Measuring forces applied by multi-cellular organisms is valuable in investigating biomechanics of their locomotion. Several technologies have been developed to measure such forces, for example, strain gauges, micro-machined sensors, and calibrated cantilevers. We introduce an innovative combination of techniques as a high throughput screening tool to assess forces applied by multiple genetic model organisms. First, we fabricated colored Polydimethylsiloxane (PDMS) micropillars where the color enhances contrast making it easier to detect and track pillar displacement driven by the organism. Second, we developed a semi-automated graphical user interface to analyze the images for pillar displacement, thus reducing the analysis time for each animal to minutes. The addition of color reduced the Young's modulus of PDMS. Therefore, the dye-PDMS composite was characterized using Yeoh's hyperelastic model and the pillars were calibrated using a silicon based force sensor. We used our device to measure forces exerted by wild type and mutant Caenorhabditis elegans moving on an agarose surface. Wild type C. elegans exert an average force of ∼1 μN on an individual pillar and a total average force of ∼7.68 μN. We show that the middle of C. elegans exerts more force than its extremities. We find that C. elegans mutants with defective body wall muscles apply significantly lower force on individual pillars, while mutants defective in sensing externally applied mechanical forces still apply the same average force per pillar compared to wild type animals. Average forces applied per pillar are independent of the length, diameter, or cuticle stiffness of the animal. We also used the device to measure, for the first time, forces applied by Drosophila melanogaster larvae. Peristaltic waves occurred at 0.4 Hz applying an average force of ∼1.58 μN on a single pillar. Our colored microfluidic device along with its displacement tracking software allows us to measure forces applied by multiple model organisms that crawl or slither to travel through their environment.
Introduction: Successful outcome in the treatment of intertrochanteric fracture in elderly lies in early mobilization of the patient so as to avoid the morbidity, complications and poor recovery. With the associated medical comorbidities and osteoporosis, presents a great challenge in selecting the surgical procedures in these patients. Even though the primary choice of surgery revolves around Osteosynthesis in these type of fractures, there is a conspiracy in the choice of implants for the fractures. Many surgeons have resorted to primary hemiarthroplasty in these fractures to avoid uncertainties and implant failures and able to allow full weight bearing walking after surgery. Off late PFNA2 nail have been preferably used to stabilize these fractures with relatively lesser complications and early mobilization of these patients. The purpose of this study is to compare the outcome of PFNA2 and hemiarthroplasty and to study advantages, disadvantages, complications of both the groups. Materials and Methods: 20 patients each were included in PFNA2 group and hemiarthroplasty group from May 2017 to August 2018 who satisfied the inclusion and exclusion criteria. Patient followed up upto 1 year. Patients were evaluated with multiple variables, complications and Harris hip score. Results: PFNA groups had significantly less blood loss, less surgery time, less hospital stay as compared to hemiarthroplasty group. Both groups had similar medical and Orthopaedic complications. PFNA patients can be mobilised early as with hemiarthroplasty group. Hemiarthroplasty groups have better Harris hip score in initial 3 months but similar score at the end of 1 year. Conclusion: PFNA2 provide less morbidity to patients with early mobilisation and good functional outcome. It can definitely be a better option than replacement in elderly intertrochanteric fracture.
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