The doctor sets it in a splint and prescribes one of these anti-inflammatory drugs (including COX-2 inhibitors) for pain," said Stuart Goodman, MD, professor of orthopaedic surgery at the Stanford School of Medicine and lead author of the study.
"We now know that could actually delay healing."
The enzyme Cyclooxygenase-2, or COX-2, is produced by the body in response to injury or inflammation.COX-2 inhibitors, including anti-inflammatory medications such as rofecoxib (Vioxx), celecoxib (Celebrex) and others, block production of this enzyme.Goodman's research shows that COX-2 inhibitors also impede the new bone growth that normally helps heal a fracture or stabilize a joint implant.
In the tibia bone of eight New Zealand white rabbits, Goodman
team implanted a titanium device called a harvest chamber, which resembles a small screw.The device has a removable, hollow inner core that allows researchers to periodically extract the tissue growing inside.The growth of new bone into the chamber simulates healing of a fracture or joint implant.
Researchers gave the rabbits the following oral treatments for four weeks each: plain water; water with naproxen; plain water again; and sugar-coated pellets of rofecoxib (a COX-2 inhibitor).After each treatment, researchers removed the harvest chamber's core and extracted the tissue growing inside.After preserving the tissue in liquid nitrogen, the researchers sectioned and processed it with special stains including monoclonal antibodies, allowing them to see how new bone had grown back.
While acknowledging the limitations of animal research, Goodman
said this study "has great applicability to humans, because the healing process is virtually the same" for rabbit and human bones.Goodman
is having his
own patients avoid COX-2 inhibitors for six weeks after a fracture or joint implant, and he
recommends other physicians do the same."This research has very practical applications." Goodman
recommended six-week "time-out" period is an educated guess, because his
study didn't address how long the bone-growth-suppressing effects of COX-2 inhibitors last.To answer that question, Goodman
colleagues recently began a follow-up study. Stanford University Medical Center
integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine
, Stanford Hospital & Clinics
and Lucile Packard Children's Hospital
.For more information, please visit the Web site of the medical center's Office of Communication & Public Affairs at http://mednews.stanford.edu.
Editor's Note: The original news release can be found here.
Note: This story has been adapted from a news release issued for journalists and other members of the public.