Study on the interactive deformation of bone needles and circum-pelvic soft tissue

During the robot-assisted pelvic fracture reduction,the needle-tissue interactive deformation characteristic is not clear,which affects the accuracy of robotic surgery.In this paper,a layered rig-id-flexible coupling model is proposed,and the needle-tissue interactive deformation under the load-ing is analyzed by the Rayleigh-Ritz method,in accordance with the principle of minimum potential energy.The pelvic musculoskeletal tissue is reversely reconstructed,and the structure of the bone is segmented into cancellous bone and cortical bone.The Mooney-Rivlin five-parameter hyperelastic model is used to simulate muscle,and the Ogden hyperelastic model is used to simulate adipose tis-sue.Finite element simulation is performed by loading different magnitudes of forces.The accuracy of the rigid-flexible coupling model is 0.432 mm,which indicates the correctness of the needle-tis-sue interactive deformation theory analysis.

Simulation of Coupling Process of Flexible Needle Insertion into Soft Tissue Based on ABAQUS

In order to get to the desired target inside the body,it is essential to investigate the needle-tissue coupling process and calculate the tissue deformation.A cantilever beam model is presented to predicting the deflection and bending angle of flexible needle by analyzing the distribution of the force on needle shaft during the procedure of needle insertion into soft tissue.Furthermore,a finite element(FE)coupling model is proposed to simulate the needle-tissue interactive process.The plane and spatial models are created to relate the needle and tissue nodes.Combined with the cantilever beam model and the finite element needle-tissue coupling model,the simulation of needle-tissue interaction was carried out by the ABAQUS software.The comparing experiments are designed to understand the needle-tissue interactions,by which the same points in the experiments and simulation are compared and analyzed.The results show that the displacements in x and z directions in the simulation can accord with the experiments,and the deformation inside the tissue mainly occurs in the axial direction.The study is beneficial to the robot-assisted and virtual needle insertion procedure,and to help the physicians to predict the inside tissue deformation during the treatments.