Objective To review the current development of the dynamic stabilization devices and their biomechanics as well as clinical application.Methods The related biomedical research papers at home and abroad were consulted and analyzed Results There were obvious advances in the theoretic foundation and the clinical application in treatment of the degenerative lumbar disorders with the dynamic stabilization devices, especially with the nonfusion dynamic stabilization devices. Conclusion The effectiveness of the dynamic stabilization devices have attracted more and more biomedical researchers, especially the posterior dynamic stabilization device, which has provided a new approach to treatment of the degenerative lumbar disorders.
Objective To compare the balance of simple randomization, stratified blocked randomization and minimization. Methods Monte Carlo technique was employed to simulate the treatment allocation of simple randomization, stratified blocked randomization and minimization respectively, then the balance of treatment allocation in each group and the balance for every prognostic factor were compared. Results The simulation demonstrated that minimization provides the best performance to ensure balance in the number of patients between groups and prognostic factors. Balance in prognostic factors achieved with stratified blocked randomization was similar to that achieved with simple randomization. Conclusion Minimization offers the best balance in the number of patients and prognostic factors between groups.
Objective To evaluate the influence on the estimation of respiratory mechanics with dynamic signal analysis approach during noninvasive positive pressure ventilation (NPPV) under different inspiratory effort conditions. Methods The Respironics V60 ventilator was connected to a ASL5000 lung simulator, which simulate lung mechanics in healthy adults with body weight from 65 to 70 kg, and patients with chronic obstructive pulmonary disease (COPD) and acute respiratory distress (ARDS). Each lung models was subjected to 4 different muscle pressures (Pmus): 0, 5.0, 10.0, and 15.0 cm H2O. Inspiratory pressure support level was adjusted to maintain tidal volume (VT) achieving 7.0 mL/kg outputted by ventilator respectively. Positive end expiratory pressure was set at 5.0 cm H2O and back-up rate was 10 beats per minute. Measurements were conducted at system leaks with 25 to 28 L/min. The respiratory system compliance (Crs), inspiratory and expiratory resistance (Rinsp and Rexp) were estimated by special equations, which was derived from the exhaled VT, flow rate and airway pressure. Results The driving pressure (DP) was decreased with Pmus increasing, and was 1.0 cm H2O after Pmus exceeding 10.0 cm H2O and the VT was larger than 7.0 mL/kg in normal adult model. The estimated value of Crs was affected by the changes of Pmus in all three lung models. The significant underestimation of Raw and the overestimation of Crs were observed when Pmus level exceed 10.0 cm H2O. The measured errors of Crs and Rexp were within 10% in COPD and ARDS model when Pmus was at 5.0 cm H2O. The underestimation of Rinsp was always existed in all Pmus level (P<0.01). Conclusions Using dynamic signal analysis approach, the real-time estimation of respiratory mechanics (Crs and Raw) is no need to interrupt the spontaneous breathing during NPPV. Excessive effort will increase the patient’s inspiratory workload, which is not benefit to accurate estimation of respiratory mechanics.
Objective To improve the knowledge on dynamic benign central airway stenosis through two typical cases. Methods The clinical features, imaging findings, and bronchial morphologic changes of two cases characterized by dynamic benign central airway stenosis were retrospectively analyzed. The etiologies for the two cases were tracheobronchomalacia (TBM) and excessive dynamic airway collapse (EDAC), respectively. Results Central airway stenosis and reversible airway obstruction were common clinical characteristics for the two cases. However, there were identifiable differences on imaging findings and bronchial morphologic changes between the two cases. Multidetector computed tomography showed sabre-sheath trachea and narrowed trachea in coronal position for TBM, while small sized trachea in exhalation phase and narrowed trachea in sagittal position for EDAC. Bronchoscopy displayed narrowed airway, swelling mucosa, and the absence of annular cartilage for TBM, while crescent airway with membranacea part protruding to lumen in inspiration phase, and the integrity of annular cartilage for EDAC. Conclusion Multidetector computed tomography and bronchoscopy examinations are valid methods to distinguish TBM and EDAC, which are both characterized by dynamic benign central airway stenosis.
Objective To compare the effectiveness and radiological changes of posterior decompression combined with Coflex interspinous dynamic reconstruction or lumbar 360° fusion for degenerative lumbar spinal disorders at L4, 5. MethodsBetween October 2008 and November 2010, a comparative study was carried out on patients with degenerative lumbar spinal disorders at L4, 5. In group A, 29 patients underwent posterior decompression combined with Coflex interspinous dynamic reconstruction; there were 20 males and 9 females with an average age of 45.1 years (range, 21-67 years); and the disease duration was 2 months to 4 years. In group B, 31 patients underwent posterior decompression combined with lumbar 360° fusion treatment; there were 16 males and 15 females with an average age of 56.2 years (range, 32-86 years); and the disease duration was 3 months to 6 years. Except the age, there was no significant difference in gender, disease duration, and etiology etc. between 2 groups (P gt; 0.05). The results were assessed by Japanese Orthopaedic Association (JOA), visual analogue scale (VAS) scores, and Oswestry disabil ity index (ODI). The range of motion (ROM) and intervertebral height of affected and adjacent segments, and the ROM of lumbar were measured before operation and last follow-up. Results Significant differences were found in the operative time and blood loss between 2 groups (P lt; 0.05). Intraoperative dural tear occurred in 1 case of group B, spinal canal venous plexus hemorrhage in 1 case of group B, and postoperative cerebrospinal fluid leakage in 2 cases of group A and B respectively, showing no significant difference (χ2=0.119, P =0.731). The follow-up was 12-21 months in group A and was 12-23 months in group B. At the last follow-up, the JOA, VAS scores, and ODI of groups A and B were significantly improvedwhen compared with the preoperative values (P lt; 0.05). The VAS score of group A was significantly higher than that of group B (P lt; 0.05). There was no significant difference in the intervertebral height of L4, 5 and L5, S1 of groups A and B between pre- and post-operation (P gt; 0.05). In group B, the intervertebral height of L3, 4 was significantly reduced (P lt; 0.05) compared with the preoperative one. There was no significant difference in the ROM of L5, S1 and ROM of lumbar in groups A and B between preand post-operation (P gt; 0.05). At last follow-up, the ROM of L4, 5 was significantly reduced in group A (P lt; 0.05), and the ROM of L3, 4 was significantly increased in group B (P lt; 0.05). Except significant differences in the intervertebral height and ROM of L3, 4 between 2 groups (P lt; 0.05), no significant difference was found in other parameters (P gt; 0.05). Conclusion Posterior decompression combined with Coflex interspinous dynamic reconstruction has the same effectiveness as lumbar 360° fusion in treating degenerative lumbar spinal disorders at L4, 5, but the former has a protective effect on the adjacent segments of fusion and is recommended for initial treatment of young adults and the elderly and frail patients with recurrent.
ObjectiveTo investigate the effect of three-dimensional cultivation with dynamic compressive stimulation on promotion of cartilage growth in vitro, by constructing tissue engineered cartilage with three-dimensional porous articular cartilage extracellular matrix (ECM) scaffolds laden with rabbit chondrocytes and performing mechanical stimulation by compressive stress in bioreactor. MethodsChondrocytes of healthy adult New Zealand rabbits were isolated, and passage 2 chondrocytes were seeded onto three-dimensional porous articular cartilage ECM scaffolds for 5 days pre-cultivation, and then were divided into 2 groups:Group A continued static culture as control; group B (dynamic culture condition) underwent dynamic compressive strain stimulation (compressive strain of 15%, frequence of 1 Hz) in a bioreactor. Cell viability and distribution in scaffolds were observed; the glycosaminoglycan (GAG) content, collagen content, and total DNA content were measured after 3 weeks of culturing; and elastic modulus was evaluated by mechanical test. ResultsLaser scanning confocal microscopy indicated that cells grew well and evenly distributed in the scaffold of group B, while poor cells growth and loss of staining in the central region of the scaffolds were observed in group A. Scanning electron microscopy showed that chondrocytes possessed good adhesion, proliferation, and growth on the scaffolds of group B; while the number of chondrocytes was significantly reduced, and cells scattered in group A. Biochemical composition analysis showed that collagen, GAG, and DNA contents of cell-scaffold constructs were (675.85±27.93) μg/mg, (621.72±26.75) μg/mg, and (16.98±3.23) μg/sample in group B, and were (438.72±6.35) μg/mg, (301.63±30.51) μg/mg, and (10.18±4.39) μg/sample in group A respectively, which were significantly higher in group B than in group A (t=18.512, P=0.000;t=17.640, P=0.000;t=2.790, P=0.024). Mechanical testing indicated that the elastic modulus of group B[(0.67±0.09) MPa] was significantly higher than that of group A[(0.49±0.16) MPa] and cell-free scaffolds[(0.43±0.12) MPa] (P < 0.05). ConclusionMimetic compressive stress with three-dimensional dynamic conditions created in the bioreactor is superior to the ordinary static three-dimensional cultivation, it can provide the optimal environment for chondrocytes on the ECM scaffolds, which may be a good way to construct tissue engineered cartilage in vitro.
OBJECTIVE: To study the changes of neural electrophysiology properties of cauda equina under double level compression and dynamic burdens, and to clarify the mechanisms of intermittent neurogenic claudication. METHODS: Thirty SD rats were divided into 5 groups (6 in each group). The laminectomy of L5 was performed in control group. In the experimental groups, the silicon sheets were inserted into the spinal canal of L4 and L6 to cause double level compression of cauda equina by 30%. Two hours after onset of compression, no dynamic burden was introduced in experimental group 1. Only high frequency stimulation(HFS) was introduced for 6 minutes in experimental group 2. Both HFS and additional increased compression were introduced for 6 minutes in experimental group 3. While only additional increased compression was introduced for 6 minutes in experimental group 4. After 6 minutes of dynamic burdens, all were returned to the status of static compression for another 30 minutes and then electrical examination was made. RESULTS: After 2 hours of compression, motor and sensory nerve conduction velocity (NCV) of all the four experimental groups decreased significantly (P lt; 0.05), but there was no significant difference between them. There was no significant change in the control group. There was no significant change of NCV in experimental group 1 during the last 30 minutes of experiment. NCV in the other three experimental groups decreased after introduction of dynamic burdens, especially in the experimental group 3. CONCLUSION: The above results showed that NCV of cauda equina decreased significantly under dynamic burdens during static compression. Two kinds of dynamic burdens introduced at the same time can cause more profound change than a single one.
Brain functional network changes over time along with the process of brain development, disease, and aging. However, most of the available measurements for evaluation of the difference (or similarity) between the individual brain functional networks are for charactering static networks, which do not work with the dynamic characteristics of the brain networks that typically involve a long-span and large-scale evolution over the time. The current study proposes an index for measuring the similarity of dynamic brain networks, named as dynamic network similarity (DNS). It measures the similarity by combining the “evolutional” and “structural” properties of the dynamic network. Four sets of simulated dynamic networks with different evolutional and structural properties (varying amplitude of changes, trend of changes, distribution of connectivity strength, range of connectivity strength) were generated to validate the performance of DNS. In addition, real world imaging datasets, acquired from 13 stroke patients who were treated by transcranial direct current stimulation (tDCS), were used to further validate the proposed method and compared with the traditional similarity measurements that were developed for static network similarity. The results showed that DNS was significantly correlated with the varying amplitude of changes, trend of changes, distribution of connectivity strength and range of connectivity strength of the dynamic networks. DNS was able to appropriately measure the significant similarity of the dynamics of network changes over the time for the patients before and after the tDCS treatments. However, the traditional methods failed, which showed significantly differences between the data before and after the tDCS treatments. The experiment results demonstrate that DNS may robustly measure the similarity of evolutional and structural properties of dynamic networks. The new method appears to be superior to the traditional methods in that the new one is capable of assessing the temporal similarity of dynamic functional imaging data.
Traditional Chinese medicine (TCM) has some unique advantages in the prevention and treatment of cancer. Due to different ideas and mechanism of between TCM and biomedicine in the prevention and treatment of cancer, the clinial effect evaluation approches of biomedicine could not be used as a beneficial method to scientifically evaluate the effects of TCM. From three angles, this article analyzes the key issues regardsing the evaluation methods of TCM as an adjuvant therapy of cancer. It draws lessons from the idea of quality-adjusted survival (QAS), proposes Two-in-One (TIO) method to evaluate the effects of TCM as adjuvant therapy of cancer, which reflects the combined value of the individual patient dynamic information and provides methodological support for the effect evaluation of TCM.
Objective To compare the curative effect of dynamic hi p screw (DHS) combined with anti-rotation screw and cannulated screw in treating patients with Pauwels type II or III femoral neck fracture and to provide the basis for the choice of surgical procedure. Methods Between March 2008 and September 2009, 51 patients with fresh Pauwels type II or III femoral neck fracture were treated with DHS combined with anti-rotation screw (DHS group) and three cannulated screws (cannulated screw group). The DHS group included 23 patients, 13 males and 10 females, aging 27-59 years (mean, 43.2 years); fracture was caused by fall ing in 1 case, by traffic accident in 17, by fall ing from height in 5 with a mean time of 27 hoursfrom injury to hospital ization (range, 12-70 hours); and 23 fractures included 9 Pauwels type II and 14 Pauwels type III femoral neck fracture. The cannulated screw group included 28 patients, 12 males and 16 females, aging 20-60 years (mean, 40.7 years); fracture was caused by fall ing in 1 case, by traffic accident in 22, by fall ing from height in 5 with a mean time of 25 hours from injury to hospital ization (range, 9-38 hours); and 28 fractures included 12 Pauwels type II and 16 Pauwels type III femoral neck fracture. There was no significant difference in the basel ine characteristics between 2 groups (P gt; 0.05). Results The incision heal ing of both groups by first intention was achieved. There were significant differences in operation time, incision size, operation blood loss, the cases of blood transfusion, the amount of blood transfusion, C reaction protein level on the 2nd postoperative day, and hospital ization days between 2 groups (P lt; 0.05). In DHS group, anatomic reduction was observed in 20 cases (86.96%) and satisfactory reduction in 3 cases (13.04%), while in cannulated screw group, anatomic reduction was observed in 25 cases (89.29%) and satisfactory reduction in 3 cases (10.71%) ; there was no significant difference (χ2=0.660, P=1.000). The patients were followed up 12-30 months with an average of 14.8 months. There was no significant difference (P gt; 0.05) in the rate of nonunion (10.71% vs. 0), the implant failure (3.57% vs. 0), and avascular necrosis of the femoral head (10.71% vs. 0) between the DHS group and the cannulated screw group. The union time was (94.5 ± 2.0) days in the DHS group and (106.0 ± 33.5) days in the cannulated screw group, showing no significant difference (t=—1.641, P=0.107). The re-opereation rates and the overall success rates were 25% and 75% in the cannulated group and were 0 and 100% in the DHS group, showing significant differences (χ2=6.650, P=0.012). At last follow-up, there was no significant difference in Harris hip score and visualanalogue scale (VAS) score between DHS group and cannulated screw group (P gt; 0.05). Conclusion The optimal treatment of young adults Pauwels type II or III femoral neck fracture is DHS combined with anti-rotation screw with an high overall success and less compl ications.