplacement of the three groups of specimens under the conditions of axial decompression, anteflection, post-extention, and lateral flexion.RESULTS: Fifteen fresh adult spinal specimens were involved in this study and all entered the stage of result analysis. Under the maximal load of 500 N,the average straining for Z-plate, NTP and Dunn Ⅲ was 410 uε,430 uε, 477 uε respectively. The average longitude displacement for the above three devices was 2.23 mm, 2.38 mm and 2.85 mm respectively.The thoracolumbar fracture was fixed with three anterior internal fixation devices and it was proved that Z-plate and NTP fixations were better than fixation with Dunn Ⅲ in respect of spinal strength, rigidity and stability (P ＜ 0.05), but the difference between Z-plate and NTP had no statistical significance (P ＞ 0.05).CONCLUSION: NTP and Z-plate devices are conformed to the spinal biomechanical principles and were capable of reconstructing spinal biomechanical stability effectively, and it is a preferable anterior spinal internal fixation device.