Open MRI validation of a hip model driven with subject-specific motion capture data in predicting anterior femoroacetabular clearance

Background Cam and/or pincer morphologies (CPM) are potential precursors to hip osteoarthritis (OA) and important contributors to non-arthritic hip pain. However, only some CPM hips develop OA and/or pain, and it is not clear why. Anterior impingement between the femoral head/neck contour and acetabular rim during motion is a proposed pathomechanism. Understanding how activity and deformity combine to produce impingement may shed light on the causes of hip degeneration/pain. The objective of this study was to determine the accuracy of a subject-specific hip model driven by subject-specific motion data in predicting anterior impingement. Methods We recruited 22 participants with CPM (both with and without pain) and 11 controls. We collected subject-specific 3D kinematics during squatting and sitting flexion, adduction, and internal rotation (FADIR) (an active and a passive maneuver, respectively, proposed to provoke impingement). We then developed 3D subject-specific hip models from supine 3T hip MRI scans that predicted the beta angle (a measure of anterior femoroacetabular clearance) for each frame of acquired kinematics. To assess the accuracy of these predictions, we measured the beta angle directly in the final position of squatting and sitting FADIR using open MRI scans. We selected the frame of motion data matching the static imaged posture using the least-squares error in hip angles. Model accuracy for each subject was calculated as the absolute error between the open MRI measure of beta and the model prediction of beta at the matched time frame. To make the final model accuracy independent of goodness of match between open MRI position and motion data, a threshold was set for least-squares error in hip angles, and only participants that were below this threshold were considered in the final model accuracy calculation, yielding results from 10 participants for squatting and 7 participants for sitting FADIR. Results For squatting and sitting FADIR, we found an accuracy of 1.1°(0.8°) and 1.3°(mean (SD), and root mean squared error, respectively) and 0.5°(0.3°) and 0.6°, respectively. Conclusion This subject-specific hip model predicts anterior femoroacetabular clearance with an accuracy of about 1°, making it useful to predict anterior impingement during activities measured with motion analysis.

Evaluation and Correlation of Beta Angle with Wits Appraisal and ANB Angle in Various Skeletal Malocclusion Groups—A Cephalometric Study

Introduction Sagittal skeletal discrepancies are frequently assessed by Wits appraisal and point A–Nasion–point B (ANB) angle. These angular and linear measurements depend upon various factors and sometime produced inaccurate results. Beta angle has been introduced recently and possesses significant advantage over ANB and Wits appraisal, because it is independent of cranial landmarks and dental occlusion. Aim To evaluate and correlate beta angle in various skeletal malocclusions and its correlation with Wits appraisal and ANB angle. Material and Methods The present study was carried out in Bhojia Dental College and Hospital, Baddi, Himachal Pradesh, India. A total of 63 pretreatment lateral cephalograms (23 skeletal class I, 20 skeletal class II, and 20 skeletal class III) of patients aged between 14 to 25 years were included. Various landmarks and planes were identified and marked. Values of Wits appraisal, ANB angle, and beta angle were recorded. Comparisons of group were made with the chi-square test. Spearman correlation coefficient was calculated to see relation between different values. Results Values of correlation coefficient of beta angle with Wits appraisal and ANB angle were –0.645 and –0.815, respectively. Conclusion Overall beta angle showed strong correlation with Wits appraisal and ANB angle, however correlation of beta angle with Wits appraisal and ANB angle among various skeletal malocclusion groups (skeletal class I, II, and III) was not statistically significant.

Cephalometric analysis for assessing sagittal jaw relationship- A comparative study

The successful treatment of Orthodontic patient is dependent on careful diagnosis. Three planes of discrepancies are commonly described in orthodontics namely, transverse, sagittal and vertical. Of these, the sagittal discrepancies are most commonly encountered in day to day practice. This study was aimed to compare various methods of cephalometric analysis for assessing sagittal jaw relationship. There were total of 180 lateral cephalograms used and each samples were divided into 2 groups based on their skeletal relationship according to ANB angle. i.e Class I and Class II. Class I and Class II were again divided into average, horizontal and vertical group. Pretreatment records were taken and tracing were performed on the lateral cephalogram and measured values were recorded and subjected to statistical analysis.In class I, the highest frequency was seen in A-B plane angle and FABA angle and in class II the highest frequency found in K angle followed by A-B plane angle. In class I horizontal group, a strong level of agreement was found between AXB angle with AF-BF distance while in class II average group, A-B plane angle shows strong level of agreement with WITS and FABA angle. In terms of reliability, all the ten parameters (A-B plane angle, WITS, AF-BF distance, APP-BPP distance, FABA angle, BETA angle, YEN angle, W angle and K angle) show good reliability in class II average and vertical group. : No single measurement is perfect in all the cases. A combination of different measurements should be used to have a true assessment of sagittal jaw relationship.

Evaluation of Skeletal Jaw Relation by Different Cephalometric Angles for Sample of Kurdish Young Adults in Sulaimani City-A Cephalometric Study

Background/Objectives An accurate evaluation of skeletal sagittal jaw relationship has an important role in orthodontic diagnosis and treatment planning. This study was done to establish cephalometric norms of all types of malocclusion using ANB, Wits appraisal and Beta angle, and evaluate the significance of W angle in comparison to these parameters. Subjects and Methods Ninety pre-treatment lateral cephalograms of male and female patients aged 18-28 years from Sulaimani City that met the sample criteria were traced digitally by the Easy Dent 4 software program. The sample was divided into three groups of skeletal malocclusion, class I, II, and III, based on ANB angle, Beta angle, and Wits appraisal, each group consisting of 30 patients. For each subject the following cephalometric parameters were measured: ANB angle, Beta angle, Wits apprasial, and W angle.Statistical analysis The Statistical Package for Social Sciences was used for analyzing data. ANOVA test was used to compare means of the three study groups. The post-hoc test was used to compare each two groups, Pearson correlation coefficient (r) was used to assess the strength of correlation between two numerical variables, and coefficient of variability was used to measure the extent of variability of each variable in relation to the population. The p value of ≤ 0.05 was considered statistically significant. ResultsSignificant differences were found in the ANB angle, Beta angle, Wits appraisal and W-angle in all 90 patients. The coefficient of variability showed that Wits appraisal was the most variable parameter and W angle was the least variable parameter. Conclusions ANB angle, Beta angle, Wits appraisal and W-angle are significant parameters to assess the sagittal jaw relationship. The use of W angle, along with other parameters, can provide more accurate assessment of the sagittal skeletal jaw relationship as it has the least coefficient of variance; it should therefore enable better diagnosis and treatment planning for patients.

Recoverability of Callisto gravity field influenced by orbiter mission characteristics

<p>The exploration of Callisto is part of the extensive interest in the icy moons characterization. Indeed, Callisto is the Galilean moon with the best-preserved records of the Jovian system formation. Led by the National Space Science Center (NSSC), Chinese Academy of Science (CAS), the planned Gan De mission aims to send an orbiter around Callisto in order to characterize its surface and interior. Potential orbit configurations are currently under study for the Gan De mission proposal.</p><p>As part of a global characterization of Callisto, its gravity field can be inferred using radio tracking data from an orbiter. Mission characteristics such as orbit type, Earth beta angle and solar elongation will have a direct influence on the recoverability of its gravity field parameters. In this study, we will analyse this influence from closed-loop simulations using the planetary extension of the Bernese GNSS Softwareai.</p><p>A number of reference orbits with different orbital characteristics will be selected for the Gan De mission and, using an extended force model, will be propagated from different starting dates and different initial Earth beta angles. Realistic Doppler tracking data (2-way X-band Doppler range rate) will be simulated as measurements from ground stations, with a dedicated noise model. These observations will then be used to reconstruct the orbit along with dynamical parameters. The focus of this presentation will be on the quality of the retrieved gravity field parameters and tidal Love number k2.</p>

Correlation of frankfort horizontal with the sellanasion line angular data in different sagittal skeletal bases

It is of interest to establish the cephalometric correlation of angular data between frankfort horizontal and the sella-nasion line in different sagittal skeletal bases. Beta angle was used to divide the sample based on their sagittal skeletal base relationship. The FH-SN angle was measured for each group. The data were tabulated into IBM SPSS software. Kolmogorov-Smirnov and Shapiro-Wilk test was done to test the normal distribution of the data. One-way ANOVA analysis was done to test the difference of the FH-SN angle among the groups. Independent samples t-Test was done to test for gender dimorphism. The mean FH-SN angle of the sample was 6.33°3.35°. The results of the One-Way ANOVA and independent samples t-Test were insignificant. Results show that is no statistically significant difference in FHSN angle between skeletal class I, II and III.The mean FH-SN angle of the sample was 6.33°3.35°. The distribution of the data was normal. The results of the One-Way ANOVA and Independent samples t-Test were insignificant. There was no statistically significant difference in FH-SN angle between skeletal class I, II and III.

Determination of Sagittal Skeletal Discrepancy through Beta Angle: A Lateral Cephalometric Study

Introduction: Accurate classification and treatment planning relies on correct diagnosis of skeletal and dentalrelationships. Commonly used measurements used to classify sagittal relationship ANB and Wit’s appraisal are not without potential inherent problems which might lead to less accurate classification of sagittal dysplasia. To avoid these problems, a new approach Beta angle was introduced by Baik in 2004. Beta angle as it involves different landmarks of classifying anterior-posterior relationships is said to be devoid of those problems thus more reliable. We conducted a cross sectional study to measure the angle among patients presenting in Nishtar Institute of Dentistry Multan Pakistan. Materials and Method: Ninety pretreatment cephalometric x-rays of patients between ages 12 to 30 years were selected and studied. They were divided into three classes based on ANB angle and Wit’s appraisal. For the measurement of Beta angle, a line was drawn from the center of condyle (C) to point A and other to point B. A third line joining A to B was drawn. A line from point A perpendicular to line C-B was drawn and angle was measured between this perpendicular and line joining A-B. ANOVA was used to compare means of three groups. Pearson correlational coefficient was used to correlate relationship between Beta angle and ANB angle. Result: The results showed Beta angle ranged between 27° and 34° for class I. Subjects having angle less than 27° can be classified as skeletal class II and those with angles larger than 34° as skeletal class III subjects. Conclusion: Beta angle is reliable method for assessing and classifying sagittal skeletal discrepancies