Surgical complications and re-operation rates in spinal metastases surgery: a systematic review.

OBJECTIVE: The goal of this study was to review the incidence of complications and unplanned re-operations after surgery for metastatic spinal tumors. BACKGROUND: The spinal column is the most common osseous site for metastatic spread. The goals of the treatment of spinal metastases are largely palliative. The surgical aims include establishing a diagnosis, providing stability, relieving neurological compression and deterioration, decreasing pain and increasing patient independence. Patients with spinal metastases who undergo surgery are considered high risk, with higher morbidity and mortality rates. MATERIALS AND METHODS: A systematic review was undertaken; PubMed and Embase databases were searched between (2010-2020) for relevant publications in English language with the following search items: metastasis OR metastases AND spine AND surgery AND complications OR revision. Using a standard PRISMA template, 2293 articles were identified. Full-text articles of interest were assessed for inclusion criteria of greater than 30 patients. RESULTS: A final number of 19 articles fully met the search criteria. Four were level II evidence, and the remaining were level III/IV. Surgical site infection 6.5% (135/2088) was reported as the main complication following surgery for spinal metastases followed by neurological deterioration 3.3% (53/1595) and instrumentation failure 2.0% (30/1501). Re-operation rate was 8.3% (54/651), with SSI (27.8%) being the most common reason for revision surgery. CONCLUSION: Patients with spinal metastases frequently present with complex therapeutic challenges requiring multidisciplinary team assessment. Surgical site infection (6.5%) was the main reason for a re-operation in patients undergoing surgery for spinal metastases.

Cervical spine fragility fractures in older people: 5-year experience at a regional spine centre.

BACKGROUND: cervical spine fractures are particularly prevalent in older people and commonly occur following a fall from standing height or less. Atlanto-axial complex (AAC) and, particularly, odontoid process (OP) fractures are the most prevalent injuries. OBJECTIVE: to investigate the incidence and characteristics of cervical spine fractures in older patients presenting to a regional spine centre. METHODS: a retrospective review of the clinical records and imaging of all patients aged 70 years and over presenting to a regional spinal unit with a cervical injury over a 5-year period was performed. Patient demographics, mechanism of injury, level of fracture, stability of the fracture, treatment modality, imaging modality and mortality rates were collected and analysed. RESULTS: during the period between 2015 and 2019, a total of 209 patients aged 70 years and over were presented to the regional spine unit. The mean age at presentation was 82.4 (±7.5) years. Low-energy trauma was the commonest mechanism of injury (n = 169; 80.9%). MRI was undertaken in a quarter of the patients. One-hundred and fifty-one patients (72.2%) suffered an AAC Injury with OP fractures forming the majority of this group (n = 119; 78.8%). One-hundred and ninety-nine patients were treated conservatively, and the overall 30-day mortality rate was 8.1%. CONCLUSION: cervical spine fractures are not uncommon amongst older people and are mostly the result of low-energy trauma and predominantly affect the axial cervical spine. The majority of these injuries are managed conservatively with an orthosis. The fractures nevertheless are a serious injury, with a high mortality rate at 30 days.

Clinical outcomes of sacroplasty for metastatic sacral tumours: a systematic review and meta-analysis.

STUDY DESIGN: A systematic review and meta-analysis. OBJECTIVE: The purpose of this study was to evaluate the clinical outcome and safety of sacroplasty for patients with secondary metastatic lesions to the sacrum. METHODS: Several databases, including the Cochrane library, PubMed and EMBASE, were systematically searched to identify potentially eligible articles in English language. All the above databases were searched until December 2019. The search strategy was based on the combination of the following keywords: sacroplasty AND secondary tumours OR metastasis OR metastases. The reference list of the selected literature was also reviewed and a standard PRISMA template utilised. RESULTS: From a total of 102 articles initially identified, a final seven studies were identified as meeting the inclusion criteria. A total of 107 patients from these studies were included. The follow-up ranged from immediate post-operatively to 30.5 months. The mean preoperative VAS was 8.38 (range 6.9-9.3), which improved significantly to 3.01 (range 1.12-4.7) post-operatively (p < 0.001). The most frequent complication reported was cement leakage, which occurred in 26 patients (25.4%), but without any neurological or other adverse sequelae. CONCLUSIONS: Sacroplasty in the management of secondary sacral tumours is a safe procedure that can achieve a significant reduction in pain, as quantified by VAS scores, and low complication rate.

Impact of pedicle subtraction osteotomy on health-related quality of life (HRQOL) measures in patients undergoing surgery for adult spinal deformity: a systematic review and meta-analysis.

STUDY DESIGN: Systematic review and meta-analysis. BACKGROUND: Three-column osteotomies (3-CO) have gained popularity in the last decade as part of the armamentarium for the surgical correction of sagittal imbalance in patients with adult spinal deformity (ASD). Three-column osteotomies in the form of pedicle subtraction osteotomy (PSO) may be necessary to achieve adequate correction for severe and rigid spinal deformity. Studies reporting improvement in health-related quality of life (HRQOL) with validated outcome measures after PSO surgery are sparse and currently consist of small series. OBJECTIVE: Evaluate the improvement in HRQOL measures following PSO for adult spinal deformity. METHODS: Two independent reviewers conducted a systematic review of the English literature between period 1996 and 2019 for articles reporting outcome of PSO in patients with ASD according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Inclusion criteria were studies consisting of patient-reported outcome Oswestry Disability Index (ODI) and Scoliosis Research Society 22 or 24 (SRS) outcomes after PSO surgery for adult spine deformity patients (18 years or older) with a minimum follow-up of 1 year. RESULTS: Eight studies with 431 PSOs were included in the meta-analysis. The results showed a statistically significant improvement in ODI in PSO (P < 0.0001), and the mean clinically important difference was achieved with both ODI (50.46 (45.5-55.4) preoperatively to 32.78 (29.7-39) postoperatively) and SRS (2.49 (2.38-2.7) preoperatively to 3.26 (2.8-4.1) postoperatively) scores. CONCLUSION: This meta-analysis did find improvements in the health-related quality of life in patients undergoing PSO surgery for adult spinal deformity.

Surgical approaches to L5 corpectomy: a systematic review.

INTRODUCTION: Surgical approaches to pathologies of the L5 vertebra constitute a significant challenge. Our aim was to review the efficacy and safety of the surgical approaches to L5 corpectomy and reconstruction across the range of presenting pathology. MATERIALS AND METHODS: This systematic review was conducted according to PRISMA guidelines, and databases were searched from 1970 to January 2020. The search inclusion criteria were L5 Corpectomy AND/OR Spondylectomy AND/OR Vertebrectomy. The outcome measures studied were length of surgery, blood loss, fusion or failure of fusion/instrumentation, complications and mortality. RESULTS: Initial 36 articles were identified, and final 6 studies met our inclusion criteria. The mean reported blood loss was 2265 ml (400-4700 ml) and was higher for the two-stage posterior-anterior surgery group than the posterior-only surgery group (mean 3230 mls vs. 1260 mls) but not the operative time. All surgical approaches shared high fusion rates (94%) and relatively low complication rates (11.7%). However, surgical strategies incorporating an anterior approach were notable for vascular complications (4-7%), as well as perioperative mortality (9%) not seen in the posterior-only surgery group. CONCLUSION: Where there is clinical and circumstantial equipoise regarding the choice of surgical approaches for a L5 corpectomy, this review indicates a reported mean blood loss of 2265 ml (400-4700 ml), high fusion rates (94%) and relatively low complication rates (11.7%). It is difficult to make direct comparisons between approaches due to small case series, the variability in primary pathology, clinical intent and surgeon experience.

Can MRI findings predict the outcome of cervical spinal cord Injury? a systematic review.

INTRODUCTION: MRI is the established gold standard for imaging acute spinal cord injury (SCI). Our aim was to identify the prognostic value, in terms of neurological outcome, of extradural and intradural features detected on MRI performed acutely following traumatic cervical SCI. MATERIALS AND METHODS: Several databases were systematically searched to identify potentially eligible articles until December 2019. Using a standard PRISMA template, 2606 articles were initially identified. RESULTS: A final 6 full-text articles met the inclusion criteria and were analyzed. An extradural factor, namely the maximal spinal cord compression, was associated with poor neurological outcome and statistically significant (P = 0.02 and P = 0.001 in 2 out of 3 studies). The intradural factors of length of the cord edema (P = 0.001, P = 0.006, and P < 0.001 in 3 studies), intramedullary hemorrhage (P = 0.002, P < 0.001, P < 0.001, and P = 0.002 in 4 studies), and the length of intramedullary hemorrhage (P = 0.028, P = 0.022 in 2 studies) also significantly correlated with poor neurological recovery at follow-up. CONCLUSION: While early MRI is established as a gold standard imaging of acute spinal trauma, it also serves to provide prognostic value on the neurological recovery. From our systematic review, there is a strong association of the extradural finding of maximal spinal cord compression, intradural MRI findings of length of cord edema, intramedullary hemorrhage, and length of intramedullary hemorrhage with neurological recovery in traumatic cervical spinal cord injuries. LEVEL OF EVIDENCE: III.

Out of proportion pulmonary hypertension in obstructive lung diseases.

PURPOSE OF REVIEW: Pulmonary hypertension is common (25-90%) in chronic obstructive pulmonary diseases (COPDs). Severe pulmonary hypertension, however, is quite rare (1-3%). The term 'out of proportion' pulmonary hypertension is still widely used. New guidelines instead propose to use the term 'Severe pulmonary hypertension' if mean pulmonary arterial pressure at least 35 mmHg or cardiac index (CI) is less than 2.0 l/min/m on right heart catheterization (RHC). Why only a minority of COPD patients develop severe pulmonary hypertension is unclear. RECENT FINDINGS: When present, severe pulmonary hypertension in COPD is associated with increased dyspnea and decreased survival and often does not closely correlate with degree of obstructive abnormality on pulmonary function testing. COPD patients with severe pulmonary hypertension experience circulatory limitation at maximum exercise, and not ventilatory limitation, which is typical for moderate-to-severe COPD patients with no or moderate pulmonary hypertension. SUMMARY: There is no conclusive evidence to support or completely reject the possibility of the use of specific pulmonary arterial hypertension (PAH) therapies in pulmonary hypertension associated with COPD. In mild-to-moderate COPD patients who have severe and progressive symptoms, and have evidence of severe pulmonary hypertension on RHC, specific PAH therapies may be used similar to WHO group-I PAH guidelines.

Predicting 90-day prognosis for patients with stroke: a machine learning approach.

Background: Stroke is a significant global health burden and ranks as the second leading cause of death worldwide. Objective: This study aims to develop and evaluate a machine learning-based predictive tool for forecasting the 90-day prognosis of stroke patients after discharge as measured by the modified Rankin Score. Methods: The study utilized data from a large national multiethnic stroke registry comprising 15,859 adult patients diagnosed with ischemic or hemorrhagic stroke. Of these, 7,452 patients satisfied the study's inclusion criteria. Feature selection was performed using the correlation and permutation importance methods. Six classifiers, including Random Forest (RF), Classification and Regression Tree, Linear Discriminant Analysis, Support Vector Machine, and k-Nearest Neighbors, were employed for prediction. Results: The RF model demonstrated superior performance, achieving the highest accuracy (0.823) and excellent discrimination power (AUC 0.893). Notably, stroke type, hospital acquired infections, admission location, and hospital length of stay emerged as the top-ranked predictors. Conclusion: The RF model shows promise in predicting stroke prognosis, enabling personalized care plans and enhanced preventive measures for stroke patients. Prospective validation is essential to assess its real-world clinical performance and ensure successful implementation across diverse healthcare settings.

Study of Adherence Level and the Relationship Between Treatment Adherence, and Superstitious Thinking Related to Health Issues Among Chronic Disease Patients in Southern Jordan: Cross-Sectional Study.

Background: For disease management, numerous drugs are prescribed. However, long-term treatment adherence is still unsatisfactory. Culture influences beliefs regarding medication, particularly irrational ideas that affect treatment adherence. The Middle East, notably Jordan, is affected by a lack of awareness of these attitudes with regard to treatment adherence. Objective: Investigating the adherence level among patients with chronic diseases in southern Jordan. To determine whether certain demographic traits, different disease factors, and superstitions have any impact on treatment adherence. Patients and Methods: A cross-sectional study that assessed treatment adherence and superstitious thinking-related health issues were conducted among chronic disease patients who had reviewed intrinsic medicine clinics at the Karak governmental hospital. Results: For 314 participants, treatment adherence was categorized into three levels low-adherent patients made up 27.7% highly-adherent patients made up 49.4%, and the remaining adhered at a medium level. Treatment non-adherence was more common in the elderly and female, according to the chi-square analysis. Additionally, the classification of superstitious beliefs into three categories revealed that different percentages of the study population held low superstitious beliefs 21%, medium superstitions 54.1% and high superstitions 24.8% beliefs. The chi-square analysis revealed that the elderly, female, and low-educated patient groups were the highest in superstitious thinking. Multiple regression analysis revealed that educational level and superstitious thinking explained 0.223 of the treatment adherence variances. Treatment adherence is positively influenced by educational level ß (0.244) value, but superstitious thinking is negatively influenced by ß (-0.302) value. Conclusion: In conclusion, about half of the participants highly adhered. The results of the multiple-regression analysis indicate that superstition and education were two variables that impacted treatment adherence in this study. While superstitious beliefs lead to lower treatment adherence, education has the opposite effect. Finally, it is recommended to promote patient education to reduce superstitious beliefs, improve medication adherence.

A Systematic Review and Meta-analysis of Randomized Controlled Trials Comparing the Accuracy and Clinical Outcome of Pedicle Screw Placement Using Robot-Assisted Technology and Conventional Freehand Technique.

STUDY DESIGN: Systematic review and meta-analysis of randomized controlled trials (RCTs). OBJECTIVE: This systematic review and meta-analysis was performed with the aim of exploring the differences in pedicle screw positioning accuracy, surgical time, length of hospital stay, postoperative back and leg Visual Analog Scale, revision surgeries, and intraoperative radiation time and exposure between robot-assisted technology and conventional freehand technique based on RCTs. METHODS: Several databases, including the Cochrane library, PubMed, and EMBASE were systematically searched to identify potentially eligible articles. Meta-analysis was done using STATA 13 software. The odds ratios and 95% CIs were calculated for the studied categories. RESULTS: Seven RCTs involving 290 patients (1298 pedicle screws) in the robot-assisted group and 288 patients (1348 pedicle screws) in the conventional freehand group were analyzed. The results revealed that grade (A) and grade (A+B) screw accuracies were significantly superior in the robot-assisted group (P = .008 and P = .009, respectively). Overall surgical duration and number of revision surgeries were significantly higher in the robot-assisted group (P = .014 and P < .0001, respectively). Intraoperative radiation time and dosage were significantly lower in the robot-assisted group (P < .0001 and P = .036, respectively). CONCLUSION: It was demonstrated that robot-assisted technology is superior to the conventional freehand technique in terms of grade (A) and grade (A+B) screw accuracies and in the reduction of intraoperative radiation time and dosage. On the other hand, the freehand technique showed superior results in terms of overall surgical duration and revision surgery rates.

The comparative accuracy and safety of fluoroscopic and navigation-based techniques in cervical pedicle screw fixation: systematic review and meta-analysis.

OBJECTIVE: The goal of this study was to evaluate the comparative accuracy and safety of navigation-based approaches for cervical pedicle screw (CPS) placement over fluoroscopic techniques. METHODS: A systematic search of the literature published between January 2006 and December 2019 relating to CPS instrumentation and the comparative accuracy and safety of fluoroscopic and intraoperative computer-based navigation techniques was conducted. Several databases, including the Cochrane Library, PubMed, and EMBASE, were systematically searched to identify potentially eligible studies. Data relating to CPS insertion accuracy and associated complications, in particular neurovascular complications, were extrapolated from the included studies and summarized for analysis. RESULTS: A total of 17 studies were identified from the search methodology. Eleven studies evaluated CPS placement under traditional fluoroscopic guidance and 6 studies addressed outcomes following navigation-assisted placement (3D C-arm or CT-guided placement). Overall, a total of 4278 screws were placed in 1065 patients. Misplacement rates of CPS were significantly lower (p < 0.0001) in navigation-assisted techniques (12.51% [range 2.5%-20.5%]) compared to fluoroscopy-guided techniques (18.8% [range 0%-43.5%]). Fluoroscopy-guided CPS insertion was associated with a significantly higher incidence of postoperative complications relating to neurovascular injuries (p < 0.038), with a mean incidence of 1.9% compared with 0.3% in navigation-assisted techniques. CONCLUSIONS: This systematic review supports a logical conclusion that navigation-based techniques confer a statistically significantly more accurate screw placement and resultant lower complication rates.

COVID-19 With an Initial Presentation of Intraperitoneal Hemorrhage Secondary to Spontaneous Splenic Rupture.

The WHO declared coronavirus disease 2019 (COVID-19) a global pandemic in early 2020. As the pandemic has continued to evolve over a period of several months, many cases of unusual presentations are now emerging, which pose a greater challenge for physicians in terms of quickly identifying COVID-19 patients based on initial signs and symptoms. In this report, we present one such unusual presentation in a patient with sudden intraperitoneal hemorrhage and spontaneous splenic rupture with COVID-19 as the likely etiology and contributing factor. The patient was a 75-year-old Caucasian woman who presented to the emergency department (ED) with complaints of severe left-sided abdominal pain for several days without any preceding trauma. A CT of the abdomen/pelvis revealed a large amount of fluid in the abdomen, which raised suspicion of bleeding. An exploratory laparotomy revealed splenic rupture with hemoperitoneum, and the patient subsequently underwent an emergent splenectomy. The patient's COVID-19 antigen test returned positive during the surgery and was subsequently confirmed with a polymerase chain reaction (PCR) test. COVID-19 has been found to result primarily in respiratory symptoms through its ability to invade endothelial cells via angiotensin-converting enzyme 2 affinity. It is speculated that this mechanism may cause a predisposition to micro-thromboses, which can eventually lead to manifestations such as large lymphoid organ thrombosis. Based on this case presentation and the evolving literature on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), spontaneous splenic rupture is an emergent differential diagnosis that should be considered in COVID-19 patients presenting with gastrointestinal complaints such as abdominal pain and nausea.

Petersen Graph Multi-Orientation Based Multi-Scale Ternary Pattern (PGMO-MSTP): An Efficient Descriptor for Texture and Material Recognition.

Classifying and modeling texture images, especially those with significant rotation, illumination, scale, and view-point variations, is a hot topic in the computer vision field. Inspired by local graph structure (LGS), local ternary patterns (LTP), and their variants, this paper proposes a novel image feature descriptor for texture and material classification, which we call Petersen Graph Multi-Orientation based Multi-Scale Ternary Pattern (PGMO-MSTP). PGMO-MSTP is a histogram representation that efficiently encodes the joint information within an image across feature and scale spaces, exploiting the concepts of both LTP-like and LGS-like descriptors, in order to overcome the shortcomings of these approaches. We first designed two single-scale horizontal and vertical Petersen Graph-based Ternary Pattern descriptors ( PGTPh and PGTPv ). The essence of PGTPh and PGTPv is to encode each 5×5 image patch, extending the ideas of the LTP and LGS concepts, according to relationships between pixels sampled in a variety of spatial arrangements (i.e., up, down, left, and right) of Petersen graph-shaped oriented sampling structures. The histograms obtained from the single-scale descriptors PGTPh and PGTPv are then combined, in order to build the effective multi-scale PGMO-MSTP model. Extensive experiments are conducted on sixteen challenging texture data sets, demonstrating that PGMO-MSTP can outperform state-of-the-art handcrafted texture descriptors and deep learning-based feature extraction approaches. Moreover, a statistical comparison based on the Wilcoxon signed rank test demonstrates that PGMO-MSTP performed the best over all tested data sets.

Differences in identification of attention deficit hyperactivity disorder in children between teachers and parents.

BACKGROUND: The worldwide prevalence estimates for attention deficit hyperactive disorder (ADHD) are extremely heterogeneous. Diagnosis in children demands symptoms be present in at least 2 different settings, mainly school and home. The proportion of children estimated to have ADHD can vary based on whether the symptoms are evaluated by parents or teachers. AIMS: This study determined whether ADHD and its subtypes are better recognized by parents or teachers. METHODS: Our study included 1326 schoolchildren (boys = 712, girls = 614; age range: 6-12 years). We prepared 2 questionnaires for each student enrolled in the study; one was completed by the student's parents and the other by the teacher. We included students who attended 3 selected schools in the cities of Amman and Karak in Jordan during the first term of 2017. The Arabic version of the Diagnostic and statistical manual of mental disorders, 4th edition, was used for the diagnosis and classification of ADHD. RESULTS: Of the 1326 students included in this study, 254 (19.2%) were considered to have ADHD by the teachers and 172 (13.0%) by the parents. The Wilcoxon signed-ranks test showed that teachers gave statistically higher scores on the questionnaire than parents. However, overall agreement between parents and teachers, as measured by the κ-value, reached 77.2%. CONCLUSIONS: Although both teachers and parents recognized ADHD symptoms, they were generally more recognized by teachers than by parents.

Thresholds of Abnormality Perception in Facial Esthetics among Laypersons and Dental Professionals: Profile Esthetics.

AIM: To find thresholds at which laypersons and dental professionals from Jordanian population perceive abnormalities in sagittal positioning of upper and lower jaws as a major determinant to facial profile esthetics. MATERIALS AND METHODS: Using photo editing software, a baseline profile image of a young male was manipulated on a 2 mm incremental basis to move each of the upper and lower jaws backward and forward relative to true vertical line (TVL) at which four variables of maxillary and mandibular retrusion and protrusion were researched. A total of 120 participants divided equally into four groups of laypersons, general dental practitioners (GDPs), orthodontists, and oral and maxillofacial surgeons (OMFSs) rated the images using an analog scale of 100 mm long. The image that showed the first statistical difference compared to the baseline was considered as a threshold of abnormality. RESULTS: Laypersons, GDPs, and OMFSs perceived the abnormality in the maxillary retrusion at -5 mm to TVL, while orthodontists defined that at -3 mm. All dental professionals perceived the abnormality in the maxillary protrusion at +1 mm to TVL while the layperson group at +3 mm. A threshold of -7 mm mandibular retrusion to TVL was abnormally perceived by all groups. All dental professionals realized the abnormality in the mandibular protrusion at 0 mm to TVL while the laypersons at +2 mm. CONCLUSION: These thresholds regarding profile esthetics may contribute to the process of establishing proper orthodontic treatment planning that suits the highest facial esthetic standards.

Thresholds of Abnormality Perception in Facial Esthetics among Laypersons and Dental Professionals: Frontal Esthetics.

AIM: To find thresholds at which laypersons and dental professionals perceive abnormalities in two facial frontal esthetics variables: facial symmetry and vertical harmony. MATERIALS AND METHODS: A baseline frontal image of a young male face with optimum facial proportions was generated from a real image using a photo editing software. Different facial asymmetry images were then generated from this image by manipulating the chin point position at 2 mm increment to the left side. Vertical harmony was perceived through manipulating lower anterior facial height (LAFH) at a ratio of 2% of increased and decreased heights. A total of 120 raters divided equally into four groups of laypersons, general dental practitioners (GDPs), orthodontists, and oral and maxillofacial surgeons (OMFSs) rated these images using an analog scale of 100 mm long. Using ANOVA and Tukey post hoc tests at P < 0.05, the image that showed the first statistical difference compared to the baseline was considered as a threshold of abnormality. RESULTS: The image of 4 mm asymmetry was defined by the laypersons and GDPs as the threshold of abnormality, while the orthodontists and OMFSs realized that at 2 mm. Laypersons and GDPs defined a threshold of 46% as an abnormal decrease in the LAFH and the other 2 groups at 48%. All dental professionals groups rated the image of 54% as an abnormal increase in the LAFH while laypersons perceived that at 56%. CONCLUSION: These thresholds regarding frontal esthetics may contribute to the process of establishing proper orthodontic treatment planning that suits the highest facial esthetic standards.

Effects of Distance Measure Choice on K-Nearest Neighbor Classifier Performance: A Review.

The K-nearest neighbor (KNN) classifier is one of the simplest and most common classifiers, yet its performance competes with the most complex classifiers in the literature. The core of this classifier depends mainly on measuring the distance or similarity between the tested examples and the training examples. This raises a major question about which distance measures to be used for the KNN classifier among a large number of distance and similarity measures available? This review attempts to answer this question through evaluating the performance (measured by accuracy, precision, and recall) of the KNN using a large number of distance measures, tested on a number of real-world data sets, with and without adding different levels of noise. The experimental results show that the performance of KNN classifier depends significantly on the distance used, and the results showed large gaps between the performances of different distances. We found that a recently proposed nonconvex distance performed the best when applied on most data sets comparing with the other tested distances. In addition, the performance of the KNN with this top performing distance degraded only ∼20% while the noise level reaches 90%, this is true for most of the distances used as well. This means that the KNN classifier using any of the top 10 distances tolerates noise to a certain degree. Moreover, the results show that some distances are less affected by the added noise comparing with other distances.

Central Venous Line Insertion Revealing Partial Anomalous Pulmonary Venous Return: Diagnosis and Management.

Central venous line malposition is a well-known complication of line insertion. Rarely, it can be mal-positioned in an anomalous pulmonary vein. We present an unusual case of a 56-year-old woman that was found to have partial anomalous pulmonary venous return on central venous line insertion. In this report, we describe a systematic approach to diagnosis and management of this unusual situation.

Foreign body ingestion and aspiration in dentistry: a review of the literature and reports of three cases.

This article reviews several cases of foreign body ingestion or inhalation reported in the literature. Prevention, complication and management of this event are discussed and three case reports presented. Two of the cases were bridge ingestion and one was ingestion of an orthodontic band. The three cases were managed by watchful waiting and the ingested foreign bodies came out in the stools without complications.

Optimal force magnitude loaded to orthodontic microimplants: A finite element analysis.

OBJECTIVE: To find an optimal force that can be loaded onto an orthodontic microimplant to fulfill the biomechanical demands of orthodontic treatment without diminishing the stability of the microimplant. MATERIALS AND METHODS: Using the finite element analysis method, 3-D computer-aided design models of a microimplant and four cylindrical bone pieces (incorporating cortical bone thicknesses of 0.5, 1.2, 2.0, and 3.0 mm) into which the microimplant was inserted were used. Various force magnitudes of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 N were then horizontally and separately applied to the microimplant head as inserted into the different bone assemblies. For each bone/force assembly tested, peak stresses developed at areas of intimate contact with the microimplant along the force direction were then calculated using regression analysis and compared with a threshold value at which pathologic bone resorption might develop. RESULTS: The resulting peak stresses showed that bone pieces with thicker cortical bone tolerated higher force magnitudes better than did thinner ones. For cortical bone thicknesses of 0.5, 1.2, 2.0, and 3.0 mm, the maximum force magnitudes that could be applied safely were 3.75, 4.1, 4.3, and 4.45 N, respectively. CONCLUSIONS: For the purpose of diminishing orthodontic microimplant failure, an optimal force that can be safely loaded onto a microimplant should not exceed a value of around 3.75-4.5 N.