Radiographic total disc replacement angle measurement accuracy using the Oxford Cobbometer: precision and bias

Total disc replacement (TDR) clinical success has been reported to be related to the residual motion of the operated level. Thus, accurate measurement of TDR range of motion (ROM) is of utmost importance. One commonly used tool in measuring ROM is the Oxford Cobbometer. Little is known however on its accuracy (precision and bias) in measuring TDR angles. The aim of this study was to assess the ability of the Cobbometer to accurately measure radiographic TDR angles. An anatomically accurate synthetic L4–L5 motion segment was instrumented with a CHARITE artificial disc. The TDR angle and anatomical position between L4 and L5 was fixed to prohibit motion while the motion segment was radiographically imaged in various degrees of rotation and elevation, representing a sample of possible patient placement positions. An experienced observer made ten readings of the TDR angle using the Cobbometer at each different position. The Cobbometer readings were analyzed to determine measurement accuracy at each position. Furthermore, analysis of variance was used to study rotation and elevation of the motion segment as treatment factors. Cobbometer TDR angle measurements were most accurate (highest precision and lowest bias) at the centered position (95.5%), which placed the TDR directly inline with the x-ray beam source without any rotation. In contrast, the lowest accuracy (75.2%) was observed in the most rotated and off-centered view. A difference as high as 4° between readings at any individual position, and as high as 6° between all the positions was observed. Furthermore, the Cobbometer was unable to detect the expected trend in TDR angle projection with changing position. Although the Cobbometer has been reported to be reliable in different clinical applications, it lacks the needed accuracy to measure TDR angles and ROM. More accurate ROM measurement methods need to be developed to help surgeons and researchers assess radiological success of TDRs.     

Quantification of error in measurement of radial inclination angle and radial-carpal distance

Posteroanterior wrist radiographs of eight patients were evaluated by eight orthopedists. Radial inclination angle and radial-carpal distance were measured by use of a standardized technique. The standard deviation for radial inclination angle was 2 degrees. The standard deviation for radial-carpal distance was 1 mm. The measured rotational variation of radial inclination and radial-carpal distance is 1 degree and 1 mm, respectively, through a 10-degree arc of supination and pronation.     

Three-dimensional measurement of wedged scoliotic vertebrae and intervertebral disks

Idiopathic scoliosis involves complex spinal intrinsic deformations such as the wedging of vertebral bodies (VB) and intervertebral disks (ID), and it is obvious that the clinical evaluation obtained by the spinal projections on the two-dimensional (2D) radiographic planes do not give a full and accurate interpretation of scoliotic deformities. This paper presents a method that allows reconstruction in 3D of the vertebral body endplates and measurement of the 3D wedging angles. This approach was also used to verify whether 2D radiographic measurements could lead to a biased evaluation of scoliotic spine wedging. The 3D reconstruction of VB contours was done using calibrated biplanar X-rays and an iterative projection computer procedure that fits 3D oriented ellipses of adequate diameters onto the 3D endplate contours. “3D wedging angles” of the VB and ID (representing the maximum angle between adjacent vertebrae) as well as their angular locations with respect to the vertebral frontal planes were computed by finding the positions of the shortest and longest distances between consecutive endplates along their contour. This method was extensively validated using several approaches: (1) by comparing the 3D reconstructed endplates of a cadaveric functional unit (T₈-T₉) with precise 3D measurements obtained using a coordinate measuring machine for 11 different combinations of vertebral angular positions; (2) by a sensitivity study on 400 different vertebral segments mathematically generated, with errors randomly introduced on the digitized points (standard deviations of 0.5, 1, 2, and 3 mm); (3) by comparing the clinical wedging measurements (on postero-anterior and lateral radiographs) at the thoracic apical level of 34 scoliotic patients (15° < Cobb < 45°) to the computed values. Mean errors for the 11 vertebral positions were 0.5 ± 0.4 mm for VB thickness, less than 2.2° for endplate orientation, and about 11° (3 mm) for the location of the maximum 3D wedging angle along the endplate contour. The errors below 2 mm (introduced on the digitized points) slightly affected the 3D wedging angle (< 2°) and its location (< 4°) for the ID. As for the clinical evaluation, average angular errors were less than 0.4° in the radiographic frontal and lateral planes. The mean 3D wedged angles were about 4.9°± 1.9° for the VB and 6.0°± 1.7° for the ID. Linear relations were found between the 2D and the 3D angles, but the 3D angles were located on diagonal planes statistically different than the radiographic ones (between 100° and 221°). There was no statistical relation between the 2D radiographic angles and the locations of the 3D intervertebral wedging angles. These results clearly indicate that VB and ID endplates are wedged in 3D, and that measurements on plain radiographs allow incomplete evaluation of spinal wedging. Clinicians should be aware of these limitations while using wedging measurements from plain radiographs for diagnosis and/or research on scoliotic deformities. Received: 4 January 1997 Revised: 26 July 1997 Accepted: 1 August 1997     

Radiographic measurement of the sagittal plane deformity in patients with osteoporotic spinal fractures evaluation of intrinsic error

Cobb method has been shown to be the most reliable technique with a reasonable measurement error to determine the kyphosis in fresh fractures of young patients. However, measurement errors may be higher for elderly patients as it may be difficult to determine the landmarks due to osteopenia and the degenerative changes. The aim of this study is to investigate the intrinsic error for different techniques used in evaluation of local sagittal plane deformity caused by OVCF. Lateral X-rays of OVCF patients were randomly selected. Patient group was composed of 28 females and 7 males and the mean age was 62.7 (55–75) years. The kyphosis angle and the vertebral body height were analyzed to reveal the severity of sagittal plane deformity. Kyphotic deformity was measured by using four different techniques; and the vertebral body heights (VBH) were measured at three different points. The mean intra-observer agreement interval for kyphosis angle measurement techniques ranged from ±7.1 to ±9.3° while it ranged from ±4.5 to ±6.5 mm for VBH measurement techniques. The mean interobserver agreement interval for kyphosis angle ranged from ±8.2 to ±11.1°, while it was between ±4.5 to ±6.5 mm for vertebral body height measurement techniques. This study revealed that although the intra and interobserver agreement were similar for all techniques, they are still higher than expected. These high intervals for measurement errors should be taken into account when interpreting the results of correction in local sagittal plane deformities of OVCF patients after surgical procedures such as vertebral augmentation techniques.     

Efficacy and side effects of epidural opioids depending on the site of surgery

We reported the requirement of supplemental analgesics following epidural opioids including Opial 5mg and 10mg, and morphine HCl 2.5mg, for 24 hours in postoperative period after surgery of body surface, and lower and upper abdominal surgeries. Incidence of their side effects was also observed. Opial contains 50% morphine HCl and other opioids such as codeine, thebaine, papaverine, and noscapine etc. After upper abdominal surgeries, patients required additional analgesics more frequently. Kinds and doses of opioids used, suggest that epidural administration of other opioids contained in Opial has some analgesic effect. After the surgery of body surface the opioid requirement may be influenced by the intraoperative anesthetic technics and the state of mind of the patient. Urinary retention was the most interesting side effect observed and our data suggest that papaverine contained in Opial may have favorable effect and morphine HCl may have adverse effects regarding its incidence.     

Evaluation of the efficiency of Boston brace on scoliotic curve control: A review of literature

Context: Bracing is one of the most important treatment approaches that have been utilized in patients with scoliosis. Boston brace used to manage a scoliotic curve especially in lumbar and thoracolumbar areas.Objective: The aim of this review was to evaluate the efficiency of Boston brace to control the progression of the curve based on the available literature.Methods: A search was carried out using the following databases including Scopus, ISI Web of knowledge, PubMed, Ebsco, and Embasco. The key words used for the search were Boston brace, Boston orthosis which were used in combination with scoliosis. Articles identified were screened based on titles and abstracts. The quality of the studies was evaluated using Black and Down tool. Data were summarized based on PICO style.Results: Based on the aforementioned key words, 18 papers were selected, in which 7 studies focused on efficiency of Boston brace, 3 papers focused on quality of life, 5 papers on finite element analysis and 3 papers on comparison of efficiency of Boston with other available braces. The quality of the selected studies varied between 14 and 21.Conclusion: The results of most of the studies support the efficiency of this brace to control the progression of scoliotic curve, especially for the curve between T6 and L2. The efficiency of this brace may be due to its rigid structure and also location and direction of the straps.     

Impact of patient position on coronal Cobb angle measurement in non-ambulatory myelodysplastic patients

European Journal of Orthopaedic Surgery & Traumatology - The purpose of this study was to assess the impact of patient position on the magnitude of the coronal Cobb angle measurements in...     

Accuracy and applicability of measurement of the scoliotic angle at the frontal plane by Cobb's method,by Ferguson's method and by a new method

Summary A new method for the measurement of scoliotic curves in antero-posterior (AP) radiographs is presented, in which the centre of the surface image of the vertebral bodies of the apical and two end vertebrae of the curvature are defined on the basis of geometric principles. Measurements using the Cobb, the Ferguson, and the new method were performed on ten AP radiographs from each of three groups of young patients with right convex thoracic idiopathic scoliosis with Cobb angles of between 7 and 15°, 16 and 45° and 46 and 80°, respectively. Measurements using the Cobb method yielded significantly higher values than measurements using either the Ferguson method or the new method. In curves with Cobb angles of between 7 and 15°, the values using Ferguson's method were significantly lower than those using the new method; the difference increased significantly in curves with a Cobb angle of 16° or more. The level of significance of the intra- and interobserver differences between the new, the Cobb and the Ferguson methods was significantly higher in curves with a Cobb angle of 16° or more. It is argued that measures of the scoliotic angle obtained by the new method are of greater clinical relevance than those obtained by the two other methods. Unlike the Cobb method, the new method takes into consideration the translation of the apical vertebra in relation to the end vertebrae and not only the tilt of the end vertebrae of the curve. As compared to the Ferguson method, the new method is based on standardised geometric principles, and is not influenced by changes in the shape of the vertebral body. Moreover, the repeatability of the new method is greater than that of both the Cobb method and the Ferguson method. Therefore, it is believed that the new method provides a more accurate measure of the scoliotic curve than do the two other methods, and it is to be preferred over the other two methods in longitudinal evaluation of the development of the curve.     

Computed tomography measurement of humeral head retroversion: Influence of patient positioning

For accurate humeral head arthroplasty, the surgeon needs to know some geometric data, such as, for example, the retroversion angle of the humeral head. Only a few reports have described and evaluated the use of computed tomography (CT) to measure humeral head retroversion. The humerus position relative to the roentgen beam is variable from one subject to another depending on the patients' morphology. It could influence the retroversion measurement and has not been investigated previously. This study analyzes in 9 cadaver humeri the variability of retroversion angle measurements with different humerus positioning relative to the roentgen beam during CT examination. The truest retroversion angle can be obtained when true axial slices, perpendicular to the humeral diaphysis, are obtained. Our study tries to clarify technical problems that occur during CT examination. Geometric considerations that can modify the measurements are presented. A reliable method of humeral head retroversion angle measurement is recommended, which could be useful to the shoulder surgeon.     

The first intermetatarsal angle in hallux valgus: an analysis of measurement reliability and the error involved

In view of the importance placed on the first intermetatarsal angle in the assessment of surgical intervention in hallux valgus, we assessed the reliability with which one measures this angle. The study involved 10 observers of varying experience measuring the angle using a standard technique on 10 weightbearing AP X-rays of the foot on three separate occasions. The margin of error in measuring the angle was +/-3.60 degrees with a 95% confidence interval. Increasing and averaging the number of readings per observer or the readings of a number of observers, reduces the error. Experience doesn't improve reliability. In conclusion, improvement in the reliability of the measurements can be achieved by careful technique, performing the measurements at least twice, and averaging them.     

Radiographic method to measure the inclination angle of the acetabulum

Background Various attempts have been made to assess the inclination angle of the acetabulum utilizing new imageprocessing technologies to enable three-dimensional reconstruction of the acetabulum. However, reliability of these methods has not been estimated in comparison with anatomical measurements. This study developed a geometric method for measuring the acetabular inclination with radiograms and evaluated the reliability of this method by comparing the anatomically measured acetabular inclination angle of the same dry pelvic bone. Methods One hundred and ten acetabulums from 55 human pelvis specimens were used. The uppermost, most frontal, and posterior lowermost points of the acetabular rim were determined, and an axis perpendicular to the triangular plane formed by these three points was defined as the anatomical inclination axis of the acetabulum. The anatomical lateral and anterior opening angles were directly measured using a tool we devised for this purpose. Posteroanterior and lateral radiograms of each pelvis were taken concurrently and three points were marked by small metal plates. Based on projections of these three points onto the posteroanterior and lateral images, we geometrically measured and calculated the lateral and anterior opening angles of the acetabulum. Results Anatomical measurements of the lateral opening angles ranged from 38° to 63° (mean 51.0°), and anterior opening angles from 10° to 36° (mean 20.8°). Geometric measurements of the lateral opening angles ranged from 40° to 61° (mean 50.5°), and anterior opening angles ranged from 7° to 35° (mean 20.8°). Geometrically measured acetabular inclination angles were highly correlated with the anatomically measured ones for both the lateral and anterior opening angles, with correlation coefficients of 0.803 and 0.822, respectively. Conclusions Our geometric measurement method of the acetabular inclination angle enabled us to calculate the lateral and anterior opening angles, which were very close to the corresponding anatomical measurements. This method allows three-dimensional evaluation of the anatomical structure of the hip and may be useful in predicting progression of coxarthrosis by measuring the femoral neck shaft and anteversion angles.     

A complementary thoracic implant for the surgical correction of the scoliotic curve. A preliminary report

Summary The results of the surgical correction of scoliosis through posterior approach have significantly improved by the introduction of new implants during the past decades. Even with these improvements the available implants only allow limited correction especially regarding axial rotation, and also their application is rather complicated. We developed a new implant which simultaneously grasps and exerts forces on both transverse processes of the vertebrae, to achieve a more efficient and safer correction with a simple surgical technique. In our paper we report on the concept of the new implant, its most important features, its mechanical tests, cadaver experimentations, and biomechanical assessments.     

Preoperative management of scoliosis by positioning the trunk on its convex side

A new method, hanging the scoliotic trunk on its convex side, for preoperative management of scoliosis was described and has been used on 36 patients with good result. The weight used varied individually from 10 kg to 40 kg to lift the convex side 5 to 8 cm above the bed surface on which he or she lay. Hanging in this way in about 2 weeks would stretch out and relax the soft tissues on the convex side, resulting in maximum correction. This method is simple, effective and without side effect. We would think that it is an ideal way for preoperative correction of idiopathic scoliosis.     

Reliability of the quadriceps angle measurement

The quadriceps angle (Q-angle) is used to determine patellofemoral alignment. Although this measurement has been used to evaluate and treat patellofemoral joint pathology, few studies have examined its reliability. This study evaluated the interobserver and intraobserver reliability of the Q-angle measurement. To investigate the interobserver reliability of the Q-angle, 25 individuals of varying levels of training served as observers and participants as each measured the other 24 participants. To investigate the intraobserver reliability of the Q-angle, 3 of the observers measured 13 of the participants an additional 2 times. Additionally, clinically derived Q-angle measurements were compared with radiographically derived measurements. The reliability analysis was performed using intraclass correlation coefficients. For interobserver measurements, the intraclass correlation coefficients ranged from 0.17-0.29 for the four variables evaluated (right and left, extension and flexion). For intraobserver measurements, the intraclass correlation coefficients ranged from 0.14-0.37. The average intraclass correlation coefficient between the clinically and radiographically derived measurements ranged from 0.13-0.32. This study demonstrates poor interobserver and intraobserver reliability of Q-angle measurement and poor correlation between clinically and radiographically derived Q-angles.     

髂骨钉进钉外展角度的影像解剖学研究

目的 通过对成人螺旋CT三维重建骨盆的影像解剖学测量,了解髂骨钉进钉时在水平面上的外展角度,从而保证髂骨钉置入的准确性与安全性.方法 选取200例患者的骨盆螺旋CT电子影像资料(男107例,女93例,排除明显骨盆畸形、外伤等疾病),平均年龄(55.6±18.3)岁.通过骶1水平的CT平面,测量脊柱-髂骨角(Thespi...     

动态颈神经根管率的X线片测量

目的　应用新的颈椎斜位X线片测量方法测量颈神经根管矢状径、动态颈神经根管矢状径率 ,确定诊断神经根管狭窄敏感指标。方法　取 2 0 0名不同年龄段的成人摄取颈椎动态斜位X线片 (斜位、过伸斜位、过屈斜位 ) ,测量动态神经根管的矢状径 (a )、椎体斜位矢状径 (b )、计算颈神经根管率 (a/b )。分年龄、性别及组别进行统计分析。结果　①同一节段不同年龄、不同性别颈神经根管率差异无统计学意义。②不同组别动态颈神经根管率差异有非常显著性 (P <0 .0 1)。结论　①动态神经根管率是诊断神经根型颈椎病有效和敏感指标。②颈椎动态神经根管率 95 %理想值范围底限为 0 .30。颈椎动态神经根管率≤ 0 .30时应考虑颈神经根管狭窄     

Influence of the patient positioning on respiratory mechanics during pneumoperitoneum

The aim of this study was to evaluate the effect of patient positioning during laparoscopic cholecystectomy on respiratory mechanics and arterial blood gases. Thirty patients of ASA I were included. Ventilation was controlled mechanically. Tidal volume and ventilator frequency were kept unchanged throughout the operation. Intra-abdominal pressure was kept constant at 12 mmHg. Ventrak respiratory system was used for measuring respiratory mechanics. The airway resistance (Raw), the dynamic compliance (Cdyn), and the peak inspiratory pressure (PIP) were monitored. Measurements were made in five intervals: "a" after induction of general anesthesia, "b" after insufflation, "c" in the Trendelenburg position of 40 degree, "d" in the Fowler position of 40 degree, and "e" after desufflation. Samples of arterial blood gases were collected while the respiratory mechanics were being recorded. The mean arterial pressure (MAP) and heart rate (HR) were also monitored. In our study, during intervals "c" and "d", PCO2, was increased and pH decreased. With the initiation of insufflation, Cdyn, PIP, and Rawx, were altered (P < 0.05). The patient positioning had a significant effect on respiratory mechanics. After desufflation only Cdyn changed (P < 0.05). Although HR remained in normal limits, MAP increased during pneumoperitoneum (P < 0.05). We conclude that blood gas changes and respiratory mechanics were affected by the duration of pneumoperitoneum and patient positioning. The Fowler position had the least influence on respiratory mechanics.