Description
mRNA gene expression was measured in intact female Sprague-Dawley rats at 6 (young), 26 (adult) and 52 (older) weeks of age at the time of fracture. Samples were collected at 0, 0.4, 1, 2, 4, and 6 weeks after fracture. RNA from two rats were pooled for each Affymetrix Rat U34A array. Mid-shaft, simple, transverse left femoral fractures were induced after retrograde intramedullary rod fixation with a Bonnarens and Einhorn device. Samples were collected from one third of the femoral length, centered on the fracture site, including the external callus, cortical bone, and marrow elements.