Increase in clivo-axial angle is associated with clinical improvement in children undergoing occipitocervical fusion for complex Chiari malformation: patient series

BACKGROUND The authors analyzed the pre- and postoperative morphometric properties of pediatric patients with complex Chiari malformation undergoing occipitocervical fusion (OCF) to assess clinical outcomes and morphometric properties that might influence postoperative outcomes. OBSERVATIONS The authors retrospectively reviewed 35 patients younger than 22 years with Chiari malformation who underwent posterior fossa decompression and OCF with or without endoscopic endonasal odontoidectomy at their institution (13 with and 22 without odontoidectomy). Clivo-axial angle (CXA), pB-C2, atlantodental interval, basion-dens interval, basion-axial interval, and canal diameter at the level of C1 were measured on preoperative and approximately 3-month postoperative computed tomography or magnetic resonance imaging. The authors further stratified the patient cohort into three age groups and compared the three cohorts. The most common presenting symptoms were headache, neck/shoulder pain, and dysphagia; 80% of the cohort had improved clinical outcomes. CXA increased significantly after surgery. When stratified into those who showed postoperative improvement and those who did not, only the former showed a significant increase in CXA. After age stratification, the significant changes in CXA were observed in the 7- to 13-year-old and 14- to 21-year-old cohorts. LESSONS CXA may be the most important morphometric predictor of clinical outcomes after OCF in pediatric patients with complex Chiari malformation.

Image registration analysis of the motion characteristics of sternoclavicular joints in sagittal motion of the upper limbs

OBJECTIVE: This study aims to accurately measure the range of motion of the sternoclavicular (SC) joint using 3D reconstruction and image registration. The motion of the SC joint is analyzed by means of axial angle representation to identify the kinematical characteristics of this joint. METHODS: A total of 13 healthy volunteers were enrolled in the study. The limit postures of four SC joint movements were scanned by computerized tomography. The images were integrated with reconstruction and registration techniques. The range of motion of the SC joint was measured using 3D modelling. The axial angle was used to indicate the range of motion of the SC joint. The difference between the dominant side and non-dominant side was compared and the differences in axial angle of the SC joint in different postures were compared. RESULTS: The active axial angle of the SC joint on the dominant side was approximately 1∘ higher than that of the non-dominant side when the upper limb moved from a rest position to a posteroinferior position. In the sagittal motion of the upper limbs, the axial angle of the SC joint was greatest when moving from a horizontal position to a posterosuperior position, with an average of 23.55∘. Of the flexion and extension movements of the upper limbs from a rest position to a horizontal position, 13.66% (the smallest proportion) were completed by the SC joint. CONCLUSION: The combination of 3D reconstruction and image registration is a direct and accurate method of measuring the motion of the SC joint. Axial angle representation is an intuitive method of expressing rotation in a 3D space that allows for more convenient comparison; it is also more in line with the characteristics of human anatomy and kinesiology and therefore more accurately reflects the characteristics of joint motion. It is therefore useful for guiding clinical practice. In a physical examination, the extension of the upper limb from the horizontal position to the posterosuperior position and from the rest position to the posteroinferior position can best reflect the rotation function of the SC joint in the combined motion of shoulder joints.

Effect of cervical flexion and extension on thoracic sagittal alignment

Introduction: The cervical spine has the largest sagittal motion in the whole spine, and cervical alignment affects the thoracic sagittal alignment. However, the effects of cervical flexion and extension on thoracic sagittal alignment have not been investigated in detail. The purpose of this study was to analyze the change of thoracic sagittal alignment following cervical flexion and extension. Subjects and methods: A total of 55 consecutive patients (42 men and 13 women; average age 49.1 years) who presented to our department with spinal degenerative disease between January 2016 and September 2017 were enrolled in our study. Subjects with a history of trauma, infection, tumor, inflammatory disease, ossification, or cervical deformities, and those who had undergone spinal surgery were excluded. The following parameters were analyzed: occipito-axial angle (O–C2), C2 slope (C2S), C2–C7 angle, T1 slope (T1S), thoracic kyphosis, T1–T4 angle, T5–T8 angle, T9–T12 angle, lumbar lordosis, sacral slope, pelvic tilt in cervical flexion, neutral, and extension. Results: Cervical flexion significantly decreased O–C2, C2–C7 angles and T1S, and increased C2S. Cervical extension conversely changed these parameters. At cervical flexion, the correlation of C2–C7 angle with thoracic parameters was maintained, except for the T1–T4 angle. At cervical extension, the correlation was observed with T1S and T1–T4 angle. Conclusion: Cervical flexion affects the T1S and T5–T8 angle, but there is no significant change in T1–T4 and T9 and lower spino-pelvic columns. This study suggests that T2–T4 can be considered as a stable distal end when cervical long fixation for corrective surgery is performed.

A Comparison Study of Marginal and Internal Fit Assessment Methods for Fixed Dental Prostheses

Numerous studies have previously evaluated the marginal and internal fit of fixed prostheses; however, few reports have performed an objective comparison of the various methods used for their assessment. The purpose of this study was to compare five marginal and internal fit assessment methods for fixed prostheses. A specially designed sample was used to measure the marginal and internal fit of the prosthesis according to the cross-sectional method (CSM), silicone replica technique (SRT), triple scan method (TSM), micro-computed tomography (MCT), and optical coherence tomography (OCT). The five methods showed significant differences in the four regions that were assessed (p < 0.001). The marginal, axial, angle, and occlusal regions showed low mean values: CSM (23.2 µm), TSM (56.3 µm), MCT (84.3 µm), and MCT (102.6 µm), respectively. The marginal fit for each method was in the range of 23.2–83.4 µm and internal fit (axial, angle, and occlusal) ranged from 44.8–95.9 µm, 84.3–128.6 µm, and 102.6–140.5 µm, respectively. The marginal and internal fit showed significant differences depending on the method. Even if the assessment values of the marginal and internal fit are found to be in the allowable clinical range, the differences in the values according to the method should be considered.

FM1-7 Cranio-cervical instability in ehlers-danlos syndrome employing upright, dynamic MR imaging; a comparative study

ObjectivesEhlers-Danlos syndrome (EDS) is a hereditary connective tissue disorder leading to hypemobile joints including the craniocervical junction. Neck pain is a prominent feature. Structural abnormalities may have a dynamic element and thus may not be captured in a recumbent MRI. There is currently a lack of evidence1 assessing the use and diagnostic impact of positional MRI in Ehlers-Danlos syndrome. We aim to evaluate structural features and dynamic instability in an EDS cohort employing dynamic MR imaging against a non EDS symptomatic cohort.DesignComparative Study.SubjectsPatients diagnosed with Ehlers-Danlos syndrome and control subjects (non EDS with cervical spondylosis) were included in this study.MethodsCranio – cervical spine global and segmental movement parameters in the neutral, extension and flexion positions were measured from T2-weighted images in the midline sagittal plane. These parameters included the clivo axial angle, grabb oakes line, C2 sagittal vertical axis, C0-C1 angle, C1-2 angle, cervical lordosis and T1 slope.ResultsThe clivo- axial angle measured in neutral was 139.7±10.4 degrees in the EDS group vs 148.9±8.4 in the control group (p<0.01) The cervical range of movement between flexion and extension was 74.6±24.4 in the EDS group vs 39.4±11.3 in the controls (p<0.0001).ConclusionsEDS patients with neck symptoms exhibit different static as well as dynamic craniocervical structural features compared to a general population control.ReferenceOnt Health Technol Assess Ser [Internet]2015July;15(13):1–24.