Biomechanical stability of unilateral pedicle screw fixation on cadaveric model simulated two-level posterior lumbar interbody fusion / 中华外科杂志

<p><b>OBJECTIVE</b>To analyze the biomechanical efficacy of unilateral pedicle screw fixation on human cadaveric lumbar spine model simulated by two-level posterior lumbar interbody fusion (PLIF).</p><p><b>METHODS</b>Six fresh-frozen adult human cadaveric lumbar spine motion segments (L(2)-S(2)) were simulated to unilateral/bilateral L(4)-S(1) PLIF constructs augmented by unilateral/bilateral pedicle screw fixation sequentially and respectively. All configurations were tested by MTS 858 in the following sequential construct order: the intact, UI (unilateral instability), UIUF1C (unilateral instability via unilateral pedicle screw fixation plus one cage), BIUF1C (bilateral instability via unilateral pedicle screw fixation plus one cage), BIBF1C (bilateral instability via bilateral pedicle screw fixation plus one cage) and BI (bilateral instability without pedicle screw and cage). Each specimen was nondestructively tested in flexion/extension, lateral bending, and axial rotation. An axial compressive load ranged from 40 N to 360 N and the maximum peak moment of 8 N·m was applied during testing. The range of motion (ROM) and neutral zone (NZ) of fusion segment were recorded by a 6-Eagle Motion Analysis F40 system, and then statistic comparison were performed between different simulated constructs with One Way of ANOVA and Post hoc LSD tests.</p><p><b>RESULTS</b>BIBF1C had the lowest ROM and NZ of L(4)-S(1) fusion segments in all loading models, which were significantly lower than those of any uninstrumented construct (the intact, UI and BI) (P < 0.05). In flexion/extension, lateral bending, and axial rotation, the ROM of UIUF1C was respectively 2.53 ± 1.12, 4.03 ± 2.19, 2.78 ± 1.00 and the NZ of UIUF1C was respectively 1.14 ± 0.70, 1.96 ± 1.13, 1.28 ± 0.71, which were significantly lower than those of the intact (P < 0.05). Compared to BIBF1C, the ROM and NZ were respectively increased 60.13% and 17.52% in flexion/extension, 315.46% and 243.86% in lateral bending, 8.17% and 6.20% in axial rotation, however, there were no significant differences between these two constructs (P > 0.05). In lateral-bending and axial rotation, the ROM and NZ of BIUF1C were significantly higher than those of BIBF1C (P < 0.05). In flexion/extension, the ROM and NZ of BIUF1C were higher than those of BIBF1C but there were no significant differences (P > 0.05). Compared to the intact, BIUF1C had lower ROM and NZ except for higher NZ in axial rotation, and there were significant differences only in flexion/extension (P < 0.05).</p><p><b>CONCLUSIONS</b>All tested two-level unilateral fixation on simulated human cadaveric model with unilateral PLIF can achieve similar initial biomechanical stability in comparison with two-level bilateral pedicle screw fixation. However in most test modes, two-level unilateral pedicle screw fixation on simulated human cadaveric model with bilateral PLIF can not achieve enough biomechanical efficacy in comparison with two-level bilateral pedicle screw fixation.</p>

Effects on VEGF and VEGF mRNA expression of the tissues of periosteum in three-period treatment of TCM for the fractures in rabbit / 中国骨伤

<p><b>OBJECTIVE</b>To observe the effects of the three-period treatment theory of bone fracture in TCM (Traditional Chinese Medicine) on VEGF and VEGF mRNA expression in the issues of outer periosteum, endosteum and bone marrow of rabbits, and to explore the rationality of phasing method in TCM in treating fracture.</p><p><b>METHODS</b>3 mm bone defection were made at lower one third part of both radius in 140 male healthy rabbits. The rabbits were randomly divided into four groups, including three-period treatment group (TTG), one-period treatment group(OTG), positive medicine treatment group(PTG) and model control group (MCG). The rabbits in TG were treated with three-period treatment, rabbits in OTG were treated with one-period treatment, rabbits in PTG were fed by Guzhe-Cuoshangsan (a Chinese patent medicine which was used to treat bone fracture), rabbits in model control group were given no prescription or drug but distilled water as same dose as that of other groups. At day 3, 6, 9, 14, 28, 42 and 56, five rabbits from every group were randomly selected and were killed by aeroembolism. The left radiuses were taken out as the research object. Immunohistochemistry stain and in situ hybridization stain were performed to examinate the VEGF and VEGF mRNA expression in the outer periosteum, endosteum and bone marrow.</p><p><b>RESULTS</b>The VEGF and VEGF mRNA expression of all TCM treatment groups were enhanced in the outer periosteum, endosteum and bone marrow at different time points in fracture healing. The VEGF and VEGF mRNA expression in the three tissues of TTG had the tendency of higher than that of the other groups at the most time points after operation.</p><p><b>CONCLUSION</b>Treating fracture in stages has more predominant effect on the expression of VEGF and VEGF mRNA in the outer periosteum, endosteum and bone marrow than that of treating fracture with single prescription or drug.</p>

Additional screws fixation on fractured vertebrae versus only short-segment posterior instrumentation for thoracolumbar A3 fracture without neurologic deficit / 中华外科杂志

<p><b>OBJECTIVE</b>To compare the clinical results of additional screws fixation on fractured vertebrae versus only short-segment posterior transpedicular instrumentation for A3 thoracolumbar fracture without neurologic deficit.</p><p><b>METHODS</b>Clinical data of 52 cases of thoracolumbar burst fracture without neurologic deficit were retrospectively analyzed. All patients were divided into 2 groups due to different instrumentation and all fractures were classified as type A3 according to AO Classification.From January 2005 to December 2006, 23 cases in group A were treated by short-segment posterior instrumentation combined with additional screws fixation on fractured vertebrae. There were 18 male and 5 female with a mean age of (35.3+/-8.3) years. The fracture segment included 1 in T11, 9 in T12, 11 in L1 and 2 in L2. From January 1999 to December 2004, 29 cases in group B were treated only by conventional short-segment posterior transpedicular instrumentation. There were 20 male and 9 female with a mean age of (37.3+/-6.8) years. The fracture segment included 1 in T11, 7 in T12, 20 in L1 and 1 in L2. The clinical effect and radiographic measurements were respectively compared preoperatively, immediate and 2 years postoperatively.</p><p><b>RESULTS</b>All patients were followed up and the mean follow-up time was (37.4+/-10.9) months (from 24 to 48 months). There was no statistic difference of mean JOA and VAS score between 2 groups preoperatively, immediate and 2 years postoperatively (P>0.05). The average immediate postoperative correction of Cobb's angle was 13.7 degrees+/-7.7 degrees in group A, which was statistically significantly higher than that of 8.8 degrees+/-5.0 degrees in group B (P<0.01). The mean kyphosis correction loss of 2.9 degrees+/-1.5 degrees in group A was statistically significantly lower than that of 5.0 degrees+/-2.9 degrees in group B 2 years postoperatively (P<0.01). The average restoration of anterior height of fractured vertebral body immediate postoperatively was (29.4+/-6.0)% and (21.7+/-6.9)% respectively. The mean correction loss of anterior height 2 years postoperatively was (3.1+/-0.8)% and (6.6+/-3.0)% respectively. The average restoration of posterior height of fractured vertebral body immediate postoperatively was (8.5+/-3.2)% and (6.1+/-1.8)% respectively. The mean correction loss of posterior height 2 years postoperatively was (2.0+/-0.8)% and (3.4+/-1.0)% respectively. There were significant differences in average restoration of anterior/posterior height immediate postoperatively and correction loss of anterior/posterior height 2 years postoperatively between the 2 groups (P<0.01). According to fracture fragments protruded into the spinal canal on immediate postoperative CT image, there were complete reduction in 11 cases (47.8%) and partial reduction in 12 cases (52.2%) in group A, which was statistically significantly better than those in group B (P<0.01). There was no severe neurologic complications and no other complications related to additional screws fixation postoperatively. Pedicle screw breakage occurred in 2 cases in group B and none in group A.</p><p><b>CONCLUSIONS</b>Better initial kyphosis correction and less loss of correction 2 years after operation can be obtained by using additional screws fixation on fractured vertebra for thoracolumbar A3 fracture without neurologic deficit.</p>

Spinal surgeons' learning curve for lumbar microendoscopic discectomy: a prospective study of our first 50 and latest 10 cases / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Microendoscopic discectomy (MED) is a minimally invasive operation that allows rapid recovery from surgery for lumbar disc herniation, but has replaced traditional open surgery in few hospitals because most surgeons avoid its long learning curve. We evaluated the effectiveness and safety of lumbar MED at stages of spinal surgeons' learning curve.</p><p><b>METHODS</b>Fifty patients receiving MED from June 2002 to February 2003 were divided into chronological groups of ten each: A - E. The control group F was ten MED patients treated later by the same medical team (September - October 2006). All operations were performed by the same team of spinal surgeons with no MED experience before June 2002. We compared groups by operation time, blood loss, complications and need for open surgery after MED failure.</p><p><b>RESULTS</b>Operation times by group were: A, (107 +/- 14) minutes; B, (85 +/- 13) minutes; C, (55 +/- 19) minutes; D, (52 +/- 12) minutes; E, (51 +/- 13) minutes; and F, (49+/- 15) minutes. Blood loss were: A, (131 +/- 73) ml; B, (75 +/- 20) ml; C, (48 +/- 16) ml; D, (44 +/- 17) ml; E, (45 +/- 18) ml; and F, (45 +/- 16) ml. Both operation time and blood loss in groups C, D, E and F were smaller and more stable compared with groups A and B. Japanese Orthopedic Association assessment (JOA) score of each group in improvement rate immediately and one year after operation were as follows (in percentage): A, (79.8 +/- 8.8)/(89.8 +/- 7.7); B, (78.6 +/- 8.5)/(88.5 +/- 7.8); C, (80.8 +/- 11.3)/(90.8 +/- 6.7); D, (77.7 +/- 11.4)/(88.9 +/- 9.3); E, (84.0 +/- 8.7)/(89.6 +/- 9.0); and F, (77.8 +/- 11.6)/(86.9 +/- 8.4). Groups showed no statistical difference in improvement rates. Complications developed in three patients in group A, two in group B, and none in the other groups.</p><p><b>CONCLUSIONS</b>Spinal surgeons performing MED become proficient after 10 - 20 operations, when their skill becomes fairly sophisticated. Patients' improvement rate is the same regardless of surgeons' phase of learning curve.</p>

Effects on VEGF and VEGF mRNA expression in issues of callus in treating fracture of rabbit with three-period treatment theory of bone fracture in traditional Chinese medicine / 中国中药杂志

<p><b>OBJECTIVE</b>To observe the effects of the three-period treatment theory of bone fracture in traditional Chinese medicine (TCM) on VEGF and VEGF mRNA expression in the issues of callus of rabbits. And to explore the rationality of phasing method in TCM in treating fracture.</p><p><b>METHOD</b>one hundred and forty male and healthy rabbits were made 3 mm wide bone defection at lower one third part of both radius as fracture healing model. Then those rabbits were divided into four groups randomly, which are three-period treatment group (TTG), one-period treatment group (OTG), positive medicine treatment group (PTG) and model control group (MCG). Those rabbits in TTG were treated with three-period treatment. Those in OTG were treated with one-period treatment. Those in PTG were feed by guzhecuoshangsan, a Chinese patent medicine which is used to treat bone fracture. Those in model control group were given no prescription or drug but distilled water as same dose as that of other groups. At day 3, 6, 9, 14, 28, 42 and 56, five rabbits were selected from every group randomly and were killed by aeroembolism respectively. Their radius were taken out and the left one was taken as the research object. Immunohistochemistry stain and in situ hybridization stain were performed to examinate the VEGF and VEGF mRNA expression in the haematoma, fibrous callus and soft callus.</p><p><b>RESULT</b>All TCM treatment groups can enhance the VEGF and VEGF mRNA expression in the haematoma, fibrous callus and soft callus at different time points in fracture healing. The VEGF and VEGF mRNA expression in the three issues of TTG had the tendency of higher than that of the other groups at the most time points after operation.</p><p><b>CONCLUSION</b>TCM can promote the VEGF and VEGF mRNA expression in the haematoma, fibrous callus and soft callus. Different Chinese medicines play various roles on VEGF and VEGF mRNA expression at different stage of fracture healing. Treating fracture in three-period treatment has more predominant effect on the expression of VEGF and VEGF mRNA in the haematoma, fibrous callus and soft callus than that of treating fracture with single prescription or drug. It is necessary to treat fracture in stages.</p>

Inhibitors of Na+/H+ and Na+/Ca2+ exchange depress intracellular calcium elevation induced by ischemia/reperfusion in rat cardiac myocytes / 生理学报

An increase in cytosolic free calcium has been shown to occur during ischemia in perfused hearts and plays a pivotal role in ischemia/reperfusion injury. The objective of this study was to investigate the contributions of Na(+)/H(+) exchange and Na(+)/Ca(2+) exchange to changes in intracellular calcium ([Ca(2+)](i)) during simulated ischemia and reperfusion in quiescent isolated rat cardiac myocytes. [Ca(2+)](i) was measured by laser confocal microscope using the fluorescent indicator Fluo 3 and expressed as the corrected intensity of Fluo 3 fluorescence. [Ca(2+)](i) increased to 140.3+/-13.0% (P<0.05 vs preischemic control 100%) after 5 min simulated ischemia, and remained at high level of 142.8+/-15.5% (P<0.05) after the following 15 min reperfusion. The increase in [Ca(2+)](i) during simulated ischemia and reperfusion was suppressed by 100 micromol/L amiloride (inhibitor of Na(+)/H(+) exchanger), 5 mmol/L NiCl2 (inhibitor of Na(+)/Ca(2+) exchanger) and calcium-free solution; [Ca(2+)](i) was 101.4+/-16.3%, 110.4+/-11.1% and 107.1+/-10.8%, respectively, after 5 min simulated ischemia, and 97.8+/-14.3%, 106.2+/-14.5% and 106.6+/-15.7%, respectively, after 15 min reperfusion. Compared with control cells, the amplitude of spontaneous calcium oscillation was lessened in cells treated with Ca-free perfusion and NiCl2 during reperfusion. In addition, no calcium oscillation was observed in cells pretreated with amiloride. These results suggest that Na(+)/H(+) exchange and Na(+)/Ca(2+) exchange are activated during simulated ischemia in isolated quiescent cardiac myocytes, leading to the elevation of [Ca(2+)](i) induced by simulated ischemia and reperfusion.

The effects of simulated microgravity on pulmonary arteries and aortae / 中国应用生理学杂志

<p><b>AIM</b>Through studying local regulatory mechanisms in pulmonary arteries (PA) and thoracic aortae (TA) under simulated microgravity (SM), to collect some data for the researches of adaptive mechanisms in pulmonary and systemic arteries and for the mechanisms accounting for orthostatic intolerance after SM.</p><p><b>METHODS</b>Cardiopulmonary circulatory function during 7-day 6 degrees head down bed rest (HDT) in male young volunteers was measured with a XXH-2000 pulmonary circulation and cardiac function instrument. - 30 degrees C tail suspended (TS) rats were used as the model to simulate the physiological effects of M. The PA and TA changes of vasoreactivity were respectively observed by vitro vessel rings perfusion.</p><p><b>RESULTS</b>The changes in volume of PA and pulmonary vein during a cardiac cycle and the preload in left cardiac ventricle in men increased significantly in the initial HDT. The super-regulatory phenomena appeared in both pulmonary and systemic circulation, but earlier and more obviously in pulmonary circulation than systemic circulation during 96-144 h. The dilatory reactivity in TS7 PA increased significantly, tended to decrease in TS14. The dilatory reactivity of TA in TS7 had a significant increase, had a slight increase in TS14. The contractile reactivity of PA decreased slightly in TS7 from CON, and were attenuated significantly in TS14. The contractile reactivity of TA in TS14 decreased significantly. The responsiveness to KCl, phenylephrine and sodium nitroprusside in VEC- removed PA had no differences among all groups.</p><p><b>CONCLUSION</b>The differences in changes between pulmonary and systemic arteries under SM could be an important sign of depressed local regulatory function, which might be mainly due to dilatory function in VEC and contribute to the occurrence of orthostatic intolerance after SM.</p>