Astute observations led a team of clinicians and researchers to uncover how this drug can also boost our bodies' bone stem cell production to the point that adults' bones appear to have the ability to heal at a rate typically seen when they were young kids.
"The decreased healing time is significant, especially when fractures are in hard-to-heal areas like the pelvis and the spine, where you can't easily immobilize the bone - and stop the pain," Bukata added. "Typically, a pelvic fracture will take months to heal, and people are in extreme pain for the first eight to 12 weeks. This [healing] time was more than cut in half; we saw complete pain relief, callus formation, and stability of the fracture in people who had fractures that up to that point had not healed."
When a fracture occurs, a bone becomes unstable and can move back and forth creating a painful phenomenon known as micromotion. As the bone begins healing it must progress through specific, well-defined stages. First, osteoclasts - cells that can break down bone - clean up any fragments or debris produced during the break. Next, a layer of cartilage - called a callus - forms around the fracture that ultimately calcifies, preventing the bony ends from moving, providing relief from the significant pain brought on by micromotion.
Only after the callus is calcified do the bone forming cells - osteoblasts - begin their work. They replace the cartilage with true bone, and eventually reform the fracture to match the shape and structure of the bone into what it was before the break.
According to Puzas, teriparatide significantly speeds up fracture healing by changing the behavior and number of the cartilage and the bone stem cells involved in the process.
"Teriparatide dramatically stimulates the bone's stem cells into action," Puzas said. "As a result, the callus forms quicker and stronger. Osteoblasts form more bone and the micromotion associated with the fracture is more rapidly eliminated. All of this activity explains why people with non-healing fractures can now return to normal function sooner."
I had patients with severe osteoporosis, in tremendous pain from multiple fractures throughout their spine and pelvis, who I would put on teriparatide," said Bukata. "When they would come back for their follow-up visits three months later, it was amazing to see not just the significant healing in their fractures, but to realize they were pain-free - a new and welcome experience for many of these patients."
Bukata began prescribing teriparatide to patients with non-healing fractures, and was amazed at her findings: 93 percent showed significant healing and pain control after being on teriparatide for only eight to 12 weeks. And in the lab, Puzas began to understand how teriparatide stimulates bone stem cells into action.