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.

LEDs and Medicine: Diffuse Optical Tomography Uses LEDs to Scan Brain

A look at current DOT testing

A look at current DOT testing

According to a report in BioOptics World, scientists at the Washington School of Medicine in St. Louis, Missouri have developed a new way to study the brain, diffuse optical tomography (DOT), a new non-invasive technique that relies on LEDs rather than magnets or radiation. While still experimental, it offers promise for a new non-invasive test for the human brain.

While it looks primitive now, DOT scans use LED light to measure brain activity. For a DOT scan, a subject wears a cap composed of many light sources and sensors connected to cables. A DOT cap covers two-thirds of the head and involves shining LED lights directly into the head. DOT images show brain processes taking place in multiple regions and brain networks, like those involved in language processing and self-reflection (daydreaming). It also avoids radiation exposure and bulky magnets required by positron emission tomography (PET) and magnetic resonance imaging (MRI) respectively.

DOT works best for patients with electronic implants that can be problematic with MRI testing such as pacemakers, cochlear implants, and deep brain stimulators (used to treat Parkinson’s disease). The magnetic fields in MRI may disrupt either the function or safety of implanted electrical devices while DOT doesn’t impact these types of devices.

How does DOT work? According to author Joseph Culver, Ph.D., associate professor of radiology, DOT can detect the movement of highly oxygenated blood flows to the parts of the brain that are working harder when the neuronal activity of a region in the brain increases. He told BioOptics World that, “It’s roughly akin to spotting the rush of blood to someone’s cheeks when they blush.”  According to the magazine, DOT works by detecting light transmitted through the head and capturing the dynamic changes in the colors of the brain tissue.

DOT has a lot of potential benefits for medicine concerning the brain.  Since DOT technology does not use radiation, doctors could monitor progress of patients using multiple scans performed over time without worry. It could be useful for patients recovering from brain injuries, patients with developmental disorders such as autism, and patients with neurodegenerative disorders such as Parkinson’s.

Currently, a full-scale DOT unit takes up an area slightly larger than a phone booth, but Culver and his team have built versions of the scanner mounted on wheeled carts. The DOT device is designed to be portable, so it could be used at a patient’s bedside in the hospital or at home, in a doctor’s office, or even in the operating room in the future.

For more details about DOT, visit:


Nature, Mapping distributed brain function and networks with diffuse optical tomography, (registration required)



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,

IMS Research/Rubicon Technology, White Paper: Opportunities for Sapphire, Jamie Fox,,

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