Medical MEMS tackles knee replacement

Medical MEMS tackles knee replacement

Technology News |
By eeNews Europe

"The high-precision of Analog Devices’ IMU enables our KneeAlign system to perform as well as optical systems that cost $400,000 or more," said Darius Kharabi, OrthAlign’s vice president of corporate development. "Now surgeons can now get virtually perfect alignment with an easy-to-use device that costs a fraction of the price."

The stakes are huge, since more than 675,000 knee replacements are performed every year in the U.S. alone, with trends indicating that as many as 3.5 million Americans will have the procedure performed by 2030, according to the Agency for Healthcare Research and Quality.

Unfortunately, today most knee replacements are performed using antiquated mechanical alignment tools which are imprecise, resulting in a success rate of less than 70 percent, according to Journal of Arthroplasty. Until now, the only alternative was purchasing an optical alignment system to increase success rates. But the instruments are bulky, hard-to-use and expensive, resulting in less than 5 percent of knee replacement surgeons using them.

The OrthAlign medical device uses three-axis gyroscopes and accelerometers in an Analog Devices’ inertial measurement unit (IMU) to guide the surgeon’s scalpel for knee replacements.

The new OthAllign MEMS-based instrument, on the other hand, is small enough to hand hold, cheap enough to throw away after a single use, works in just a few seconds, and is as precise as the optical systems costing hundreds of thousands of dollars more, according to OrthAllign.

OrthAllign was founded in 2008 and has already demonstrated a MEMS-based knee-surgery alignment tool for performing one part of the total knee arthroplasty (TKA) procedure. The company received this month Food and Drug Administration approval for its second-generation KneeAlign instrument, which guides the surgeon when making both the top and bottom severances necessary to remove the natural knee and insert the mechanical one during TKA.

The IMU from Analog Devices was chosen for its high-precision use of three-axis gyroscopes and accelerometers to track knee orientation in real time, according to OrthAllign. After attaching the IMU-bearing module to the natural knee, the surgeon merely moves the natural knee threw its normal range of motion—a procedure that takes less than a minute—after which algorithms uses the precision motion tracking data from the MEMS sensors to calculate exactly where the bones need to be severed. A display on the front panel of the KneeAlign instrument shows surgeons exactly how to adjust their cutting instrument to insure perfect alignment for the artificial knee.

OrthAllign’s MEMS-based KneeAlign instrument is currently being used by the Hospital for Special Surgery (New York) and the Scripps Green Hospital (San Diego), but will be available to hospitals nationwide in the first quarter of 2012.

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