We tested the hypothesis that when one bone of the skeleton is injured,
others experience an osteogenic response. Although similar or related
phenomena have been observed previously, the purposes of the study were to
determine if this response was reproducible, to characterize it in terms of
its magnitude and duration, and to show how it is related to the type of
injury sustained. To obtain this information, a model was used in which an
intramedullary nail was implanted in the femur and a standard closed
fracture was subsequently produced. The osteogenic response was measured by
histomorphometry. Eight-four nine-week-old male Sprague-Dawley rats were
divided into seven groups of twelve animals each. Groups I and II consisted
of control animals in which no injury was produced. In Group-III rats,
cortical drilling of the intercondylar notch and piriformis fossa of the
right femur was performed, without intramedullary nailing. In Groups IV
through VII, half of each group received intramedullary nails only, and in
the other half intramedullary nailing was done and a closed transverse
diaphyseal fracture was produced. With two different fluorochrome labels,
rates of mineral apposition were measured in the left and right tibiae of
all animals. The labeling periods differed in each group and were designed
to determine when the peak response occurred, how long it lasted, and
whether aging during the course of the experiment affected the
response.(ABSTRACT TRUNCATED AT 250 WORDS)