Simulation of phased array ultrasound propagation for fluid flow regulation in enhancement of bone adaptation

Abstract

Osteoporosis and induced risk of fracture have impact on aging population and our society. It has been shown that low-intensity mechanical intervention can promote local tissue formation using non-invasive ultrasound. The goal of this work was to evaluate dynamic acoustic radiation force (ARF) induced bone fluid flow (BFF) at the site of interests using nonlinear finite element analysis. ARF simulation was first generated by a 1x5 linear array transducer and then extended to a 5x5 array submerged under degassed water used for regulating fluid pressure gradient and flow. Both acoustic and porous media constitutive models were used to generate dynamic ARF wave propagation in the tissue. Simulations were modeled on a cortical bone specimen with a signal frequency of 1MHz for a series of Duty Cycle(%) and Pulse Repetition Frequency(PRF). The results showed that the displacement values obtained against a varying PRF follows the experimental trends of (Dayton et al., 1997) and displacement increases significantly for a Duty Cycle increase from 12% to 15%. Induced displacements plotted against time agrees with the experimental trends (Fan et al., 2013). The dynamic ARF created a pressure gradient of 0.6MPa/cm resulting in a relative displacement of 8μm between two points separated by 1mm.

Study on the biomechanical responses of the loaded bone in macroscale and mesoscale by multiscale poroelastic FE analysis

“…Therefore, the distribution of stress and strain in bone affects the bone microstructure and the activity of bone cells. Fluid flow in osteons can produce a series of effect, such as fluid shear stress, pore pressure gradient, solute transport, and streaming potential, and some of these effects can be sensed by osteocytes as signals to trigger bone formation and bone resorption to adapt the continuous change of the mechanical environment [8]. The bone will produce deformation which induced fluid flow in bone under physiological loading, and osteocytes are sensitive to fluid flow and its induced effects [9].…”

Beam-steering ultrasonic guided waves in a bone-mimicking plate by time-delaying the excitation of the elements in a multi-element array: a numerical study

“…Using ultrasonic PA technique to study UGWs in long bones is relatively new and the number of study is still limited. 32,33) In this investigation, we implemented the SAFE method to simulate the UGW excitations in a bone mimicking plate under beam steering by a non-focusing PA system which models the measurement setup in the Ref. 3.…”