EARLY BONE-MATRIX FORMATION DURING DISTRACTION - A BIOCHEMICAL-STUDY IN SHEEP

Osteotomy of the distal radius and gradual distraction were performed on 20 sheep. Bone matrix synthesized between the osteotomized bone end s was biochemically characterized at 3, 5, 7, and 14 days after the st art of distraction. The deposition of mineral was negligible during th e 14-day period. No change was observed in the amount of organic matri x, which comprised 15 +/- 1.4 percent of the wet weight of the tissue. The amount of total protein of the wet weight in the matrix increased from 4.6 to 7.6 percent between 5 and 7 days of distraction. During t he first 7 days, the nonprotein component decreased from 11 to 7.3 per cent. The proportion of collagen of the total matrix protein increased gradually from 29 to 59 percent. In view of the patterns of the cyano gen bromide peptides of the matrix proteins, the heteropolymer type I[ 1(I)(2)2(I)(1)] collagen was consisted to be the principle fibrillar c ollagen synthesized in the distraction gap. The results suggest that t ension-stress markedly affects the synthesis of fibrillar collagen tow ards the formation of mature bone matrix. In this process, a prelimina ry lag phase probably exists during which the capacity for protein syn thesis is low while the synthesis of Type I collagen has started. In t he secondary phase an augmented synthesis of Type I collagen takes pla ce.