Unilateral pedicle screws asymmetric tethering: an innovative method to create idiopathic deformity

<p>Abstract</p> <p>Objective</p> <p>To evaluate the feasibility of the method that unilateral pedicle screws asymmetric tethering in concave side in combination with convex rib resection for creating idiopathic deformity.</p> <p>Summary of background data</p> <p>Various methods are performed to create idiopathic deformity. Among these methods, posterior asmmetric tethering of the spine shows satisfying result, but some drawbacks related to the current posterior asymmetric tether were still evident.</p> <p>Materials and methods</p> <p>Unilateral pedicle screws asymmetric tethering was performed to 14 female goats (age: 5–8 week-old, weight: 6–8 kg) in concave side in combination with convex rib resection. Dorsoventral and lateral plain radiographs were taken of each thoracic spine in the frontal and sagittal planes right after the surgery and later every 4 weeks.</p> <p>Results</p> <p>All animals ambulated freely after surgery. For technical reasons, 2 goats were excluded (one animal died for anesthetic during the surgery, and one animal was lost for instrumental fail due to postoperative infection). Radiography showed that 11 goats exhibited scoliosis with convex toward to the right side, and as the curve increased with time, only 1 goat showed nonprogressive. The initial scoliosis generated in the progressors after the procedures measured 29.0° on average (range 23.0°–38.5°) and increased to 43.0° on average (range 36.0°–58.0°) over 8 to 10 weeks. The average progression of 14.0° was measured. The curvature immediately after tethering surgery (the initial Cobb angle) did have a highly significant correlation with the final curvature (p < 0.001). The progressive goats showed an idiopathic-like deformity not only by radiography, but in general appearance.</p> <p>Conclusion</p> <p>Unilateral pedicle screws asymmetric tethering is a practical method to create experimental scoliosis, especially for those who would like to study the correction of this deformity.</p

Effect of Low Tube Voltage on Image Quality, Radiation Dose, and Low-Contrast Detectability at Abdominal Multidetector CT: Phantom Study

Purpose. To investigate the effect of low tube voltage (80 kV) on image quality, radiation dose, and low-contrast detectability (LCD) at abdominal computed tomography (CT). Materials and Methods. A phantom containing low-contrast objects was scanned with a CT scanner at 80 and 120 kV, with tube current-time product settings at 150–650 mAs. The differences between image noise, contrast-to-noise ratio (CNR), and scores of LCD obtained with 80 kV at 150–650 mAs and those obtained with 120 kV at 300 mAs were compared respectively. Results. The image noise substantially increased with low tube voltage. However, with identical dose, use of 80 kV resulted in higher CNR compared with CNR at 120 kV. There were no statistically significant difference in CNR and scores of LCD between 120 kV at 300 mAs and 80 kV at 550–650 mAs (P > 0.05). The relative dose delivered at 80 kV ranged from 58% at 550 mAs to 68% at 650 mAs. Conclusion. With a reduction of the tube voltage from 120 kV to 80 kV at abdominal CT, the radiation dose can be reduced by 32% to 42% without degradation of CNR and LCD

Temporary use of shape memory spinal rod in the treatment of scoliosis

NiTinol shape memory alloy is characterized by its malleability at low temperatures and its ability to return to a preconfigured shape above its activation temperature. This process can be utilized to assist in scoliosis correction. The goal of this retrospective study was to evaluate the clinical and radiographic results of intraoperative use of shape memory alloy rod in the correction of scoliosis. From May 2002 to September 2006, 38 scoliosis patients (ranging from 50° to 120°; 22 cases over 70°) who underwent shape memory alloy-assisted correction in our institute were reviewed. During the operation, a shape memory alloy rod served as a temporary correction tool. Following correction, the rod was replaced by a rigid rod. The mean blood loss at surgery was 680 ± 584 ml; the mean operative time was 278 ± 62 min. The major Cobb angle improved from an average 78.4° preoperatively to 24.3° postoperatively (total percent correction 71.4%). In 16 patients with a major curve <70° and flexibility of 52.7%, the deformity improved from 58.4° preoperatively to 12.3° postoperatively (percent correction, 78.9%). In 22 patients with a major curve >70° and flexibility of 25.6%, the deformity improved from 94.1° preoperatively to 30.1° postoperatively (percent correction, 68.1%). Only one case had a deep infection. There were no neurologic, vascular or correction-related complications such as screw pullout or metal fracture. The study shows that the intraoperative use of a shape memory rod is a safe and effective method to correct scoliosis

Comparative analysis between shape memory alloy-based correction and traditional correction technique in pedicle screws constructs for treating severe scoliosis

The three-dimensional correction of severe rigid scoliosis has been improved by segmental pedicle screw instrumentation. However, there can be significant difficulty related to the use of a rigid rod, especially in the apex region of severe scoliosis. This study is a retrospective matched cohort study to evaluate the advantages of Nitinol shape memory alloy (SMA) rod-based correction by comparing the clinical and radiographic results obtained from using a temporary SMA rod and those from a standard rod in the correction of severe scoliosis. From May 2004 to September 2006, patients with matched curve type, ages at surgery, operative methods and fusion levels in our institute and instrumented with either SMA rods (n = 14) or traditional correction techniques (n = 16) were reviewed. In SMA group, the SMA rods served as a temporary intraoperative tool for deformity correction and were replaced by standard rods. The blood loss at surgery averaged 778 ± 285 ml in the traditional group and 585 ± 188 ml in the SMA group (P < 0.05). Operative time averaged 284 ± 53 min in the SMA group and 324 ± 41 min in the traditional group (P < 0.05). In the SMA group, the preoperative major curve was 92.6° ± 13.7° with a flexibility of 25.5 ± 7.3% was corrected to 29.4° ± 5.7° demonstrating a 68.4% immediate postoperative correction. In the traditional group, the preoperative major curve was 88.6° ± 14.6° with a flexibility of 29.3 ± 6.6% was corrected to 37.2° ± 7.3° demonstrating a 57.8% immediate postoperative correction. There was a statistic difference between the SMA group and traditional group in correction rate of the major thoracic curve. In the SMA group, one case suffered from deep infection 2 months postoperatively. In the traditional group, 6 of 16 cases suffered pedicle screw pull out or loosening during placement of the standard rod at the apex vertebrae on the concave side. In three cases, the mono-axial pedicle screws near the apex were abandoned and in five cases replaced with poly-axial pedicle screws. This study shows that the temporary use of SMA rod may reduce the operative time, blood loss, while improve the correction of the coronal plane when compared with standard techniques

Measuring and Evaluating the Commodification of Sustainable Rural Living Areas in Zhejiang, China

This study aims to construct an evaluation index system to measure the commodification of living space in Chinese rural areas and investigate the spatial characteristics of the commodification. Based on the dataset collected from public institutions in Zhejiang province, this study applies the entropy method to calculate the weights of the evaluation indicators and the commodification level. The results reveal that overall commodification levels of rural spaces in Zhejiang Province are different from each other due to different levels of economic development, transportation, tourism resources, and government support. In addition, this study suggests appropriate commodification strategies corresponding to the commodification development potential of the four types of rural living spaces (i.e., advanced development areas, promotion development areas, transformation development areas, and potential development areas). This study provides an evaluation index system measuring the commodification of rural living places and guidelines for effectively developing commodification of rural places

Electrochemical Reduction of Oxygen on Anthraquinone/Carbon Nanotubes Nanohybrid Modified Glassy Carbon Electrode in Neutral Medium

The electrochemical behaviors of monohydroxy-anthraquinone/multiwall carbon nanotubes (MHAQ/MWCNTs) nanohybrid modified glassy carbon (MHAQ/MWCNTs/GC) electrodes in neutral medium were investigated; also reported was their application in the electrocatalysis of oxygen reduction reaction (ORR). The resulting MHAQ/MWCNTs nanohybrid was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). It was found that the ORR at the MHAQ/MWCNTs/GC electrode occurs irreversibly at a potential about 214 mV less negative than at a bare GC electrode in pH 7.0 buffer solution. Cyclic voltammetric and rotating disk electrode (RDE) techniques indicated that the MHAQ/MWCNTs nanohybrid has high electrocatalytic activity for the two-electron reduction of oxygen in the studied potential range. The kinetic parameters of ORR at the MHAQ/MWCNTs nanohybrid modified GC electrode were also determined by RDE and EIS techniques