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.

Objective To explore the dose-effect relationship and optimal concentration of sodium taurocholate (NaTc) to establish acute necrosis pancreatitis (ANP) complicating MODS in a rat. Methods 280 SD rats were randomly divided into control group (n =40) and 3.5%, 4%, 4.5%, 5% ANP group (n = 60, respectively). ANP groups were induced by retrograde injection of NaTc solution into the pancreatic duct of rats. Rats in each model group were sacrificed at 1, 3, 6, 12 and 24 h after the model induction. Serum amylase, serum total bilirubin, creatinine, blood gas analysis, and pathological changes of pancreas were determined. Survival rate at 24 h after the model induction was observed in other 20 ANP rats in each group. Results In each groups, the serum amylase level, creatinine, blood gas analysis and pathological changes all increased corresponding to the increase of NaTc, and there was significant dose-effect relationship and time-effect. In 4.5% group, the dysfunction of liver and kidney reached the peak at 6 h,while the respiratory dysfunction reached its peak at 12 h. Its incidence of MODS was 52.5%, which was significantly higher than those in 3.5%, 4.0% group (15.0% and 37.5%) ;and 24 h survival rate of 4.5% group was 65%, which was significantly higher than that in 5% group (30%). Conclusions 4.5% NaTc solution may be the optimal concentration to establish the ANP model, which had higher incidence of MODS and 24 h survival rate.

Objective To investigate the time-course change of intra-abdominal pressure (IAP), TNF-α in rat with acute necrotizing pancreatitis (ANP) and its mechanism. Methods 80 SD rats were randomly divided into ANP group and control group. ANP group was induced by retrograde injection of 4.5% sodium taurocholate into the pancreatic duct in SD rats, while control group was induced by injection of saline at the same dosage. Eight rats in each group were killed at 1 h, 3 h, 6 h, 12 h and 24 h, respectively. The serum levels of amylase, TNF-α were determined;IAP, amount of abdominal ascites, pancreatic pathologic changes were evaluated. Results The levels of amylase in ANP group increased progressively with time, which were 32-folds higher than those in control group at 24 h. The serum levels of TNF-α in ANP group reached the peak at 6 h, and were significantly higher than those in the control group. The amount of abdominal ascites increased post-ANP induction and reached the peak at 24 h, which was 4.7-folds higher than that in the control group. The IAP significantly increased 1 h after induction, which was 3 times as high as the control group in 3 h group and 9 times in 12 h group. Pathologic injuries deteriorated progressively and reached the peak at 24 h. Conclusions Significant IAP occurred in ANP rats and reached the peak at 12 h, TNF-α reached the peak at 6 h, therefore IAP may be the secondary response to inflammatory reaction.

0.05), while the strength and stiffness were significantly different (P

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.

Objective To evaluate the relationship between emergence agitation (EA) during recovery from general anesthesia and postoperative cognitive dysfunction (POCD).Methods Two hundred and eighty ASA Ⅰ or Ⅱ patients,aged 18-70 yr,weighing 52-80 kg,undergoing elective surgery,were included.Anesthesia was induced with midazolam,fentanyl,propofol and cisatracurium.The patients were tracheal intubated and mechanically ventilated.Anesthesia was maintained with remifentanil,propofol and cisatracurium.EA was assessed at 15-40 min after extubation by using Post-operative Quality Recovery Scale and the cognitive function was assessed at day 1 before operation and days 1-7 after operation.Patients were divided into POCD or nonPOCD group according to the occurrence of POCD.The general data of patients,preoperative complications and types of surgery were recorded.If there was significant difference between the 2 groups,the factor was analyzed using multi-factor logistic regression to select the risk factor for incidence of POCD.Results The incidence of POCD was 40.7 ％.The results of logistic regression analysis showed that the dangerous degree of the risk factors for POCD in order from high to low were emergence agitation,duration of anesthesia and age.Conclusion EA during recovery from general anesthesia is an independent risk factor for POCD.

Objective To investigate the regulative role of N-Acetyl-D-glucosamine(GlcNAc) on the stressed mice macrophages function.Methods The stressed mice model was established by electric footshock method.The mice were divided into 5 groups:normal control group,stressed mice model group,low dose Glc-NAc treatment group(0.25 ml 15% GlcNAc),medium-dose GlcNAc treatment group(0.5 ml 15% GlcNAc) and high-dose GlcNAc treatment group(1 ml 15% GlcNAc).GlcNAc was intragastrically injected to corresponding mice 2 h before the electrical stimulation.Peritoneal macrophage(PM?) phagocytosis capability was detected by phagocytosis saccharomycete assay,and PM? energy metabolism was detected by MTT assay.Results Compared with normal control group,stressed mice PM? phagocytosis capability was significantly lower(P

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.

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.

Objective To analyze clinical prognosis, risk factors and predictive indexes of hyperkalemia in recipients after heart transplantation. Methods Clinical data of 158 recipients were retrospectively analyzed. According to the serum potassium levels within postoperative 1-year follow-up, all recipients were divided into the normal serum potassium level group (n=83), hyperkalemia group (n=43) and severe hyperkalemia group (n=32). The incidence and prognosis of hyperkalemia after heart transplantation were summarized. The risk factors and predictive indexes of hyperkalemia after heart transplantation were identified. Results The incidence of hyperkalemia and severe hyperkalemia within postoperative 1 year was 47.5%(75/158) and 20.3%(32/158), respectively. In the severe hyperkalemia group, the fatality was 16%(5/32), higher than 8%(7/83) in the normal serum potassium level group and 7%(3/43) in the hyperkalemia group. The mean serum creatinine (Scr) within 6 months before heart transplantation, the final total bilirubin level before heart transplantation, postoperative hemodialysis time, the Scr level and N-terminal pro-brain natriuretic peptide level at postoperative 1 d were the independent risk factors for hyperkalemia following heart transplantation (all P < 0.05). The mean Scr level within 6 months before heart transplantation, postoperative hemodialysis time, and Scr levels at postoperative 1 and 7 d could be used to predict postoperative severe hyperkalemia. Conclusions The recipients with severe hyperkalemia after heart transplantation obtain poor prognosis. The mean Scr level within 6 months before heart transplantation, the final total bilirubin level before heart transplantation, postoperative hemodialysis time, and the Scr level and N-terminal pro-brain natriuretic peptide level at postoperative 1 d are the independent risk factors for hyperkalemia after heart transplantation. Perioperative Scr level and postoperative hemodialysis time may be used to predict the incidence of severe hyperkalemia within 1 year after heart transplantation.