A person has a tumor¹ removed from her femur（大腿骨） . A soldier is struck by an improved explosive device and loses a portion of his tibia（胫骨） . A child undergoes chemotherapy for osteosarcoma（骨肉瘤） 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 grafted⁴. But a study presented at the Orthopaedic Research Society (ORS) 2012 Annual Meeting in San Francisco offers new hope for those who sustain these traumas⁵（外伤） .

Orthopaedic researchers with the University of California, San Francisco (UCSF), Orthopaedic Trauma⁶ Institute, have found a very promising⁷, novel way to regenerate⁸ bone. "Cartilage graft³ 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 grafting⁹ -- autograft（自身移植物） bone (a person's own bone) or allograft materials (donor bone). For various reasons, these two grafting techniques can result in poor graft integration¹⁰ and osteonecrosis（骨坏死） .

"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 mechanism¹¹."

"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 ossification¹², cartilage grafts¹³ 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 fully² vascularized.

"We're just taking a very similar cartilage that can induce bone formation, putting it into a bone defect and letting it just do its thing," Dr. Marcucio said.

In the study, the researchers chose a non-stabilized tibial fracture callus as a source of a cartilage graft. "Healing of the transplanted cartilage grafts supported our hypothesis by producing a well-vascularized bone that integrated well with the host," Dr. Bahney said.

"A cartilage graft could offer a promising alternative approach for stimulating¹⁴ bone regeneration," Dr. Marcucio said. "Future work will focus on developing a translatable technology suitable for repairing bone through a cartilage intermediate at a clinical level."