1. The osteoporosis which rapidly appears distal to a fracture is largely due to stasis.
2. It is frequently stated that the marked osteoporosis seen in the foot and ankle following a tibial fracture is due to disuse. The authors feel that disuse plays little part in the production of this osteoporosis for the following reasons:
A. Roentgenographic evidence of disuse osteoporosis is seen only after many months of immobilization, as has been shown both experimentally and clinically.
B. The intensity of bone absorption is too great to be due to disuse. Even after a year or more of disuse, there is seldom the degree of bone absorption seen a few weeks after a fracture.
C. The character of acute osteoporosis following trauma differs from that of disuse osteoporosis in that the former is irregular and involves predominantly the portion of bone distal to the trauma. Osteoporosis of disuse is homogemnous and diffuse, involving proximal and distal portions alike.