A novel type of implant, Titanium foam, may help improve bone injury treatment, a new study has revealed.
The foam resembles the inside of a bone in terms of its structural configuration. Not only does this make it less stiff than conventional massive implants. It also promotes ingrowth into surrounding bones.
To ensure that the implants bond to their patients' bones on more sustained and stable basis. To do so, however, the bone replacement must be shaped in a manner that fosters ingrowth - featuring pores and channels into which blood vessels and bone cells can grow unimpeded.
The titanium alloy Ti6Al4V is the material of choice. It is durable, stable, resilient, and well tolerated by the body. But it is somewhat difficult to manufacture: titanium reacts with oxygen, nitrogen and carbon at high temperatures, for example. This makes it brittle and breakable. The range of production processes is equally limited.
"The adjacent bone bears hardly any load any more, and even deteriorates in the worst case. Then the implant becomes loose and has to be replaced," explained Dr.Peter Quadbeck of the Fraunhofer Institute for Manufacturing and Advanced Materials IFAM in Dresden.
"The mechanical properties of titanium foams made this way closely approach those of the human bone," reported Quadbeck.
"This applies foremost to the balance between extreme durability and minimal rigidity," he said.
The former is an important precondition for its use on bones, which have to sustain the forces of both weight and motion.Bone-like rigidity allows for stress forces to be transmitted; with the new formation of bone cells, it also fosters healing of the implant. Consequently, stress can and should be applied to the implant immediately after insertion.
The foam is equally suitable for repairing other severely stressed bones.