Research areas

The Notre Dame Tissue Mechanics Laboratory is dedicated to both graduate and undergraduate student research. Research is focused broadly on the biomechanics and mechanobiology of the musculoskeletal system.

All images copyright 2001-2015 Notre Dame Tissue Mechanics Laboratory

Mechanobiology of Bone Marrow

We are using multi-scale experimental and computational approaches to better understand the mechanobiology of bone marrow. Marrow is a complex tissue composed of a heterogeneous cell population and a loose connective tissue, or stroma. Most of the cells have been shown to respond to mechanical stimuli in 2-D culture. Our experiments and models demonstrate that typical activities of daily living can sufficiently deform the bone and the encased marrow to impart mechanical stimuli to these cells through adheren junctions and cell-cell contact. We are developing novel bioreactor culture systems using native and artificial tissue to study these interactions in a controlled environment.

U.S. National Science Foundation

Finite element solutions of marrow mechanics in trabecular bone

Finite element simulations of permeability of trabecular bone from the distal femur of a 7 year old ewe, 2 years post ovariectomy, were performed. The volume fraction of the bone was approximately 0.28. The geometry was obtained from a 20 micron resolution Micro-CT scan, and a tetrahedral mesh was created using the Visualization Toolkit. The mesh was translated to the Adina finite element program. The models have from 7 to 8 million elements. The goal of this research is to understand the stress induced in bone marrow during activities of daily living.

U.S. National Science Foundation

Explant Culture of Trabecular Bone

Trabecular bone explants were harvested from bones immediately after slaughter, then placed in culture in custom bioreactors that imparted mechanical loading to the explant. Bone marrow morphology was assessed to demonstrate its viability after long term culture. Future studies will investigate bone marrow adaptation and response to mechanical stimuli.

This research was conducted at The National University of Ireland, Galway in collaboration with Peter McHugh, Laosie McNamara, Evelyn Birmingham, Frank Barry, and the Regenerative Medicine Institute, and supported by Science Foundation Ireland.

Science Foundation Ireland Remedi

Microdamage formation and propagation in trabecular bone

The role of microdamage in osteoporosis and age related fractures is being studied. We are currently studying the damage behavior of trabecular bone subjected to multiple sequential loading scenarios. Changes in loading mode cause microcracks in trabecular bone to propagate, while a single loading mode results in increased numbers of cracks without propagation. The mechanical consequences of this behavior are currently being investigated.

The figures show fluorescent labeled micrographs of trabecular bone following a sequence of on-axis compressive and torsional overloads. Damage due to each loading mode is differentiated by the labeling color.

This research is in collaboration with Dr. Jen MacLeay at the Small Ruminant Comparative Orthopaedic Laboratory at Colorado State University.

NIAMS National Institutes of Health

Three-dimensional labeling and imaging of microdamage

Visualization and quantification of microdamage in three dimensions would provide improved understanding of the relationship between microdamage and bone fracture. Current techniques are limited to finite numbers of slices or regions, and cannot provide spatial understanding of microdamage development. We have developed techniques to measure microdamage in both cortical and trabecular bone using micro-CT imaging.

The top image shows a notch in a four-point bending specimen with labeled damage near the notch root. Finite element results are overlayed demonstrating that damage occurs in the region where the strains exceed 0.7%. The scale bar is 1 mm long.

The bottom image shows similar labeling of damaged regions in a trabecular bone specimen. The relationship of trabecular bone microdamage to fracture susceptibility due to osteoporosis and aging will be investigated.

NIAMS National Institutes of Health

Simulation of creep in trabecular bone

A computational simulation of creep in trabecular bone using constitutive models consistent with experimental data was developed. The simulation captured the primary creep behavior of trabecular bone.

Histological evaluation of tissues

Histology is used to detect morphological features of biological tissues. H & E staining was used here to investigate the morphology of the enthesis of the bovine patellar ligament. Future studies will be aimed at measuring the mechaical properties of the various layers of the enthesis.

Mechanics of lumbar spinal fusion

We are also modeling the biomechanics of a fused lumbar motion segment to understand how fusion location and size or the use of hardware affect the overall load carrying capability.

Effects of Vitamin D receptor on bone mechanics

The properties of bones in mice lacking a nuclear vitamin-D receptor were studied during gestation and lactation. If sufficient calcium is supplied, mice are able to adapt their skeletal mass effectively in the absence of the vitamin-D receptor.

Casey Korecki was awarded second prize in the 2003 ASME Summer Bioengineering Conference student paper competition for this work.

Research Funding

Ongoing research in the Notre Dame Tissue Mechanics Laboratory is supported by:

For more information, or if you are interested in working in the Tissue Mechanics Laboratory, contact Glen Niebur or see the prospective student information.

For information on other research in the department, see the individual faculty profiles. Students wishing to apply for graduate school at Notre Dame should apply through the Mechanical Engineering department.