Bayesian mixture modelling with ranked set samples.

We consider the Bayesian estimation of the parameters of a finite mixture model from independent order statistics arising from imperfect ranked set sampling designs. As a cost-effective method, ranked set sampling enables us to incorporate easily attainable characteristics, as ranking information, into data collection and Bayesian estimation. To handle the special structure of the ranked set samples, we develop a Bayesian estimation approach exploiting the Expectation-Maximization (EM) algorithm in estimating the ranking parameters and Metropolis within Gibbs Sampling to estimate the parameters of the underlying mixture model. Our findings show that the proposed RSS-based Bayesian estimation method outperforms the commonly used Bayesian counterpart using simple random sampling. The developed method is finally applied to estimate the bone disorder status of women aged 50 and older.

Central venous catheter tip misplacement: A multicentre cohort study of 8556 thoracocervical central venous catheterisations.

BACKGROUND: There is a paucity of data on the incidence of central venous catheter tip misplacements after the implementation of ultrasound guidance during insertion. The aims of the present study were to determine the incidence of tip misplacements and to identify independent variables associated with tip misplacement. METHODS: All jugular and subclavian central venous catheter insertions in patients ≥16 years with a post-procedural chest radiography at four hospitals were included. Each case was reviewed for relevant catheter data and radiologic evaluations of chest radiographies. Tip misplacements were classified as 'any tip misplacement', 'minor tip misplacement' or 'major tip misplacement'. Multivariable logistic regression analyses were used to investigate associations between predefined independent variables and tip misplacements. RESULTS: A total of 8556 central venous catheter insertions in 5587 patients were included. Real-time ultrasound guidance was used in 91% of all insertions. Any tip misplacement occurred (95% confidence interval) in 3.7 (3.3-4.1)% of the catheterisations, and 2.1 (1.8-2.4)% were classified as major tip misplacements. The multivariable logistic regression analyses showed that female patient gender, subclavian vein insertions, number of skin punctures and limited operator experience were associated with a higher risk of major tip misplacement, whereas increasing age and height were associated with a lower risk. CONCLUSIONS: In this large prospective multicentre cohort study, performed in the ultrasound-guided era, we demonstrated the incidence of tip misplacements to be 3.7 (3.3-4.1)%. Right internal jugular vein catheterisation had the lowest incidence of both minor and major tip misplacement.

Impact of osteosclerosis on cervical pedicle screw insertion using preoperative CT-based navigation.

PURPOSE: Preoperative computed tomography (CT)-based navigation is used for cervical pedicle screw (CPS) insertion to mitigate the risk of spinal cord and vertebral artery injury. In vertebrae with osteosclerosis due to degeneration or other factors, however, probing may not proceed easily, with difficulty creating the CPS insertion hole. This study investigated the impact of osteosclerosis on the accuracy of CPS insertion. METHODS: A total of 138 patients with CPS inserted at the C3-C7 level using preoperative CT navigation were retrospectively analyzed. Pre- and postoperative CT was employed to investigate screw position and Hounsfield unit (HU) values at the lateral mass to evaluate the degree of osteosclerosis in the CPS insertion pathway. RESULTS: Among 561 CPS insertions, the Grade 3 perforation rate was 1.8%, and the Grade 2 or higher perforation rate was 8.0%. When comparing insertions with and without CPS perforation, HU values were significantly higher in the perforation group (578 ± 191 vs. 318 ± 191, p < 0.01). The frequency of CPS insertion into the mid-cervical spine was also significantly greater in the perforation group (68.9% vs. 62.5%, p < 0.01). Logistic regression analysis revealed that a high HU value at the lateral mass (odds ratio 1.09, 95% confidence interval: 1.07-1.11, p < 0.01) was a significant independent factor associated with CPS deviation. CONCLUSIONS: The screw perforation rate of Grade 2 or higher in CPS insertion using preoperative CT-based navigation was 8.0%. Since osteosclerosis was an independent factor related to CPS deviation, additional care may be required during insertion into affected vertebrae.

Respiratory symptoms due to a twisted nasogastric tube: A case report.

Insertion of a nasogastric tube (NGT) is generally considered safe; however, it is not without risk, and in cases of misplacement, complications and even death may occur. In this article, we reported a case of NGT misplacement in a 75-year-old male, which resulted in aspiration pneumonia. We also reviewed published cases of NGT misplacement. Clinicians should pay enough attention to the confirmation of the proper placement of an NGT. A systematic approach for NGT insertion and confirmation is required to prevent misplacement.

ECG lead misplacement in the frontal and horizontal plane mimicking A myocardial infarction.

BACKGROUND/AIMS: Electrocardiogram (ECG) is an inexpensive, fundamental screening tool used in daily clinical practice. It is essential in the diagnosis of life-threatening conditions, such as acute myocardial infarctions, ventricular arrhythmias etc. However, ECG lead misplacement is a common technical error, which may translate into wrong interpretations, unnecessary investigations, and improper treatments. METHODS/RESULTS: We report a case of a multiple ECG lead misplacement made across two different planes of the heart, resulting in a bizarre series of ECG, mimicking an acute high lateral myocardial infarction. Multiple ECGs were done as there were abrupt changes compared to previous ECGS. Patient was pain free and administration of potentially harmful procedures and treatments were prevented. CONCLUSION: Our case demonstrated the importance of high clinical suspicion in diagnosing ECG lead misplacement. It is the responsibility of both the healthcare workers who are performing and interpreting the ECG to be alert of a possible lead malposition, to prevent untoward consequences to the patient.

Pedicle Screw Placement Aided by C-Arm Fluoroscopy: A "Nevermore without" Technology to Pursue Optimal Spine Fixation.

The surgical technique and the intraoperative technology that support spinal pedicle screw placement have consistently evolved over the past decades to decrease the misplacement rate of pedicle screws. We retrospectively evaluated our case series by analyzing the period 2016-2020. Patients undergoing pedicle screw fixation for cervical, thoracic, or lumbar spine degenerative diseases have been included. Surgery was carried out with the aid of intraoperative 3D C-arm fluoroscopy to assess and optimize screw placement and/or correct possible mispositioning. Each patient underwent a postoperative CT scan. Our aim was to evaluate the safety and accuracy of pedicle screw placement and estimate the variation in mispositioning rates. We carried out 329 surgical procedures, as follows: 70 cervical, 78 thoracic spine, and 181 lumbar spine surgeries. An excellent overall pedicle screw positioning was obtained, with slight differences between the cervical (98.6%), thoracic (100%), and lumbar (98.9%) tracts. Accordingly, only three patients required a revision surgery owing to mispositioning (0.91%). In particular, intraoperative C-arm fluoroscopy significatively improved the accuracy of thoracic screw positioning, as shown by postoperative CT scans. Our experience proves the crucial role of intraoperative C-arm fluoroscopy in pursuing optimal technical results and improving patient outcomes at follow-up.

Identification and Subsequent Extraction of an Atrial Pacing Lead Inadvertently Positioned Within the Pulmonary Venous Atrium of a Patient With D-Transposition of the Great Arteries.

In a male patient with D-transposition of the great arteries post Mustard repair, we report the inadvertent placement of an atrial pacemaker lead across the baffle into the pulmonary venous atrium managed with extraction and re-implantation.

The Bowel Cancer Screening Programme Expert Board: an analysis of activity during 2017-2020.

AIMS: The inception of the National Health Service Bowel Cancer Screening Programme in England in 2006 highlighted the fact that the differential diagnosis between the presence of epithelial misplacement and adenocarcinoma occurring in colorectal adenomas is problematic. The pathology Expert Board (EB) was created to facilitate the review of difficult cases by a panel of three experienced gastrointestinal pathologists. This article describes a review of the work of the EB over a 4-year period (2017-2020). METHODS AND RESULTS: Four hundred and thirty polyps were referred to the EB from 193 pathologists and 76 hospitals during this time. The EB diagnosis was benign for 67%, malignant for 28%, and equivocal for 2% (with no consensus in the remainder). The most common diagnosis change made by the EB was from malignant to benign-made in 50% of polyps referred with an initially malignant diagnosis. The level of agreement between the individual EB members was 'good' (kappa score of 0.619) but that between the EB and the referring diagnosis was 'poor' (kappa score of 0.149). Data from one EB member indicated that the presence of lamina propria, features of torsion and cytological similarity between the superficial and deep glands were predictors of a benign diagnosis, whereas the presence of irregular neoplastic glands, a desmoplastic reaction and lymphovascular invasion were commonly observed features in polyps with a malignant diagnosis. CONCLUSION: Diagnostic agreement between EB members is better than that between the EB and referring pathologists. There was a consistent trend for the EB to change diagnoses from malignant to benign.

The right supraclavicular fossa ultrasound view for correct catheter tip positioning in right subclavian vein catheterisation: a prospective observational study.

Central venous catheter misplacement is common (approximately 7%) after right subclavian vein catheterisation. To avoid it, ultrasound-guided tip navigation may be used during the catheterisation procedure to help direct the guidewire towards the lower superior vena cava. We aimed to determine the number of central venous catheter misplacements when using the right supraclavicular fossa ultrasound view to aid guidewire positioning in right infraclavicular subclavian vein catheterisation. We hypothesised that the incidence of catheter misplacements could be reduced to 1% when using this ultrasound technique. One -hundred and three adult patients were prospectively included. After vein puncture and guidewire insertion, we used the right supraclavicular fossa ultrasound view to confirm correct guidewire J-tip position in the lower superior vena cava and corrected the position of misplaced guidewires using real-time ultrasound guidance. Successful catheterisation of the right subclavian vein was achieved in all patients. The guidewire J-tip was initially misplaced in 15 patients, either in the ipsilateral internal jugular vein (n = 8) or in the left brachiocephalic vein (n = 7). In 12 patients it was possible to adjust the guidewire J-tip to a correct position in the lower superior vena cava. All ultrasound-determined final guidewire J-tip positions were consistent with the central venous catheter tip positions on chest X-ray. Three out of 103 catheters were misplaced, corresponding to an incidence (95%CI) of 2.9 (0.6-8.3) %. Although the hypothesis could not be confirmed, this study demonstrated the usefulness of the right supraclavicular fossa ultrasound view for real-time confirmation and correction of the guidewire position in right infraclavicular subclavian vein catheterisation.

Nephrostomy Tube Misplaced into the Right Atrium: An Extremely Rare Case and Review of the Literature.

Although percutaneous nephrolithotomy is generally safe, it has various complications. We present an extremely rare case in which the nephrostomy tube pierced renal parenchyma, proceeded through the right renal vein and inferior vena cava, finally reaching the right atrium. Such a tube misplaced to atrium level was firstly reported, which was safely withdrawn using a 2-step process under fluoroscopic monitoring. We also recommend the tube be marked with different color lines to maintain awareness of the tube length that has passed the peel-away sheath. Such information might help to avoid such complication.

Pedicle screw accuracy in thoracolumbar fractures- is routine postoperative CT scan necessary?

BACKGROUND: While several studies report on accuracy rates of pedicle screws, risk factors associated with inaccurate pedicle screw positioning in patients with thoracolumbar fractures are reported rarely. CT scan as a routine postoperative control is advocated by various authors, however its necessity remains unclear. METHODS: Two hundred forty-five patients were included in this retrospective study. Percutaneous dorsal instrumentation was most commonly performed (n = 201). Classification of Zdichavsky et al. and Rao et al. were used to classify screw misplacement and anterior perforation was further evaluated according to the extent of perforation (< 2 mm; > 2 mm). Multivariate analysis was performed to identify risk factors for misplacement of screws. RESULTS: One thousand sixty-eight pedicle screws were inserted in 245 patients. Misplacement was found in 51 screws (4.8%) in 42 patients (17.1%) according to the classification of Zdichavsky et al. and in 75 screws (7.0%) in 64 patients (26.1%) according to the classification of Rao et al.. An anterior perforation of the vertebral cortex was found in 56 screws (5.2%). Multivariate analysis showed fracture location in the upper thoracic (p = 0.048) and lumbar spine (p = 0.013) to be the only independent predictors for screw misplacement. In addition a significant correlation between pedicle diameter and the occurrence of screw malposition was found (p = 0.003). No consequences were drawn from postoperative routine CT in asymptomatic patients. CONCLUSION: An overall low rate of screw misplacement was found with fracture location in the upper thoracic and lumbar spine being the only factors independently associated with the risk of screw misplacement. No consequences were drawn from postoperative routine CT in asymptomatic patients. Therefore its use has to be discussed critically.

Comparison of a ceiling-mounted 3D flat panel detector vs. conventional intraoperative 2D fluoroscopy in plate osteosynthesis of distal radius fractures with volar locking plate systems.

OBJECTIVES: To compare intraoperative 3D fluoroscopy with a ceiling-mounted flat panel detector in plate osteosynthesis of distal radius fractures (AO/OTA 2R3C1.2) with volar locking plate systems to conventional 2D fluoroscopy for detection of insufficient fracture reduction, plate misplacement and protruding screws. METHODS: Using a common volar approach on 12 cadaver forearms, total intraarticular distal radius fractures were induced, manually reduced and internally fixated with a 2.4 distal radius locking compression plate. 2D (anterior-posterior and lateral) and 3D (rotational) fluoroscopic images were taken as well as computed tomographies. Fluoroscopic images, Cone Beam CT (CBCT), 360° rotating sequences (so called "Movies") and CT scans were co-evaluated by a specialist orthopedic surgeon and a specialist radiologist regarding quality of fracture reduction, position of plate, position of the three distal locking screws and position of the three diaphyseal screws. In reference to gold standard CT, sensitivity and specifity were analyzed. RESULTS: "Movie" showed highest sensitivity for detection of insufficient fracture reduction (88%). Sensitivity for detection of incorrect position of plate was 100% for CBCT and 90% for "Movie." For intraarticular position of screws, 2D fluoroscopy and CBCT showed highest sensitivity and specifity (100 and 91%, respectively). Regarding detection of only marginal intraarticular position of screws, sensitivity and specifity of 2D fluoroscopy reached 100% (CBCT: 100 and 83%). "Movie" showed highest sensitivity for detection of overlapping position of screws (100%). When it comes to specifity, CBCT achieved 100%. Regarding detection of only marginal overlapping position of screws, 2D fluoroscopy and "Movie" showed highest sensitivity (100%). CBCT achieved highest specifity (100%). CONCLUSION: As for assessment of quality of fracture reduction and detection of incorrect position of plate as well as overlapping position of the three diaphyseal screws CBCT and "Movie" are comparable to CT - especially when combined. Particularly sensitivity is high compared to standard 2D fluoroscopy.

CT imaging of extraglottic airway device-pictorial review.

Compared to intubation with a cuffed endotracheal tube, extraglottic airway devices (EGDs), such as laryngeal mask airways, are considered less definitive ventilation conduit devices and are therefore often exchanged via endotracheal intubation (ETI) prior to obtaining CT images. With more widespread use and growing comfort among providers, reports have now described use of EGDs for up to 24 h including cases for which clinicians obtained CT scans with an EGD in situ. The term EGD encompasses a wide variety of devices with more complex structure and CT appearance compared to ETI. All EGDs are typically placed without direct visualization and require less training and time for insertion compared to ETI. While blind insertion generally results in functional positioning, numerous studies have reported misplacements of EGDs identified by CT in the emergency department or post-mortem. A CT-based classification system has recently been suggested to categorize these misplacements in six dimensions: depth, size, rotation, device kinking, mechanical blockage of the ventilation opening(s), and injury from EGD placement. Identifying the type of EGD and its correct placement is critically important both to provide prompt feedback to clinicians and prevent inappropriate medicolegal problems. In this review, we introduce the main types of EGDs, demonstrate their appearance on CT images, and describe examples of misplacements.

Central venous catheters misplaced in paraspinal veins: A systematic literature review based on case reports.

BACKGROUND: Paraspinal vein misplacement is an uncommon complication of central venous catheterization via lower extremities, most of which have been reported in case reports. AIM: To determine the clinical characteristics of paraspinal vein misplacement. DESIGN: This was a systematic review. METHODS: A systematic literature search in the PubMed, EMBASE, Scopus, and Web of Science databases was performed from their inception to 18 June 2019. Case reports and small case series describing central venous catheter misplacement in the paraspinal vein were included. Data on the catheterization procedure, catheter tip position, complications, and radiographic features of misplacement were extracted. RESULTS: Thirty studies with a total of 36 patients were included. The ascending lumbar vein accounted for the majority of misplacements (n = 30), followed by the lumbar vein (n = 4), iliolumbar vein (n = 1), and vertebral venous plexus (n = 1). Six patients had eventful catheterization procedures. Twenty-six patients experienced misplacement-induced complications, of whom seven died. The most common complications included cerebrospinal fluid abnormalities, neurological symptoms, and deteriorated respiration. Among the entire case cohort, the onset of complications was the primary sign that alerted medical staff to misplacement (n = 23). The typical radiographic characteristics were posterior deviation of the catheter course overlapping with the spine on lateral X-rays and a bend, kink, or hump in the catheter course on anteroposterior X-rays at the L4 to L5 levels. CONCLUSIONS: Nurses should be aware of this particular complication if a patient who has undergone catheterization via a lower extremity presents deterioration of neurological function and respiration. RELEVANCE TO CLINICAL PRACTICE: Lateral X-ray radiography is an effective method to verify misplacement and is recommended as routine practice during catheterization via lower extremities.

Tips for Dealing with Common Beginner's Mistakes Made during Endoscopic Ultrasound-Guided Gallbladder Drainage.

Endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) has been performed as an alternative to percutaneous drainage in surgically high-risk patients. Technical failures of EUS-GBD made by beginners are often attributed to failure of over-the-wire insertion of a fistula-dilating device or stent delivery system into the gallbladder, or stent misplacement in the final technical step. We herein report technical tips to prevent the failure of fistula dilation and provide tricks to avoid inward or outward stent misplacement.

Axial pelvic tilt in direct anterior Total hip Arthroplasty using a traction table.

BACKGROUND: Direct anterior approach total hip arthroplasty may be undertaken on a traction table, but the effects that patient positioning can have on axial pelvic tilt (aPT) are unknown. The aim of this study was to assess the degree of error from patient positioning on the traction table during anterior minimally-invasive surgery (AMIS) THA. METHODS: Patients were included who underwent direct anterior THA via the AMIS technique at a single institution between 11/2018 and 03/2019. Axial pelvic tilt was measured (a) in the supine position on the operating table, and (b) after positioning on the traction table, by the same consultant surgeon in all cases. RESULTS: In the above-mentioned study period, 50 patients (F: 32; M: 18) with an average age of 60.6 ± 13.6 (range: 26.5 to 88.3) years, and an average BMI of 27.2 ± 5.0 (range: 17.9 to 41.5) kg/m2 met the inclusion criteria. When measured in supine position, the average aPT was - 0.2 ± 1.7 (range: - 5.6 to 3.8) degrees. After positioning on the traction table, the average aPT was - 3.5 ± 2.1 (- 8.5 to 1.6) degrees (p < 0.001). In patients with an aPT of more than 5 degrees, the caput-collum-diaphyseal (CCD) angle was significantly lower (125 ± 11° vs. 134 ± 8°, p = 0.007). CONCLUSION: This study raises awareness for the potential risk of aPT during positioning of the patient on the traction table, commonly used during direct anterior THA via the AMIS technique.

Machine learning techniques for detecting electrode misplacement and interchanges when recording ECGs: A systematic review and meta-analysis.

INTRODUCTION: Electrode misplacement and interchange errors are known problems when recording the 12­lead electrocardiogram (ECG). Automatic detection of these errors could play an important role for improving clinical decision making and outcomes in cardiac care. The objectives of this systematic review and meta-analysis is to 1) study the impact of electrode misplacement on ECG signals and ECG interpretation, 2) to determine the most challenging electrode misplacements to detect using machine learning (ML), 3) to analyse the ML performance of algorithms that detect electrode misplacement or interchange according to sensitivity and specificity and 4) to identify the most commonly used ML technique for detecting electrode misplacement/interchange. This review analysed the current literature regarding electrode misplacement/interchange recognition accuracy using machine learning techniques. METHOD: A search of three online databases including IEEE, PubMed and ScienceDirect identified 228 articles, while 3 articles were included from additional sources from co-authors. According to the eligibility criteria, 14 articles were selected. The selected articles were considered for qualitative analysis and meta-analysis. RESULTS: The articles showed the effect of lead interchange on ECG morphology and as a consequence on patient diagnoses. Statistical analysis of the included articles found that machine learning performance is high in detecting electrode misplacement/interchange except left arm/left leg interchange. CONCLUSION: This review emphasises the importance of detecting electrode misplacement detection in ECG diagnosis and the effects on decision making. Machine learning shows promise in detecting lead misplacement/interchange and highlights an opportunity for developing and operationalising deep learning algorithms such as convolutional neural network (CNN) to detect electrode misplacement/interchange.

Spectral Reflectance Can Differentiate Tracheal and Esophageal Tissue in the Presence of Bodily Fluids and Soot.

Endotracheal intubation is a common life-saving procedure implemented in emergency care to ensure patient oxygenation, but it is difficult and often performed in suboptimal conditions leading to high rates of patient complications. Undetected misplacement in the esophagus is a preventable complication that can lead to fatalities in 5-10% of patients who undergo emergency intubation. End-tidal carbon dioxide monitoring and other proper placement detection methods are useful, yet the problem of misplacement persists. Our previous work demonstrated the utility of spectral reflectance sensors for differentiating esophageal and tracheal tissues, which can be used to confirm proper endotracheal tube placement. In this study, we examine the effectiveness of spectral characterization in the presence of saline, blood, "vomit", and soot in the trachea. Our results show that spectral properties of the trachea that differentiate it from the esophagus persist in the presence of these substances. This work further confirms the potential usefulness of this novel detection technology in field applications.

Part 1: Outcome of Posterior Pelvic Ring Injuries and Associated Prognostic Factors - A Five-Year Retrospective Study of One Hundred and Sixty Five Operated Cases with Closed Reduction and Percutaneous Fixation.

PURPOSES: The aim of this study was to evaluate: 1. the outcome of pelvic ring fractures treated by closed reduction and percutaneous fixation, 2. the prognostic factors associated with a poor quality reduction, 3. the prognostic factors associated with ilio-sacral screws misplacement and 4. the prognostic factors associated with nonunion. METHODS: Data from medical charts for all patients admitted with unstable posterior pelvic ring injuries from 2009 to 2013 were extracted. A total of 165 patients with a mean age of 40 years were included. One hundred and five patients were reviewed at a mean of 32 months of follow-up. The prognostic factors analyzed were clinical and radiological factors. Tile B and Tile C pelvic ring fractures were compared and analyzed separately. Then specific statistical analysis was performed using a logistic regression model to eliminate confusion factors. RESULTS: An excellent or good clinical result was achieved for 94 patients (90%). An excellent or good reduction was achieved for 141 patients (85%). Nonunion rate, smoking patients, bad reductions, age of patients and ISS score were significantly higher in Tile C group. To eliminate confusion factors we used a multivariate analysis logistic regression model. Only unstable vertical bilateral posterior injuries (Tile C2 and C3) were independent prognostic factors for unsatisfactory reduction (p = 0.001; OR = 4.72; CI 95% [2.08-16.72]). Screw misplacement was recorded for 30 patients (16%) and sacral dysmorphia was an associated prognostic factor (p = 0.0001; OR = 15.6; CI95% [3.41-98.11]). Nonunion was recorded for ten patients (6%) and smoking was an associated prognostic factor (p = 0.01, OR = 5.12; CI95% [1.1-24.1]). CONCLUSIONS: Posterior pelvic ring fractures treated by closed reduction and percutaneous fixation are associated with excellent/good clinical results if excellent/good reduction and bone healing are achieved without screw misplacement. Bilateral unstable vertical posterior pelvic ring injuries, and sacral dysmorphia are risk factors for bad quality reduction and screw misplacement respectively.

Cortrak feeding tube placement: accuracy of the 'GI flexure system' versus manufacturer guidance.

Electromagnetic (EM) guided enteral tube placement may reduce lung misplacement to almost zero in expert centres, but more than 60 undetected misplacements had occurred by 2016 resulting in major morbidity or death. AIM: Determine the accuracy of manufacturer guidance in trace interpretation against what is referred to as the 'GI flexure system'. METHODS: The authors prospectively observed the accuracy of the 'GI flexure system' of trace interpretation against manufacturer guidance in primary nasointestinal (NI) tube placements. FINDINGS: Contrary to manufacturer guidance, 33% of traces deviated >5 cm from the sagittal midline and 26.5% were oesophageal when entering the lower left quadrant, incorrectly indicating lung and gastric placement, respectively. Conversely, the GI flexure system identified ≥99.4% of GI traces when they reached the gastric body flexure; 100% at the superior duodenal flexure. All lung misplacements were identified by the absence of GI flexures. CONCLUSION: Current manufacturer guidance should be updated to the GI flexure system of interpretation.