TO THE EDITOR:
I enjoyed the article "Treatment of Acute Fractures with a Collagen-Calcium Phosphate Graft Material. A Randomized Clinical Trial" (79-A: 495—502, April 1997), by Chapman et al. I was interested to note that the collagen component of the graft material was purified bovine dermal collagen. There are concerns that bovine spongiform encephalopathy, or mad-cow disease (a prion disease closely related to Creutzfeldt-Jakob syndrome), may be transmitted from cattle to humans. Prion protein is extremely difficult to destroy, and I am interested to know what steps are taken during the production of the collagen graft to ensure that these proteins are not present within the graft material.
Christopher G. Moran, M.D., F.R.C.S.(Ed), University Hospital, Nottingham NG7 2UH, England
Dr. Chapman, Dr. Bucholz, and Dr. Cornell reply:
The production of collagen for injectable and implantable applications is closely regulated to ensure the absence of infectious agents, including bovine spongiform encephalopathy. The collagen is derived from a closed herd of cattle raised on a ranch in California. Bovine spongiform encephalopathy has not been reported in North America. The cattle are born and raised, and live their entire lives, within the closed herd. Their feed is grown on the same ranch, and their diet includes no products of animal origin. The cattle are killed at an abattoir located on the ranch that is used only for this herd. Finally, the collagen is derived only from the hides, which are classified by the European community as a category-IV tissue with no detectable infectivity. We consider that, with these measures, a surgeon using the collagen-ceramic graft can be confident that the collagen moiety of the graft material is not a source of bovine spongiform encephalopathy.
Michael W. Chapman, M.D.: Department of Orthopaedic Surgery, University of California, Davis Medical Center, 2230 Stockton Boulevard, Sacramento, California 95817
Robert Bucholz, M.D.: University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75235
Charles Cornell, M.D.: The Hospital for Special Surgery, 535 East 70th Street, New York, N.Y. 10021