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Topography, not chemistry, may be most important factor in bone formation
New data suggest that bone surface roughness may 'jump-start' bone growth.
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BOSTON — New insights into nanotechnology and what influences bone to heal may redirect fracture treatments from chemical stimulants to topographic influences.
"One of the myths of bone formation is, 'All we need is more chemistry: Bone will grow anywhere with the right chemical stimuli,'" said Edward J. Harvey, MD, of McGill University in Montreal.
Much discussion occurs in the areas of allograft, autograft and biologic agents, such as bone morphogenetic proteins (BMPs), "but that may be too simplistic," he said.
Harvey made his comments in a premeeting course during the Basic Science Forum at the 23rd Annual Meeting of the Orthopaedic Trauma Association, here.
In an effort to better understand the roles of chemistry and topography, McGill investigators undertook an earlier study, which showed that even a titanium-masked implant with a rough surface had better bone ingrowth than a flat surface. Next, the researchers used nano and micro technologies to study the bone surface at the point of fracture and found a striking similarity.
"Bone breaks in many different patterns, but we found that the fracture surfaces are all very similar," he said. "They all have a very similar micro and nano structure. Material should break differently when it is fractured in different ways, so why is bone always so similar? Probably the reason is that there is an optimum healing response that has been chosen through evolution."
Investigations into surface technologies in total hip arthroplasty have shown that bone ingrowth and ongrowth can be influenced by mimicking the roughness seen at the ends of the bone around fractures, Harvey said.
"There must be something that is in the rough surface that jump-starts bone growth," he said.
To determine whether something can be done to the native bone surrounding a fracture to influence healing, the investigators performed a sham-controlled study on femurs and tibia that had a rough area of bone. "We found there was much more of a reaction on the textured side," Harvey said. However, he acknowledged that many surgeons may not embrace a technique that damages healthy bone.
The research is currently experimental, but future indications may include better treatments for nonunions, difficult fractures and open fractures.
"By using a surface that has a specific pattern, you may be able to elicit a better healing response," Harvey said. "Taking it to the next level, this may pave the way for the development of grafts with different roughness and through manipulation of the nano surfaces, different shapes and different materials to elicit that response."
For more information:
- Harvey EJ. Symposium: Nanotechnology. Presented as a premeeting course in the Basic Science Forum at the 23rd Annual Meeting of the Orthopaedic Trauma Association. Oct. 17, 2007. Boston.