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Special high-tech glass can outperform rival porous materials and cadaver grafts

A lot of attention has been paid of late to the potential of porous bone implants/grafts as a means of fostering new growth and healing, in the case of serious breaks.  While printed porous plastics have proven an effective technique for non-load bearing parts of the skeleton -- such as the skull -- in limbs (particularly the leg bones) they produce more mixed results.

Load bearing bone repair is today typically handled in one of two ways.  The first approach is to implant a metal mesh, while the second is to graft bone tissue from a cadaver.  The former approach typically does not heal properly, risking a second break, while the latter approach risks rejection by the body.

But researchers at the Missouri University of Science and Technology (Missouri S&T) think they have a solution, which combines the healing capabilities of soft, porous plastic scaffolds with the strength of a metal scaffold.

Their approach involves using silicate 13-93, a porous glass scaffold.  Past studies have shown the pores in silicate 13-93 to readily be replaced with hydroxyapatite (HPA), the key mineral in bone.  Eventually bone-building cells dissolve and replace the scaffold as well.

Silicate 13-93
Silicate 13-93 is strong, but porous, ideal for promoting healing. [Image Source: ScienceDirect]

Silicate 13-93 is an attractive candidate for bone bearing as it offers 300 µm pores -- just the right size for inviting in new growth -- while offering a compressive strength of 142 +/- 20 Megapascals (MPa) [source], similar to the natural compressive strength of 170 MPa [source].

The key is developing a technique to build the implant.

The Missouri S&T team has done precisely that, developing a ceramic deposition process that bears some similarity to 3D printing of polymers.  In the process, the porous implant is built layer by layer into the proper shape using computer controlled ceramic slurry deposition.  This approach insures that the resulting structure has relatively uniform composition and hence no weak points.

The material has passed a key preliminary study, showing significant bone regrowth in rodent test subjects in just six weeks.  The rodents had part of their skullcap removed; yet quickly recovered with the porous glass implant.  Dr. Mohamed N. Rahaman, a materials science professor at Missouri S&T, says that three to six months is a reasonable healing time -- six weeks is terrific.

He comments, "Right now, there is no synthetic material that is practical for structural [load-bearing] bone repair.  You can have the strongest material in the world, but it also must encourage bone growth in a reasonable amount of time."

Silicate 13-93
The printed Silicate 13-93 promoted healing in just six weeks. [Image Source: Missouri S&T]

Dr. Rahaman -- along with Xin Liu, a Ph.D. student in materials science and engineering at Missouri S&T; Dr. Yongxing Liu, an assistant research professor of materials science and engineering; Dr. B. Sonny Bal, associate professor of orthopedic surgery at the University of Missouri-Columbia; and Dr. Lynda Bonewald, Curators' Professor director of the bone biology research program at the University of Missouri-Kansas City School of Dentistry -- have published [abstract] a paper on the skullcap success in the peer-reviewed bioengineering journal Acta Biomaterialia.

They are currently actively engaged in follow-up work.  Most notably, they're testing the big-ticket item -- using the silicate 13-93 process to regrow femur bones in mice.  They're also conducting studies to test the effectiveness of doping the framework with silver to kill pathogens and with copper to promote capillary growth.

If those studies prove successful human trials are likely to soon follow.  That's good news for extreme athletes (as well as everyday folks) worldwide.

Sources: Missouri S&T [press release], Acta Biomaterialia [abstract]



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RE: Mr. Glass
By Monkey's Uncle on 7/30/2013 5:13:49 PM , Rating: 2
Right cross or upper cut.


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