P&S Journal: Spring 1994, Vol.14, No.2
The basal joint of the thumb is the joint in the body most frequently affected by osteoarthritis. Patients with this form of osteoarthritis-mostly women (it affects about one in six women over age 60)-suffer from severe disability because the thumb influences 50 percent of hand function.
To improve treatment of this type of osteoarthritis, Dr. Melvin P. Rosenwasser, associate professor of orthopedic surgery, collaborates with two Columbia mechanical engineering professors, Drs. Van C. Mow, also director of the New York Orthopedic Hospital Research Lab at CPMC, and Dr. Gerard A. Ateshian, to research the function of the basal joint of the thumb. The researchers have determined the precise anatomic forms of male and female joints, their cartilage properties, and the stresses and strains that act across the joint during such daily hand functions as grasping a heavy object or pinching a key.
The investigators believe that osteoarthritis arises from the incongruities associated with the saddle-shaped contacting surfaces within the joint. For most individuals, this multiaxial joint is very congruent. For some, however, the joint is incongruent. In general, female joints are more incongruent than male joints. This incongruency causes focal regions of high stress to occur within the joint during daily function. Over time, these high stresses cause cartilage damage and eventual wearing away of this important tissue, leading to arthritis.
"We hope to gain information on how the anatomy of the saddle-shaped joint surfaces are related to the motion of the normal thumb and how the ligaments and tendons surrounding the joint guide normal joint motion," says Dr. Mow. "This information will be useful for surgeons to develop microsurgical techniques to reposition ligaments and tendons around the joint so that the two joint surfaces may make more congruent contact against each other and thus avoid high contact stresses."
The next step in the research is development of precise computer models of a patient's joint anatomy to provide surgeons with precise radiologic imaging data. The computer-assisted surgery project is sponsored by a $2.5 million NIH grant for arthritis research. The National Science Foundation project is in collaboration with engineers and computer scientists at Rensselaer Polytechnic Institute.