FIG. 6.

Bridged teriparatide (PTH)-treated specimens demonstrate a prototypical brittle bone torsion behavior. Scaffold-grafted femurs were harvested at 9 weeks, imaged via micro-CT, and then tested in torsion at a rate of 1°/s. The representative torque-normalized rotation curve shown demonstrates that teriparatide-treated samples that developed a bridging union exhibit a torsion behavior characteristic of bone with clearly defined linear region (dashed line), yield (open arrow), and ultimate failure torque (closed arrow), and a relatively brittle fracture. In contrast, nonunion specimens for the most part did not have defined failure points and were quite ductile. Color images available online at www.liebertonline.com/ten.