Development and mechanical testing of a short intramedullary nail for fixation of femoral rotational osteotomy in cerebral palsy patients

<p>Abstract</p> <p>Background</p> <p>Rotational osteotomy is frequently indicated to correct excessive femoral anteversion in cerebral palsy patients. Angled blade plate is the standard fixation device used when performed in the proximal femur, but extensile exposure is required for plate accommodation. The authors developed a short locked intramedullary nail to be applied percutaneously in the fixation of femoral rotational osteotomies in children with cerebral palsy and evaluated its mechanical properties.</p> <p>Methods</p> <p>The study was divided into three stages. In the first part, a prototype was designed and made based on radiographic measurements of the femoral medullary canal of ten-year-old patients. In the second, synthetic femoral models based on rapid-prototyping of 3D reconstructed images of patients with cerebral palsy were obtained and were employed to adjust the nail prototype to the morphological changes observed in this disease. In the third, rotational osteotomies were simulated using synthetic femoral models stabilized by the nail and by the AO-ASIF fixed-angle blade plate. Mechanical testing was done comparing both devices in bending-compression and torsion.</p> <p>Results</p> <p>The authors observed proper adaptation of the nail to normal and morphologically altered femoral models, and during the simulated osteotomies. Stiffness in bending-compression was significantly higher in the group fixed by the plate (388.97 ± 57.25 N/mm) than in that fixed by the nail (268.26 ± 38.51 N/mm) as torsional relative stiffness was significantly higher in the group fixed by the plate (1.07 ± 0.36 Nm/°) than by the nail (0.35 ± 0.13 Nm/°).</p> <p>Conclusions</p> <p>Although the device presented adequate design and dimension to fit into the pediatric femur, mechanical tests indicated that the nail was less stable than the blade plate in bending-compression and torsion. This may be a beneficial property, and it can be attributed to the more flexible fixation found in intramedullary devices.</p

Design of a normally-off diamond JFET for high power integrated applications

© 2017 Elsevier B.V. Normally-on (depletion mode) and normally-off (enhancement mode) diamond Junction Field Effect Transistors (JFETs) have been analyzed by means of a commercially available TCAD software. First, the parameters used for describing the incomplete ionization, avalanche, and mobility models in diamond have been discussed and assessed against the state-of-the-art. The on- and off-state electrical characteristics of diamond JFETs have been simulated with the suggested parameter values and matched with a set of available experimental data. Secondly, an optimization technique which can improve the performance of an enhancement mode diamond JFET that operates in the unipolar conduction regime has been proposed. This method takes into account the unique properties and limitations of diamond and highlights the main issues that can arise from the design of a normally-off diamond JFET. In particular, the crucial effect of the high temperature on the performance of the normally-off JFET has been investigated. The adopted technique is mainly based on a design of TCAD experiments and no mathematical algorithms have been developed for the calculation of the optimized set of parameters

On the impact of substrate electron injection on dynamic Ron in GaN-on-Si HEMTs

The impact of electron injection from the substrate on the dynamic Ron of GaN-on-Si High Electron Mobility Transistors (HEMTs) has been investigated by means of back-bias transient and vertical leakage measurements and TCAD simulations. A strong correlation between electrons injected from the substrate and on-state drain current transients is demonstrated. Moreover, the contribution of the electron-type traps in the buffer layer as opposed to the usually studied hole-like traps to the dynamic Ron is discussed. In particular, the impact of electron-like traps for different levels of substrate leakage current is studied. A TCAD model has been developed and calibrated by taking into account both off-state vertical leakage and on-state drain current transient experimental results. The proposed charge dynamic has also been assessed against state-of-the-art theories. This analysis contributes to a deeper understanding of the complex scenario of different types of traps in the buffer layer of GaN-on-Si devices and highlights the impact that trap-states can have on the on-state and off-state currents

Right ventricular-arterial uncoupling independently predicts survival in COVID-19 ARDS

Aim: To investigate the prevalence and prognostic impact of right heart failure and right ventricular-arterial uncoupling in Corona Virus Infectious Disease 2019 (COVID-19) complicated by an Acute Respiratory Distress Syndrome (ARDS). Methods: Ninety-four consecutive patients (mean age 64&nbsp;years) admitted for acute respiratory failure on COVID-19 were enrolled. Coupling of right ventricular function to the pulmonary circulation was evaluated by a comprehensive trans-thoracic echocardiography with focus on the tricuspid annular plane systolic excursion (TAPSE) to systolic pulmonary artery pressure (PASP) ratio Results: The majority of patients needed ventilatory support, which was noninvasive in 22 and invasive in 37. There were 25 deaths, all in the invasively ventilated patients. Survivors were younger (62 ± 13 vs. 68 ± 12&nbsp;years, p = 0.033), less often overweight or usual smokers, had lower NT-proBNP and interleukin-6, and higher arterial partial pressure of oxygen (PaO2)/fraction of inspired O2 (FIO2) ratio (270 ± 104 vs. 117 ± 57&nbsp;mmHg, p &lt; 0.001). In the non-survivors, PASP was increased (42 ± 12 vs. 30 ± 7&nbsp;mmHg, p &lt; 0.001), while TAPSE was decreased (19 ± 4 vs. 25 ± 4&nbsp;mm, p &lt; 0.001). Accordingly, the TAPSE/PASP ratio was lower than in the survivors (0.51 ± 0.22 vs. 0.89 ± 0.29&nbsp;mm/mmHg, p &lt; 0.001). At univariate/multivariable analysis, the TAPSE/PASP (HR: 0.026; 95%CI 0.01–0.579; p: 0.019) and PaO2/FIO2 (HR: 0.988; 95%CI 0.988–0.998; p: 0.018) ratios were the only independent predictors of mortality, with ROC-determined cutoff values of 159&nbsp;mmHg and 0.635&nbsp;mm/mmHg, respectively. Conclusions: COVID-19 ARDS is associated with clinically relevant uncoupling of right ventricular function from the pulmonary circulation; bedside echocardiography of TAPSE/PASP adds to the prognostic relevance of PaO2/FIO2 in ARDS on COVID-19

A MULTICENTER, OBSERVATIONAL, AMBISPECTIVE STUDY EVALUATING EFFICACY AND SAFETY OF GENERIC IMATINIB COMPARED TO GLEEVEC IN CHRONIC MYELOGENOUS LEUKEMIA IN CHRONIC PHASE-3 MONTHS RESPONSE ANALYSIS

Univ Estadual Campinas, Hematol & Hemotherapy Ctr, Campinas, SP, BrazilUniv Fed Minas Gerais, Hosp Clin, Belo Horizonte, MG, BrazilInst Nacl Cancer, Rio De Janeiro, BrazilFac Med, Sao Paulo, BrazilUniv Sao Paulo, Sao Paulo, BrazilHemorio, Rio De Janeiro, BrazilHosp Clin Porto Alegre, Porto Alegre, RS, BrazilCtr Pesquisa Oncol Santa Catarina, Florianopolis, SC, BrazilUniv Fed Bahia, Salvador, BA, BrazilUniv Fed Sao Paulo, Sao Paulo, BrazilInst Estudos & Pesquisas Sao Lucas, Sao Paulo, BrazilUniv Estadual Campinas, Campinas, SP, BrazilUniv Fed Sao Paulo, Sao Paulo, BrazilWeb of Scienc

Less Anterior Knee Pain with a Mobile-bearing Prosthesis Compared with a Fixed-bearing Prosthesis

Anterior knee pain is one of the major short-term complaints after TKA. Since the introduction of the mobile-bearing TKA, numerous studies have attempted to confirm the theoretical advantages of a mobile-bearing TKA over a fixed-bearing TKA but most show little or no actual benefits. The concept of self-alignment for the mobile bearing suggests the posterior-stabilized mobile-bearing TKA would provide a lower incidence of anterior knee pain compared with a fixed-bearing TKA. We therefore asked whether the posterior-stabilized mobile-bearing knee would in fact reduce anterior knee pain. We randomized 103 patients scheduled for cemented three-component TKA for osteoarthrosis in a prospective, double-blind clinical trial. With a 1-year followup, more patients experienced persistent anterior knee pain in the posterior-stabilized fixed-bearing group (10 of 53, 18.9%) than in the posterior-stabilized mobile-bearing group (two of 47, 4.3%). No differences were observed for range of motion, visual analog scale for pain, Oxford 12-item questionnaire, SF-36, or the American Knee Society score. The posterior-stabilized mobile-bearing knee therefore seems to provide a short-term advantage compared with the posterior-stabilized fixed-bearing knee

Comparison of intra-articular injections of Hyaluronic Acid and Corticosteroid in the treatment of Osteoarthritis of the hip in comparison with intra-articular injections of Bupivacaine. Design of a prospective, randomized, controlled study with blinding of the patients and outcome assessors

<p>Abstract</p> <p>Background</p> <p>Although intra-articular hyaluronic acid is well established as a treatment for osteoarthritis of the knee, its use in hip osteoarthritis is not based on large randomized controlled trials. There is a need for more rigorously designed studies on hip osteoarthritis treatment as this subject is still very much under debate.</p> <p>Methods/Design</p> <p>Randomized, controlled trial with a three-armed, parallel-group design. Approximately 315 patients complying with the inclusion and exclusion criteria will be randomized into one of the following treatment groups: infiltration of the hip joint with hyaluronic acid, with a corticosteroid or with 0.125% bupivacaine.</p> <p>The following outcome measure instruments will be assessed at baseline, i.e. before the intra-articular injection of one of the study products, and then again at six weeks, 3 and 6 months after the initial injection: Pain (100 mm VAS), Harris Hip Score and HOOS, patient assessment of their clinical status (worse, stable or better then at the time of enrollment) and intake of pain rescue medication (number per week). In addition patients will be asked if they have complications/adverse events. The six-month follow-up period for all patients will begin on the date the first injection is administered.</p> <p>Discussion</p> <p>This randomized, controlled, three-arm study will hopefully provide robust information on two of the intra-articular treatments used in hip osteoarthritis, in comparison to bupivacaine.</p> <p>Trial registration</p> <p>NCT01079455</p

Influence of surgical approach on component positioning in primary total hip arthroplasty

Background: Minimal invasive surgery (MIS) has gained growing popularity in total hip arthroplasty (THA) but concerns exist regarding component malpositioning. The aim of the present study was to evaluate femoral and acetabular component positioning in primary cementless THA comparing a lateral to a MIS anterolateral approach. Methods: We evaluated 6 week postoperative radiographs of 52 hips with a minimal invasive anterolateral approach compared to 54 hips with a standard lateral approach. All hips had received the same type of implant for primary cementless unilateral THA and had a healthy hip contralaterally. Results: Hip offset was equally restored comparing both approaches. No influence of the approach was observed with regard to reconstruction of acetabular offset, femoral offset, vertical placement of the center of rotation, stem alignment and leg length discrepancy. However, with the MIS approach, a significantly higher percentage of cups (38.5 %) was malpositioned compared to the standard approach (16.7 %) (p = 0.022). Conclusions: The MIS anterolateral approach allows for comparable reconstruction of stem position, offset and center of rotation compared to the lateral approach. However, surgeons must be aware of a higher risk of cup malpositioning for inclination and anteversion using the MIS anterolateral approach

The controversy of patellar resurfacing in total knee arthroplasty: Ibisne in medio tutissimus?

Early arthroplasty designs were associated with a high level of anterior knee pain as they failed to cater for the patello-femoral joint. Patellar resurfacing was heralded as the saviour safeguarding patient satisfaction and success but opinion on its necessity has since deeply divided the scientific community and has become synonymous to topics of religion or politics. Opponents of resurfacing contend that the native patella provides better patellar tracking, improved clinical function, and avoids implant-related complications, whilst proponents argue that patients have less pain, are overall more satisfied, and avert the need for secondary resurfacing. The question remains whether complications associated with patellar resurfacing including those arising from future component revision outweigh the somewhat increased incidence of anterior knee pain recorded in unresurfaced patients. The current scientific literature, which is often affected by methodological limitations and observer bias, remains confusing as it provides evidence in support of both sides of the argument, whilst blinded satisfaction studies comparing resurfaced and non-resurfaced knees generally reveal equivalent results. Even national arthroplasty register data show wide variations in the proportion of patellar resurfacing between countries that cannot be explained by cultural differences alone. Advocates who always resurface or never resurface indiscriminately expose the patella to a random choice. Selective resurfacing offers a compromise by providing a decision algorithm based on a propensity for improved clinical success, whilst avoiding potential complications associated with unnecessary resurfacing. Evidence regarding the validity of selection criteria, however, is missing, and the decision when to resurface is often based on intuitive reasoning. Our lack of understanding why, irrespective of pre-operative symptoms and patellar resurfacing, some patients may suffer pain following TKA and others may not have so far stifled our efforts to make the strategy of selective resurfacing succeed. We should hence devote our efforts in defining predictive criteria and indicators that will enable us to reliably identify those individuals who might benefit from a resurfacing procedure. Level of evidence V