CONTACT: JENNIFER BROWN
Iowa City IA 52242
(319) 335-9917; fax(319) 384-4638
Release: Nov. 26, 2002
UI orthopaedic surgeons to receive national award
decades of research leading to important improvements in total hip replacements
have earned a University of Iowa professor of orthopaedic surgery and biomedical
engineering and his colleagues the Orthopaedic Research and Education Foundation
(OREF) Clinical Research Award from the American Academy of Orthopaedic Surgeons
John Callaghan, M.D., the Dr. Lawrence and Marilyn Dorr Endowed Chair for
Hip Reconstruction and Research, will be presented with the award and $20,000
at the AAOS annual meeting in February 2003.
The award, which was established in 1994, recognizes outstanding clinical
research related directly to musculoskeletal disease or injury. It is one
of four awards for orthopaedic research presented annually at the Kappa Delta
"We are honored to receive this very prestigious award," Callaghan
said. "The UI's Department of Orthopaedic Surgery has a long tradition
of receiving both the OREF award and Kappa Delta awards and we are proud to
continue that tradition."
Callaghan will share the award with his UI colleagues, Douglas Pedersen,
Ph.D., research scientist in orthopaedic surgery, Richard Johnston, M.D.,
professor of orthopaedic surgery, and Thomas Brown, Ph.D., the Richard and
Janice Johnston Chair in Orthopaedic Biomechanics and professor of engineering
and biomechanical engineering, for their work on the clinical biomechanics
of wear in total hip replacement.
Callaghan and his colleagues contributed to the important discovery that
wear at the bearing surface between the artificial ball and socket is the
most important factor determining long-term durability of hip replacements.
The researchers followed 4,000 hip replacement patients over a span of 30
years and used a unique combination of clinical studies and biomechanical
models to identify causes of hip replacement failure.
"Our studies have shown that at 30 years, about 30 percent of patients
have had a failure and many times the failure is related to wear of the bearing
surface," Callaghan said. "As we saw the problems, we developed
models to explain the failure modes."
Wear of the bearing surface produces small particles, which cause a biologic
response of bone resorption (a process known as osteolysis). Osteolysis is
a major cause of hip replacement failure.
The UI researchers were the first to show that wear is related to how much
the ball of the artificial hip has to slide across the socket. They also discovered
that the debris can get into the joint and cause accelerated wear. In addition,
models developed by the researchers showed that contact between the socket's
cup corner and the neck of the ball can cause high stresses and failure.
"Through this accumulated knowledge we have learned to redesign hip
replacement components," Callaghan said. "Surgeons now use as small
a head size as possible and we try to eliminate anything in the system that
will cause third-body particulate debris. Manufacturers have also redesigned
the head-neck junctions to prevent impingement on the cup corners."
The novel biomechanical models and techniques developed during this work
also are useful tools for evaluating new bearing surface designs.
"This recognition of research excellence is richly deserved,"
said Joseph A. Buckwalter, M.D., UI professor and head of orthopaedic surgery,
and a researcher and staff physician at the Iowa City Veterans Affairs Medical
Center. "Dr. Callaghan has earned international renown for his expertise
in hip and knee surgery and for his critical contributions to research and
education. This award appropriately recognizes the work of Dr. Callaghan and
his colleagues that forms the foundation for improvements in total hip replacement
that will benefit millions of people with severe hip arthritis."
Callaghan earned his medical degree from Loyola Medical School and received
his bachelor's degree from Notre Dame University, majoring in science and
engineering. After completing his residency in orthopaedics at the UI, Callaghan
moved to New York for a year to undertake two fellowships, one in orthopaedic
surgery at Memorial Sloan-Kettering Cancer Center and one in hip surgery at
the Hospital for Special Surgery. Callaghan also was a faculty member at Duke
University before returning to the UI as an associate professor of orthopaedic
surgery in 1990. He was promoted to professor in 1993. Callaghan also is a
researcher and staff physician at the Iowa City Veterans Affairs Medical Center.
Stuart Weinstein, M.D., UI professor and the Ignacio V. Ponseti Chair in
Orthopaedics, won the OREF Clinical Research Award in 1998. Members of the
UI Department of Orthopaedic Surgery also have received Kappa Delta awards
in 1956,1971,1972,1980, 1982 and 1986. For more information on the AAOS's
Kappa Delta/ OREF Clinical Research Awards visit http://www.aaos.org/wordhtml/research/comittee/research/rsrch_6.htm
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