125 W Mcdowell Rd Suite B
Phoenix AZ 85003
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License #: D008788
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Mechanical characterization of thin film, water-based polymer gels through simple tension testing of laminated bilayers. - Journal of the mechanical behavior of biomedical materials
We present a method of characterizing the nonlinear stress-strain behavior of thin films of extremely soft, water-based polymer gels using uniaxial tension testing of bilayer laminates, in conjunction with methods of membrane nonlinear elasticity. A custom tensile testing apparatus is used to conduct quasi-static, uniaxial extension tests of narrow strips of thin, laminated sheets of bonded hydrogel and silicone rubber, submerged in a saline bath. The tensile load is measured via sensitive load cell and the position of material markers, at a central test-section of the sample, is optically tracked via digital image tracking methods. Stress-strain relationships are calculated for the hydrogel component of the bilayer, considered hyperelastic, homogeneous, isotropic, and incompressible, using membrane theories of finite hyperelasticity. We present the stress response for strains up to about 35% for poly(ethylene glycol) (PEG)-based hydrogels (>90% water) with polymer concentrations by weight of 5% to 10%. Polynomial functions are fit to the data for each formulation, whereby the one-dimensional strain-energy function for each formulation is determined by taking the indefinite integral.Â© 2013 Elsevier Ltd. All rights reserved.
Robotic vs. conventional laparoscopic gastric banding: a comparison of 407 cases. - Surgical endoscopy
The current indications for using a robotic technique in bariatric surgery remain unclear. The objective of this study was to quantify the safety and potential benefits of this novel technology as compared to the conventional laparoscopic approach.A retrospective database of patients who underwent laparoscopic adjustable gastric banding (LAGB) between December 2006 and June 2009 was examined. During this period 407 consecutive patients underwent LAGB: 287 robotically and 120 conventionally. Patient demographics, operative complications, operating times, and clinical outcomes were examined.The patients in the robotic and conventional cohorts did not vary significantly in demographics. The prevalence of preoperative comorbidities was similar between the two groups. The rates of intraoperative and postoperative complications did not differ significantly between the two approaches. The length of postoperative hospital stay (1.3Â±0.6 days for both approaches) and the operating time (91.5Â±21.1 vs. 92.1Â±30.9 min for robotic and conventional, respectively) did not differ significantly between the two approaches. However, for patients with a preoperative BMIâ‰¥50 kg/m2 (n=89, 64 robotic and 25 conventional), the operating time was significantly shorter using the robotic approach (91.3Â±19.7 min for robotic vs. 101.3Â±23.7 min for conventional, p=0.04).In this series, robotic and conventional approaches were similar in complication rates, operating time, and length of postoperative hospital stay. However, for patients with a preoperative BMIâ‰¥50 kg/m2, the operating time is significantly shorter using the robotic approach despite the adoption of this new technique. These data suggest that the robotic approach is at least as safe as the conventional laparoscopic approach in LAGB, and that the robotic approach should be considered for gastric banding candidates with BMIâ‰¥50 kg/m2.
Profiling surgical staplers: effect of staple height, buttress, and overlap on staple line failure. - Surgery for obesity and related diseases : official journal of the American Society for Bariatric Surgery
Few studies have been designed to assess the performance of surgical staplers. In this study, we analyzed the effect of staple height, buttressing, and overlapping of staple lines on staple line failure.Staple lines created on fresh porcine small bowel segments ex vivo were tested for leak pressure by insufflating air into the bowel under water and recording pressure at failure. Three separate experiments were done and included staple height (white, 2.5 mm, n = 16; blue, 3.5 mm, n = 16; green, 4.1 mm, n = 16; one half of them buttressed); the absence (n = 12) or presence (n = 12) of an overlap in 3.5-mm staple lines; and the absence (n = 14) or presence (n = 11) of buttresses in 3.5-mm overlapping staple lines. Data are reported in median values and ranges; nonparametric tests were used for data analysis.In the porcine small bowel, leak pressure was related to staple height; green loads had the worst profile (35 mm Hg, range 19-105) compared with the blue (79 mm Hg, range 9-177), and white (108 mm Hg, range 28-280) loads (P = .006). Buttressing uniformly improved leak pressure for all staple loads (P <.0001). No significant difference was found between lines with overlapping (59 mm Hg, range 32-121) and those without (42 mm Hg, range 22-75; P = .162). Buttressing also improved the leak pressure of overlapping staple lines from 65 mm Hg (range 47-121) to 93 mm Hg (range 75-187; P = .0014).Great variability was found in the leak pressures among the different applications of the same stapler. Staple height is an important determinant of leak pressure. The presence of an overlap did not affect leak pressure; in fact, a trend toward improvement was seen with overlapping staple lines. Buttressing improved all types of staple lines.
Inventing our future: training the next generation of surgeon innovators. - Seminars in pediatric surgery
Current surgical care and technology has evolved over the centuries from the interplay between creative surgeons and new technologies. As both fields become more specialized, that interplay is threatened. A 2-year educational fellowship is described which teaches both the process and the discipline of medical/surgical device innovation. Multi-disciplinary teams (surgeons, engineers, business grads) are assembled to educate a generation of translators, who can bridge the gap between scientific and technologic advances and the needs of the physician and the patient.
Biomaterials: a primer for surgeons. - Seminars in pediatric surgery
Biomaterials offer the surgeon a powerful set of clinical tools for patient treatment and are found in virtually every instrument, device, implant, or piece of equipment in the operating room. In fact, surgeons have historically driven clinical application of biomaterials and stand uniquely positioned to contribute to the ongoing development of biomaterials. Having an understanding of the materials available and their basic properties can contribute to better and more effective outcomes. This article provides an overview of the biomaterials field. It begins with a definition and abbreviated history of the field, highlighting its clinical roots. An introduction to the four material classifications--metals, polymers, ceramics, and composites--is then presented, providing the reader with basic properties of each group and examples of materials. Sections on nanotechnology and tissue engineering also briefly describe development within the field. Finally, the evolution of treatments for pectus excavatum and congenital diaphragmatic hernias are presented, highlighting the role of biomaterials. While providing a primer of the field, this paper shows the broad interdisciplinary reach of material science in surgery and suggests sources for further investigations.
Molecular imaging and radioimmunoguided surgery. - Seminars in pediatric surgery
Molecular imaging comprises a series of diagnostic modalities that provide information on the physiology and molecular composition of cells and tissues. One of these modalities, radioimmunodetection, uses radiolabeled monoclonal antibodies (mAbs) to image tissues. Two radioimmunodetection modalities are described in this article: immunoscintigraphy and radioimmunoguided surgery (RIGS). In immunoscintigraphy, the radioactivity is measured with the use of an external gamma camera and used to create images. In RIGS, the radioactivity is detected intraoperatively with the use of a handheld gamma probe to help the surgeon detect foci of otherwise occult disease. Both techniques have the potential to improve the preoperative and intraoperative localization of cancer. Multiple studies have been performed on the efficacy of RIGS on different malignancies, especially colorectal cancer. Despite the good sensitivity of the technique, some concerns revolve around the high rate of false positives and the real significance of leaving RIGS-positive tissue behind in terms of long-term outcomes and survival. More studies are warranted to further develop the technique and determine the specific role it will play on the diagnosis and management of surgical disease. Surgeons should actively participate in these studies and in expanding the applications of this promising technology.
Natural orifice translumenal endoscopic surgery (NOTES). - Seminars in pediatric surgery
Surgery has rapidly evolved as new technologies are adopted. With the introduction of laparoscopic surgery, patient outcomes have improved, with faster recovery from smaller incisions. In an effort to continually improve these outcomes and offer alternative options to higher risk patients, a number of investigators have proposed the concept of operating in the peritoneal space through natural orifices, obviating the need for any abdominal skin incisions. Natural orifice translumenal endoscopic surgery (NOTES) offers the same advantages as laparoscopic surgery without skin incisions, and possibly without general anesthesia. This article gives a conceptual and technical description of NOTES, discusses its challenges and potential pitfalls, reviews the early efforts at NOTES-specific device development, and predicts potential future directions of this exciting new area of surgery.
Proposal of a modified, treatment-oriented classification of odontoid fractures. - The spine journal : official journal of the North American Spine Society
The classification scheme of odontoid fractures described by Anderson and D'Alonzo is the one most commonly used. However, uncertainty exists in the distinction between Type II and "shallow" Type III fractures. Moreover, fractures at the base of the odontoid (Anderson and D'Alonzo Type II) include a spectrum of injury patterns.To modify the Anderson and D'Alonzo classification of odontoid fractures based on current clinical treatment options.Proposal of a modified classification system for odontoid fractures.A more precise distinction between Type II and III fractures based on the presence/absence of C1-C2 facet involvement is proposed. A modified classification of Type II fractures based on fracture line obliquity, displacement and comminution is then proposed, because these are factors deemed to influence management. To evaluate the reproducibility of this classification, 52 odontoid fractures were reviewed and classified by four attending spine surgeons and three spine fellows.There was substantial agreement (at least five of seven respondents) in 70% of cases. The overall kappa value for the modified classification system was 0.48, indicating moderate agreement, and there were no differences in kappa values between attending spine surgeons and fellows.The reproducibility of this system was demonstrated by the moderate agreement observed when applied to odontoid fractures at our institution. The proposed utility of this system is its ability to guide clinical decision making in the treatment of odontoid fractures. Prospective application of this modified classification system and suggested treatment options is now required.
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125 W Mcdowell Rd Suite B Phoenix, AZ 85003
111 W. Monroe Street #131 Downtown Phoenix Dental
355 N 5Th Ave Pappas Medical Clinic