Objective To study the feasibility of polylactic acid(PLA) as carrier of bone morphogenetic protein(BMP), and observe its results of inducing osteogenesis. Methods A 12 mm bone defect experimental model in the left ulna of rabbits was made, the animals were divided into three groups at random, bovine BMP 10 mg with PLA carrier was implanted into the defect area in the experimental group, bovine BMP 10 mg with bovine cancellous bone matrix carrier was implanted in the control group, and nothing was implanted in the blank group. The osteogenesis of the bone in the defect area was observed by regular roentgenography, the histological changes of the bone defect tissue in 4th, 8th, 12th week after operation were studied and the new bone formation was measured by image analysis. Results The results revealed that the bone defect in the experimental group had excellent repair than that seen in the control and blank group, both bone union and the period of bone mature were earlier than that seen in the control and blank groups. There was fibration in the blank group at 12th week. Conclusion The result indicated that PLA is a material able to be used as a carrier of BMP in inducing osteogenesis, it has a better effect of inducing osteogenesis than xenogenous cancellous bone matrix. Compared with other carriers, PLA has the following advantages: 1)It releases BMP gradually during degradation, so the BMP concentration in bone defect can be maintained effectively. 2)It is a material with some rigidity, so is able to exert flexible fixation of the fractures. 3)It can be shaped to adjust itself for the individual fractures. 4)It has a good histocompatibility and an adjustable property. However, the relationship between the molecule weight, aperture of PLA and the best inducing osteogenesis need a further study.

Objective To observe the short-term and long-term effect of preventive therapy of bionic pulsed electromagnetic fields(BEMF) on the osteoporosis model of Wistar rats.Methods Thirty-two 3-month-old female Wistar rats were randomly divided into 4 groups with 8 rats in each group: control group(group A),desamethasone group(group B),calcitonin group(group C) and BEMF group(group D).Rats in group A were raised normally and received normal saline.Rats in group B were injected with desamethasone only(1 mg/kg,intramuscularly,twice a week).Rats in group C were injected with calcitonin(2 IU/kg,subcutaneously,once a day) and rats in group D were irradiated with BEMF for preventive therapy,simultaneouly all rats were injected with desamethasone(1 mg/kg,intramuscularly,twice a week).The rat bone mineral density(BMD) was measured under narcosis at 4,8,12 weeks after starting preventive therapy.Results No significant differences in BMD were found among all groups 4 weeks later.The significant differences in BMD were observed between group D and group B 8 weeks later and lasted to 12 weeks(P

Objective To study the protective effect of bionics-pulsed electromagnetic field (BEMF) on the biomechanical property of the bones of Wistar rats. Methods Thirty-two 3-month-old female Wistar rats were divided into 4 groups (n=8 in each group). The 8 rats of group A (the control) were treated normally and received injections of saline in the same amount of drugs for the rats of other 3 groups. The rats of group B received injections of desamethasone (1 mg/kg, 2 intramuscular injections/week). The rats of groups C and D received injections of desamethasone in the same procedure as that of group B. In addition, the rats of group C received daily subcutaneous injections of calcitonin in the dosage of 2 IU/kg and those of group D were irradiated with BEMF once daily. The results of the 3 kinds of therapeutic procedures were observed 8 weeks later. Results After the irradiation of BEMF, the biomechanical parameters of the lumbar vertebrae and the femur were far higher in the rats of group D than in those of group B. Conclusion BEMF irradiation is effective to prevent the decrease of biomechanical properties of the bones of the rats.

ObjectiveTo observe the effect of bionics pulsed electromagnetic fields (BEMF) on the biomechanical property of ovariectomized Wistar rats.MethodsForty 6 month old female Wistar rats were randomly divided into four different groups: ovariectomy group (group A), sham operation group (group B), BEMF+ovariectomized group (group C) and estrogen+ovariectomized group (group D). All rats were subjected to bilateral ovariectomy except group B. 8 weeks after operation, rats of group D were given estrogen 0.5 mg/kg/2 w. Rats of group C were exposed to BEMF, 1 h /d. Rats of group A and B were given nothing as control groups. All treatments was being kept for 10 weeks. After treatments finished, measuring the biomechanical property of femur and lumbar spine.ResultsThere were significant differences in the biomechanical property between group D and group A, and group C and group A (P<0.05).ConclusionBEMF can improve the biomechanical property of ovariectomized Wistar rats significantly and increase the capability of resisting fracture significantly.

Objective To evaluate clinical efficacy of treating femoral intertrochanteric and subtrochanteric fractures combined with femoral shaft fractures using anatomic locking plate.Methods From January 2009 to June 2011,we treated 72 cases of femoral intertrochanteric and subtrochanteric fractures combined with femoral shaft fractures using anatomic locking plate.Sixty-four cases were followed up.There were 50 males and 14 female,with an average age of 42.8 years (range,21-79).All patients suffered from closed femoral unilateral fractures.The interval between injury and surgery was 2 h-16 d (average,4.6 d).All patients were followed up at regular interval.During the follow-up period,clinical and radiographic data were recorded.The clinical efficacy was evaluated with Harris hip function score.Results The mean operative time was 65 min (range,45-120 min); the mean blood loss was 210 ml (range,50-650 ml).All patients began to walk with crutches 3-35 d after surgery.During the follow-up period,no infection,deep vein thrombosis,screwed cut-out and implant failure occurred in all patients.Coxa vara with shortening deformity was noted in 2 cases,solid bone union was found in all the cases.The mean time of fracture healing was 5.2 months (range,3.6-10.5 months).According to Harris hip score,45 cases were classified as excellent,14 as good and 5 as fair,with excellent and good rate being 92.19％ (59/64).Conclusion Anatomic locking plate fixation provides stable fixation,with a high union rate and a minimal complication rate in treatment of intertrochanteric and subtrochanteric fractures combined with femoral shaft fracture.

BACKGROUND: An ideal repairing material characterizes by both great biocompatibility and osteogenesis ability. Any biomaterials should meet excellent biological security and biocompatibility prior to clinical application.OBJECTIVE: To evaluate the biocompatibility and the biological security of the TiO_2-Ag-nano-hydroxyapatite/polyamide66 (TiO_2-Ag-nHA/PA66) composite.DESIGN, TIME AND SETTING: A randomized controlled duplicated design was performed in Chongqing Medical University from July 2008 to July 2009.MATERIALS: A total of 40 Kunming mice aged 3 weeks and of clean grade and 32 healthy adult New Zealand rabbits were provided by Experimental Animal Center of Chongqing Medical University. TiO_2-Ag-nHA/PA66 composite powder (10 g),TiO_2-Ag-nHA/PA66 composites (n=32, 5 mm ×25 mm), and TiO_2-Ag-nHA/PA66 composites (n=32, 3 mm × 5 mm) were provided by Research Center of Nano-Biomaterials of Sichuan University.METHODS: General toxicity test: Forty mice were randomly divided into experimental and control groups. Composite powder was used to prepare leaching liquor which was treated on experimental mice by an intraperitoneal injection. While, an equal amount saline was inserted into the control mice. Intramuscular implanting test: The 16 rabbits were randomly divided into experimental and control groups. Two TiO_2-Ag-nHA/PA66 composite (5 mm × 25 mm) were implanted into left and right erector spinae, respectively. A similar surgery with the exception of implantation was performed on the control rabbits. Intrabony implanting test: The resting 16 rabbits were implanted one TiO_2-Ag-nHA/PA66 composite (3 mm × 5 mm) into left and right lateral epicondyle, respectively. Hemolytic test: A 8-mL anti-coagulation blood was obtained and added with composite powder (0.1,0.15, and 0.2 g).MAIN OUTCOME MEASURES: Biocompatibility and biological security of TiO_2-Ag-nHA/PA66 composite.RESULTS: General toxicity test demonstrated that mice in the two groups had good activity and eating, normal breathing, stable body mass, no paralysis, convulsion, and death. Intramuscular implanting test and intrabony implanting test showed that there was no significant difference in levels of alanine aminotransferase, aspartate transaminase, urea nitrogen, and creatinine and leukocyte numbers between the two groups before implantation and at day 4,1 week, and 2 weeks after implantation (P> 0.05).In particular, there was no significant difference in the experimental group at varying time points (P> 0.05). Intramuscular implanting test indicated that tissue sections in the experimental group displayed coated tissue of materials. The inflammatory variation in the experimental group was generally similar to that in the control group. Intrabony implanting test indicated that tissue sections in the experimental group displayed new bone formation. Hemolytic test suggested that hemolytic ratio of three varying concentrations of TiOrAg-nHA/PA66 composites was less than 5%, which met the normal criterion.CONCLUSION: TiO_2-Ag-nHA/PA66 composite has a good biocompatibility and biological security.

Objective To discuss and analyze effect of biotype common handle (short handle) prosthesis in treating aged patients with femoral intertrochanteric fracture.Methods A retrospective analysis was carried out on 321 patients,among which 280 (102 males and 178 females,at age of 72-98years,average 82.5 years) obtained follow-up.According to a new fracture classification method (Piansui Classification),the typeⅠ a fracture was found in 65 cases and type Ⅰ b in 215.Most patients were combined with medical diseases,and after related medical collaborative treatment,standard biotype common handle prosthesis (artificial bipolar femoral head) replacement was applied to all patients.Early rehabilitation exercise was performed postoperatively.Results All the 321 patients lived through perioperative period successively,with no death in hospitalization.Meanwhile,postoperative complications were all cured in hospitalization.The patients could take out-of-bed activity at 1-3 weeks after operation.All 280 patients could take care of themselves at 12-46 months (average 28 months) of follow-up.According to Harris score,the results were excellent in 129 cases,good in 121,fair in 22 and poor in eight,with excellence rate of 89.3％.Conclusion Biotype common handle artificial femoral head replacement is an effective method to allow early ambulation,reduce complications and improve quality of life in treatment of intertrochanteric fractures in the elderly.

Objective To investigate the stress distribution in a cemented femoral component in elderly patients with a partial marrow type Ⅰ intertrochanteric fractures and to compare differences in the stress distribution after a long-and short-stem prosthetic replacement.Methods Spiral CT images of right femur of the volunteer were obtained and processed with Mimics software and modeling software to reconstruct a three-dimensional model of the femur.Based on this,a three-dimensional physical model for partial marrow type Ⅰ intertrochanteric fractures,long-and short-stem femoral prostheses,and cement mantle was established.Subsequently,a three-dimensional finite element model of long-and short-stem prosthetic replacement for intertrochanteric fractures was established using the finite element analysis software,and biomechanical analysis was implemented for the model.Results No significant changes in stress distribution of the femur occurred after long-or short-stem prosthetic replacement.Stress on the femur still presented a gradual increase from the proximal end to the distal end,peaked at the lower 1/3 of the medial and lateral junction and then decreased at the end.A stress concentration zone formed in the medial and lateral end of cement-stem interface in short-stem prosthetic replacement.Besides,the maximum value of stress in the lateral interface reached 15.3 MPa,but without surpassing the fatigue strength of the bone cement.Whereas,a stress concentration zone formed in the distal medial and lateral part of cement-stem interface and the medial middle part of the interface in long-stem prosthetic replacement and the maximum value was also lower than the fatigue strength of bone cement.No significant stress concentration zones were found in the femoral calcar reconstructed using bone cement.Conclusions Cemented long-or short-stem prosthetic replacement achieves no significant alteration in stress distribution of the femur.Loosening probability of the cemented long-or short-stem prosthesis is almost the same,but the latter has advantages of shorter surgery time,minor trauma,and fewer complications and may be more suitable for treatment of the elderly patients with a partial marrow type Ⅰ intertrochanteric fractures.

Objective To investigate the effect of α7 nicotinic acetylcholine receptor(α7nAChR) agonist agent PNU282987 on bone cement particles stimulated secretion of inflammatory cytokines in peripheral blood monocytes and its molecular mechanism.Methods Mouse peripheral blood monocytes were isolated and the inflammatory response were induced by PMMA particles.TNF-α, IL-1β and IL-6 concentration in culture supernatant were measured by ELISA.TNF-α, IL-1β and IL-6 mRNA expression were measured by RT-PCR.p-p65, p65, p-JAK2, JAK2, p-STAT3, STAT3, and β-actin expression were detected by Western blot.NF-κB DNA binding activity were measured by ELISA.ResultsAfter stimulation of PMMA particles, TNF-α, IL-1β and IL-6 concentration in culture supernatant was significantly increased(P<0.05), TNF-α, IL-1β and IL-6 mRNA expression was significantly increased (P<0.05), p-p65, p-JAK2 and p-STAT3 expression and NF-κB DNA binding activity was also increased significantly (P<0.05).However, after PNU282987 treatment, TNF-α, IL-1β and IL-6 concentration in culture supernatant decreased(P<0.05), TNF-α, IL-1β and IL-6 mRNA expression decreased in a concentration gradient way(P<0.05), p-p65, p-JAK2 and p-STAT3expression and NF-κB p65 DNA binding activity was also decreased(P<0.05).Conclusions α7nAChR agonist PNU282987 significantly inhibites PMMA bone cement particles induced secretion of inflammatory cytokines in peripheral blood monocytes of mice.

Objective To evaluate the effects of unilateral and bilateral diffusion of cement on osteoporotic vertebral compression fractures treated with percutaneous kyphoplasty (PKP). Methods A retrospective case control study was conducted on the clinical data of 127 patients with single segment osteoporosis vertebral compression fracture (OVCF) treated by unilateral puncture PKP between July 2013 and July 2015. According to whether the diffusion of bone cement crossed the median, all cases with OVCF were divided into unilateral and bilateral diffusion groups. The unilateral diffusion group (72 cases) included 29 males and 43 females, with an average age of 69.5 ± 2.6 years (range, 63-76 years). In terms of the injured segment, there were 38 cases of L1, 20 L2, 11 L3, two L4, and one L5. In the unilateral diffusion group, the preoperative visual analog score (VAS) was (7.8 ±0.9) points, the preoperative anterior vertebral height compression ratio was (32.5 ±6. 3)％, and the preoperative Cobb's angle of the injured vertebra was (9.2±1.3)°. The bilateral diffusion group (55 cases) included 22 males and 33 females, with an average age of 71.2 ±2.9 years (range, 61-80 years). In terms of the injured segment, there were 32 cases of L1, 13 L2, six L3, three L4, and one L5. In the bilateral diffusion group, the preoperative VAS was (7.6 ±0. 9)points, the preoperative anterior vertebral height compression ratio was (34.5 ±5.8)％, and the preoperative Cobb's angle of the injured vertebra (9.8± 1.5)°. The VAS, anterior vertebral height compression ratio of the injured vertebra, Cobb's angle of the injured vertebra, and injured and non-injured vertebra refracture 1 month and 1 year after operation were recorded. Results The patients were followed up for 12-16 months (mean, 14.6 ± 0.6 months) in unilateral diffusion group and for 13- 16 months (mean, 15.2 ±0.2 months) in bilateral diffusion group. The VAS score of the unilateral diffusion group was (3.0 ±0.4) points at 1 month after the operation and (2.2±0. 4) points at 1 year after the operation, respectively. The VAS score of the bilateral diffusion group was (2.1 ±0.4) points at 1 month after the operation and (1.5 ± 0.4) points at 1 year after the operation, respectively. The VAS score decreased significantly 1 year after operation compared with that before operation (P ＜0.05), and significant difference was noted between two groups (P ＜0.05). The anterior vertebral height compression ratio of the unilateral diffusion group was (15.2±3.9)％ at 1 month after the operation and (16.3 ±3.4)％ at 1 year after the operation, respectively. The anterior vertebral height compression ratio of the bilateral diffusion group was (15.6±3.5)％ at 1 month after the operation and (16.8 ±3.9)％ at 1 year after the operation, respectively. The Cobb's angle of the injured vertebra of the unilateral diffusion group was (2.9±0.7)° at 1 month after the operation and (3.0±0.6)°at 1 year after the operation, respectively. The Cobb's angle of the injured vertebra of the bilateral diffusion group was (3.0 ± 0.7) ° at 1 month after the operation and (3.2 ± 0.7) ° at 1 year after the operation, respectively. The anterior vertebral height compression ratio and Cobb's angle of the injured vertebra decreased significantly after surgery (P ＜ 0.05), but no statistically significant differences were observed between two groups (P＞0.05). The injured vertebra refracture ratio was 6.9％ in unilateral diffusion group and 0 in bilateral diffusion group. The non-injured vertebra refracture ratio was 5.6％ in unilateral diffusion group and 5.5％ in bilateral diffusion group. No nerve root injury, cerebrospinal fluid leakage, pulmonary embolism, anaphylactic shock and postoperative infection were found in the two groups. Paravertebral bone cement leakage occurred in two cases of the unilateral diffusion group and anterior vertebral bone cement leakage occurred in one case of the bilateral diffusion group. Conclusion Compared with unilateral diffusion, bilateral diffusion of bone cement has better analgesic effect and can reduce the incidence of re fracture of injured vertebra, without increasing the risk of re-fracture of the non-injured vertebrae.