With a growing number of retiring baby boomers, the joint replacement market is also growing.   Medical officials estimate that joint replacement surgeries will increase more than 670% by 2030 — a remarkable total of 3.48 million replacements.   The need for better, longer lasting, and safer joint materials is pressing.   More joint replacements means more risk to infection or rejection by the body.   Two things have been done to create better joints:

•  Alter the joint material composition
  Tradition artificial joints currently being used are made of titanium and titanium dioxide (TiO2).   Though the titanium is lights and strong, the initial bone adhesion as well as long-term resistance to wear could be better.   Research done by Thomas Webster and Hicham Fenniri, professors at Purdue University and the University of Alberta respectively, shows that self-assembled nanotubes positively affect osteoplast adhesion to the titanium.   For a joint replacement to be effective, the artificial joint needs to mesh or bond well with the surrounding bone.   Quick, strong bonds between osteoplasts and the joint are also important for a quicker recovery.   The nanotubes are composed of two common DNA components, guanine and cytosine.   When the two molecules interact, they self-assemble into hexagonal rings.   When the individual rings interact, they assemble into longer nanotube shapes without any external work.   Studies at Purdue show a 30% increase in the number of bone cells adhering to the nanotube-coated titanium over the traditional titanium.  
  
  
•  Change the topology of the material
  Webster's work focuses on the topology of the joint's material.   One advantage of downsizing to the nanoscale is a larger amount of available surface area.   The normal titanium joint surface patterns has dimensions on the micrometer level.   Therefore, when placed into the body, the joint surface appears large or foreign when compared to the bone cells to which it need to bond.   Instead of microlevel patterns, Webster has researched more chaotic, jagged surfaces at the nanolevel.  
  

  Top: Rough surface topology of modified metal surface at the nanolevel Bottom: Smoother surface topology of microstructured metal surface Dimensions are in micrometers Image courtesy of T. J. Webster

  
  The result is a greater surface and better recognition of the material by osteoplasts.   Webster has also shown the titanium dioxide can be combined with zinc oxide (ZnO) to include important anti-microbial properties.