The effects of sacral nerve root electrostimulation on the colon function and its mechanisms in a rat model of spinal cord injury / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To study the effects of sacral nerve root electrostimulation (SNS) on the colon function and its mechanisms in rats with spinal cord injury (SCI).</p><p><b>METHODS</b>One hundred and four Wistar rats were divided into three groups: A, B and C. A group ( n = 24) was divided into three subgroups (n = 8) for studying the bioelectricity: Normal group (NG), SCI group (SCI) and SCI group with SNS(SNS); B group( n = 24) was divided into three subgroups( n = 8) for studying the colon motility: NG, SCI and SNS. C group( n = 56) were divided into three groups for studying the change of morphology and neurotransmitters(SP and VIP): NG (n = 8), SCI (n = 24), and SNS (n = 24) . In SCI and SNS, included of three subgroups: 24, 48, 72 h after spinal cord injury (n = 8).</p><p><b>RESULTS</b>In SCI group, the activity of bioelectricity in proximal and distal colon was reduced; the colon motility was lessened, and colon mucosa appeared different degree of damage; cell-cell connections between intestinal epithelial cells were destroyed. The expressions of substance P(SP) and vasoactive intestinal peptide (VIP) in colon were decreased obviously. SNS was found to activate the bioelectricity, promote the colon motility, improve the intestinal mucosal, and increase the expressions of SP and VIP. Conclusion: SNS can activate the peristalsis, rehabilitate the motility of denervated colon, protection of the intestinal mechanical barrier between intestinal epithelial cells and tight junction, rebuild the colon function through activating the bioelectricity and increase the expressions of SP and VIP.</p>

Effect of naringin on osteoclast differentiation / 中国中药杂志

<p><b>OBJECTIVE</b>To discuss the effect of Drynariae Rhizoma's naringin on osteoclasts induced by mouse monocyte RAW264.7.</p><p><b>METHOD</b>RAW264.7 cells were induced by 100 μg x L(-1) nuclear factor-κB receptor activator ligand (RANKL) and became mature osteoclasts, which were identified through TRAP specific staining and bone resorption. MTT method was sued to screen and inhibit and the highest concentration of osteoclasts. After being cultured with the screened medium containing naringin for 5 days, positive TRAP cell counting and bone absorption area analysis were adopted to observe the effect of naringin on the formation of osteoclast sells and the bone absorption function. The osteoclast proliferation was measured by flow cytometry. The effects of RANK, TRAP, MMP-9, NFATc1 and C-fos mRNA expressions on nuclear factor-κB were detected by RT-PCR.</p><p><b>RESULT</b>Naringin could inhibit osteoclast differentiation, bone absorption function and proliferation activity of osteoclasts, significantly down-regulate RANK, TRAP, MMP-9 and NFATc1 mRNA expressions in the osteoclast differentiation process, and up-regulate the C-fos mRNA expression.</p><p><b>CONCLUSION</b>Naringin could inhibit osteoclast differentiation, proliferation and bone absorption function. Its mechanism may be achieved by inhibiting the specific gene expression during the osteoclast differentiation process.</p>

Biomechanical properties of trabecular bones in femoral head under loads with different angles / 医用生物力学

Objective To investigate the effects from loads with different angles on morphological and biomechanical properties of trabecular bones in femoral head, so as to provide theoretical basis for studying biomechanical mechanism of necrosis and collapse of femoral head. Methods Ninety-four specimens of 12-month-old ovine trabecular bones in femoral head and forty-three specimens of human cadaver trabecular bones in femoral head were prepared. According to different angles between loading direction and principle compression direction, all the trabecular bones were divided into five groups by 10° interval (i.e. varus 10° and 0°, valgus 10°, 20° and 30°) to simulate the reduction condition under different Garden index after internal fixation of femoral neck fractures. Micro-CT scanning and calculation, compression failure test on ovine trabecular bones in femoral head and cyclic compression test on human cadaver trabecular bones in femoral head were performed to investigate morphological and mechanical indices, including BV/TV (bone volume vs. total volume), BS/BV (bone surface vs. bone volume), Tb.Th (thickness of trabecular bone), Tb.N (number of trabecular bone), Tb.Sp (trabecular separation), elastic modulus, ultimate strength, yield strength, initial secant modulus and number of cycles. Results When the angle between loading direction and principle compression direction of trabecular bones was 0°, BV/TV, Tb.Th, elastic modulus, ultimate strength, yield strength, initial secant modulus and number of cycles for trabecular bones were the maximum while BS/BV and Tb.N were the minimum, and all the formers presented decreasing tendency while BS/BV and Tb.N showed increasing tendency along with the angle increasing. ConclusionsAlong with the angle changes, the tendency of BV/TV and ultimate strength for 12-month-old ovine trabecular bones in femoral head displayed as the same as human trabecular bones in femoral head. Both the morphological and biomechanical properties of trabecular bones in femoral head will decrease when the angle between loading direction and principle compression direction of trabecular bones increases. The more the Garden index deviating from 160°, the more likely trabecular bones in femoral head to be damaged.

Ultrastructural study on route of gut bacterial translocation in a rat after spinal cord injury / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To observe the ultrastructural change of the route of gut bacterial translocation in a rat with spinal cord injury (SCI).</p><p><b>METHODS</b>Forty Wistar rats were divided into the following groups: control group and 3 SCI groups (10 in each group). The rats in the SCI groups were established SCI model at 24 h, 48 h, and 72 h after SCI. Small intestine mucous membrane tissue was identified and assayed by transmission electron microscope, scanning electron microscope and immunofluorescence microscopy.</p><p><b>RESULTS</b>Small intestine mucous membrane tissue in control group was not damaged significantly, but those in SCI groups were damaged significantly. Proliferation bacteria in gut lumen attached on microvilli. The extracellular bacteria torn the intestinal barrier and perforated into the small intestinal mucosal epithelial cell. The bacteria and a lot of particles of the seriously damaged region penetrated into the lymphatic system and the blood system directly. Some bacteria were internalized into the goblet cell through the apical granule. Some bacteria and particles perforated into the submucosa of the M cell running the long axis of M cells through the tight junctions. In the microcirculation of mucosa, the bacteria that had already broken through the microvilli into blood circulation swim accompanying with erythrocytes.</p><p><b>CONCLUSION</b>The routes of bacterial translocation interact and format a vicious circle. At early step, the transcellular pathway of bacterial translocation is major. Following with the destroyed small intestine mucous, the routes of bacterial translocation through the lymphatic system and the blood system become direct pathways. The goblet cell-dendritic cell and M cell pathway also play an important role in the bacterial translocation.</p>

Biomechanical comparison of monosegmental and short transpedicular fixation for stabilization of thoracolumbar fractures / 医用生物力学

Objective To establish the monosegmental transpedicular fixation model and short segmental fixation model by three-dimensional finite element technique, and evaluate the biomechanical properties of monosegmental transpedicular fixation for thoracolumbar fractures and verify its feasibility for application. Methods T10-L2 motion segment of a young healthy subject was used to establish the normal finite element model. The superior 1/2 cortical bone of the T12 segment was removed and superior 1/2 cancellous bone of the same vertebrae was assigned material property of the injured bone to simulate the thoracolumbar fracture. Transpedicular screw fixation of the T11 and T12 segment was performed in monosegmental fixation model. T11 and L1 segment were instrumented in the short segmental fixation model. All the four finite element models were applied with loading of axial compression, anteflexion, extension, lateroflexion and axial rotation, respectively. Motion difference of each functional unit and the stress of implants were measured to evaluate biomechanical behaviors of monosegmental fixation. Results The motion difference of all the functional units (T10-11, T11-12, T12-L1) in the fractured model was obviously increased under all loading conditions as compared to the normal model, but the motion difference in the fractured models was decreased after monosegmental fixation and short segmental fixation, and no significant differences were found between monosegmental fixation and short segmental fixation. The stress on screws in monosegmental fixation model was significantly lower than that in short segmental fixation under axial compression and anteflexion, but the stress on screws of two fixation models had no significant difference under extension, lateroflexion and axial rotation. The stress on the rods of monosegmental fixation model was apparently higher than that of short segmental fixation under extension and lateroflexion, and lower under axial rotation, but no significant difference was found for two fixation models under axial compression and anteflexion. Conclusions Monosegmental transpedicular screw fixation would give the similar stabilization as short segmental fixtion and could be an effective alternative to treat incomplete fractures in thoracolumbar spine.

Preparation and biomechanical properties of acellularized nerve scaffold using the technique of hypotonic buffer combined with freeze-drying / 医用生物力学

Objective To study the morphology and biomechanical properties of the improved acellularized nerve scaffold using the technique of hypotonic buffer combined with freeze-drying. Methods The traditional acellularized nerve scaffold (traditional group) was made to be improved with the technique of hypotonic buffer combined with freeze-drying (improved group). After the acellularization process was completed, the histological structure of nerves in each group was observed by HE staining and scanning electron microscope. The interval porosity and void diameter in each group were measured by Mimics software. The biomechanical properties of nerves in each group were tested by mechanical apparatus (Endura TEC ELF3200). Results The acellularization effect of the improved chemical method with the technique of hypotonic buffer combined with freeze-drying was similar to that of the traditional Hudson method, but the histological structure was more porous in improved group than that in traditional group. The interval porosity of traditional group and improved group were 34.5% and 49.3%, respectively; the void diameter of traditional group and improved group were 11.96 and 17.61 μm, respectively. Biomechanical testing results showed that there was no statistical difference in ultimate load, ultimate stress, ultimate strain and mechanical work to fracture in each group (P>0.05). Conclusions The acellularized nerve prepared by hypotonic buffer combined with freeze-drying can be used as a new kind of nerve scaffold material to make better contribution to cell combination.

Effects of different decellularization methods on biomechanical properties and histological structure of annulus fibrosus in pigtail / 医用生物力学

Objective To investigate effects of different de-cellularization methods on biomechanical properties and histological structure of annulus fibrosus in pigtails and provide experimental evidence for the construction of tissue engineering annulus fibrosus. Methods Sixty Fresh annulus fibrosus were dissected from caudal disks of pigs and randomly assigned to 4 groups with 15 in each group. Triton X-100 group(Group A): annulus fibrosus were treated with hypotonic Tris-HCl buffer for 48 hours and de-cellularized with Triton X-100, DNase Ⅰ and RNase A. SDS group (Group B): annulus fibrosus were subjected to 3 cycles of freeze-thaw and subsequently de-cellularized with SDS, DNaseⅠ and RNase A. Trypsin group (Group C): annulus fibrosus were de-cellularized with Tris buffer containing trypsin, DNase Ⅰ and RNase A. Control group: fresh annulus fibrosus underwent no treatment. After the de-cellularization process was completed, hematoxylin-eosin (HE) staining was carried out to examine the efficacy on cell removal, and the ultrastructure of annulus fibrosus were observed by scanning electron microscopy. The collagen content, glycosaminoglycan (GAG) content and biomechanical parameters in each group were also detected. Results HE staining and scanning electron microscopy showed that no residual cells were found in Group A, B and C. The structure of annulus fibrosus in Group A was not disturbed, while that in Group B and C was damaged severely and slightly, respectively. There was no statistical difference in collagen content among Group A, B and C, as compared to the control group (P>0.05). But the GAG content was significantly more lower in Group A, B and C than in the control group (P0.05), while these parameters of Group B were lower than those in the control group (P<0.05). Conclusions The Triton X-100-treated annulus fibrosus retained the major extracellular matrix composition after cell removal and preserved the major structure and mechanical strength, which is preferable for the construction of tissue engineering annulus fibrosus.

Biomechanical differences of embalmed and PMMA femurs / 医用生物力学

Objective To compare the differences in biomechanical properties of embalmed and PMMA femurs under axial loads, so as to provide a more reliable and unified femoral model for replacement. Methods Ten embalmed femurs and ten PMMA femurs were selected, and each femur was instrumented with 49 strain gauges totally on the medial and lateral side. The axial load was applied dynamically up to a maximum of 1.2 kN, and the strain of each strain gauge and load displacement curve were recorded. Results The strain distributions on two types of femur were similar, and the load displacement presented a linear relationship, but the vertical displacements under different loads were significantly different (P<0.05). The axial stiffness value of PMMA femur and embalmed femur were (259.84±24.63) and (600.40±78.56) N/mm, respectively, showing significant difference (P<0.01). The strain concentration parts at the proximal part of two femurs were the same, but the average strain value of the PMMA femur was significantly different from that of the embalmed femur (strain gauge No. 1~5: PMMA femur (-3 420.63±373.31) με, embalmed femur (-1 289.42±417.89) με; strain gauge No. 26~27: PMMA femur (1 748.67±193.98) με, embalmed femur (673.42±104.49) με; strain gauge No. 7~10: PMMA femur (-4 028.25±267.27) με, embalmed femurs (-1 139.01±288.83) με; strain gauge No. 30~36: PMMA femur (1 599.02±194.68) με, embalmed femurs (590.52±153.18) με, P<0.01). The strain concentration parts at the distal part of the two femurs were different. The medial and lateral parts of strain transformation between positive and negative of PMMA femurs were similar to embalmed femurs. The strain-load curves of strain gauge No. 2, 26, 6, 29, 8 and 33 indicated a linear relationship, but the strain value of the two femurs had significant differences (P<0.05). Conclusions The PMMA femur can replace the embalmed femur to a certain degree in biomechanical experiments on the upper part of femur. Due to the difficulty of obtaining fresh femurs, the PMMA femurs provide a more reliable and unified femoral model for replacement.

Biomechanical study on open fracture model with plate fixation compared with closed fracture model with intramedullary nail fixation in rats / 中国骨伤

<p><b>OBJECTIVE</b>To compare biomechanical effect of the closed fracture model with intramedullary nail fixation and the open fracture model with plate fixation in rats.</p><p><b>METHODS</b>Forty 8-week-old Spragu-Dawley male rats were divided into two groups randomly. Left femoral shaft closed fractures model was created in 20 rats, and treated with intramedullary nail. Other 20 rats received open osteotomy on the left femoral shaft, and were fixed by plate. Rats were sacrificed and draw the materials at 4, 6, 8 and 12 weeks in batch. Across section area and volume of callus were measured, peak load, restoration rate of peak load were tested. The biomechanical efficency of two methods of femoral shaft fracture fixation were compared.</p><p><b>RESULTS</b>The difference of surgical duration was statistically significant between two groups (P < 0.001). At 4, 6, 8 and 12 weeks, the difference of peak load, restoration rate of peak load, volume and area of callus was also statistically significant between two groups (P < 0.05).</p><p><b>CONCLUSION</b>Open fracture model with plate fixation led to delayed healing compared with closed fracture model with intramedullary nail. However, open fracture model with plate fixation model could be a valuable research tool to study the healing consequences of cortical bone, which may provide insight into the pathogenesis and ideal treatment of fractures or nonunions.</p>

In vitro cartilage production using an extracellular matrix-derived scaffold and bone marrow-derived mesenchymal stem cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cartilage repair is a challenging research area because of the limited healing capacity of adult articular cartilage. We had previously developed a natural, human cartilage extracellular matrix (ECM)-derived scaffold for in vivo cartilage tissue engineering in nude mice. However, before these scaffolds can be used in clinical applications in vivo, the in vitro effects should be further explored.</p><p><b>METHODS</b>We produced cartilage in vitro using a natural cartilage ECM-derived scaffold. The scaffolds were fabricated by combining a decellularization procedure with a freeze-drying technique and were characterized by scanning electron microscopy (SEM), micro-computed tomography (micro-CT), histological staining, cytotoxicity assay, biochemical and biomechanical analysis. After being chondrogenically induced, the induction results of BMSCs were analyzed by histology and Immunohisto-chemistry. The attachment and viability assessment of the cells on scaffolds were analyzed using SEM and LIVE/DEAD staining. Cell-scaffold constructs cultured in vitro for 1 week and 3 weeks were analyzed using histological and immunohistochemical methods.</p><p><b>RESULTS</b>SEM and micro-CT revealed a 3-D interconnected porous structure. The majority of the cartilage ECM was found in the scaffold following the removal of cellular debris, and stained positive for safranin O and collagen II. Viability staining indicated no cytotoxic effects of the scaffold. Biochemical analysis showed that collagen content was (708.2-44.7) µg/mg, with GAG (254.7 ± 25.9) µg/mg. Mechanical testing showed the compression moduli (E) were (1.226 ± 0.288) and (0.052 ± 0.007) MPa in dry and wet conditions, respectively. Isolated canine bone marrow-derived stem cells (BMSCs) were induced down a chondrogenic pathway, labeled with PKH26, and seeded onto the scaffold. Immunofluorescent staining of the cell-scaffold constructs indicated that chondrocyte-like cells were derived from seeded BMSCs and excreted ECM. The cell-scaffold constructs contained pink, smooth and translucent cartilage-like tissue after 3 weeks of culture. We observed evenly distributed cartilage ECM proteoglycans and collagen type II around seeded BMSCs on the surface and inside the pores throughout the scaffold.</p><p><b>CONCLUSION</b>This study suggests that a cartilage ECM scaffold holds much promise for in vitro cartilage tissue engineering.</p>

Effect of naringin monomer on osteogenic differentiation of bone mesenchymal stem cells under microstrain environment / 中草药

Objective: Under the microstrain environment, to investigate the impact and mechanisms of osteoblast differentiation of the naringin monomer on marrow stem cells (MSCs) in vitro. Methods: The cyclical stretch microstrain was loaded on silicone rubber membrane with cultured rabbit MSCs using EF3200 mechanical tester with the system of BioDynamic biological reaction tank. The experiment was divided into eight groups, A: the blank control group in conventional cultured environment; B: the group of alone microstrain loading; C: the group cultured in environment containing naringin and the naringin concentrations, respectively were 2, 20, and 200 ng/mL; D: under microstrain environment, the joint application with naringin at concentration of 2, 20, and 200 ng/mL. Flow cytometry was used to test the proliferation index (PI) of MSCs after microstrain loading. The gene expression of the cells in osteocalcin (OCN), osteoblast specific transcription factor (Runx2) and collagen type I (Col I) were assayed by RT-PCR. Results: Under the microstrain environment combined with naringin, MSCs showed obvious polarity and the long axis of cells parallel to the direction of mechanical stimulus direction. The combination of naringin and microstrain stimulation can significantly improve the MSCs proliferation activity. Naringin (200 ng/mL) could improve the gene expression of OCN under the stimulation of 50000 microstrain. Under 50000 microstrain stimulation, naringin at different concentration could significantly enhance the Runx2 gene expression and the effect between the enhancement and the naringin concentration was positive. Under the microstrain stimulation, naringin at low concentration could promote the Col I gene expression, on the contrary, naringin at high concentration could inhibit the Col I gene expression. Conclusion: Under the microstrain environment, naringin monomer could enhance the proliferation of MSCs and promote the osteogenetic differentiation of MSCs.

Clinical efficiency of computer-assisted pedicle screw placement versus conventional method: a meta-analysis / 中国骨伤

<p><b>OBJECTIVE</b>To compare the clinical efficacy of computer-assisted pedicle screw placement and conventional placement in the treatment of spinal disease.</p><p><b>METHODS</b>A systematic search of studies published between Jan. 1990 and Feb. 2012 was conducted using Medline, Embase, OVID, ScienceDirect and Cochrane Review databases. Randomized controlled trials (RCTs) and prospective controlled trials of comparing computer-assisted pedicle screw placement to conventional method performed at one center or multi-centers providing data on accuracy of placement and clinical effects were identified. Two study authors independently reviewed the 93 articles originally identified and selected 10 for analysis. Study title,demographic characteristics,number of pedicle screw,anatomical area and outcomes were extracted manually from all selected studies. RevMan 5.1 software was used for meta-analysis.</p><p><b>RESULTS</b>Ten studies encompassing 2813 pedicle screws met the inclusion criteria. Overall,the result of meta-analysis indicated that there were significant differences between two groups in accuracy in placement of pedicle screw [OR = 2.58, 95% CI (1.18, 5.63)], insertion time [WMD = -2.15, 95% CI (-2.36, -1.94)]. However, there was only one study reported preparation time of pedicle screw of navigation group was longer than conventional group. No neurological complication in navigation group was reported.</p><p><b>CONCLUSION</b>As a safety supplementary measure, computer navigation provide better accuracy in placement of pedicle screw and insertion time. The preparation time of pedicle screw may prolong due to the complexity of navigation system. Further reseach should include randomized controlled trials with well-planned methodology to limit bias.</p>

Influence of anteversion angles on stress distributions of the proximal femur after femoral neck fracture fixation: A finite element analysis / 医用生物力学

Objective To investigate the effects of different anteversion angles on stress distributions of the proximal femur after femoral neck fracture fixation by cannulated screw, and to provide biomechanical evidences for the importance of anatomical reduction in internal fixation in clinic. Methods Femoral neck fracture with Pauwells angle 70°was treated with cannulated screw internal fixation, and its three-dimensional finite element models with five different anteversion angles set at 0°，5°，10°，15°and 20°, respectively, were constructed based on normal human anatomical data from multi slice spiral CT as well as reverse engineering and CAD software. Loads were applied on each model to simulate normal walking status. Changes in stress distributions of the proximal femur in each model were observed. Results When the anteversion angle was 10°, the stress, displacement and equivalent strain of the femur was were the minimum, as the maximum stress of the proximal femur was 1.7 MPa, and the displacement was 1.1 mm. With the anteversion angle increasing or decreasing, the effective stress and displacement of the proximal femur was gradually increasing. When the anteversion angle was 20°, the stress of on the proximal femur and on the cannulated screw was became the maximum. When the anteversion angle was 0°, the displacement and equivalent strain of the femur also became the maximum. The stress concentration site of the femoral neck was gradually transferred from the inside rear to the outer top of the head and neck junction. The three cannulated screws there stood the higher stress than the surrounding bone tissues, and with the bottom screw stood the higher stress than the other top two screws. Conclusions Anatomic reduction is essential for femoral neck fracture fixation treated by cannulated screw. Changes in biomechanical factors after femoral neck fracture may play an important role in postoperative femoral head necrosis.

Five-level noncontiguous spinal injuries of cervical region: report of a case and literature review / 中华医学杂志(英文版)

The incidence of multiple noncontiguous spinal injuries (MNSI) in the cervical spine is rare but has catastrophic consequences. The patient in this report was a 34-year-old woman with five-level cervical MNSI. CT and MRI showed that injuries included atlantoaxial instability, burst fracture of C6, dislocation of C6/7, rupture of the intervertebal disc or ligamentous complex, and irreversible cord damage. The mechanism for this case was a combined pattern of hyperflexion, compression, and hyperextension injuries. A review of the literature revealed that this case is the first report in the literature of a vehicle related accident causing five-level noncontiguous injuries of the cervical spine.

Long-term results and radiographic findings of percutanous vertebroplasties with polymethylmethacrylate for vertebral osteoporotic fractures / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Percutaneous vertebroplasty (PVP) has become a popular procedure for painful vertebral osteoporotic fracture (VOF), with immediate pain relief and improved mobility; however, polymethylmethacrylate (PMMA) injected into the vertebral body is not absorbable and little information is available concerning the long-term results. In this retrospective study, we evaluated the long-term clinical results and radiological changes after PVPs for VOFs.</p><p><b>METHODS</b>Fifty-one patients with VOFs were treated by PVPs with PMMA between 2000 and 2004. After > 7 years of follow-up, eight patients had died from causes unrelated to the intervention and 12 patients were lost to follow-up, thus leaving 31 patients available for evaluation with an average length of follow-up of 9.2 years (follow-up rate, 72.1%). Among these 31 patients, the PMMA was injected at 43 levels with a mean volume of 4.3 ml per level (range, 2 - 6 ml). The pain was assessed with a visual analog scale (VAS), and the mobility was graded as walking without difficulty (grade 1), walking with assistance (grade 2), and bedridden (grade 3). Plain radiographs and computed tomography (CT) were obtained and assessed pre-operatively, immediately post-operatively, and after 7 years of follow-up. The PMMA, vertebral height, and Cobb angle were assessed and compared.</p><p><b>RESULTS</b>All of the patients experienced pain relief and improved mobility after intervention and during the follow-up period. Cement leakage was detected in post-operative CT scans in 9 of 51 patients, but without neurological compromise. For the 31 patients followed up over 7 years, the VAS decreased from 8.3 ± 2.6 pre-operatively, to 2.1 ± 1.6 immediately post-operatively, and 1.0 ± 0.9 at the final follow-up evaluation, with significantly improved mobility. Additional compression fractures occurred at adjacent levels in three patients, and there were no new fractures at the augmented vertebrae. Based on a review of the radiographs, neither loose nor displaced cement was detected. The changes in vertebral height and Cobb angle were not significant. On CT scans, the cement closely contacted or infiltrated the trabecular bone. The boundary between the cement and trabecular bone was indistinct and there was no evident radiolucent gap between the cement and trabecular bone.</p><p><b>CONCLUSIONS</b>At an average follow-up of 9.2 years, PVPs provided sustained pain relief and improved mobility in patients with VOFs. The PMMA injected into the vertebral body combined closely with the host trabecular bone without adverse reactions.</p>

Unilateral versus bilateral pedicle screw fixation in lumbar spinal fusion: a meta-analysis of available evidence / 中华外科杂志

<p><b>OBJECTIVE</b>To evaluate the effectiveness of unilateral versus bilateral pedicle screw fixation in lumbar spinal fusion.</p><p><b>METHODS</b>Studies on comparison between unilateral and bilateral pedicle screw fixation in lumbar spinal fusion were identified from Medline, EMBASE, Cochrane CENTRAL (Third Quarter 2011), ScienceDirect, OVID, SpringerLink and The China Biological Medicine Database, and searched several related journals by hand. The included trials were screened out according to the criterion of inclusion and exclusion. The quality of included trials was evaluated. Data were extracted by two reviewers independently. RevMan 5.1.1 was used for data analysis.</p><p><b>RESULTS</b>Seven studies involving 480 patients were included, 246 in unilateral group, and 234 in bilateral group. The results of meta-analysis indicated that statistically significant difference were observed between the two fixation procedures in mean operation time (MD = -24.39, 95%CI: -33.16 to 15.61, P < 0.01), the amount of bleeding (MD = -118.73, 95%CI: -143.43 to -94.03, P < 0.01). There were no difference in inpatient stay, fusion rate, complication rate and excellent and good rate.</p><p><b>CONCLUSIONS</b>Both unilateral and bilateral pedicle screw fixation are effective in lumbar spinal fusion. To compare with bilateral fixation, unilateral fixation can shorten operation time, reduce amount of bleeding and medical expenses. And there is a similar effect of inpatient stay, fusion rate, complication rate and excellent and good rate.</p>

Three-dimensional reconstruction study of the displacement of undisplaced femoral neck fractures / 中华外科杂志

<p><b>OBJECTIVE</b>To measure the displacement parameters of femoral head in space through three-dimensional reconstruction so as to reunderstand undisplaced femoral neck fractures.</p><p><b>METHODS</b>The clinical data of 80 undisplaced femoral neck fractures from January 2010 to June 2011 were selected, included Garden I 40 cases (group Garden I) and Garden II 40 cases (group Garden II), bilateral proximal femurs of everyone were scanned by CT and reconstructed by professional software. Registered the normal femur and fracture with mirror model, marked key points in the model and measured the displacement parameters of femoral head. The measurement accuracy of distance and angle were 0.01 mm and 0.01°, respectively. The parameters of femoral head displacement between group Garden I and Garden II were analyzed by independent-sample t-test.</p><p><b>RESULTS</b>Eighty cases on X-ray films were not found rotated displacement. But 24 cases of them (30.0%) showed rotated displacement and rotation direction of the femoral head through three-dimensional reconstruction. Ten cases showed incomplete fractures on X-ray films, but only 3 cases were incomplete fractures with three-dimensional reconstruction. In group Garden I, the femoral head displacement angle was 18° ± 11°, the average displacement distance of femoral head center and deepest point of fovea capitis were (6 ± 3) mm and (10 ± 6) mm respectively. In group Garden II, the femoral head displacement angle was 17° ± 10°, the average displacement distance of femoral head center and deepest point of fovea capitis were (7 ± 5) mm and (13 ± 8) mm respectively. There were not statistical significance of the parameters of femoral head displacement between group Garden I and Garden II (P > 0.05).</p><p><b>CONCLUSIONS</b>Three-dimensional reconstruction and digital measurement is a precise, efficient method for the measurement of femoral head displacement parameters in femoral neck fractures, has important clinical significance in the diagnosis and treatment of the femoral neck fractures. There are certain defects and limitations of the classical Garden classification for undisplaced femoral neck fractures.</p>

Test on compressive properties of trabecular bone in proximal femur using digital image correlation technique / 医用生物力学

Objective To improve the method used for traditional compression test to reflect the compressive elastic modulus of trabecular bone in proximal femur more accurately and investigate its biomechanical properties to provide experimental evidences for clinical treatment. Methods The properties of trabecular bone from normal cadaveric proximal femur(45~60 years old) were measured by the micro material mechanics testing system. Results The elastic modulus in the direction of principle compression and principle tension on trabecular bone were (335.26±183.85) MPa and (59.27±23.88) MPa, respectively. The biomechanical properties of trabecular bone in the direction of principle compression were significantly higher than those in its vertical direction.The displacement and strain distribution profiles under the loading were recorded, which showed to be asymmetric. Conclusions It is feasible to test the biomechanical properties of trabecular bone more accurately by the micro material mechanics testing system. The compressive properties of trabecular bone in proximal femur are obviously anisotropic and heterogeneous.

Stress analysis and biocompatibility research on a cell carrier with silicone rubber membrane / 医用生物力学

Objective To report a self-developed cell carrier made of silicone rubber membrane, and to calculate the strain distributions on the membrane and analyze biocompatibility of the silicone rubber by three dimensional (3D) finite element method (FEM) so as to make a comprehensive evaluation on this silicon rubber membrane and provide theoretical basis for cellular research under stress stimulation. Methods The silicon rubber was made into a membrane with the thickness of 0.1 cm. Based on elastic modulus and Poisson’s ratio of the silicone rubber membrane, 3D FEM was used to simulate the deformation of the membrane induced by the stretch stress. MTT method was used to compare the growing situation of cells cultured on the silicone membranes and in standard plastic plates, respectively. Embedding experiment was also conducted to find out whether the material had biological toxicity or not. ResultsUnder the loading of 0.5%~20% strain, the area with effective strain was in the center of the membrane, accounting for 90% of the total area. There still existed some differences in biocompatibility between the silicon rubber membrane and standard plastic plate, but the material itself showed no toxicity. Conclusions Stress distributions on the surface of this self-developed silicon rubber membrane and its biocompatibility were generally acceptable for cell culture, but its surface should be further improved to fit for cell stress experiment.

Analysis on the risk factors of second fracture in osteoporosis-related fractures / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To explore the clinical characteristics and risk factors of refracture in patients suffering from osteoporosis-related fractures as well as effective interventions.</p><p><b>METHODS</b>From January 2006 to January 2008, both out-patients and in-patients in our hospital who were over 50 years old and suffered from osteoporosis-related fractures were selected for this research. They were divided into fracture group and refracture group. The refracture rate was followed up for 2 years, during which 11 patients developed refracture, thus were included in the refracture group. Therefore, 273 patients, 225 first-fracture cases, aged (67.7+/-8.5) years, and 48 refracture cases, aged (72.7+/-9.5) years, were included in this study. General data including age and sex, fracture types, femoral neck bone mineral density (BMD) T-scores tested by dual-energy X-rays absorptiometry (DEXA), Charlson index, time-frame between two fractures as well as mobility skill assessment were collected and analyzed by single-factor and multivariate statistical methods.</p><p><b>RESULTS</b>Females accounted for 70.2% of the fracture group and 77.1% of the refracture group. The most common refracture type was vertebral fracture for the first time and femoral neck fracture for the second time during the follow-up. The second fracture happened 3.7 years after the first one on average. The refracture rate was 2.12% within one year, and 4.66% within two years. Risk factors for a second fracture in osteoporotic fracture patients included age (larger than 75 years, HR equal to 1.23, 95%CI 1.18-1.29; larger than 85 years, HR equal to 1.68, 95% CI 1.60-1.76), female sex (HR equal to 1.36, 95%CI 1.32-1.40), prior vertebral fractures (HR equal to 1.62, 95%CI 1.01-2.07), prior hip fractures (HR equal to 1.27, 95%CI 0.89-2.42), BMD T-score less than -3.5 (HR equal to 1.38, 95%CI 1.17-1.72) and weakened motor skills (HR equal to 1.27, 95%CI 1.09-1.40).</p><p><b>CONCLUSIONS</b>The risks of second fracture among patients with initial brittle fracture are substantial. There is adequate time between the first and second fractures for interventions to reduce the risks of refracture, especially for the old women with a vertebral or hip fracture. Medication, motor functional rehabilitation and fall-down prevention training are helpful.</p>