Sapphire Hips

More than 7 million people in the United States alone are currently living with knee or hip replacements, 2.5 million of which have had total hip replacement (THR) surgeries, according to Mayo Clinic researchers.

While current metal-on-metal and ceramic endoprotheses have had a dramatic effect on mobilizing this fairly large segment of the population, these replacements must be replaced again after 15 to 30 years and have even been known to fail in just a few years.

Sapphire is breaking ground in the medical industry after having been successfully implanted into the hips of five patients.

Of this small experimental group, none have reportedly shown any complications since the implants were put in five years ago. Having long been considered an attractive material for artificial joint replacements, the success of these clinical trials proves sapphire has a promising future for use inside the human body.

One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Amongst other characteristics, extensive research has shown that durability and bio-inertness are necessary traits of materials used in hip replacements. The Ukrainian Academy of Medical Sciences, Kharkov, has been studying sapphire friction pairs, which prove to fit the bill.

Made from highly purified materials with crystals grown at 2,100℃ in a vacuum, sapphire friction pairs are aluminum oxides in the purest form have no porosity or grain boundaries. Under such conditions, additional purification of the material takes place and the content of the main substance (aluminum oxide) achieved is 99.99%.

These extremely pure sapphire friction pairs hold the following physical advantages over metal and ceramic endoprostheses:

  • Hardness
  • Durability
  • Biochemical inertness
  • Biocompatibility
  • Low friction coefficient
  • Extraordinarily high wear capacity
  • Availability at a low cost
  • Optical transparency

These characteristics make sapphire not only suitable for artificial bone replacements, but also other external medical applications, such as implants and braces. As clinical trials of the material continue, it is clear we are just scratching the surface of sapphire medical applications.

New Applications for Sapphire: Medical (Part 2 of 3)

rod of asclepiusNew industries are finding man-made sapphire a desirable material. The field of medicine is looking at sapphire for its optical transmission range, durability and chemical inertness for bio-compatibility.

Sapphire’s optical properties and durability offer advantages for specific medical laser applications in dermatology, ophthalmology and dentistry. Sapphire is widely used in surgical systems for its laser transmission, high resistance to heat and non-thrombogenic properties (meaning it doesn’t promote clotting).  It is used as a laser window for endoscope lenses, laser hair removal systems and blood cell counters.  In addition, sapphire products are used for surgical tools, implants, braces.  Sapphire microscalpels are transparent blades that make it easier to visualize and illuminate capillary vessels, nerves, cutting zones and cutting depth compared with traditional metal alternatives.

One area that has potential for sapphire is in artificial joint replacements.  Many joint replacements include metal, ceramic, metal-polymer and ceramic polymer endoprosthesis. This is an area that may develop friction and wear over time causing the joint to fail.  Endoprostheses made of metal and ceramics may interact with the body and also degrade from friction over time.  For example, metal-on-metal artificial hips have a lifetime of 15 to 30 years, but have been known to fail earlier.  Sapphire is attractive for endoprostheses for its bio-compatibility since it is chemically inert and won’t react with the body as well as its low friction coefficient, hardness and durability

For Further Reading

The New York Times, The High Cost of Failing Artificial Hips, http://www.nytimes.com/2011/12/28/business/the-high-cost-of-failing-artificial-hips.html?pagewanted=all

IMS Research/Rubicon Technology, White Paper: Opportunities for Sapphire, Jamie Fox, http://rubicontechnology.com/resources/papers,

Sapphire: Material, Manufacturing, Applications, by E. R. Dobrovinskaya, Leonid A. Lytvynov, V. V. Pishchik. Springer Sciences Business Media, ISBN: 978-1441946737.