Impaired fracture repair in patients with type 2 diabetes mellitus (T2DM) is not fully understood. In this study, we aimed to characterize the local changes in gene expression (GE) associated with diabetic fracture. We used an unbiased approach to compare GE in the fracture callus of Zucker diabetic fatty (ZDF) rats relative to wild-type (WT) littermates at three weeks following femoral osteotomy. Zucker rats, WT and homozygous for leptin receptor mutation (ZDF), were fed a moderately high-fat diet to induce T2DM only in the ZDF animals. At ten weeks of age, open femoral fractures were simulated using a unilateral osteotomy stabilized with an external fixator. At three weeks post-surgery, the fractured femur from each animal was retrieved for analysis. Callus formation and the extent of healing were assessed by radiograph and histology. Bone tissue was processed for total RNA extraction and messenger RNA (mRNA) sequencing (mRNA-Seq).Aims
Methods
The tibial nutrient artery supplies 62% of cortical blood flow in the diaphysis and normal blood flow is centrifugal (Willans 1987). Intramedullary reaming destroys the nutrient artery and injures the endosteal surface of the cortex. Trueta (1974) suggested that the direction of blood flow can reverse from centrifugal to centripetal after loss of the endosteal supply. We examined this hypothesis by measuring cortical and periosteal blood flow after intramedullary reaming of the tibia in eight sheep, using 57Co radiolabelled microspheres. The unreamed contralateral tibiae served as a control group. Thirty minutes after reaming there was no significant change in cortical blood flow, but a sixfold increase in the periosteal flow. Our study confirms Trueta's hypothesis; after trauma or in other pathological states, flow can become centripetal.
