The ideal bone screw: naturally "organic", but nevertheless strong

There is hardly a medical field that does not use an implant of one kind or another, from dental to ENT medicine to orthopedics and, of course, accident surgery. Easier said than done since the challenge in bone surgery is to make an implant strong enough to stabilize fractures, for instance, but which will dissolve over time, eliminating the need for its surgical removal. Magnesium implants do just that. The latest innovative implant developments will be showcased at the trade fair MEDICA, world forum for medicine (to take place from November 16 - 19, 2011 in Düsseldorf, Germany) and at the parallel held trade fair for the medical supplier industry COMPAMED - High tech solutions for medical technology (November 16 - 18, 2011).

Implants such as those successfully used for decades in orthopedic and accident surgery should, in general, meet multiple criteria such as:
• must have a surface that will readily grow into one with the bone,

• must be biocompatible and not release any toxic substances,

• must be bioresorbable, being replaced with the body's own tissue,

• must be able to withstand sterilization without losing any positive properties

• must be porous enough that cells and blood vessels can grow into it,

• and must be mechanically stable so that patients can use their limbs as soon as possible after the surgery.

Still a great challenge

"Despite all efforts, there is still no implant or bone replacement material that completely fulfils all these criteria," says Dr. Sascha Heinemann of the Max Bergmann Center of Biomaterials at the Technical University of Dresden.

Decisive for implant quality is not only the correct choice of material but also an optimal surface structure. For instance, the biocompatibility is clearly determined by the roughness of the surface. This also applies for dental implants, whose roughness in the nanometre range (billionths of a meter) determines its protein binding capacity and consequently how fast it will grow into the jaw bone. In light of this, Alicona Imaging GmbH (exhibitor at COMPAMED) has developed an innovative 3-D surface measuring technology that is excellently suited for the surface characterization of implants. "Cost-efficient measuring means analyzing all the relevant parameters with a single system, and that's exactly what our InfiniteFocus does," explains Dr. Stefan Scherer, CEO of Alicona Imaging GmbH. It combines the options of a roughness and a shape-measuring device, thus providing all the functionalities of an optical profilometer and a micro-coordinate measuring machine. Even with complex shapes and different material properties, the user obtains a resolution of up to 10 nanometres and that even over large vertical and lateral scanning areas. For complete measurement of the shape, it has an optional rotation unit that turns the sample 360°. "We know of no comparable optical measuring system that provides such substantiated information on roughness, even over wide measuring ranges," confirms Dr. Frank Rupp, Head of the "Interface analysis of medical materials" team at the Tübingen Polyclinic.

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