An experimental study on free autogenous bone transplantation including a growth zone--effects of age factor on growth capacity.

An experimental study was conducted to determine how age affects growth capacity and development of a growth zone in cases of free autogenous bone transplantation. Using immature Japanese white rabbits, the second metatarsus was removed together with the epiphyseal cartilage and a small portion of the surrounding soft tissues, and was implanted under the skin of the foreleg. Animals were divided into a 1-week-old group, a 2-week-old group and a 4-week-old group, and these groups were studied comparatively by periodic radiography, histopathology, and microangiography. In terms of bone length, a notable growth capacity was observed in the 1-week-old group, but was reduced in the 2-week-old group, with no growth being seen in the 4-week-old group. The width of the bone was reduced in all groups. In clinical applications of this technique, it is preferable to operate as soon as possible after birth. Moreover, transplantation should be carried out before the appearance of the epiphyseal nucleus of the donor for best bone growth.