Lung recruitment manoeuvres for reducing mortality and respiratory morbidity in mechanically ventilated neonates.

BACKGROUND: Preterm infants and neonates with respiratory conditions commonly require intubation and conventional mechanical ventilation (CMV) to maintain airway patency and support their respiration. Whilst this therapy is often lifesaving, it simultaneously carries the risk of lung injury. The use of lung recruitment manoeuvres (LRMs) has been found to reduce the incidence of lung injury, and improve oxygenation and lung compliance in ventilated adults. However, evidence pertaining to their use in neonates is limited, and there is no consensus of opinion as to whether LRMs are appropriate or effective in this population. OBJECTIVES: To determine the effects of LRMs on mortality and respiratory outcomes in mechanically ventilated neonates, when compared to no recruitment (routine care).  SEARCH METHODS: We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2020, Issue 4) in the Cochrane Library, MEDLINE via Ovid (1946 to 13 April 2020), and CINAHL via EBSCOhost (1989 to 13 April 2020). We also handsearched the reference lists of retrieved studies to source additional articles.  SELECTION CRITERIA: We included randomised controlled trials (RCTs), quasi-RCTs and randomised cross-over studies that compared the effect of LRMs to no recruitment (routine care) in mechanically ventilated neonates. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trial eligibility, extracted data and evaluated risk of bias in the included studies. When studies were sufficiently similar, we performed a meta-analysis using mean difference (MD) for continuous data and risk ratio (RR) for dichotomous data, with their respective 95% confidence intervals (CIs). We used the GRADE approach to assess the certainty of the evidence for key (clinically important) outcomes. MAIN RESULTS: We included four studies (152 participants in total) in this review. Three of these studies, enrolling 56 participants, contributed data to our prespecified outcomes. Two studies enrolling 44 participants on CMV for respiratory distress syndrome compared a stepwise LRM with positive end-expiratory pressure (PEEP) to routine care. Meta-analysis demonstrated no evidence of a difference between the LRM and routine care on mortality by hospital discharge (RR 1.00, 95% CI 0.17 to 5.77; low-certainty evidence), incidence of bronchopulmonary dysplasia (RR 0.25, 95% CI 0.03 to 2.07; low-certainty evidence), duration of supplemental oxygen (MD -7.52 days, 95% CI -20.83 to 5.78; very low-certainty evidence), and duration of ventilatory support (MD -3.59 days, 95% CI -12.97 to 5.79; very low-certainty evidence). The certainty of the evidence for these outcomes was downgraded due to risk of bias, imprecision, and inconsistency. Whilst these studies contributed data to four of our primary outcomes, we were unable to identify any studies that reported our other primary outcomes: duration of continuous positive airway pressure therapy, duration of neonatal intensive care unit stay, and duration of hospital stay.  The third study that contributed data to the review enrolled 12 participants on CMV for respiratory and non-respiratory causes, and compared two different LRMs applied after endotracheal tube suctioning to routine care. It was determined that both LRMs may slightly improve end-expiratory lung volume at 120 minutes' post-suctioning, when compared to routine care (incremental PEEP LRM versus routine care: MD -0.21, 95% CI -0.37 to -0.06; double PEEP LRM versus routine care: MD -0.18, 95% CI -0.35 to -0.02). It was also demonstrated that a double PEEP LRM may slightly reduce mean arterial pressure at 30 minutes' post-suctioning, when compared with routine care (MD -16.00, 95% CI -29.35 to -2.65).  AUTHORS' CONCLUSIONS: There is insufficient evidence to guide the use of LRMs in mechanically ventilated neonates. Well-designed randomised trials with larger sample sizes are needed to further evaluate the potential benefits and risks of LRM application in this population.

Characterization of progressive changes in pedicle morphometry and neurovascular anatomy during growth in adolescent idiopathic scoliosis versus adolescents without scoliosis.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: Investigate the progressive changes in pedicle morphometry and the spatial relationship between the pedicles and neurovascular structures in patients with AIS during growth. Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional spine deformity. AIS pedicles are known to be asymmetrical when compared to adolescents without scoliosis. Defining the anatomical changes occurring progressively in scoliosis as it increases with time and growth is essential for understanding the pathophysiology of scoliosis and for treatment planning. MRI is the ideal method to study the growing spine without ionising radiation. METHODS: 24 females with AIS (mean 12.6 years, right sided main thoracic curves) and 20 non-scoliotic females (mean 11.5 years) were selected from an ongoing database. Participants underwent two 3D MRI scans (3 T scanner, T1, 0.5 mm isotropic voxels) approximately 1 year apart (AIS: mean 1.3 ± 0.05 years, control: mean 1.0 ± 0.1 years). The pedicle width, chord length, pedicle height, transverse pedicle angle, sagittal pedicle angle, distance from vertebrae to aorta and distance from pedicle to dural sac were measured from T5 to T12. Inter- and intra-observer variability was assessed. RESULTS: From scans 1-2 in the AIS group, the dural sac became closer to the left pedicle (p < 0.05, T6, T8-T10 and T12) while the distance from the vertebrae to the aorta increased (p < 0.05, T6-T10). No significant changes in these measurements were observed in the non-scoliotic group. Between scans, the AIS chord length and transverse pedicle angle increased on the left side around the apex (p < 0.05) creating asymmetries not seen in the non-scoliotic cohort. The mean pedicle height increased symmetrically in the non-scoliosis cohort (p < 0.05) and asymmetrically in the AIS group with the right side growing faster than the left at T6-T7 (p < 0.05). CONCLUSION: Asymmetrical growth patterns occur in the vertebral posterior elements of AIS patients compared to the symmetrical growth patterns found in the non-scoliotic participants. LEVEL OF EVIDENCE: Level II prospective comparative study.

Sequential MRI reveals vertebral body wedging significantly contributes to coronal plane deformity progression in adolescent idiopathic scoliosis during growth.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To provide a comprehensive, multi-stage investigation of vertebral body (VB) and intervertebral disc (IVD) coronal plane deformities for adolescent idiopathic scoliosis (AIS) patients with a main thoracic curve type, using a series of sequential magnetic resonance images (MRIs). Despite numerous investigations of AIS deformity at the spinal segmental level, there is little consensus as to the major contributor to the lateral curvature of a scoliotic spine. Moreover, scoliotic deformity is often described along a continuum of progression, with few studies having characterised the change in segmental deformity for AIS patients whose deformity progresses clinically over time. METHODS: 30 female AIS patients with primary thoracic curves were included between 2012 and 2016. Three sequential MRIs were captured for each patient. Datasets were reformatted to produce true coronal plane images of the thoracic spine (T4-L1). Overall curve morphology, coronal plane IVD and VB segmental deformity and rates of growth were analysed. RESULTS: Right-side asymmetry was greater in IVDs (18.5 ± 23.9%) when compared to VBs (8.3 ± 9.2%) (P < 0.05) by third scans. Despite this, 77% of patients demonstrated the majority (> 50%) of their coronal curvature was attributed to VB wedging when measured across all three scans. Regardless of progression status, scan number, or region, the sum of the VB wedging angle was greater than the sum of the IVD wedging angle (all P ≤ 0.05). There was no correlation between the rates of major curve angle progression and standing height increase, VB height growth, or IVD height growth (P > 0.05). CONCLUSIONS: VB wedging contributed more to the lateral deformity observed in primary thoracic subtypes of AIS patients than IVD wedging. While IVDs demonstrated the greatest asymmetric deformity, their relatively smaller height resulted in a smaller proportional change in lateral curve angle compared to the VBs. LEVEL OF EVIDENCE: IV.

Determining a reliably visible and inexpensive surface fiducial marker for use in MRI: a research study in a busy Australian Radiology Department.

OBJECTIVES: Single-use commercial surface fiducial markers are used in clinical imaging for a variety of applications. The current study sought to find a new, reliably visible, easily sourced and inexpensive fiducial marker alternative for use with MRI. DESIGN: Five commonly requested MRI sequences were determined (three-dimensional (3D) T1-weighted, T1 coronal, 3D T2-weighted, T2 fat suppressed, proton density), to examine the visibility of 18 items (including a commercial fiducial marker). SETTING: Clinical 3T MRI scanner in an Australian Tertiary Hospital and an Australian University Biomedical Engineering research group. INTERVENTIONS: 18 marker alternatives were scanned using five common MRI sequences. Images were reformatted to obtain both an image through the mid-height of each marker and a maximum intensity z-projection image over the volume of the marker. Variations in marker intensity were profiled across each visible marker and a visibility rating defined. MAIN OUTCOME MEASURES: Outcome measures were based on quantitative assessment of a clear intensity contrast ratio between the marker and the adjacent tissue and a qualitative assessment of visibility via a 3-point scale. RESULTS: The fish oil capsule, vitamin D capsule, paint ball pellet, soy sauce sushi tube and commercial markers were typically visible to a high quality on all the imaging sequences and demonstrated a clear differential in intensity contrast against the adjacent tissue. Other common items, such as plasticine 'play doh' and a soft 'Jelly baby' sweet, were surprise candidates, demonstrating high-quality visibility and intensity contrast for the 3D T1-weighted sequence. CONCLUSIONS: Depending on the basis for referral and MRI sequence chosen, four alternative fiducial markers were determined to be inexpensive, easily sourced and consistently visible. Of these, the vitamin D capsule provided an excellent balance between availability, size, cost, usability and quality of the visualised marker for all the commonly used MRI sequences analysed.

Accuracy of 3D surface scanners for clinical torso and spinal deformity assessment.

Externally visible deformities are cosmetic features of great concern for Adolescent Idiopathic Scoliosis (AIS) patients. Current assessment techniques for AIS do not fully encompass the external deformity. A non-invasive method capable of capturing superficial anatomy, such as 3D scanning, would enable better qualitative and quantitative evaluation of cosmesis. This study aimed to quantify the accuracy of commonly available scanners, in assessing posterior asymmetry in AIS. The technique of 3D surface deviation analysis was proposed as a suitable method for comparing the models created by each scanner. Eight plaster cast moulds manufactured to create braces for AIS patients were used as test samples. Four 3D scanners were selected: Solutionix RexScan CS+; Artec Eva; Microsoft Kinect V1; iPhone with 123D Catch App. These scanners were selected from those available as representative of a range of scanning technologies. Each cast was scanned and 3D models created. A simulated rib hump measurement was obtained and the surface-to-surface deviations between the Solutionix scan and all other scans were determined. The Solutionix scanner is a metrology scanner of very high quality and so it was selected as the reference. Surface-to-surface deviations were calculated in the positive and negative directions separately to specifically identify size and volume inaccuracies created by the scans. Surface deviations showed excellent agreement between the Solutionix and the Eva with deviations of +0.17 ±â€¯0.17 mm (Eva regions larger) and -0.20 ±â€¯0.32 mm (Eva regions smaller) (mean±SD). The Kinect showed lower agreement (+1.58 ±â€¯1.50 mm and -0.58 ±â€¯0.58 mm). The iPhone scans were not able to be scaled to the correct size, so were excluded. Rib hump measurements with all scanners were within clinical measurement variability (±4.9 deg) of the known values. These commercially available 3D scanners are capable of imaging torso shape in 3D and deriving clinically relevant external deformity measures. The non-invasive 3D topographic information provided can be used to improve assessment of torso shape in spinal deformity patients.

Change in Lung Volume Following Thoracoscopic Anterior Spinal Fusion Surgery: A 3-Dimensional Computed Tomography Investigation.

STUDY DESIGN: Lung volumes and thoracic anatomy were measured from low-dose computed tomography (CT) scans preoperatively and 2 years following thoracoscopic anterior spinal fusion (TASF) for adolescent idiopathic scoliosis (AIS). OBJECTIVE: The aim of this study was to assess changes in lung volume after TASF surgical correction. SUMMARY OF BACKGROUND DATA: AIS patients are known to have decreased pulmonary function as a consequence of their spinal and ribcage deformity. Several studies have evaluated changes in pulmonary function clinically after scoliosis correction surgery showing varied results. To date, there have been no published studies using CT to evaluate lung volume changes following TASF. METHODS: Twenty-three female AIS patients with both pre- and 2 years postoperative low-dose CT scans were selected from an ethically approved, historical databank. Three-dimensional lung volumes were reconstructed to determine anatomical lung volumes. Right and left lung volumes, total lung volume, and right-to-left lung volume ratio were obtained as well as hemithoracic symmetry, to indicate the extent of thorax deformity. Cobb angle, rib hump, levels fused in surgery, and patient height were used for correlation analysis with the lung volume results. RESULTS: Left lung volume, total lung volume, and hemithoracic ratio all increased significantly 2 years after surgery. There was no significant change in right-to-left lung volume ratio (P = 0.36). Statistical regression found significant positive correlation between lung volume changes, reduction in Cobb angle, increase in height, and improvement in hemithoracic symmetry ratio. CONCLUSION: TASF resulted in a statistically significant increase in lung volume following surgery, as well as improvement in the symmetry of the thoracic architecture; however, the postoperative lung volumes remained in the lower 50th percentile relative to females without thoracic deformity. Furthermore, change in lung volume was significantly correlated with changes in Cobb angle, hemithoracic asymmetry, and increased patient height, which are important consequences of thoracic deformity correction surgery. LEVEL OF EVIDENCE: 3.

A comparison of four techniques to measure anterior and posterior vertebral body heights and sagittal plane wedge angles in adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) is a three-dimensional (3D) spinal deformity of unknown aetiology. Increased growth of the anterior part of the vertebrae known as anterior overgrowth has been proposed as a potential driver for AIS initiation and progression. To date, there has been no objective evaluation of the 3D measurement techniques used to identify this phenomenon and the majority of previous studies use 2D planar assessments which contain inherent projection errors due to the vertebral rotation which is part of the AIS deformity. In this study, vertebral body (VB) heights and wedge angles were measured in a test group of AIS patients and healthy controls using four different image analysis and measurement techniques. Significant differences were seen between the techniques in terms of VB heights and VB wedge angles. The low variability, and the fact that the rotation and tilt of the deformed VBs are taken into account, suggests that the proposed technique using the full 3D orientation of the vertebrae is the most reliable method to measure anterior and posterior VB heights and sagittal plane wedge angles in 3D image data sets. These results have relevance for future investigations that aim to quantify anterior overgrowth in AIS patients for comparison with healthy controls.

A comparison of vertebral venous networks in adolescent idiopathic scoliosis patients and healthy controls.

PURPOSE: Cadaveric studies have previously documented a typical pattern of venous drainage within vertebral bodies (VBs), comprised primarily of the basivertebral vein. These studies, however, are limited by the number of samples available. MRI is able to provide 3D images of soft tissue structures in the spine, including the basivertebral vein without the use of contrast in both healthy controls and subjects with abnormal anatomy such as adolescent idiopathic scoliosis (AIS). This study aimed to quantify the venous networks within VBs of 15 healthy adolescent controls and 15 AIS patients. METHODS: Five transverse slices through the VBs were examined simultaneously and the observable vascular network traced. The length of the network on the left and right sides of the VB was calculated, and the spatial patterning assessed level-by-level within each subject. RESULTS: Significant differences were seen in the left/right distribution of vessels in both the control and AIS subjects, with both groups having greater length on the right side of all of their VBs. No difference was seen between AIS and control subjects in any region. Large individual variations in patterns were seen in both groups; however, the control group showed more consistent spatial patterning of the vascular networks across levels in comparison to the AIS group. CONCLUSION: The length of the basivertebral vein was seen to have a significant bias to the right hand side of the VB in both healthy and AIS adolescents. The spatial pattern of this vein showed large variations in branching both within and across individuals. No significant differences were seen between AIS and control subjects, suggesting both that this network is preserved in deformed AIS vertebrae, and that the vertebral venous system does not play a role in the etiology of AIS.

Is There Asymmetry Between the Concave and Convex Pedicles in Adolescent Idiopathic Scoliosis? A CT Investigation.

BACKGROUND: Adolescent idiopathic scoliosis is a complex three-dimensional deformity of the spine characterized by deformities in the sagittal, coronal, and axial planes. Spinal fusion using pedicle screw instrumentation is a widely used method for surgical correction in severe (coronal deformity, Cobb angle > 45°) adolescent idiopathic scoliosis curves. Understanding the anatomic difference in the pedicles of patients with adolescent idiopathic scoliosis is essential to reduce the risk of neurovascular or visceral injury through pedicle screw misplacement. QUESTIONS/PURPOSES: To use CT scans (1) to analyze pedicle anatomy in the adolescent thoracic scoliotic spine comparing concave and convex pedicles and (2) to assess the intra- and interobserver reliability of these measurements to provide critical information to spine surgeons regarding size, length, and angle of projection. METHODS: Between 2007 and 2009, 27 patients with adolescent idiopathic scoliosis underwent thoracoscopic anterior correction surgery by two experienced spinal surgeons. Preoperatively, each patient underwent a CT scan as was their standard of care at that time. Twenty-two patients (mean age, 15.7 years; SD, 2.4 years; range, 11.6-22 years) (mean Cobb angle, 53°; SD, 5.3°; range, 42°-63°) were selected. Inclusion criteria were a clinical diagnosis of adolescent idiopathic scoliosis, female, and Lenke type 1 adolescent idiopathic scoliosis with the major curve confined to the thoracic spine. Using three-dimensional image analysis software, the pedicle width, inner cortical pedicle width, pedicle height, inner cortical pedicle height, pedicle length, chord length, transverse pedicle angle, and sagittal pedicle angles were measured. Randomly selected scans were remeasured by two of the authors and the reproducibility of the measurement definitions was validated through limit of agreement analysis. RESULTS: The concave pedicle widths were smaller compared with the convex pedicle widths at T7, T8, and T9 by 37% (3.44 mm ± 1.16 mm vs 4.72 mm ± 1.02 mm; p < 0.001; mean difference, 1.27 mm; 95% CI, 0.92 mm-1.62 mm), 32% (3.66 mm ± 1.00 mm vs 4.82 mm ± 1.10 mm; p < 0.001; mean difference, 1.16 mm; 95% CI, 0.84 mm-1.49 mm), and 25% (4.10 mm ± 1.57 mm vs 5.12 mm ± 1.17 mm; p < 0.001; mean difference, 1.02 mm; 95% CI, 0.66 mm-1.39 mm), respectively. The concave pedicle heights were smaller than the convex at T5 (9.43 mm ± 0.98 vs 10.63 mm ± 1.10 mm; p = 0.002; mean difference, 1.02 mm; 95% CI, 0.59 mm-1.45 mm), T6 (8.87 mm ± 1.37 mm vs 10.88 mm ± 0.81 mm; p < 0.001; mean difference, 2.02 mm; 95% CI, 1.40 mm-2.63 mm), T7 (9.09 mm ± 1.24 mm vs 11.35 mm ± 0.84 mm; p < 0.001; mean difference, 2.26 mm; 95% CI, 1.81 mm-2.72 mm), and T8 (10.11 mm ± 1.05 mm vs 11.86 mm ± 0.88 mm; p < 0.001; mean difference, 1.75 mm; 95% CI, 1.30 mm-2.19 mm). Conversely, the concave transverse pedicle angle was larger than the convex at levels T6 (11.37° ± 4.48° vs 8.82° ± 4.31°; p = 0.004; mean difference, 2.54°; 95% CI, 1.10°-3.99°), T7 (12.69° ± 5.93° vs 8.65° ± 3.79°; p = 0.002; mean difference, 4.04°; 95% CI, 1.90°-6.17°), T8 (13.24° ± 5.28° vs 7.66° ± 4.87°; p < 0.001; mean difference, 5.58°; 95% CI, 2.99°-8.17°), and T9 (19.95° ± 5.69° vs 8.21° ± 4.02°; p < 0.001; mean difference, 4.74°; 95% CI, 2.68°-6.80°), indicating a more posterolateral to anteromedial pedicle orientation. CONCLUSIONS: There is clinically important asymmetry in the morphologic features of pedicles in individuals with adolescent idiopathic scoliosis. The concave side of the curve compared with the convex side is smaller in height and width periapically. Furthermore, the trajectory of the pedicle is more acute on the convex side of the curve compared with the concave side around the apex of the curve. Knowledge of these anatomic variations is essential when performing scoliosis correction surgery to assist with selecting the correct pedicle screw size and trajectory of insertion to reduce the risk of pedicle wall perforation and neurovascular injury.

Apophyseal Ossification of the Iliac Crest in Forensic Age Estimation: Computed Tomography Standards for Modern Australian Subadults.

This study contrasts the ontogeny of the iliac crest apophysis using conventional radiography and multislice computed tomography (MSCT), providing probabilistic information for age estimation of modern Australian subadults. Retrospective abdominopelvic MSCT data acquired from 524 Australian individuals aged 7-25 and surveillance radiographs of adolescent idiopathic scoliosis patients included in the Paediatric Spine Research Group Progression Study (n = 531) were assessed. Ossification scoring of pseudo-radiographs and three-dimensional (3D) volume-rendered reconstructions using Risser (1958) quantitative descriptors indicate discrepancies in age estimates, stage allocation, and conflicting morphological progression. To mitigate visualization limitations associated with two-dimensional radiographs, we provide and validate a modified 3D-MSCT scoring tier of ossification, demonstrating complete fusion between 17.3-19.2 and 17.1-20.1 years in males and females. Legal demarcation for doli incapax presumption and age of majority (18 years) can be achieved using probability estimates from a fitted cumulative probit model for apophyseal fusion using the recalibrated standards.

A software program to measure the three-dimensional length of the spine from radiographic images: Validation and reliability assessment for adolescent idiopathic scoliosis.

BACKGROUND AND OBJECTIVE: The aim of this study was to validate a new program which aims at measuring the three-dimensional length of the spine's midline based on two calibrated orthogonal radiographic images. The traditional uniplanar T1-S1 measurement method is not reflecting the actual three dimensional curvature of a scoliotic spine and is therefore not accurate. The Spinal Measurement Software (SMS) is an alternative to conveniently measure the true spine's length. METHODS: The validity, inter- and intra-observer variability and usability of the program were evaluated. The usability was quantified based on a subjective questionnaire filled by eight participants using the program for the first time. The validity and variability were assessed by comparing the length of five phantom spines measured based on CT-scan data and on radiographic images with the SMS. The lengths were measured independently by each participant using both techniques. RESULTS: The SMS is easy and intuitive to use, even for non-clinicians. The SMS measured spinal length with an error below 2 millimeters compared to length obtained using CT scan datasets. The inter- and intra-observer variability of the SMS measurements was below 5 millimeters. CONCLUSIONS: The SMS provides accurate measurement of the spinal length based on orthogonal radiographic images. The software is easy to use and could easily integrate the clinical workflow and replace current approximations of the spinal length based on a single radiographic image such as the traditional T1-S1 measurement.

Role of the Middle Lumbar Fascia on Spinal Mechanics: A Human Biomechanical Assessment.

STUDY DESIGN: Biomechanical experiment. OBJECTIVE: The aims of the present study were to test the effect of fascial tension on lumbar segmental axial rotation and lateral flexion and the effect of the angle of fascial attachment. SUMMARY OF BACKGROUND DATA: Tension in the middle layer of lumbar fascia has been demonstrated to affect mechanical properties of lumbar segmental flexion and extension in the neutral zone. The effect of tension on segmental axial rotation and lateral flexion has, however, not been investigated. METHODS: Seven unembalmed lumbar spines were divided into segments and mounted for testing. A 6 degree-of-freedom robotic testing facility was used to displace the segments in each anatomical plane (flexion-extension, lateral bending, and axial rotation) with force and moment data recorded by a load cell positioned beneath the test specimen. Tests were performed with and without a 20 N fascia load and the subsequent forces and moments were compared. In addition, forces and moments were compared when the specimens were held in a set position and the fascia loading angle was varied. RESULTS: A fascial tension of 20 N had no measurable effect on the forces or moments measured when the specimens were displaced in any plane of motion (P > 0.05). When 20 N of fascial load were applied to motion segments in a set position small segmental forces and moments were measured. Changing the angle of the fascial load did not significantly alter these measurements. CONCLUSION: Application of a 20 N fascial load did not produce a measureable effect on the mechanics of a motion segment, even though it did produce small measurable forces and moments on the segments when in a fixed position. Results from the present study are inconsistent with previous studies, suggesting that further investigation using multiple testing protocols and different loading conditions is required to determine the effects of fascial loading on spinal segment behavior. LEVEL OF EVIDENCE: N/A.

Quantifying Progressive Anterior Overgrowth in the Thoracic Vertebrae of Adolescent Idiopathic Scoliosis Patients: A Sequential Magnetic Resonance Imaging Study.

STUDY DESIGN: Anterior and posterior vertebral body heights were measured from sequential magnetic resonance imaging (MRI) scans of adolescent idiopathic scoliosis (AIS) patients and healthy controls. OBJECTIVE: To measure changes in vertebral body height over time during scoliosis progression to assess how vertebral body height discrepancies change during growth. SUMMARY OF BACKGROUND DATA: Relative anterior overgrowth has been proposed as a potential driver for AIS initiation and progression. This theory proposes that the anterior column grows faster, and the posterior column slower, in AIS patients when compared with healthy controls. There is a disagreement in the literature as to whether the anterior vertebral body heights are proportionally greater than posterior vertebral body heights in AIS patients when compared with healthy controls. To some extent, these discrepancies may be attributed to methodological differences. METHODS: MRI scans of the major curve of 21 AIS patients (mean age 12.5 ±â€Š1.4 years, mean Cobb 32.2 ±â€Š12.8 degrees) and between T4 and T12 of 21 healthy adolescents (mean age 12.1 ±â€Š0.5 years) were captured for this study. Of the 21 AIS patients, 14 had a second scan on average 10.8 ±â€Š4.7 months after the first. Anterior and posterior vertebral body heights were measured from the true sagittal plane of each vertebra such that anterior overgrowth could be quantified. RESULTS: The difference between anterior and posterior vertebral body height in healthy, nonscoliotic children was significantly greater than in AIS patients with mild to moderate scoliosis. There was; however, no significant relationship between the overall anterior-posterior vertebral body height difference in AIS and either severity of the curve or its progression over time. CONCLUSION: Whilst AIS patients have a proportionally longer anterior column than nonscoliotic controls, the degree of anterior overgrowth was not related to the rate of progression or the severity of the scoliotic curve. LEVEL OF EVIDENCE: 3.

Mechanical testing of internal fixation devices: A theoretical and practical examination of current methods.

Successful healing of long bone fractures is dependent on the mechanical environment created within the fracture, which in turn is dependent on the fixation strategy. Recent literature reports have suggested that locked plating devices are too stiff to reliably promote healing. However, in vitro testing of these devices has been inconsistent in both method of constraint and reported outcomes, making comparisons between studies and the assessment of construct stiffness problematic. Each of the methods previously used in the literature were assessed for their effect on the bending of the sample and concordant stiffness. The choice of outcome measures used in in vitro fracture studies was also assessed. Mechanical testing was conducted on seven hole locked plated constructs in each method for comparison. Based on the assessment of each method the use of spherical bearings, ball joints or similar is suggested at both ends of the sample. The use of near and far cortex movement was found to be more comprehensive and more accurate than traditional centrally calculated interfragmentary movement values; stiffness was found to be highly susceptible to the accuracy of deformation measurements and constraint method, and should only be used as a within study comparison method. The reported stiffness values of locked plate constructs from in vitro mechanical testing is highly susceptible to testing constraints and output measures, with many standard techniques overestimating the stiffness of the construct. This raises the need for further investigation into the actual mechanical behaviour within the fracture gap of these devices.

A semiautomatic method to identify vertebral end plate lesions (Schmorl's nodes).

BACKGROUND CONTEXT: There are differences in the definitions of end plate lesions (EPLs), often referred to as Schmorl's nodes, that may, to some extent, account for the large range of reported prevalence (3.8%-76%). PURPOSE: The purpose of this study was to develop a technique to measure the size, prevalence, and location of EPLs in a consistent manner. STUDY DESIGN/SETTING: This study proposed a method using a detection algorithm that was applied to five adolescent females (average age, 15.1 [range, 13.0-19.2] years) with idiopathic scoliosis (average major Cobb angle, 60° [range, 55°-67°]). METHODS: Existing low-dose, computed tomography scans were segmented semiautomatically to extract three-dimensional morphology of each vertebral end plate. Any remaining attachments to the posterior elements of adjacent vertebrae or end plates were then manually sectioned. An automatic algorithm was used to determine the presence and position of EPLs. RESULTS: End plate lesions were identified in 15 of the 170 (8.8%) end plates analyzed with an average depth of 3.1 mm. Eleven of the 15 EPLs were seen in the lumbar spine. The algorithm was found to be most sensitive to changes in the minimum EPL gradient at the edges of the EPL. CONCLUSIONS: This study describes an imaging analysis technique for consistent measurement of the prevalence, location, and size of EPLs. The technique can be used to analyze large populations without observer errors in EPL definitions.

Lung recruitment and endotracheal suction in ventilated preterm infants measured with electrical impedance tomography.

AIMS: Although suctioning is a standard airway maintenance procedure, there are significant associated risks, such as loss of lung volume due to high negative suction pressures. This study aims to assess the extent and duration of change in end-expiratory level (EEL) resulting from endotracheal tube (ETT) suction and to examine the relationship between EEL and regional lung ventilation in ventilated preterm infants with respiratory distress syndrome. METHODS: A prospective observational clinical study of the effect of ETT suction on 20 non-muscle-relaxed preterm infants with respiratory distress syndrome (RDS) on conventional mechanical ventilation was conducted in a neonatal intensive care unit. Ventilation distribution was measured with regional impedance amplitudes and EEL using electrical impedance tomography. RESULTS: ETT suction resulted in a significant increase in EEL post-suction (P < 0.01). Regionally, anterior EEL decreased and posterior EEL increased post-suction, suggesting heterogeneity. Tidal volume was significantly lower in volume-guarantee ventilation compared with pressure-controlled ventilation (P = 0.04). CONCLUSIONS: ETT suction in non-muscle-relaxed and ventilated preterm infants with RDS results in significant lung volume increase that is maintained for at least 90 min. Regional differences in distribution of ventilation with ETT suction suggest that the behaviour of the lung is heterogeneous in nature.

Comparison of mechanical and ultrasound elastic modulus of ovine tibial cortical bone.

Finite element models of bones can be created by deriving geometry from an X-ray CT scan. Material properties such as the elastic modulus can then be applied using either a single or set of homogeneous values, or individual elements can have local values mapped onto them. Values for the elastic modulus can be derived from the CT density values using an elasticity versus density relationship. Many elasticity-density relationships have been reported in the literature for human bone. However, while ovine in vivo models are common in orthopaedic research, no work has been done to date on creating FE models of ovine bones. To create these models and apply relevant material properties, an ovine elasticity-density relationship needs to be determined. Using fresh frozen ovine tibias the apparent density of regions of interest was determined from a clinical CT scan. The bones were the sectioned into cuboid samples of cortical bone from the regions of interest. Ultrasound was used to determine the elastic modulus in each of three directions - longitudinally, radially and tangentially. Samples then underwent traditional compression testing in each direction. The relationships between apparent density and both ultrasound, and compression modulus in each direction were determined. Ultrasound testing was found to be a highly repeatable non-destructive method of calculating the elastic modulus, particularly suited to samples of this size. The elasticity-density relationships determined in the longitudinal direction were very similar between the compression and ultrasound data over the density range examined. A clear difference was seen in the elastic modulus between the longitudinal and transverse directions of the bone samples, and a transverse elasticity-density relationship is also reported.

Measurement of ventilation and cardiac related impedance changes with electrical impedance tomography.

INTRODUCTION: Electrical impedance tomography (EIT) has been shown to be able to distinguish both ventilation and perfusion. With adequate filtering the regional distributions of both ventilation and perfusion and their relationships could be analysed. Several methods of separation have been suggested previously, including breath holding, electrocardiograph (ECG) gating and frequency filtering. Many of these methods require interventions inappropriate in a clinical setting. This study therefore aims to extend a previously reported frequency filtering technique to a spontaneously breathing cohort and assess the regional distributions of ventilation and perfusion and their relationship. METHODS: Ten healthy adults were measured during a breath hold and while spontaneously breathing in supine, prone, left and right lateral positions. EIT data were analysed with and without filtering at the respiratory and heart rate. Profiles of ventilation, perfusion and ventilation/perfusion related impedance change were generated and regions of ventilation and pulmonary perfusion were identified and compared. RESULTS: Analysis of the filtration technique demonstrated its ability to separate the ventilation and cardiac related impedance signals without negative impact. It was, therefore, deemed suitable for use in this spontaneously breathing cohort.Regional distributions of ventilation, perfusion and the combined ΔZV/ΔZQ were calculated along the gravity axis and anatomically in each position. Along the gravity axis, gravity dependence was seen only in the lateral positions in ventilation distribution, with the dependent lung being better ventilated regardless of position. This gravity dependence was not seen in perfusion.When looking anatomically, differences were only apparent in the lateral positions. The lateral position ventilation distributions showed a difference in the left lung, with the right lung maintaining a similar distribution in both lateral positions. This is likely caused by more pronounced anatomical changes in the left lung when changing positions. CONCLUSIONS: The modified filtration technique was demonstrated to be effective in separating the ventilation and perfusion signals in spontaneously breathing subjects. Gravity dependence was seen only in ventilation distribution in the left lung in lateral positions, suggesting gravity based shifts in anatomical structures. Gravity dependence was not seen in any perfusion distributions.

The assessment of regional lung mechanics with electrical impedance tomography: a pilot study during recruitment manoeuvres.

OBJECTIVE: The purpose of lung recruitment manoeuvres is to open collapsed lung regions, improve gas exchange and optimise regional lung mechanics. This study investigates the efficacy of recruitment manoeuvres for improving regional ventilation distribution as characterised using electrical impedance tomography (EIT). DESIGN, SUBJECTS, INTERVENTIONS: A ventilated ovine smoke inhalation lung injury model was used. Respiratory mechanics and regional filling capacity of the lung were measured using EIT pre- and post- recruitment and compared to a control group. MEASUREMENTS: EIT, expressed as the time course relation of the regional versus the global impedance change, measured the regional filling capacities of the lung. MAIN RESULTS: After smoke inhalation injury, the dependent lung showed a significantly larger area of collapse and a reduced filling capacity compared to the non-dependent lung. After recruitment the ventilated volume increased and the dependent lung showed improved respiratory mechanics, whereas the non-dependent lung was more likely to be hyper-inflated during tidal breathing. CONCLUSIONS: Lung recruitment manoeuvres have a significant impact on regional lung mechanics and individual measurement of ventilation distribution using EIT may assist to improve ventilatory management.