The aim of the present study was to establish a computed tomographic angiography protocol using a dual-head power injector as well as measure the attenuation values and diameters of the major arteries in African Grey parrots (Psittacus erithacus). A 16-slice computed tomography (CT) scanner was used to measure the region of interest (ROI) in six major arteries. Before scanning, each bird underwent physical, blood, and cardiological examinations and were considered healthy. Each bird was sedated under general anesthesia during the CT-angiography (CT-A) procedure. A dual-head power injector with a saline chaser technique was used to administer the contrast medium and saline flush. We used a real-time bolus-tracking method and triggered the scan manually once the peak enhancement of ascending aorta was reached. All measurements were made by two double-blinded clinicians. The reference ranges before and after contrast medium administration via the body, pulmonary, and bone windows were set up accordingly. Inter-observer consistency in measurements was high in post-contrast values via the body window. Hence, the present study concluded that it is feasible to use saline chaser with dual-head power injector upon performing CT-A in parrots and analyze the image in a body window. Also, an anesthetic protocol during CT-A was also proved to be practical. However, further studies are needed to improve the diagnostic potential and utility of CT-A in parrots.
Exposure of human lower extremities to mechanical loading will lead to different biological responses, e.g., degenerative and post-traumatic osteoarthritis. Relations among injuries and impact energy have been well studied. However, how the external force is attenuated by the internal joint is not known yet. The objective of the current study is to find the shock attenuation properties of knee joint using different shock absorbers. A "drop-tower type" impact apparatus was used for testing. Ten fresh porcine knee joints were aligned at full extension for testing. All specimens were tested at 30 and 40 mm levels of height, 12 and 16 kg levels of weight, and with shock absorbers of 20 (stiff), 40 (medium), and 60 (soft) mini-seconds levels of contact time. The impact forces, flexion moment and all directions of acceleration were found to decrease with a softer shock absorber. A medium shock absorber produces 33% less axial force, 68% less shear force, 53% less bending moment and more than 70% less accelerations at femur and tibia compared to the stiff shock absorber. The results of the current research can be used for reference in designing sports footwear.
Degenerative osteoarthritis is the consequence of impact force applied to articular cartilage that results in surface fissuring. Soft cushions and flexed posture are two important factors to reduce the impact force; however, no quantitative information of how soft should the cushion be to prevent the injury and the mechanism of force attenuation of knee joint at neutral and flexed posture was not well documented yet. The objective of current study is hence to find the quantitative shock attenuation of knee joint using different stiffness of cushions when the knee is at neutral posture and flexed posture. A “drop-tower type” impact apparatus was used for testing. Nineteen fresh porcine knee joints were divided into two posture groups, i.e. neutral and flexed posture. All specimens were tested using stiff, medium, and soft cushions. The axial reaction force, anteroposterior shear force, and flexion bending moment were recorded for analysis. We found the flexed posture decreased the axial reaction force and anterior shear force but increased the flexion bending moment. The effect of stiffness of cushions on the mechanical response of knee joint during impact loading was significant for neutral posture but not for flexed posture.
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