Less Is More: Hollow-Truss Microlattice Metamaterials with Dual Sound Dissipation Mechanisms and Enhanced Broadband Sound Absorption.

Being a lightweight material with high design freedoms, there are increasing research interests in microlattice metamaterials as sound absorbers. However, thus far, microlattices are limited to one sound dissipation mechanism, and this inhibits their broadband absorption capabilities. Herein, as opposed to improving performances via the addition of features, a dissipation mechanism is subtractively introduced by hollowing out the struts of the microlattice. Then, a class of hollow-truss metamaterial (HTM) that is capable of harnessing dual concurrent dissipation mechanisms from its complex truss interconnectivity and its hollow interior is presented. Experimental sound absorption measurements reveal superior and/or customizable absorption properties in the HTMs as compared to their constitutive solid-trusses. An optimal HTM displays a high average broadband coefficient of 0.72 at a low thickness of 24 mm. Numerically derived, a dissipation theorem based on the superimposed acoustic impedance of the critically coupled resistance and reactance of the outer-solid and inner-hollow phases, across different frequency bands, is proposed in the HTM. Complementary mechanical property studies also reveal improved compressive toughness in the HTMs. This work demonstrates the potential of hollow-trusses, where they gain the dissipation mechanism through the subtraction of the material and display excellent acoustic properties.

Use of Three-dimensional Titanium Trusses for Arthrodesis Procedures in Foot and Ankle Surgery: A Retrospective Case Series.

Periarticular osseous defects pose a challenge when considering arthrodesis. Failure to restore the cubic content of bone can result in shortening and malalignment, as well as subsequent biomechanical issues. This study reports on 12 patients treated with patient-specific 3-D printed (7) and prefabricated titanium trusses (5). Twelve consecutive patients were treated for osseous defects of the forefoot, hindfoot, and ankle with patient-specific, 3D printed or prefabricated manufacturer titanium trusses. Seven were customized, patient-specific 3D printed trusses (4WEB, Frisco, Texas) and 5 were prefabricated manufacturer titanium trusses. All patients had a minimum of 6 months of clinical and radiographic follow-up. and no patients were lost to follow-up. Seven of the 12 patients had a computed tomography (CT) scan performed following surgery. Successful limb or ray salvage was achieved in 11 of 12 patients (91.7%). Six of 7 patients (85.7%) with a postoperative CT scan, went on to complete radiographic consolidation across all arthrodesis sites. The remaining 5 patients showed complete consolidation across the arthrodesis sites on plain film radiographs. Complications included one patient with a residual midfoot deformity that required a subsequent midfoot osteotomy in order to obtain a plantigrade foot following successful tibiotalocalcaneal (TTC) arthrodesis, and a below knee amputation in one patient who underwent revision TTC arthrodesis to salvage avascular necrosis of the talus that developed following the index procedure. Eleven of 12 patients undergoing arthrodesis demonstrated successful union with both customized, patient-specific 3D printed and prefabricated manufacturer titanium trusses on CT scans or radiographs. The average follow-up was 14 months. Reports on traditional methods of addressing periarticular defects in patients requiring arthrodesis show mixed results and relatively high complication rates. Custom, 3D printed and prefabricated titanium truss technology offers an alternative to traditional methods for large, periarticular osseous defects.

Intraoesophageal migration of Teflon pledgets used for hiatal hernia repair: a serious adverse event.

11 months following an elective paraoesophageal hernia repair, a female patient presents to the emergency department with severe dysphagia. A CT showed a distention of the distal oesophagus caused by a foreign body and dense material inside and outside the oesophagus wall. A gastroscopy confirmed the presence of a bezoar and secondary oesophagitis due to the intraoesophageal migration of Teflon pledgets. Even when used appropriately, only for the crus repair, the use of Teflon pledgets may result in fistulisation through the oesophagus. This complication suggests that the use of Teflon pledgets to buttress a hiatal hernia repair should be used with caution and that an alternative technique (eg, resorbable pledgets) could be preferred.

NiTi-Nb micro-trusses fabricated via extrusion-based 3D-printing of powders and transient-liquid-phase sintering.

We present a novel additive manufacturing method for NiTi-Nb micro-trusses combining (i) extrusion-based 3D-printing of liquid inks containing NiTi and Nb powders, solvents, and a polymer binder into micro-trusses with 0/90° ABAB layers of parallel, ∼600 µm struts spaced 1 mm apart and (ii) subsequent heat-treatment to remove the binder and solvents, and then bond the NiTi powders using liquid phase sintering via the formation of a transient NiTi-Nb eutectic phase. We investigate the effects of Nb concentration (0, 1.5, 3.1, 6.7 at.% Nb) on the porosity, microstructure, and phase transformations of the printed NiTi-Nb micro-trusses. Micro-trusses with the highest Nb content exhibit long channels (from 3D-printing) and struts with smaller interconnected porosity (from partial sintering), resulting in overall porosities of ∼75% and low compressive stiffnesses of 1-1.6 GPa, similar to those of trabecular bone and in agreement with analytical and finite element modeling predictions. Diffusion of Nb into the NiTi particles from the bond regions results in a Ni-rich composition as the Nb replaces Ti atoms, leading to decreased martensite/austenite transformation temperatures. Adult human mesenchymal stem cells seeded on these micro-trusses showed excellent viability, proliferation, and extracellular matrix deposition over 14 days in culture. STATEMENT OF SIGNIFICANCE: Near-equiatomic NiTi micro-trusses are attractive for biomedical applications such as stents, actuators, and bone implants because of their combination of biocompatibility, low compressive stiffness, high surface area, and shape-memory or superelasticity. Extrusion-based 3D-printing of NiTi powder-based inks into micro-trusses is feasible, but the subsequent sintering of the powders into dense struts is unachievable due to low diffusivity, large particle size, and low packing density of the NiTi powders. We present a solution, whereby Nb powders are added to the NiTi inks, thus forming during sintering a eutectic NiTi-Nb liquid phase which bonds the solid NiTi powders and improves densification of the struts. This study investigates the microstructure, porosity, phase transformation behavior, compressive stiffness, and cytocompatibility of these printed NiTi-Nb micro-trusses.

Randomized controlled trial of abdominal binders for postoperative pain, distress, and blood loss after cesarean delivery.

OBJECTIVE: To assess the effect of using abdominal binders on pain, distress, and postpartum hemorrhage after cesarean delivery. METHODS: The present prospective randomized controlled trial enrolled patients undergoing non-emergency cesarean deliveries in Gonbad-e Kavus, Golestan Province, Iran, between January 22 and October 23, 2015. Patients were randomized in a 1:1 ratio by blocks of four or six to a control group or to use an abdominal binder after delivery; all patients received routine care. The primary outcomes were visual analog scale-assessed pain, symptom distress scale (SDS)-assessed distress, and hemoglobin and hematocrit levels. Participants and researchers were masked to treatment assignments until after cesarean delivery, and data analysis was unmasked; intention-to-treat analyses were performed. RESULTS: There were 89 patients enrolled in each group, with no differences in baseline pain scores, SDS scores, and hemoglobin and hematocrit levels between the groups (all P>0.05). Pain and SDS scores were lower in the binder group at all post-baseline time points compared with the control group (all P<0.001). Hemoglobin and hematocrit levels were higher among patients who received binders 36 hours after baseline (both P<0.001). There was one patient who experienced hemorrhage in the binders group and one patient requested removal of their binder. CONCLUSION: Patients who received abdominal binders reported less pain, lower SDS scores, and higher hemoglobin and hematocrit levels following cesarean delivery. IRANIAN REGISTRY OF CLINICAL TRIALS: IRCT2015042521917N2.

Randomized clinical trial on the postoperative use of an abdominal binder after laparoscopic umbilical and epigastric hernia repair.

PURPOSE: Application of an abdominal binder is often part of a standard postoperative regimen after ventral hernia repair to reduce pain and seroma formation. However, there is lack of evidence of the clinical effects. The aim of the present study was to investigate the pain- and seroma-reducing effect of an abdominal binder in patients undergoing laparoscopic umbilical or epigastric hernia repair. METHODS: Based on power analysis, a minimum of 54 patients undergoing laparoscopic umbilical and epigastric hernia repair were to be included. Patients were randomized to abdominal binders vs. no abdominal binders during the first postoperative week. Standardized surgical technique, anaesthesia, and analgesic regimens were used and study observers were blinded towards the intervention. Postoperative pain (visual analogue score) on day 1 was the primary outcome. In addition, ultrasonographic evaluation of seroma formation and several subjective patient-related parameters were registered. Furthermore, patients in the abdominal binder group were asked to rate benefits or discomforts of wearing the binder. RESULTS: Data from 56 patients (abdominal binder, n = 28; no binder, n = 28) were available for analysis. No significant intergroup differences in postoperative pain or any of the other surgical outcomes, including seroma formation, were found. However, the abdominal binder group reported subjective beneficial effect of wearing the binder in 24 of the 28 patients (86%). No adverse effects of the abdominal binder were found. CONCLUSIONS: There were no effects of an abdominal binder on pain, movement limitation, fatigue, seroma formation, general well-being, or quality of life. However, most patients claimed a subjective beneficial effect of using their abdominal binder.

[Inguinal hernia repair: an experimental study on mesh migration with the tension-free suturless technique. 10 year follow-up]. / Ernioplastica inguinale: studio sperimentale sulla mobilità protesica con tecnica tension-free suturless. Follow-up a dieci anni.

AIM: Can the tension-free suturless technique, used in the surgical treatment of inguinal hernia, to be the gold standard for treatment of inguinal hernia? METHODS: The tension-free suturless technique is often criticized as a fundamental principle: do not have suture. The criticism stems from concern that the mesh can migrate and cause damage to important anatomical structures. We conducted a study on the mobility of prosthesis on 33 patients, by using titanium clips that we have fixed on the meshes corner, X-rays over time, done at last, a follow-up of ten years. RESULTS: The study shows that the prosthesis moves together with the anatomical space in which there is the forces present in the inguinal canal: gravity, intra-abdominal pressure, reactive force ascending gait. Across thirty-three patients have relapsed in the first six months and two recurrences in ten years, in the reconstitution of the neo-orifice, through which passes the cord. In the remaining patients the mesh were relocated upward and medially (as identified by the clips of the increase of 10-15%). CONCLUSION: Our study shows that the mesh migrates upwards and medially. Migration is more or less, depending on the patient's age and quality of its tissue. Fix the prosthesis is good practice to secure at the flag on the inguinal ligament leads to two advantages: not to frustrate the principle tension-free, since the fixed prosthesis on one side does not create moments of tension, and prevent the prosthesis returns to the opening road to relapse.

Preformed silastic silos in the management of necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is sometimes complicated by abdominal compartment syndrome, a clinical syndrome characterized by multiple organ dysfunction that arises as a consequence of increased intra-abdominal pressure. The evolving clinical picture of NEC sometimes requires "second-look" operations done after initial abdominal exploration to more accurately gauge the optimal extent of surgery. Placing intestines in a preformed, spring-loaded, transparent Silastic silo, traditionally used in the staged treatment of gastroschisis, addresses both situations: decompression of the abdomen and allowing periodic inspection of the intestines. Standard silos were used in three infants with advanced (Bell Class 3) NEC without perforation before definitive surgery. Clinical indices and laboratory values were recorded during the patients' hospital courses. All three infants had extensive areas of intestinal ischemia and necrosis. FiO2, acidosis, and urinary output remained stable or improved in two patients. Silo placement corrected abdominal compartment syndrome in the third patient. Intestinal resection was required in all infants, each achieving surgical resolution of NEC. Two patients ultimately died from respiratory and neurologic complications. Application of a silo addresses abdominal compartment syndrome as a complication of NEC and allows continual inspection of the intestines. Physiological indices may improve the patient's overall clinical status.

Privates on parade: soldiers, medicine and the treatment of inguinal hernias in Georgian England.

Hernias were prevalent among servicemen, typically recruited from amongst the malnourished. Civilian medical practice deemed the rupture incurable, taking a palliative approach. For the military this was unacceptable: wastage rates due to ruptures were high, servicemen were valuable commodities. Examples here are used to illustrate that experimentation was a contentious activity, reliant on the whims of patronage and war-time budgets. Although military hospitals provided a good venue to engage in experimentation it was contested.

[Laparoscopic incisional hernia repair as first therapeutic choice]. / L'approccio laparoscopico nella riparazione del laparocele quale prima scelta terapeutica.

AIM: Incisional hernias are one of the most frequent complications of open abdominal surgery. Historically, the best results have been obtained with the open rives-stoppa approach. This is done by fixing a large piece of prosthetic mesh behind the rectus muscle. Laparoscopic approach allows similar mesh placement with minimal dissection and lower recurrence rate compared to the open mesh repair. METHODS: Between October 2001 to September 2003, 75 consecutive patients were scheduled to undergo laparoscopic incisional hernia repair with ePTFE mesh (Gore-Tex Dualmesh Plus). Postoperative complications were recorded and analysed. RESULTS: Most were obese affected by multiple wall defects Conversion to open surgery was required in 1 case Postoperative complications occurred 13.3%. Recurrence occurred in one only case. CONCLUSIONS: The key to the success of this procedure is avoidance of complications. The laparoscopic approach is safe, effective and relatively complication-free option in the management of patients presenting with a first time or recurrent incisional hernia and recommended as the treatment of choice.

Hernias: inguinal and incisional.

In the past decade hernia surgery has been challenged by two new technologies: by laparoscopy, which has attempted to change the traditional open operative techniques, and by prosthetic mesh, which has achieved much lower recurrence rates. The demand by health care providers for increasingly efficient and cost-effective surgery has resulted in modifications to pathways of care to encourage more widespread adoption of day case, outpatient surgery, and local anaesthesia. In addition, the UK National Institute for Clinical Excellence has recommended strategies for bilateral and recurrent hernias. Here, we discuss these strategies and review some neglected aspects of hernia management such as trusses, antibiotic cover, return to work and activity, and emergency surgery. Many of the principles of management apply equally to inguinal and incisional hernias. We recommend that the more difficult and complex of the procedures be referred to specialists.

[Trusses in the current management of hernia]. / Stellenwert der Bruchbandtherapie im Zeitalter moderner Hernienchirurgie.

To assess the frequency and reasons for truss prescription, we surveyed 437 general practitioners collaborating with the surgical department of the Kantonsspital Winterthur and all members of the Swiss Association of Orthotists. 59% of the general practitioners answered. For 85% of them trusses are obsolete. Based on the data of the orthotists, an estimated 1740 trusses are issued in Switzerland annually (250 per million population). In Switzerland approximately 16,000 hernia operations are performed annually. Therefore, 11% of hernia patients are supplied with a truss rather than referred for a consultant surgical opinion. Patients can be divided into groups, one that wears the truss only for a short time in order to delay surgery for medical or occupational reasons and another group, especially elderly patients, that wears the truss permanently. Poor hernia control and pain, hernia incarceration, or dissatisfaction with the uncomfortable truss are reasons for referral to a surgeon. In our personal experience with 14 patients, all judged their situation after the operation better than with the truss. Our study confirms that despite advances in hernia surgery and in the use of regional and local anesthesia trusses are often prescribed.