Neutral wedge osteotomy assisted by determination of the center of rotation of angulation at the distal humerus anatomical axis for cubitus varus deformity in children / 中华创伤骨科杂志

Objective:To evaluate the clinical outcomes of neutral wedge osteotomy assisted by determination of the center of rotation of angulation (CORA) at the distal humerus anatomical axis for cubitus varus deformity in children.Methods:From 2016 to December 2019, 20 children with cubitus varus after supracondylar fracture of the humerus were treated at Department of Orthopeadics, Children's Hospital of Wujiang District. They were 8 boys and 12 girls, aged from 4 to 12 years (average, 7.0 years). Standard anteroposterior X-ray films of bilateral humerus were taken preoperatively for measurement of Baumann angle, proximal anatomical axis (PAA) and distal anatomical axis (DAA) of bilateral humerus to determine the CORA and the varus deformity angle. A lateral closed neutral wedge osteotomy was performed around the CORA to correct the varus deformity. All children were immobilized with elbow plaster cast after operation. Elbow flexion and extension function, postoperative scar, and body surface carrying angle were recorded. The carrying angle and Baumann angle were also measured on elbow X-ray films. Elbow function was evaluated according to the modified Flynn elbow score at 24 months after operation.Results:All patients were followed up for 24 to 36 months (mean, 29.3 months). Elbow hyperextension was close to normal in 18 cases, and 5° hyperextension existed in 2 cases. The flexion was greater than 130°, averaging 133.1° (from 130° to 138°), in 15 patients. The flexion ranged from 110° to 130° in 5 patients. The Baumann angle was 99.0°±1.0° preoperatively and 76.0°±1.0° postoperatively; the carrying angle was -14.0°±1.0° preoperatively and 13.6°±1.0° postoperatively. There were significant differences between the above items between preoperation and postoperation ( P<0.05). According to the modified Flynn elbow score at 24 months after operation, the elbow function was excellent in 16 and good in 4 cases. The varus of 40° was corrected during surgery in one child. Fixation failure or correction failure occurred in none of the children before removal of the plaster or the Kirschner wire. Conclusions:In neutral wedge osteotomy assisted by determination of the CORA at the distal humerus anatomical axis, the CORA and angulation of the distal humerus inversion can be accurately determined so that the osteotomy line and the angulation correction axis can pass through the CORA to restore the humerus alignment with no displacement of the broken ends.

Research Progress and Joint Evaluation on Center of Rotation for Lumbar Vertebrae / 医用生物力学

In recent years, with the growth of social development, the incidence of lumbar vertebrae diseases has increased year by year, and many surgical methods have been developed. These treatment methods mark the accumulation of surgical experience and the development of medical technology. However, a new issue appears, i.e. how to evaluate the degree of lumbar disease and postoperative rehabilitation. There is an urgent need to establish a quantitative index of preoperative examination and postoperative rehabilitation criteria for lumbar disease from both doctors’ and patients’ perspectives. The current studies show that the measurement of the center of rotation (COR) for lumbar vertebrae and surface electromyography (sEMG) can reduce the error in the evaluation of clinical curative effect for treating lumbar disease and can be applied widely. This review summarizes the relationship between COR and lumbar disease, as well as the role of COR and sEMG joint evaluation in clinical operation and postoperative rehabilitation.

Locating the Instant Center of Rotation in the Subaxial Cervical Spine with Biplanar Fluoroscopy during In Vivo Dynamic Flexion-Extension

BACKGROUND: Recently, biplanar fluoroscopy is used to evaluate the cervical kinematics, especially to locate the instant center of rotation (ICR) during in vivo motion. This study aims to ascertain the ICR at each cervical segment in the sagittal plane during dynamic motion and assess the differences from previous studies. METHODS: While three healthy subjects were performing full flexion-extension, two oblique views aligned horizontally and angled at approximately 55° were obtained by biplanar fluoroscopy. The minimum degree to detect significant movement in a helical axis model was set at 2°, and anterior-posterior and superior-inferior locations of each ICR were defined. To evaluate the possible distribution area and overlapping area of the ICR with disc space, we drew a circle by using the calculated distance between each coordination and the mean coordination of ICR as the radius. RESULTS: During flexion-extension motion, the mean superior-inferior location of the ICR became progressively more superior, except the C5–6 segment (p = 0.015), and the mean anterior-posterior location of the ICR became progressively more anterior without exception from C2–3 to C6–7 segments, but anterior-posterior ICR locations were not significantly different among segments. The overlapping area with the distribution circle of ICR was mainly located in the posterior half in the C3–4 segment, but the overlapping area was about 80% of the total disc space in C4–5 and C6–7 segments. The overlapping was more noticeable in the lower cervical segments after exclusion of the outlier data of the C5–6 segment in subject 1. CONCLUSIONS: The ICR in the cervical spine showed a trend of moving progressively more superiorly and anteriorly and the disc space overlapping the distribution circle of ICR increased along the lower motion segments except the C5–6 segment. These findings could provide a good basis for level-specific cervical arthroplasty designs.

Correction of the projection center of rotation based on the sinogram using translation matching method / 生物医学工程学杂志

The accurate position of the center of rotation (COR) is a key factor to ensure the quality of computed tomography (CT) reconstructed images. The classic cross-correlation matching algorithm can not satisfy the requirements of high-quality CT imaging when the projection angle is 0 and 180°, and thus needs to be improved and innovated. In this study, considering the symmetric characteristic of the 0° and flipped 180° projection data in sinogram, a novel COR correction algorithm based on the translation and match of the 0° and 180° projection data was proposed. The OTSU method was applied to reduce noise on the background, and the minimum offset of COR was quantified using the -norm, and then a precise COR was obtained for the image correction and reconstruction. The Sheep-Logan simulation model with random gradients and Gaussian noise and the real male SD rats samples which contained the heterogenous tooth image and the homogenous liver image, were adopted to verify the performance of the new algorithm and the cross-correlation matching algorithm. The results show that the proposed algorithm has better robustness and higher accuracy of the correction (when the sampled data is from 10% to 50% of the full projection data, the COR value can still be measured accurately using the proposed algorithm) with less computational burden compared with the cross-correlation matching algorithm, and it is able to significantly improve the quality of the reconstructed images.

Geometrical Salvage of Split Tooth.

Aims: Management of vertically fractured mandibular first molar by intra coronal splinting applying the finite centre of rotation effect of Pythagorus theorem. Case Presentations: A 28 year old male patient presented at the Department of Conservative Dentistry and Endodontics with the chief complaint of pain in the lower right back region of the mouth since last the 10 days. Past dental history revealed that affected tooth had root canal treatment done two years ago. History of present illness was that pain was elicited on chewing, and applying pressure on that area, with occasional bleeding from the same region. Intraoral examination revealed that tooth 46 was tender on percussion with vertically fractured crown in mesiodistal direction. Periapical Radiograph revealed that tooth was endodontically treated, with radiolucencies at apical and furcal area, and visible fracture line in mesiodistal direction at CEJ level. Technique Used in the Study: The tooth was endodontically retreated and Pythagorus theorem was used to locate the centres of rotation on both buccal and lingual sides of tooth 46 coronally. The technique was followed by drilling a vent at the same position approximating a fibre post (3M, Relyxfibre post). The centres were different both for buccal and lingual aspects which when approximated will provide antirotation. The post was placed in the buccolingual direction and the tooth was restored with posterior composites after which the restoration was checked for any high points. Follow up of the case was done for the period of one year. Discussion: The concept of the estimation of the finite centre of rotation is like the primary objective in tightening a screw joint to generate an optimum preload that will maximize the fatigue life of the screw while offering a reasonable degree of protection against loosening. The major advantage of this approach is that the fragment was stabilized properly and there was healthy development of periodontium over the year. Conclusion: Usually the vertically fractured tooth have poor prognosis and may likely be referred for extraction if not stabilized properly. This case report emphasizes the basic concept of stabilization and preventing rotation around an axis which will give the fractured tooth a better longevity and avoid the vibrations during crown preparation. The combined effect will restore the patient’s own natural tooth back and minimizes the chances of periodontal complication.

METODOLOGÍA PARA DIMENSIONAMIENTO DE MECANISMO POLICÉNTRICO DE RODILLA UTILIZANDO ANÁLISIS DE MARCHA Y ALGORITMOS GENÉTICOS / METHODOLOGY TO GAUGE A FOUR-BAR LINKAGE PROSTHETIC KNEE MECHANISM BASED ON GAIT ANALYSIS AND GENETIC ALGORITHMS

El objetivo de esta investigación es desarrollar una metodología para dimensionar un mecanismo policéntrico de rodilla de 4 barras para máxima estabilidad. Basado en el hecho de que la estabilidad del mecanismo durante la respuesta a la carga depende de la posición del centro instantáneo de rotación (CIR) respecto la fuerza de reacción del piso (FRP) durante la fase de apoyo, se desarrolló una plataforma de cómputo que representa el movimiento real de la pierna, el vector FRP y el mecanismo con su CIR. Para obtener los datos de entrada a la plataforma, se realizó un análisis de marcha a una paciente con amputación transfemoral unilateral, obteniendo la FRP, el ángulo de flexo-extensión de rodilla y la cinemática de los miembros inferiores. Por otra parte, a través de los algoritmos genéticos (AGs), se obtienen las dimensiones y configuración de los eslabones del mecanismo requeridas para iterar con la plataforma en la cual, comparando la ubicación de la FRP respecto al CIR en el plano sagital, se determinan las dimensiones funcionales adecuadas. El mecanismo se dimensionó exitosamente utilizando la metodología desarrollada, garantizando estabilidad de la rodilla después del contacto inicial y flexión voluntaria antes del despegue de punta.

This research was aimed to develop a methodology for establishing the proper dimensions of a four-bar linkage prosthetic knee mechanism for maximum stability. Based on the fact that the stability of a four-bar knee during load-bearing is determined by the location of the instantaneous center of rotation (ICR) with respect to the ground reaction force (GRF) vector, a computational platform was developed to simulate the movement of the leg, the GRF vector and the position of the ICR of the mechanism. On one hand, a gait analysis was carried out on a subject with unilateral transfemoral amputation, from which the GRF, the knee flexion-extension angle and the kinematics of the lower limbs were determined. On the other hand, genetic algorithms (GAs) technique provided the dimensions and mechanism links configuration required to iterate with the platform on which, comparing the location of the GRF and the ICR in the sagittal plane, the functional dimensions of the mechanism were obtained. The polycentric knee mechanism was gauged successfully by ensuring knee stability during the initial contact and load response as well as the ability to initiate voluntary flexion toward late stance before the toe-off.

Development of Geometric Calibration Method for Triple Head Pinhole SPECT System / 핵의학분자영상

PURPOSE: Micro-pinhole SPECT system with conventional multiple-head gamma cameras has the advantage of high magnification factor for imaging of rodents. However, several geometric factors should be calibrated to obtain the SPECT image with good image quality. We developed a simplified geometric calibration method for rotating triple-head pinhole SPECT system and assessed the effects of the calibration using several phantom and rodent imaging studies. MATERIAL AND METHODS: Trionix Triad XLT9 triple-head SPECT scanner with 1.0 mm pinhole apertures were used for the experiments. Approximately centered point source was scanned to track the angle-dependent positioning errors. The centroid of point source was determined by the center of mass calculation. Axially departed two point sources were scanned to calibrate radius of rotation from pinhole to center of rotation. To verify the improvements by the geometric calibration, we compared the spatial resolution of the reconstructed image of Tc-99m point source with and without the calibration. SPECT image of micro performance phantom with hot rod inserts was acquired and several animal imaging studies were performed. RESULTS: Exact sphere shape of the point source was obtained by applying the calibration and axial resolution was improved. Lesion detectibility and image quality was also much improved by the calibration in the phantom and animal studies. CONCLUSION: Serious degradation of micro-pinhole SPECT images due to the geometric errors could be corrected using a simplified calibration method using only one or two point sources.

Development and Performance Evaluation of an Animal SPECT System Using Philips ARGUS Gamma Camera and Pinhole Collimator / 대한핵의학회잡지

PURPOSE: We developed an animal SPECT system using clinical Philips ARGUS scintillation camera and pinhole collimator with specially manufactured small apertures. In this study, we evaluated the physical characteristics of this system and biological feasibility for animal experiments. MATERIALS AND METHODS: Rotating station for small animals using a step motor and operating software were developed. Pinhole inserts with small apertures (diameter of 0.5, 1.0, and 2.0 mm) were manufactured and physical parameters including planar spatial resolution and sensitivity and reconstructed resolution were measured for some apertures. In order to measure the size of the usable field of view according to the distance from the focal point, manufactured multiple line sources separated with the same distance were scanned and numbers of lines within the field of view were counted. Using a Tc-99m line source with 0.5 mm diameter and 12 mm length placed in the exact center of field of view, planar spatial resolution according to the distance was measured. Calibration factor to obtain FWHM values in 'mm' unit was calculated from the planar image of two separated line sources. Tc-99m point source with 1 mm diameter was used for the measurement of system sensitivity. In addition, SPECT data of micro phantom with cold and hot line inserts and rat brain after intravenous injection of [I-123]FP-CIT were acquired and reconstructed using filtered back projection reconstruction algorithm for pinhole collimator. RESULTS: Size of usable field of view was proportional to the distance from the focal point and their relationship could be fitted into a linear equation (y=1.4x+0.5, x: distance). System sensitivity and planar spatial resolution at 3 cm measured using 1.0 mm aperture was 71 cps/MBq and 1.24 mm, respectively. In the SPECT image of rat brain with [I-123]FP-CIT acquired using 1.0 mm aperture, the distribution of dopamine transporter in the striatum was well identified in each hemisphere. CONCLUSION: We verified that this new animal SPECT system with the Philips ARGUS scanner and small apertures had sufficient performance for small animal imaging.

An experimental study on the stress distribution in the periodontal ligament / 대한치과교정학회지

In order to achieve a desirable tooth movement, it is of great importance to control the M/F ratio and to know the location of the center of resistance. The purpose of this study was to locate the center of resistance and the axis of rotation, and to estimate the stress distribution in the periodontal ligament with experimental model. After preparing a model of an upper canine with a simulated periodontal ligament and alveolar bone, the force and moment were applied. The tooth movement was traced using measuring device with LVDTs(Linear variable differential transformers) that can measure three dimensional tooth movement in real time. The results were as follows. 1. The location of center of resistance by transverse force was 29% of root length measured from alveolar crest to apex regardless of force magnitude. The position of the center of resistance is more coronal than that of two-dimensional model(42%). 2. The center of resistance and the axis of rotation coincide when couple moment was applied. 3. As the magnitude of moment increases, tooth tends to extrude irrespective of the direction of the moment. 4. The relationship between location of force and axis of rotation (a x b =49.6mm2) was obtained. A tooth movement can be predicted through this formula. 5. The centers of rotation by transverse force were plotted linearly.

An analytical study on strain distribution using strain gauge attached on root surface / 대한치과교정학회지

Optimal orthodontic treatment could be possible when a orthodontist can predict and control tooth movement by applying a planned force system to the dentition. The moment to force(M/F) ratio at the bracket, has been shown to be a primary determinate of the pattern of tooth movement. As various M/F ratios are applied to the bracket on the tooth crown, strain distribution in periodontium can be changed, and the center of rotation in tooth movement can be determined. It is, therefore, so important in clinicalorthodontics to know the strain distribution in a force system of a M/F ratio. The purpose of this study was to analyze the strain distribution in orthodontic force system by strain gauge attached to tooth root, and to evaluate the usage of the method. For this study, an experimental upper anterior arch model was constructed, where upper central incisors, on the root surface of which, 8 strain gauges were attached, were implanted in the photoelastic resin, as in the case of 4mm midline diastema. Three types of closing of upper midline diastema closure were compared : 1. with elastomeric chain(100g force) in no arch wire, 2. elastomeric chain in .016" round steel wire, 3. elastomeric chain in .016"x.022" rectangular steel wire. The results were as follows. 1. Strain distributions on labial, lingual, mesial and distal root surface of tooth were able to be evaluated with the strain gauge method, and the patterns of tooth rotation were understood by presuming the location of moment arm. 2. Extrusion and tipping movement of tooth was seen in closing in no arch wire, and intrusion and bodily movement was seen with steel arch wire inserted.

A study on the regularity of center of rotation in the orthodontic treatment of embedded and inverted impact upper central incisor / 实用口腔医学杂志

Objective: To study the influence of different inhibition conditions for center of rotation (CR) and regularity variations of CR before and after orthodontic treatment of embedded and inverted impact upper central incisor. Methods:Based on clinical findings a computer model of rolling movement was established,then computer finite element Super DrawnⅡwas applied to establish an analytic analogue computing model for calculation. Results:The deeper the crown embedded by hard tissue,the more the edgewise displacement of CR;while the crown was normally exposed,the moving locus tended toward front and upward. Conclusions: Perpendicular orthodontic force to the long axis of tooth forced point that close to the incisal margin and the partly embedded crown by the alveolar bone,especially the bone of lingual aspect are the main factors for the upward moving and erectness of the root apex. Possible subsidence of CR may be avoided by suitable early stage orthodontic treatment.