Comparative Analysis of the Influence of Perichondrium on Conjunctival Epithelialization on Conchal Cartilage Grafts in Eyelid Reconstruction: Experimental Study in Rabbits

Background: Although the role of cartilage grafts in reconstruction of the posterior eyelid lamella is well established, spontaneous conjunctival epithelialization on such grafts has yet to be fully proven. The aim of this study was to perform a comparative analysis of the influence of perichondrium on conjunctival epithelialization over conchal cartilage grafts used in eyelid reconstruction in rabbits. Methods: The posterior lamellae of 100 lower eyelids from 50 rabbits were reconstructed with autogenous grafts of conchal ear cartilage. In the right eyelids, cartilage was grafted with the perichondrium in direct contact with the eyeball, and the left eyelids were reconstructed in a similar manner but using cartilage grafts without perichondrium. The animals were killed after 1, 2, 3, 4, and 5 weeks, and their lower eyelids were analyzed macroscopically and histologically. Results: The percentage difference in conjunctival epithelialization on the cartilage with perichondrium and that without perichondrium was 11.41 percent in the first week of the experiment, 13.64 percent in the second week, 18.69 percent in the third week, 10.38 percent in the fourth week, and 6.17 percent in the fifth week. The average percentage conjunctival epithelialization in the eyelids reconstructed with a cartilage graft with perichondrium was significantly higher throughout the 5 weeks of the experiment than in the eyelids reconstructed with cartilage without perichondrium (p < 0.0002). Conclusion: It was found that the perichondrium had an important role in conjunctival epithelialization in eyelids reconstructed with a cartilage graft in the present study. (Plast. Reconstr. Surg. 123: 55, 2009.)

Sliding wear of weld layers with application to cane mill shaft rebuilding

Three welding procedures used to rebuild worn shafts in sugar cane mills were analysed: two submerged arc welding processes and one flux cored arc welding (FCAW) process. Sliding wear tests were in accordance with ASTM G 77 standard, using rings of welding material, blocks of bronze SAE 67, and oil as lubricant. The worn surfaces of rings and blocks were analysed by scanning electron microscopy to determine the wear mechanisms. High contact pressure, high operating temperature, and low relative speed were applied in sliding wear tests to match the conditions in sugar cane mills. Transferred material and evidence of adhesive junctions were detected. Additionally, hardened fragments produced abrasive grooves on the worn surfaces. The welding deposits that presented strong adhesion on the worn surface showed higher mass loss than the materials that presented more abrasive characteristics. Plastic mechanical properties were measured and related to the mass loss. The tested materials presented similar hardness but different yield stress and hardening coefficient. A relationship between wear, strain hardening coefficient, and yield stress was found. The welding deposit that presented the highest hardening coefficient showed the highest mass loss, with evidence of severe adhesion on the worn surface.

Low-Level Laser Therapy on the Viability of Skin Flap in Rats Subjected to Deleterious Effect of Nicotine

Objective: The purpose of this study was to evaluate the effect of 830-nm laser in blocking the action of nicotine on the viability of skin flap. Background data: The authors have analyzed the deleterious effect of cigarette smoke or nicotine on the skin flap alone with evidence of increased skin necrosis in the flap. Materials and methods: Twenty-four Wistar-albino rats were divided into three groups of eight animals each: Group 1 (control), subjected to a surgical technique to obtain a flap for cranial base, laser irradiation simulation, and a subcutaneous injection of saline; Group 2, similar to Group 1, with subcutaneous injection of nicotine (2mg/kg/day) for a period of 1 week before and 1 week after surgery; and Group 3, similar to Group 2, with skin flaps subjected to a lambda 830-nm laser irradiation. The laser parameters used were: power 30 mW, beam area 0.07cm(2), irradiance 429 mW/cm(2), irradiation time 84 sec, total energy 2.52J, and energy density 36J/cm(2). The laser was used immediately after surgery and for 4 consecutive days, in one point at 2.5 cm of the flap cranial base. The areas of necrosis were examined by two macroscopic analyses: paper template and Mini-Mop (R). The pervious blood vessels were also counted. Results: The results were statistically analyzed by ANOVA and post-test contrast orthogonal method (multiple comparisons), showing that the laser decreased the area of necrosis in flaps subjected to nicotine, and consequently, increased the number of blood vessels (p < 0.05). Conclusions: The laser proved to be an effective way to decrease the area of necrosis in rats subjected to nicotine, making them similar to the control group.

Effect of Low-Level Laser Therapy on Malondialdehyde Concentration in Random Cutaneous Flap Viability

Objective: The aim of this study was to assess the effects of 830 and 670 nm laser on malondialdehyde (MDA) concentration in random skin-flap survival. Background Data: Low-level laser therapy (LLLT) has been reported to be successful in stimulating the formation of new blood vessels and activating superoxide-dismutase delivery, thus helping the inhibition of free-radical action and consequently reducing necrosis. Materials and Methods: Thirty Wistar rats were used and divided into three groups, with 10 rats in each one. A random skin flap was raised on the dorsum of each animal. Group 1 was the control group; group 2 received 830 nm laser radiation; and group 3 was submitted to 670 nm laser radiation. The animals underwent laser therapy with 36 J/cm(2) energy density immediately after surgery and on the 4 days subsequent to surgery. The application site of the laser radiation was 1 point, 2.5 cm from the flap's cranial base. The percentage of the skin-flap necrosis area was calculated 7 days postoperative using the paper-template method, and a skin sample was collected immediately after as a way of determining the MDA concentration. Results: Statistically significant differences were found between the necrosis percentages, with higher values seen in group 1 compared with groups 2 and 3. Groups 2 and 3 did not present statistically significant differences (p > 0.05). Group 3 had a lower concentration of MDA values compared to the control group (p < 0.05). Conclusion: LLLT was effective in increasing the random skin-flap viability in rats, and the 670 nm laser was efficient in reducing the MDA concentration.

Thermodynamic approaches in sliding wear: a review

In this paper, a review of the thermodynamic approaches of sliding wear is presented. These approaches are divided into the friction energy dissipation, the energy balance and the entropy production. A concise and critic account of the approaches is discussed, remarking their relative strength and weakness in explaining the phenomena occurring in the sliding wear.

Mild and severe wear of steels and cast irons in sliding abrasion

This paper presents the results obtained in pin-on-disk test apparatus using glass and alumina as abrasive materials, showing the rates and mechanisms of abrasive wear of 1070 and 52100 steels, and ductile and white cast irons. The test conditions were selected in order to obtain wear rates that correspond to mild and severe abrasion, using different metal hardness-to-abrasive hardness ratios(H/H(A)) and 0.2 or 0.06 mm abrasive grains. The use of bulk Vickers hardness, instead of microhardness, allows a better description of the different abrasion regions. Under severe abrasion, the microcutting mechanism of wear prevailed together with friction coefficients larger than 0.4. On the other hand, when relatively soft abrasives are tested, indentation of abrasive particles followed by its fragmentation, and a creation of a thin deformed layer were the main damage mechanisms, with the friction coefficient lying below 0.4. The abrasive particle size under mild regime is able to change the wear rates in an order of magnitude. (C) 2009 Elsevier B.V. All rights reserved.

Influence of hardness of the harder body on wear regime transition in a sliding pair of steels

In the unlubricated sliding wear of steels the mild-severe and severe-mild wear transitions have long been investigated. The effect of system inputs such as normal load, sliding speed, environment humidity and temperature, material properties, among others, on those transitions have also been studied. Although transitions seem to be caused by microstructural changes, surfaces oxidation and work-hardening, some questions remain regarding the way each aspect is involved. Since the early studies in sliding wear, it has usually been assumed that only the material properties of the softer body influence the wear behavior of contacting surfaces. For example, the Archard equation involves only the hardness of the softer body, without considering the hardness of the harder body. This work aims to discuss the importance of the harder body hardness in determining the wear regime operation. For this, pin-on-disk wear tests were carried out, in which the disk material was always harder than the pin material. Variations of the friction force and vertical displacement of the pin were registered during the tests. A material characterization before and after tests was conducted using stereoscopy and scanning electron microscopy (SEM) methods, in addition to mass loss, surface roughness and microhardness measurements. The wear results confirmed the occurrence of a mild-severe wear transition when the disk hardness was decreased. The disk hardness to pin hardness ratio (H(d)/H(p)) was used as a criterion to establish the nature of surface contact deformation and to determine the wear regime transition. A predominantly elastic or plastic contact, characterized by H(d)/H(p) values higher or lower than one, results in a mild or severe wear regime operation, respectively. (c) 2009 Elsevier B.V. All rights reserved.

Dynamic positioning systems: An experimental analysis of sliding mode control

Vessel dynamic positioning (DP) systems are based on conventional PID-type controllers and an extended Kalman filter. However, they present a difficult tuning procedure, and the closed-loop performance varies with environmental or loading conditions since the dynamics of the vessel are eminently nonlinear. Gain scheduling is normally used to address the nonlinearity of the system. To overcome these problems, a sliding mode control was evaluated. This controller is robust to variations in environmental and loading conditions, it maintains performance and stability for a large range of conditions, and presents an easy tuning methodology. The performance of the controller was evaluated numerically and experimentally in order to address its effectiveness. The results are compared with those obtained from conventional PID controller. (c) 2010 Elsevier Ltd. All rights reserved.

Immediate Locally Advanced Breast Cancer and Chest Wall Reconstruction: Surgical Planning and Reconstruction Strategies with Extended V-Y Latissimus Dorsi Myocutaneous Flap

Background: Surgical resection in locally advanced breast cancer produces large defects that may not be suitable for primary closure. Immediate reconstruction is controversial and presents a complicated scenario for breast surgeons and plastic surgeons. Methods: In this study, a different design was planned for the latissimus dorsi musculocutaneous flap with primary closure in V-Y for the correction of major lesions in the anterior chest wall. Twenty-five patients underwent immediate locally advanced breast cancer reconstruction with a V-Y latissimus dorsi musculocutaneous flap. This flap was raised from adjacent tissue located on the lateral and posterior thoracic region and presented a triangular shape whose base was the lateral aspect of the mastectomy wound. The technique was indicated in patients with large thoracic wounds. Results: Mean follow-up time was 16 months. Closure was obtained in the donor and recipient sites without the use of skin grafts or other more major procedures. Complications occurred in nine patients (36 percent), including dorsal wound dehiscence in five patients and seroma in three. All cases except one were treated by a conservative approach with a good result. No total flap loss was reported. All patients achieved a satisfactory thoracic reconstruction and adequate wound care. Conclusions: The V-Y latissimus dorsi musculocutaneous flap is a reliable technique for immediate locally advanced breast cancer reconstruction. The technique is advantageous because the V-Y design allows primary closure of the chest wound and donor defect. Success depends on patient selection, coordinated planning with the breast cancer surgeon, and careful intraoperative management. (Plast. Reconstr. Surg. 127: 2186, 2011.)

Mammaplasty with Inferior Pedicle Flap After Massive Weight Loss

After massive weight loss, one of the stigmas that afflict women is the remaining deformity of the breasts which become flaccid and ptotic, with an absent or flat upper pole. The authors propose the use of a well-established mammaplasty technique to fill the upper pole, reshape the breast cone, and correct ptosis with nipple-areola complex (NAC) repositioning. A total of 16 patients were analyzed; all underwent gastroplasty between 18 and 24 months prior to mammaplasty. The mean age was 41.6 years (range = 26-62) and the mean BMI previous to the mammaplasty was 29.2 kg/m(2) (range = 24.9-38.9). The technique included a dermo-lipo glandular flap pedicled on the inframammary fold (IMF) together with a superior flap containing the NAC. All patients who underwent surgery were satisfied with the outcomes since a more aesthetic breast shape was achieved, with projection of the upper pole and correction of ptosis. Adverse events included dehiscence at the junction point of the flaps in the inframammary fold, which resolved with secondary-intention wound healing in three patients; partial necrosis of the areola in one patient; epidermolysis in one of the NACs in one patient; and infection in one of the breasts in one patient, which resolved with proper antibiotic therapy. When compared to the current mammaplasty techniques performed in formerly obese patients, this is a good surgical option because it uses tissues adjacent to the breast itself and does not require silicone prosthesis for breast augmentation. The patients reported increased self-esteem and improvement in their quality of life.

Application of fibrin glue in microvascular anastomoses: Comparative analysis with the conventional suture technique using a free flap model

Background: Several studies have already reported the utilization of fibrin glue in microvascular anastomoses to minimize the number of sutures and to decrease the operative time. Despite the good results obtained in most of these experiments, its clinical application has not launched. The aim of this study was to clarify the controversies around the safeness of fibrin glue application in microvascular anastomoses, and also to demonstrate the potential benefits of fibrin glue application in a realistic free flap model. Methods: Twenty-seven rabbits were used in this study The experimental model consisted of a free groin flap transfer to the anterior cervical region. The flap`s circulation was restored by means of an end-to-side anastomosis between the femoral and carotid arteries, and an end-to-end anastomosis between the femoral and external jugular veins. The animals were divided into two groups (n = 10) according to the anastomosis technique: Group I (conventional suture) and group 11 (fibrin glue). Results: The number of sutures required to complete the arterial and venous anastomoses was reduced in 39 and 37% in group 11, respectively. Despite this reduction, the anastomoses maintained adequate patency rates and mechanical strength. Both arterial and venous anastomoses benefited from fibrin glue application, which made them easier and faster to perform. The flaps` ischemic time and the total operative time were also significantly shortened. Conclusions: In this study, the application of fibrin glue in microvascular anastomoses was safe and reliable. The risk-benefit ratio of fibrin glue application in microvascular anastomoses is favorable for its use. (c) 2008 Wiley-Liss, Inc.

Skin Coverage of the Middle-Distal Segment of the Leg With a Pedicled Perforator Flap

Objective: This is a clinical study of our experience using pedicle perforator flaps to cover skin defects in the middle and distal segment of the leg. Design: Prospective study. Setting: University hospital. Patients/Intervention: Twenty-four patients underwent treatment of a skin defect in the middle or distal segment of the leg by means of pedicled flaps based on perforating arteries. The perforating arteries were located before the operation by means of echo-Doppler examination. The flaps were planned in propeller fashion (21 cases) and as advancement (three cases). Main Outcome Measurements: The results were evaluated according the origin of perforator flap, size of the flap, and donor area and viability of the flap. The success rate of the echo-Doppler to identify the location of perforator vessel was also evaluated. Results: In nine cases, the perforating vessels originated from the fibular artery, in 10 the posterior tibial artery, and in five the anterior tibial artery. The mean size of the flaps was 5 cm in width by 12 cm in length. The success rate using an echo-Doppler was 87%. The flaps were fully viable in 20 cases and partially viable in four cases. Conclusion: On the basis of these results, it is concluded that perforating flaps are a good choice of treatment for skin losses, especially in the distal segment of the leg, and could be an alternative option for the use of free microsurgical flaps.

Use of Acoustic Doppler Sonography to Ascertain the Feasibility of the Pedicled Nasoseptal Flap After Prior Bilateral Sphenoidotomy

Objectives/Hypothesis: Blood supply to the Hadad-Bassagasteguy pedicled nasoseptal flap may be interrupted by surgery of the pterygopalatine fossa, posterior septectomy, or large sphenoidotomies. This would preclude its use for reconstruction of skull base defects after expanded endonasal approaches (EEA). We present a novel method to ascertain the patency of the nasoseptal artery after prior surgery, and consequently the availability of the nasoseptal flap, using acoustic Doppler sonography. Study Design: Retrospective clinical review. Methods: Four patients who underwent EEAs were evaluated intraoperatively with acoustic Doppler sonography. The mucosa that covers the inferior aspect of the rostrum of the sphenoid sinus was scanned with the tip of the probe. Reflection of sound waves representing intravascular blood flow was assessed. Results: In three patients, the artery was identified in at least one side. One remaining patient showed no acoustic signal suggesting loss of the nasoseptal artery bilaterally, therefore necessitating the use of a fat graft for the reconstruction. Conclusions: Acoustic Doppler sonography seems to be a feasible and effective way to ascertain the availability of the nasoseptal artery. It is a relatively inexpensive and simple technique that can be performed by any endoscopic surgeon.

The Versatile Adani`s Flap for Fingertip Coverage Indications and Case Reports

Heterodigital pedicle flaps have 2 possible patters of vascularization: anterograde flow (Littler) or reverse flow (Adani). The Adani`s flap uses the Y-V pedicle lengthening principle. The flap is raised from the adjacent uninjured finger based on the digital artery. The common digital artery is ligated and a long pedicle is formed from the 2 converging digital arteries to supply a reverse flow flap. Four patients with severe fingertips injuries were submitted to surgical treatment with the Adani`s flap. All flaps integrated and provided skin coverage. The Adani`s flap has a long vascular pedicle that allows a wide arch of transposition. An easier vascular dissection in a site distant from the trauma which evolves a higher diameter digital artery and proximal interphalangeal arterial system promotes a high survival rate and good functional results. Adani`s flap is a reliable technique for severe fingertip injuries.

Twenty seven-year experience with sternal cleft repair

Congenital sternal cleft is a rare disease, and primary repair in the neonatal period is its best management. In 1998 we presented three surgical techniques for sternal cleft correction, but since 1999 we have elected one of them as our procedure of choice. Our latest results are now presented. It is a review of 15 patients operated from October 1979 to December 2007. Surgical repair consisted of 3 sliding chondrotomies, 10 reconstructions basec on a `posterior sternal wall`, 1 reconstruction combined to Ravitch operation for pectus excavatum and 1 associated with total repair of Cantrell`s pentalogy. Data concerning epidemiological features, surgical reconstruction, aesthetic results, postoperative major complications, mortality and hospital stay, were collected from hospital charts. Follow-up ranged from 4 months to 27 years. All patients submitted to surgical, correction had a good aesthetic and functional result. Neither postoperative mortality nor major complication was observed. Two patients had subcutaneous fluid collection that prolonged the drainage duration. The mean hospital stay was 6 days. In conclusion, reconstructing sterna. cleft with a `posterior periosteal flap from sternal bars and chondral graft` is an effective option with good aesthetic and long-term functional results. (C) 2008 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.