Scientists uncover unexpected method of bone regeneration, opening doors for osteoporosis treatment

Our bodies completely overhaul our bones every seven to 10 years, breaking down old or damaged bone tissue, and replacing it with new bone. Experts have long thought there were four processes through which bones regenerate.

Now researchers from the University of Saskatchewan (USask) and the University of Southern Denmark (SDU) have discovered a fifth way that tissue rebuilds in specific parts of some of our bones. What they found, using the Canadian Light Source (CLS) at USask, deepens our understanding of bone health and could lead to new bone-strengthening treatments for osteoporosis.

Trabecular bone, also known as spongy or cancellous bone, is the porous, honeycomb-like tissue found at the ends of long bones (like the thigh bone) and in the center of flat and irregular bones (like vertebrae of the spine). It makes up roughly 20% of the adult skeleton and is vital for absorbing shock and supporting joints. It had long been assumed the holes or canals in trabecular bone visible on biopsies was evidence of bone loss caused by chronic kidney disease or disorders related to parathyroid hormone, which controls calcium levels in our blood.

Lisbeth Thomsen, a postdoctoral fellow at USask, says she and her colleagues were curious whether the holes were simply a sign of kidney disease or overproduction of the parathyroid hormone, or whether something else was happening. 

“We wanted to see what is going on because it looked like it was actually maintaining bone in a way that has never been described before,” says Thomsen. “It looked like the bone was actually renewing itself from the inside, which it is not supposed to do in the trabecular bone.”

The research team – which included professor David Cooper, a USask expert on bone aging and disease, and Thomas Andersen, a professor in the Department of Clinical Research at the University of Southern Denmark – used the ultrabright synchrotron light at the CLS to watch the bone tissue regeneration happening in real time in a healthy, live rabbit; Rabbit bone is remarkably similar to human bone. The findings are published in the Journal of Bone and Mineral Research.

By reviewing bone biopsies, the researchers determined that this bone regeneration process is normal in people of all ages, from young adults to the elderly. They speculate that it’s a naturally occurring process that might actually make our bones healthier, “because it removes micro-damaged bone that is not as strong as newer bone will be.”

Thomsen says the team’s findings suggest the remodelling process should be monitored in people with osteoporosis or high levels of parathyroid hormone. The development of holes in the tissue appears to switch into overdrive in people with these conditions.

Thomsen hopes other researchers explore how vitamin D supplements and parathyroid hormone drugs affect deep bone remodeling. Her research group are building on this work by studying the tissue regeneration in people with kidney disease -- which is known to affect skeleton health.

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Thomsen, Lisbeth Koch, Kaja Søndergaard Laursen, Tanja Sikjær, Jesper Skovhus Thomsen, Christina Møller Andreasen, Lindsay Loundagin, Kim Harrison et al. "Intratrabecular bone remodeling—a previously overlooked mode of remodeling hyperactivated by parathyroid hormone." Journal of Bone and Mineral Research (2026): zjag081. https://doi.org/10.1093/jbmr/zjag081

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