The Effects Of The Urea On Cold Weather Strength Gaining Of Fresh Concrete

Common methods of concrete placing in freeze and cold weather have not beenchanged for ages. The methods are heating materials, melting ice and curing fresh concrete byinsulation devices and applying heating systems until finishing concrete curing. Utilizingchemical compounds in fresh concrete in order to decrease freezing temperature andcontinuation of hydration process at low temperatures are very limited. In addition, the studiesrelated to the behavior of the chemical admixture and the effects of them on the properties ofthe concrete are very scarce in technical literature. There are not any standards related to theapplication of antifreeze admixture to the concrete neither in Europe nor in U.S. Because ofthe reasons the study focused on the application of urea to the cold weather concreting. One ofthe advantages of this method is having an easy curing condition after concrete placing, inwhich, only one anti-evaporation sheet is used to keep fresh concrete wet until finishing ofconcrete curing. For this reason, Urea is used at level of %6 by weight of cement dosage inthe mixes. After casting, one group of concrete samples were cured in the different deepfreezesat -5, -10, -15, -200C for 7, and then that same samples were cured in water for 28days. At -50C and -100C the admixture positive effect is evident but at -150C and -200C it hasnot got the same effect when compared to mixes without antifreeze admixtures. As a result atcold weather concreting, urea can be an effective alternative to the other precautions up to -50C without any protections

The Influence Of Calcium Nitrate On The Compressive Strength Of Concrete Exposed To Freezing Weather

Based on ACI 306R-88, the minimum temperature necessary for maintaining concretehydration and strength gaining is 50C. If the atmosphere weather becomes lower than 50Csome preserve measurements should be taken in order to prevent decrease in the rate ofhydration and to prevent fresh concrete from freezing. Most of the cold weather livingcountries spend annually plenty of money in order to facilitate concrete placing in the coldweather and to extend the construction season. It has been tried to carry out the behavior of fresh and hardened concrete contained calcium nitrate at different curing temperatures below freezing temperature of water and compare the results with the both control samples and real Erzurum winter conditions. For this reason, calcium nitrate is used at level of 6% by weightof cement dosage in the mixes. After casting, one group of concrete samples were cured in the different deepfreezes at -5,-10,-15,-200C for 7, and then that same samples were cured inwater for 28 days. With usage of calcium nitrate in the mixes, compressive strength of concrete increased between 96-297% at -50C, -100C, -150C and -200C, when compared tomixes without antifreeze admixtures that 7 days only freezer cured and 28 days water curedafter 7 days freezer cured, respectively. The results showed that it is possible to use calciumnitrate as an antifreeze admixture in concrete placing process in cold weather concreting

Posterior-Only Approach with Pedicle Screws for the Correction of Scheuermann's Kyphosis

Study DesignRetrospective study (level of evidence: level 3).PurposeThe purpose of this study was to evaluate the clinical and radiological results of the posterior-only approach with pedicle screws for the treatment of Scheuermann's kyphosis (SK).Overview of LiteratureThe correction of SK with instrumentation can be performed using posterior-only or combined anterior-posterior procedures. With the use of all-pedicle screw constructs in spine surgery, the posterior-only approach has become a popular option for the definitive treatment of SK. In a nationwide study involving 2,796 patients, a trend toward posterior-only fusion with lower complication rates was reported.MethodsWe retrospectively reviewed the data of patients who underwent posterior-only correction for SK between January 2005 and May 2013. Patients with a definite diagnosis of SK who fulfilled the minimum follow-up criterion of 24 months were included. The thoracic kyphosis (T5–T12), lumbar lordosis (L1–S1), and thoracolumbar junction (T10–L2) angles were measured from preoperative, postoperative, and last control radiographs. Sagittal balance, thoracic length, thoracic diameter, Voutsinas index and the sacral slope, pelvic tilt, proximal junction kyphosis, and distal junction kyphosis angles were also measured.ResultsForty-five patients underwent surgery for the treatment of SK between 2005 and 2013. After applying the exclusion criteria, 20 patients (18 males and 2 females) with a mean age of 19 years were included. The mean thoracic kyphosis angle was 79.8 degrees preoperatively, 44.6 degrees postoperatively, and 44.9 degrees at the last control. There were statistically significant differences between preoperative and postoperative values in the thoracic kyphosis and lumbar lordosis angles, thoracic length, thoracic diameter, and Voutsinas index (p<0.05).ConclusionsThe clinical and radiological results of the current study suggest that posterior-only fusion is an efficient technique for the treatment of SK

Experiences from a non-COVID hub referral orthopedic trauma hospital during the COVID-19 pandemic in Turkey

Background: During the COVID-19 pandemic period, resources should be reorganized to treat the increased burden of COVID-positive patients under the best conditions while simultaneously providing non-deferrable treatment to patients with no suspicion of COVID-19. In this study, we aimed to analyse the trauma patient profile and treatment strategies that emerged in the regional orthopaedic and traumatology hospital during the pandemic period after the implementation of “hub and spoke” organization among the orthopaedic and traumatology clinics.Methods: This cross-observational study was conducted in a training and research hospital in the field of orthopaedics and traumatology that was converted to a non-COVID referral orthopaedic trauma center during the pandemic. Gender, age, length of hospitalization, duration of trauma, place of trauma, severity of trauma, type of admission, type of anaesthesia and site of trauma were evaluated in the patients that presented between March 16 and May 16, 2020.Results: Of the orthopaedic trauma patients requiring surgery, 169 (62.6%) were men and 101 (37.4%) were women. In comparison of the data with that of the last year, significant increases were observed in the number of home traumas (241.5%), low-energy traumas (87.4%), patients referred from other institutions (328.9%), regional anaesthesia patients (124.2%) and patients with hip traumas (226.7%). The length of hospitalization decreased significantly (p&lt;0.05).Conclusions: The creation of hub and spoke organization through the cooperation of orthopaedics and traumatology clinics in the region can reduce the burden on pandemic hospitals by isolating trauma patients requiring orthopaedic surgery who were not suspected of COVID-19 and directing them to dedicated orthopaedics and traumatology hospital

Analysis of complications following posterior vertebral column resection for the treatment of severe angular kyphosis greater than 100°

Objective: The aim of this study was to evaluate the complications, efficacy and safety of posterior vertebral column resection (PVCR) in severe angular kyphosis (SAK) greater than 100°. Methods: The medical records of 17 patients (mean age 17.9 (range, 9–27) years) with SAK who underwent PVCR, were reviewed. Mean follow-up period was 32.2 (range, 24–64) months. Diagnosis of the patients included congenital kyphosis in 11 patients, post-tuberculosis kyphosis in 3 patients and neurofibromatosis in 3 patients. The sagittal plane parameters (local kyphosis angle, lumbar lordosis, sagittal vertical axis, pelvic tilt, sacral slope and pelvic incidence) were measured in the preoperative and the early postoperative periods and during the last follow-up on the lateral radiographs. Results: The mean preoperative localized kyphosis angle was 121.8° (range, 101°–149°). The mean local kyphosis angle (LKA) was 71.5° at postoperatively evaluation (p < 0.05). Complications were detected in 12 patients (70.6%) with spinal shock in 4 patients, hemothorax in 3 patients, postoperative infection in 2 patients, dural laceration in 2 patients, neurological deficit in 2 patients (1 paraplegia and 1 root injury), the shifted cage in 2 patients and rod fracture in 2 patients. Neurological events occurred in six patients (35%) with temporary neurological deficit in 5 patients and permanent neurological deficit in 1 patient. Conclusion: PVCR is an efficient and a successful technique for the correction of SAK. However, it can lead to a large number of major complications in SAK greater than 100°. Level of evidence: Level IV, therapeutic study. Keywords: Posterior vertebral column resection, Severe angular kyphosis, Complication, Neurological deficit, Neuromonitorin

Comparison of the pull-out strengths of three different screws in pedicular screw revisions: a biomechanical study

OBJECTIVES: We investigated the possible effects of three pedicular screws on axial pull-out strength in pedicular revision surgery. METHODS: Two study groups were formed from calf lumbar vertebrae. Initially, Alici pedicular screws with an outer diameter of 6.5 mm were applied (with or without tapping) to all the pedicles. All the pedicles were subjected to axial pull-out testing to induce pedicular insufficiency. Then, Alici pedicular screws with an outer diameter of 7 mm were applied to the left pedicles. The right pedicles in the two study groups were assigned to receive two different types of pedicular screws with an expandable (enlargeable) end, respectively. Axial pull-out testing was repeated in both groups and the results were compared with the initial pull-out strength values. RESULTS: In the first group, 65% and 64% of the initial pull-out strengths were obtained with 7-mm Alici pedicular screws and with expandable pedicular screws, for the left and right pedicles, respectively. The corresponding pull-out strengths in the other study group were 70% and 68.5% of the initial values, respectively. Tapping of the screw hole entrance resulted in a mean decrease of 13% in the pull-out strength compared to screw applications without tapping. CONCLUSION: Pedicular screw revisions using a 0.5 mm greater screw in diameter did not provide adequate screw-bone inter-face strength and pedicle filling. Similarly, expandable pedicular screws did not contribute to screw stability

The effect of distraction-based growth friendly spinal instrumentation on growth in early-onset scoliosis

The benefits and drawbacks of growth friendly spinal instrumentation have been reported as a result of developments in the treatment of early-onset scoliosis. Seventeen patients who underwent growth friendly spinal instrumentation surgery with a minimum 2-year follow-up were included in the review. The mean number of lengthenings was 3, initial surgery age took place at 108.1 ± 30.2 months and follow-up at 40.6 ± 16.6 months. Spinal height (T1–S1 and T1–T12), space available for the lungs, major Cobb angle for scoliosis, maximum thoracic kyphosis, lumbar lordosis, shoulder and pelvic balance, and coronal and sagittal balance were assessed preoperatively and during the latest follow-up. Treatment with growth friendly spinal instrumentation provided an evident increase in spine height and space available for the lungs, and a significant decrease in scoliosis and thoracic kyphosis. In growth friendly spinal instrumentation treatment, the most commonly observed complications were proximal anchor problems (76.4%) and proximal junctional kyphosis (58.8%). In treatments using growing rods, excessive thoracic kyphosis correction should not be made to avoid proximal junctional kyphosis

Effectiveness of Plantar Fascia-Specific Stretching Exercises in Plantar Fasciitis

Aim: Plantar fasciitis (PF) is a painful and disabling disease that affects the quality of life and daily activities of patients and it is the most common cause of heel pain in adults. In primary treatment, conservative treatment is suggested and different conservative options are described in the literature. In our study, we evaluated the efficacy of plantar fascia-specific stretching exercises in the treatment of PF. Methods: Twenty-nine feet - 21 patients with the mean age of 49.3 years were included in the study. The mean length of follow-up was 19.8 months and the mean length of exercise period was 4.94 months. Non-weight bearing plantar fascia-specific stretching exercise was done twice daily, for 10 times at each session. In addition to exercises, silicone heel pad and nonsteroidal anti-inflammatory drugs (NSAID) were added. Visual analog scale (VAS) was used for pain evaluation. Results: Full recovery detected in 15 feet in 10 patients (52%) and a decrease in pain was seen in 10 feet in 8 patients (34%). There was no response in 4 feet in 3 patients (14%). There was statistically significant difference between pre-treatment and post-treatment visual analog scale scores (p=0.0001). Conclusion: Plantar fascia-specific stretching exercise is an effective treatment option in PF

The results of closing wedge osteotomy with posterior instrumented fusion for the surgical treatment of congenital kyphosis

The purpose of this project is to design and fabricate a rotating cylinder 3D printer that allows manufacturing of complex cylindrical structures. Standard cartesian, extruded filament 3D printers have limited capability to produce strong parts due to z-axis layering and have trouble printing vertical lattice structures without plastic drooping. To address these limitations, a 3D printing lathe has been developed which prints on a removable rotating cylindrical surface. The project successfully met objectives to develop the mechanical motion system, extrude PLA plastic, and control the printer with GCode instructions