Subject-specific Musculoskeletal Model for Studying Bone Strain During Dynamic Motion

Summary

During landing, lower-body bones experience large mechanical loads and are deformed. It is essential to measure bone deformation to better understand the mechanisms of bone stress injuries associated with impacts. A novel approach integrating subject-specific musculoskeletal modeling and finite element analysis is used to measure tibial strain during dynamic movements.

Abstract

Bone stress injuries are common in sports and military trainings. Repetitive large ground impact forces during training could be the cause. It is essential to determine the effect of high ground impact forces on lower-body bone deformation to better understand the mechanisms of bone stress injuries. Conventional strain gauge measurement has been used to study in vivo tibia deformation. This method is associated with limitations including invasiveness of the procedure, involvement of few human subjects, and limited strain data from small bone surface areas. The current study intends to introduce a novel approach to study tibia bone strain under high impact loading conditions. A subject-specific musculoskeletal model was created to represent a healthy male (19 years, 80 kg, 1,800 mm). A flexible finite element tibia model was created based on a computed tomography (CT) scan of the subject's right tibia. Laboratory motion capture was performed to obtain kinematics and ground reaction forces of drop-landings from different heights (26, 39, 52 cm). Multibody dynamic computer simulations combined with a modal analysis of the flexible tibia were performed to quantify tibia strain during drop-landings. Calculated tibia strain data were in good agreement with previous in vivo studies. It is evident that this non-invasive approach can be applied to study tibia bone strain during high impact activities for a large cohort, which will lead to a better understanding of injury mechanism of tibia stress fractures.

Introduction

Bone stress injuries, such as stress fractures, are severe overuse injuries requiring long periods of recovery and incurring significant medical cost^1,2. Stress fractures are common both in athletic and military populations. Among all sports related injuries, stress fractures account for 10% of the total³. In particular, track athletes face a higher injury rate at 20%⁴. Soldiers also experience a high rate of stress fractures. For instance, a 6% injury rate was reported for the US Army¹ and a 31% injury rate was reported in the Israeli Arm....

Protocol

The experiment was conducted under the Helsinki Declaration. Prior to data collection, the subject reviewed and signed the consent form approved by the University Institutional Review Board before participating in the study.

1. CT Imaging Protocol

1. Take the participant to a facility where a CT scanner is housed. Prior to the CT scan, configure the CT machine with the following parameters: CT slice thickness of 0.625 mm, CT field of view of 15 cm x 15 cm, and auto setting for parameters of peak kilo-voltage (kVp) and milliampere-seconds (mAs) using machine algorithm.
2. Ask the participant to lie on a table that slides into....

Results

A healthy Caucasian male (19 years, height 1,800 mm, mass 80 kg) volunteered for the study. Prior to data collection, the subject reviewed and signed the consent form approved by the University Institutional Review Board before participating in the study. The experiment was conducted under the Helsinki Declaration. The experiment was performed based on the following protocol.

In order to verify the accuracy of the forward dynami.......

Discussion

The purpose of this study was to develop a non-invasive method to determine tibia deformation during high impact activities. Quantifying tibia strain due to impact loading will lead to a better understanding of tibia stress fracture. In this study, a subject-specific musculoskeletal model was developed, and computer simulations were run to duplicate the drop-landing movements performed in a laboratory setting. The effect of drop-landing height on tibial strain was examined. In this study, we observed that as the drop-lan.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
CT Scanner	GE Medical System	N/A	Light Speed VCT. For performing tibia CT scan.
Motion Capture System	Vicon Inc	N/A	Vicon FX40 high speed cameras. For performing 3D motion capture.
Force plates	AMTI Inc	N/A	Collecting 3D ground reaction forces
Vicon Nexus	Vicon Inc	N/A	Motion capture software program. For processing visual marker trajectory data.
Visual 3D	C-Motion Inc	N/A	Biomechanics analysis software. For computing 3D kinematics and kinetics of human movements.
MATLAB	Mathworks Inc	N/A	Computer programming software. For performing raw data filtering, data conversion, and data processing.
ADAMS 2012	MSC Software Inc	N/A	Multibody dynamic computer simulation program.
LifeMOD	Lifemodeler Inc	N/A	A software Plug-in in ADAMS. For building human body musculo-skeletal models.
MIMICS 13	Materialise Inc	N/A	Image processing program. A 3D modeling tool to process imaging data. For creating 3D tibia model from CT scans.
MARC 2012	MSC Software Inc	N/A	Finite element analysis software. For performing volumn meshing, generating tibia FE model, and running modal FE analysis.
SPSS 19	IBM Inc	N/A	Statistical analysis software.