Bone Pose Estimation in the Presence of Soft Tissue Artifact Using Triangular Cosserat Point Elements

Abstract

Accurate estimation of the position and orientation (pose) of a bone from a cluster of skin markers is limited mostly by the relative motion between the bone and the markers, which is known as the Soft Tissue Artifact (STA). This work presents a method, based on continuum mechanics, to describe the kinematics of a cluster affected by STA. The cluster is characterized by Triangular Cosserat Point Elements (TCPEs) defined by all combinations of three markers.The effects of the STA on the TCPEs are quantified using three parameters describing the strain in each TCPE and the relative rotation and translation between TCPEs. The method was evaluated using previously collected ex-vivo kinematic data. Femur pose was estimated from 12 skin markers on the thigh, while its reference pose was measured using bone pins. Analysis revealed that instantaneous subsets of TCPEs exist which estimate bone position and orientation more accurately than the Procrustes Superimposition applied to the cluster of all markers. It has been shown that some of these parameters correlate well with femur pose errors, which suggests that they can be used to select, at each instant, subsets of TCPEs leading an improved estimation of the underlying bone pose.2

A framework for measuring the time-varying shape and full-field deformation of residual limbs using 3D digital image correlation

“…Consequently, the results are dependent on the selected registration algorithm [22], [23], since there is no closed-form solution for this registration. Using our method, this problem is avoided entirely, since the correspondence between surface points is inherently tracked using 3D-DIC, thereby allowing a closed-form solution to be applied [24]. For the same reason, only 3D-DIC allows for local full-field deformation and strains measurement, while other scanning techniques can only evaluate out-of-plane displacements.…”

Chest Wall Kinematics Using Triangular Cosserat Point Elements in Healthy and Neuromuscular Subjects

“…Therefore, as a first step to achieve this goal, the present study aims at developing a method for the local analysis of the complete non-rigid kinematics of the CW surface. The kinematic methods presented in this paper are based on the triangular Cosserat point elements (TCPE) method, previously developed for bone pose estimation in the presence of soft tissue artifact [33][34][35] , and are further developed here for the purpose of respiratory kinematic analysis.…”