      
|
|
Experimental Forearm
Biomechanics: This research program is primarily focused
on determining contact pressure distributions in joints of living subjects
during functional activity. We are approaching this goal by using MRI-based
contact models.while the subject is relaxed and while the joint is loaded.
Our model joint system is the wrist, specifically the radiocarpal joint.
The functional activity is currently light grasp. While the procedure is
meant to be done on living human subjects, we are using cadaver specimens (such
as the one at the right) to validate the method. Tendon loads that produce
grasp are applied by hanging weights attached to the tendons over pulleys.
In the laboratory, we use pressure sensitive film to measure the joint contact
pressures. Then we take the specimen to the MRI scanner and collect data
with the same loads and while unloaded. Computational contact models,
described below, are then produced to determine the resulting contact pressure
distributions. Model pressures should match those from the lab
experiment. This work is performed at the University of Kansas
Medical Center, in collaboration with E.
Bruce Toby, M.D., and Terence McIff, Ph.D., in the Section
of Orthopedic Surgery., and with Mehmet Bilgen, Ph.D., at the Hoglund
Brain Imaging Center. |
|
| Computational
Joint Mechanics Models: Our current computational efforts
focus primarily on MRI-based contact modeling. The models require
two sets of MRI images of the same joint system. One set of images must be
collected while the joints are relaxed (unloaded). This set of
images is used to build the models of the bones including the undeformed
cartilage surfaces. The second set of MRI images must be collected
while the joint is loaded. From these image sets, we determine the
positions and orientations of the bones (without cartilage) during loading
(as shown at the right).
Contact modeling software is then used to
place the bone models with cartilage in the loaded configuration. By
determining the amount of overlap between the cartilage surfaces on each
bone, we calculate the contact pressures. The amount of contact
pressure is proportional to the interpenetration of the two
surfaces. At the right the contact pressures on the distal forearm
bone (radius) from two carpal bones is illustrated. Contact
pressures on the carpal bones (scaphoid, top, and lunate, bottom) are also
shown.
|
 
|
| Structural
and Mechanical Properties of Tissues: This
experimental work currently deals with quantifying changes in the structural and tissue
properties of bones in disease states (such as osteoporosis and diabetes).
In addition, these experimental research projects will often consider the
effects of disease on soft tissues, such as the tendons, joint capsule and
ligaments. Emphasis is currently focusing on the effect of exercise on
preventing and/or reversing the changes in the musculoskeletal
tissues. The research uses a rat model of diabetes, and exercise. This research area is being
conducted in collaboration with Lisa
Stehno-Bittel and Irina Smirnova in the Department
of Physical Therapy Eduation at the University
of Kansas Medical Center. |
|
| Computational
Bone Biomechanics: This research program is primarily focused
on simulations of bone adaptation to mechanical stimulus and the estimation of
bone and joint loads using bone shape and the distribution of the bone density.
Applications to human and animal bones and joints allow the simulation and
estimation techniques to be verified and refined. Application to extinct
animals, can provide paleontologists and anthropologists important, objective,
and quantitative data regarding biomechanics of these extinct animals.
This is the current thrust of the research being conducted in
collaboration with Larry D. Martin, senior curator of the KU Natural
History Museum. Faculty and students conduct
unique and interesting engineering research using state-of-the-art computers and
simulation tools in collaboration with scientists from related fields. |
|
|
|
