Collagen xenografts for bone replacement: the effects of aldehyde-induced cross-linking on degradation rate.

Collagen was extracted with acid from fresh calf skin, reconstituted and crosslinked with one of four aldehydes, and implanted into surgically created defects in rabbit mandibles. All grafts were histocompatible, with no signs of infection or rejection. There was partial degradation of simple aldehyde cross-linked collagen grafts, with new bone formation evident throughout as early as 4 weeks and complete by 3 to 4 months. The greater the degree of aldehyde-induced cross-linking, the longer the time of degradation, with dialdehyde-fixed specimens not starting to degrade for 6 months and highly cross-linked grafts intact and stable after 1 year. In grafted animals the mandible regained its original contour, while in control animals a defect remained after 1 year.