Joined: 16 Mar 2004
|Posted: Mon Aug 31, 2009 10:59 am Post subject: Artificial Implants for Joint Replacement No Longer Hip
Each year artificial implants, mostly made of titanium metal, are inserted into the hips and knees of thousands of individuals world wide. But Australian researchers have now created an implant made of real bone, which could make artificial implants a thing of the past.
Scientists from Murdoch University created a mineral powder made of the main component of bone - a ceramic called hydroxyapatite. The powder is created using nanotechnology, in which scientists work with sub-microscopic molecules to solve some of the biggest implant problems.
The new implants can be moulded into any shape, and because they are made of a substance already recognised by the body, they are accepted faster than traditional substitutes.
Dr Gerard Eddy Poinern, Head of Murdoch University's Applied Nanotechnology Research Group (MANRG) said his team's nanotechnology would replace the traditionally used titanium plate with a plate of nanohydroxyapatite that is more easily accepted by the body.
One of the risks associated with joint replacement surgery is the possibility of infection around implanted joints, and the need to remove the implant if traditional methods such as antibiotic treatment are unsuccessful, often causing long-term problems.
Dr Poinern said mixing nano-hydroxyapatite with antibiotics would attack bacteria as it was released, treating infection. “In the case of nanohydroxyapatite, you can dose it with antibiotics so when the bacteria comes in, it releases antibiotics and there is a stronger chance of the implant being accepted by the body,” Dr Poinern said.
As Hydroxyapatite is the main component of inorganic material found in bone, Dr Poinern said his team's new recipe of nanohydroxyapatite would have an easier biocompatibility and bioactivity, allowing the body to repair itself much faster.
“When it's put into the body, the body recognises it and will try to grow into it, accepting it quite well compared to other implants,” Dr Poinern said.
“The beauty about this is because it's in nanoform, like a powder, you can then shape it into screws, plates or any form you require.”
Mr Ravi Brundavanam, who is supervised by Dr Poinern and Dr Zhong Tao Jiang at the MANRG, played a major role in pioneering the new chemical recipe to make nanohydroxapatite, as part of his honours project.
“The point for us was to look at whether we could make the nanobone in a different way, so we came up with a new recipe for making it,” Dr Poinern said.
“Now that we have a prototype, we will look at the properties of this nanohydroxyapatite compared to the micron size hydroxyapatite.”
Dr Poinern said further research would map out the nanohydroxyapatite's strength and load-bearing properties, and hopefully link with a medical field collaborator to test its compatibility.
. “We know bone is made up of little rods of hydroxyapatite so we have manufactured that and created a powder that you can shape into any form to fix fractures,” Poinern said.
To create the millions of nano-hydroxyapatite for the implants Dr Poinern's team worked with spheres just 37 nanometres long, combining chemicals such as calcium nitrate and hydrogen phosphate, which when heated under ultra-sound waves formed tiny mineral spheres
The president of the Australian Orthopaedic Association John Batten said the science behind creating nano-hydroxyapatite was new, but it could become a great tool for orthopaedic surgeons.
"It has great potential for prosthesis, for implants and for fracture healing and other things we do to the skeleton," he said.
While nanotechnology offers an infinite way to improve the world from making space-flight more practical to improvements in medicine, food and technology – the implications of controlling matter at an atomic level is much debated.
Concerns about toxicity, environmental and health impacts as well as the effect of nanotechnologies on global economics have sparked doomsday predications.
Everyday products from car parts to sunscreens already contain nano-particles and advocacy groups such as Friends of the Earth are calling for better government regulation of the new technology.
The MANRG team has several ongoing projects in the nanotechnology field, including the use of iron nano-particles to remove nitrates from fertilisers, nano-polymers to deliver anti-stroke drugs and nano-skin for scarless skin regeneration. Dr Poinern said his nano-hydroxyapatite was still a few years from being implanted in anyone. ``Part of the journey ahead is to figure out its applications and to work out its toxicity,'' he said.