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Defect Size (defect + size)

Distribution by Scientific Domains

Medical Sciences	58%

Selected Abstracts

Upper Eyelid Full-Thickness Skin Graft in Facial Reconstruction

DERMATOLOGIC SURGERY, Issue 1 2005
Dogan Tuncali MD
Background The potentially available upper eyelid skin, as an alternative donor site, deserves more attention in clinical use. Objective The objective of this study was to prospectively evaluate the clinical behavioral characteristics of upper eyelid full-thickness skin grafts in facial reconstruction. Methods Sixteen patients who concluded the 12-month follow-up period were included in the study. Graft dimensions were measured in place before the graft harvest. Defect sizes were measured following lesion excision and postgrafting. Graft sizes were measured postoperatively at 1, 3, 6, and 12 months. Results The largest and smallest grafts were 46 × 22 mm and 40 × 15 mm (average 43.1 × 19.3 mm) in size, respectively. The largest and smallest defect dimensions were 33 × 23 mm and 17 × 9 mm (average 22.6 × 15.6 mm), respectively. The average postgrafting size was 21.1 × 14.6 mm. Grafts and donor sites healed very well. Generally, an acceptable to good texture and color match was observed beyond 6 months. Wound bed contraction was not observed beyond the first month (p < .05). Conclusion Special characteristics of hairless skin, good color and texture matching, and inconspicuous and hidden donor scar make the upper eyelid a good alternative donor site for small- to medium-sized facial skin defects. The main disadvantages that limit its clinical use are the age of the patient, a lack of adnexal structures, comparatively limited sun exposure, and possible insufficient thickness, especially when deep defects are of concern. DOGAN TUNCALI, MD, LEVENT ATES, MD, AND GÜRCAN ASLAN, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source]

Frequency of Use of Suturing and Repair Techniques Preferred by Dermatologic Surgeons

DERMATOLOGIC SURGERY, Issue 5 2006
BETH ADAMS MD
BACKGROUND There are many closure techniques and suture types available to cutaneous surgeons. Evidence-based data are not available regarding the frequency of use of these techniques by experienced practitioners. OBJECTIVE To quantify, by anatomic site, the frequency of use of common closure techniques and suture types by cutaneous surgeons. METHOD A prospective survey of the members of the Association of Academic Dermatologic Surgeons that used length-calibrated visual-analog scales to elicit the frequency of use of specific suture techniques. RESULTS A response rate of 60% (61/101) indicated reliability of the received data. Epidermal layers were closed most often, in descending order, by simple interrupted sutures (38,50%), simple running sutures (37,42%), and vertical mattress sutures (3,8%), with subcuticular sutures used more often on the trunk and extremities (28%). The most commonly used superficial sutures were nylon (51%) and polypropylene (44%), and the most common absorbable suture was polyglactin 910 (73%). Bilayered closures, undermining, and electrocoagulation were used, on average, in 90% or more sutured repairs. The median diameters (defined as longest extent along any axis) of most final wound defects were 1.1 to 2.0 cm (56%) or 2.1 to 3.0 cm (37%). Fifty-four percent of wounds were repaired by primary closure, 20% with local flaps, and 10% with skin grafting, with the remaining 15% left to heal by second intent (10%) or referred for repair (5%). Experience-related differences were detected in defect size and closure technique: defects less than 2 cm in diameter were seen by less experienced surgeons, and defects greater than 2 cm by more experienced surgeons (Wilcoxon's rank-sum test: p=.02). But more experienced surgeons were less likely to use bilayered closures (r=,0.28, p=.036) and undermining (r=,0.28, p=.035). CONCLUSIONS There is widespread consensus among cutaneous surgeons regarding optimal suture selection and closure technique by anatomic location. More experienced surgeons tend to repair larger defects but, possibly because of their increased confidence and skill, rely on less complicated repairs. [source]

Forehead Donor Site Full-Thickness Skin Graft

DERMATOLOGIC SURGERY, Issue 3 2005
Vassilios Dimitropoulos MD
Background Full-thickness skin grafts (FTSGs) are useful for reconstructing nasal defects. Traditional reported donor sites include the preauricular, postauricular, supraclavicular, clavicular, conchal bowl, melolabial fold, and upper eyelid skin. Selection of the "best" donor site is based on the "best" tissue match and ability to camouflage the donor scar. Objective The purpose was to report our experience with FTSGs harvested from the forehead for reconstruction of nasal defects following Mohs' surgery. Methods A retrospective query of the Mohs' surgery database was performed to identify nasal defects repaired with a FTSG harvested from the forehead skin. The research record contained the patient age and gender, defect size, and cosmetic and functional outcomes interpreted by the patient and surgeon. Results FTSGs from forehead skin were used to repair the nasal defects in three patients. The functional and cosmetic outcome of all three cases was deemed excellent by the patient and surgeon. Donor site scars were well concealed within preexisting rhytids. Conclusion FTSGs harvested from the forehead, although limited in practical utility, may offer an optimal FTSG match for limited select defects while also providing an easily camouflaged donor site scar within a forehead rhytid. VASSILIOS DIMITROPOULOS, MD, CHRISTOPHER K. BICHAKJIAN, MD, AND TIMOTHY M. JOHNSON, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source]

Predictive factors for esophageal stenosis after endoscopic submucosal dissection for superficial esophageal cancer

DISEASES OF THE ESOPHAGUS, Issue 7 2009
H. Mizuta
SUMMARY Endoscopic submucosal dissection (ESD) has been utilized as an alternative treatment to endoscopic mucosal resection for superficial esophageal cancer. We aimed to evaluate the complications associated with esophageal ESD and elucidate predictive factors for post-ESD stenosis. The study enrolled a total of 42 lesions of superficial esophageal cancer in 33 consecutive patients who underwent ESD in our department. We retrospectively reviewed ESD-associated complications and comparatively analyzed regional and technical factors between cases with and without post-ESD stenosis. The regional factors included location, endoscopic appearance, longitudinal and circumferential tumor sizes, depth of invasion, and lymphatic and vessel invasion. The technical factors included longitudinal and circumferential sizes of mucosal defects, muscle disclosure and cleavage, perforation, and en bloc resection. Esophageal stenosis was defined when a standard endoscope (9.8 mm in diameter) failed to pass through the stenosis. The results showed no cases of delayed bleeding, three cases of insidious perforation (7.1%), two cases of endoscopically confirmed perforation followed by mediastinitis (4.8%), and seven cases of esophageal stenosis (16.7%). Monovalent analysis indicated that the longitudinal and circumferential sizes of the tumor and mucosal defect were significant predictive factors for post-ESD stenosis (P < 0.005). Receiver operating characteristic analysis showed the highest sensitivity and specificity for a circumferential mucosal defect size of more than 71% (100 and 97.1%, respectively), followed by a circumferential tumor size of more than 59% (85.7 and 97.1%, respectively). It is of note that the success rate of en bloc resection was 95.2%, and balloon dilatation was effective for clinical symptoms in all seven patients with post-ESD stenosis. In conclusion, the most frequent complication with ESD was esophageal stenosis, for which the sizes of the tumor and mucosal defect were significant predictive factors. Although ESD enables large en bloc resection of esophageal cancer, practically, in cases with a lesion more than half of the circumference, great care must be taken because of the high risk of post-ESD stenosis. [source]

Probabilistic high cycle fatigue behaviour of nodular cast iron containing casting defects

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 4 2009
A. NASR
ABSTRACT Theoretical and experimental investigations were combined to characterize the influence of surface casting defects (shrinkages) on the high cycle fatigue (HCF) reliability. On fracture surfaces of fatigue samples, the defect is located at the surface. The shape used for the calculation is a spherical void with variable radius. Finite-element simulations were then performed to determine stress distribution around defects for different sizes and different loadings. Correlated expressions of the maximum hydrostatic stress and the amplitude of the shear stress were obtained by using the response surface technique. The loading representative point in the HCF criterion was then transformed into a scattering surface, which has been obtained by a random sampling of the defect sizes. The HCF reliability has been computed by using the Monte Carlo simulation method. Tension and torsion fatigue tests were conducted on nodular cast iron with quantification of defect size on the fracture surface. The S,N curves show a large fatigue life scattering; shrinkages are at the origin of the fatal crack leading to the final failure. The comparison of the computed HCF reliability to the experimental results shows a good agreement. The capability of the proposed model to take into account the influence of the range of the defect sizes and the type of its statistical distribution has been demonstrated. It is shown that the stress distribution at the fatigue limit is log-normal, which can be explained by the log-normal defect distribution in the nodular cast iron tested. [source]

The influence of porosity on the fatigue strength of high-pressure die cast aluminium

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2006
J. LINDER
ABSTRACT Aluminium is a lightweight material with high strength and good corrosion resistance among other beneficial properties. Thanks to these properties, aluminium is more extensively used in the vehicle industry. High-pressure die casting of aluminium is a manufacturing process that makes it possible to attain complex, multi-functional components with near-net shape. However, there is one disadvantage of such castings, that is, the presence of various defects such as porosity and its effect on mechanical properties. The aim of this work was to investigate the influence of porosity on the fatigue strength of high-pressure die cast aluminium. The objective was to derive the influence of defect size with respect to the fatigue load, and to generate a model for fatigue life in terms of a Kitagawa diagram. The aluminium alloy used in this study is comparable to AlSi9Cu3. Specimens were examined in X-ray prior to fatigue loading and classified with respect to porosity level and eventually fatigue tested in bending at the load ratio, R, equal to ,1. Two different specimen types with a stress concentration factor of 1.05 and 2.25 have been tested. It has been shown that the fatigue strength decreases by up to 25% as the amount of porosity of the specimen is increased. The results further showed that the influence of defects was less for the specimen type with the higher stress concentration. This is believed to be an effect of a smaller volume being exposed to the maximum stress for this specimen type. A Kitagawa diagram was constructed on the basis of the test results and fracture mechanics calculations. A value of 1.4 Mpa m1/2 was used for the so-called stress intensity threshold range. This analysis predicts that defects larger than 0.06 mm2 will reduce the fatigue strength at 5 × 106 cycles for the aluminium AlSi9Cu3 material tested. [source]

Strength estimation of ceramic,metal joints with various interlayer thickness

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2003
M. TAKAHASHI
ABSTRACT Residual stresses generated by the mismatch of thermal expansion coefficients of ceramics and metals affect the strength of ceramic,metal joints. An interlayer metal can be inserted between the ceramic and metal in order to relax this stress. An analysis was carried out of the residual stresses produced during joint-cooling and in 4-point bending tests. The effects of interlayer thickness on ceramic,metal joint strength were then studied by considering a superimposed stress distribution of the residual stress and the bending stress. Finally, joint strength was estimated from fracture mechanics and strength probability analysis by considering the residual stress distribution, defect size and position of pre-existing defects in the ceramic parts. As a result of this study, we suggest an optimum material selection and interlayer thickness for ceramic,metal joint structures. This approach is generally suitable for the design of electrical and mechanical structures. [source]

Visualization of anterior skull base defects with intraoperative cone-beam CT

HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 4 2010
Gideon Bachar MD
Abstract Background The role of cone-beam CT (CBCT) in demonstrating anterior skull base defects (ASBDs), differing in size and location, was investigated. The study was designed to describe the potential advantage of CBCT in the setting of an intraoperative cerebrospinal fluid (CSF) leak. Methods In all, 120 ASBD were evaluated in 5 cadaver heads. Orthogonal and oblique slices were reconstructed. Observer studies assessed the visibility of ASBD in each location as a function of defect size. Results For 1-, 2-, and 4-mm defects, the percentage that were undetectable ranged from 20% to 33%, 0% to 14%, and 0% to 5%, respectively. Confident breach detection increased with defect size and was most challenging in the lateral lamella and cribriform. CBCT permitted confident detection of ASBD as small as about 2 mm in the fovea ethmoidalis and planum. Oblique views were found to be superior to orthogonal planes. Conclusions The ability to identify ASBD depended on the size and location of defect. Oblique viewing planes were optimal for ASBD visualization. © 2009 Wiley Periodicals, Inc. Head Neck, 2010 [source]

The purse-string suture revisited: a useful technique for the closure of cutaneous surgical wounds

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 4 2007
Philip R. Cohen MD
The purse-string suture provides complete or partial closure of round postoperative skin defects. It is a rapid and simple procedure to perform. Tension placed on the suture uniformly advances the skin from the entire periphery of the wound, resulting in a significant reduction of the defect size and enhancement of hemostasis at the wound edge. The history, modifications of the technique, advantages, and potential complications of the purse-string suture are reviewed. It is not only useful following the removal of nonmelanoma skin cancer but also after the local excision of melanoma. In addition, this technique is especially suitable for the repair of round surgical wounds for patients who are unable to modify their active lifestyles during the week following surgery, individuals concurrently being treated with anticoagulants, antiplatelet agents or both, and people with extensive postoperative defects that would otherwise require either a skin graft or a large cutaneous flap. Typically, the site of the surgical wound following partial or complete closure with the purse-string suture demonstrates excellent long-term cosmetic and functional results. [source]

Atomic structure of pyramidal defects in GaN:Mg: Influence of annealing

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006
Z. Liliental-Weber
Abstract The atomic structure of the characteristic defects (Mg-rich hexagonal pyramids) in p-doped bulk and MOCVD GaN:Mg thin films grown with Ga polarity was determined at atomic resolution by direct reconstruction of the scattered electron wave in a transmission electron microscope. Small cavities were present inside the defects, confirmed also with positron annihilation. The inside walls of the cavities were covered by GaN of reverse polarity compared to the matrix. Annealing of the MOCVD layers lead to slight increase of the defect size and an increase of the room temperature photoluminescence intensity. Positron annihilation confirms presence of vacancy clusters of different sizes triggered by the Mg doping in as-grown samples and decrease of their concentration upon annealing at 900 and 1000 °C. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Algorithm for Reconstruction After Endoscopic Pituitary and Skull Base Surgery,

THE LARYNGOSCOPE, Issue 7 2007
Abtin Tabaee MD
Abstract Introduction: The expanding role of endoscopic skull base surgery necessitates a thorough understanding of the indications, techniques, and limitations of the various approaches to reconstruction. The technique and outcomes of endoscopic skull base reconstruction remain incompletely described in the literature. Study Design and Methods: Patients undergoing endoscopic skull base surgery underwent an algorithmic approach to reconstruction based on tumor location, defect size, and presence of intraoperative cerebrospinal fluid (CSF) leak. A prospective database was reviewed to determine the overall efficacy of reconstruction and to identify risk factors for postoperative CSF leak. Results: The diagnosis in the 127 patients in this series included pituitary tumor in 70 (55%) patients, encephalocele in 16 (12.6%) patients, meningioma in 11 (8.7%) patients, craniopharyngioma in 9 (7.1%) patients, and chordoma in 6 (4.7%) patients. Successful reconstruction was initially achieved in 91.3% of patients. Eleven (8.7%) patients experienced postoperative CSF leak, 10 of which resolved with lumbar drainage alone. One (0.8%) patient required revision surgery. Correlation between postoperative CSF leak and study variables revealed a statistically significant longer duration of surgery (243 vs. 178 min, P = .008) and hospitalization (12.1 vs. 4.5 days, P < .0001) and a trend toward larger tumors (mean, 3.2 vs. 2.3 cm; P = .058) in patients experiencing postoperative CSF leak. Conclusion: The algorithm for reconstruction after endoscopic surgery presented in this study is associated with excellent overall efficacy. A greater understanding of risk factors for postoperative CSF leak is imperative to achieve optimal results. [source]

Electron beam angiography for the evaluation of percutaneous atrial septal defect closure

CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 4 2005
Jamil AboulHosn MD
Abstract Electron beam angiography (EBA) provides excellent anatomic imaging in patients with congenital heart disease and may be useful in the assessment of atrial septal defects (ASDs). We present four patients with an ASD who were considered for percutaneous closure and underwent EBA for measurement of defect size and assessment of rim adequacy, adjacent cardiac structures, and associated congenital anomalies. © 2005 Wiley-Liss, Inc. [source]

Inorganic Layers on Polymeric Films , Influence of Defects and Morphology on Barrier Properties

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2003
M. Hanika
Abstract Flexible polymeric films are not only widely used in conventional packaging as substitute for glass and aluminum foil packaging but are also proposed as encapsulation for novel products, like flexible solar cells or organic light-emitting devices. The two essential properties of the polymeric packaging are flexibility and good permeation barrier properties against gases and vapors. This article deals with vacuum web coating as a common way of increasing barrier properties of polymeric films and the problems related to this procedure. Defects caused by particles and surface imperfections are found to dominate the permeation rate for such coated polymeric films. Atomic force microscopy, electron and also optical microscopy was used for analysis of the coating layer. Three-dimensional numerical simulations were performed for modeling of the influence of defect size, spacing and film thickness. Results of numerical modeling and of many practical experiments show that the permeability is almost independent of the substrate film thickness when a critical thickness is exceeded. In most cases the defects can be treated as independent of each other. The gas permeability of vacuum web-coated polymeric films can be quantitatively predicted by a simple formula. For gases, like oxygen, it is shown that a statistic analysis of the defect sizes by optical microscopy is sufficient. For water vapor transmission, however, the structure of the coating layer itself has also to be taken into account. [source]

Growth after ventricular septal defect repair: does defect size matter?

ACTA PAEDIATRICA, Issue 9 2010
A 10-year experience
Abstract Aim:, To evaluate whether the ventricular septal defect (VSD) size, along with the degree of preoperative growth impairment and age at repair, may influence postoperative growth, and if VSD size can be useful to identify children at risk for preoperative failure to thrive. Methods:, Sixty-eight children submitted to VSD repair in a Brazilian tertiary-care institution were evaluated. Weight and height measurements were converted to Z -scores. Ventricular septal defect size was normalized by dividing it by the aortic root diameter (VSD/Ao ratio). Results:, Twenty-six patients (38%) had significantly low weight-for-height, 10 patients (15%) had significantly low height-for-age and 13 patients (19%) had both conditions at repair. Catch-up growth occurred in 82% of patients for weight-for-age, in 75% of patients for height-for-age and in 89% of patients for weight-for-height. Weight-for-height Z -scores at surgery were significantly lower in patients who underwent repair before 9 months of age. The VSD/Ao ratio did not associate with any other data. On multivariate analysis, weight-for-age Z -scores and age at surgery were independent predictors of long-term weight and height respectively. Conclusion:, The VSD/Ao ratio was not a good predictor of preoperative failure to thrive. Most patients had preoperative growth impairment and presented catch-up growth after repair. Preoperative growth status and age at surgery influenced long-term growth. [source]

The Efficacy of Curettage in Delineating Margins of Basal Cell Carcinoma Before Mohs Micrographic Surgery

DERMATOLOGIC SURGERY, Issue 9 2003
Désirée Ratner MD
Background. Curettage may be helpful as a preliminary step to outline the gross subclinical extensions of high-risk basal cell carcinomas (BCCs) before the first stage of Mohs micrographic surgery. Although many Mohs surgeons use curettage in the Mohs surgical setting, no prospective studies have as yet been performed that demonstrate the efficacy of curettage in delineating tumor margins before Mohs surgery. Objective. To document the efficacy of curettage in delineating BCC margins before Mohs micrographic surgery. Methods. This was a prospective evaluation of 599 patients with biopsy-proven BCCs treated with Mohs surgery. The preoperative dimensions of each tumor, the curetted dimensions before the first surgical stage, the proposed excisional margins before each surgical stage, and the final defect dimensions after each surgical stage were measured. The maximum curetted margin around each tumor was calculated and compared with typical Mohs excisional margins of 1, 2, 3, and 4 mm. A hypothetical 1-, 2-, 3-, or 4-mm excisional margin was added to the preoperative X and Y dimensions of each tumor, and the actual final defect sizes were compared with the hypothetical final defect sizes to determine whether an additional surgical stage would have been needed had curettage not been performed. The amount of tissue stretch occurring after specimen removal was calculated to determine whether tissue stretch falsely elevated the number of instances in which an additional surgical stage would have been needed had curettage not been performed. Results. The curetted margin around the observed extent of each tumor exceeded 1 mm in 87.6% of cases, 2 mm in 47.1% of cases, 3 mm in 19.7% of cases, and 4 mm in 5.7% of cases. The mean curetted margin was 1.7 mm. Taking a 1-mm margin in the first stage of Mohs surgery without first performing curettage would have necessitated an extra surgical stage in 99.2% of cases, whereas taking a 2-, 3-, or 4-mm margin would have necessitated an extra surgical stage in 93.0%, 88.1%, and 49.4% of cases, respectively. After calculating and eliminating the effects of tissue stretch, it was found that a 1-mm excisional margin taken in the first stage of Mohs surgery without first performing curettage would have necessitated an extra surgical stage in 99.0% of the cases. Taking a 2-, 3-, or 4-mm margin would have necessitated an extra surgical stage in 87.5%, 57.9%, and 29.5% of cases, respectively. Conclusion. Careful debulking and palpation with the curette significantly reduce the number of Mohs surgical stages required for BCC clearance. Even after taking the effects of tissue stretch into consideration, a significant proportion of tumors would still require an additional stage for tumor clearance without aggressive presurgical curettage. [source]