Building Bone from Cartilage

Orthopaedic Researchers Take the Road Less Travelled

A person has a tumor removed from her femur. A soldier is struck by an improved explosive device and loses a portion of his tibia. A child undergoes chemotherapy for osteosarcoma but part of the bone dies as a result.

Every year, millions of Americans sustain fractures that don’t heal or lose bone that isn’t successfully grafted. But a study presented at the Orthopaedic Research Society (ORS) 2012 Annual Meeting in San Francisco offers new hope for those who sustain these traumas.

Orthopaedic researchers with the University of California, San Francisco (UCSF), Orthopaedic Trauma Institute, have found a very promising, novel way to regenerate bone. “Cartilage graft induces bone that actually integrates with the host bone and vascularizes it,” said Ralph S. Marcucio, PhD, Associate Professor, UCSF School of Medicine.

Cartilage graft is very different than the current methods used for bone grafting — autograft bone (a person’s own bone) or allograft materials (donor bone). For various reasons, these two grafting techniques can result in poor graft integration and osteonecrosis.

“With millions of bone grafting procedures performed every year in just the United States, developing improved technologies could directly enhance patient care and clinical outcomes,” Dr. Marcucio said.

Chelsea S. Bahney, PhD, Postdoctoral Scholar, UCSF School of Medicine, concedes their approach is less orthodox. “It is not the pathway that most people think about, but it made a lot more sense to follow the normal developmental mechanism.”

“This cartilage is naturally bioactive. It makes factors that help induce vascularization and bone formation,” added Dr. Bahney. “When people use a bone graft, it is often dead bone which requires something exogenous to be added to it or some property of the matrix in the graft.”

Through a process called endochondral ossification, cartilage grafts produce new tissue that is very similar to the person’s own bone. Without additional properties to it, the researchers found the cartilage graft integrated well and was fully vascularized.