Fine-Tuning Computer-Assisted Orthopedic Surgery
BY LAUREN UZDIENSKI, MAY 8, 2007
The National Institute of Standards and Technology announced an initiative last week to improve the precision and reliability of computer-assisted orthopedic surgery (CAOS) instruments in hip replacement surgery. NIST researchers have built a "phantom" hip that can be used by both manufacturers and surgeons to confirm the accuracy of their CAOS instruments prior to surgery. Pending review by a team of orthopedic surgeons, the agency hopes to begin clinical trials on the device, which should help to support assertions that CAOS has the potential to "improve accuracy and reproducibility" in orthopedic surgery. Future applications for the phantom include knee and shoulder.
CAOS offers advantages like reliability, precision and reproducibility, as well as general benefits of minimally-invasive procedures (such as reduced blood loss). There are also concerns with navigation, with the American Association of Hip and Knee Surgeons describing potential disadvantages as increased OR time, additional incisions for attaching reference arrays, increased costs for the equipment, software and OR time, and fractures or infections relating to attaching reference devices to the bone (though the AAHKS points out that this is a less than 1% complication rate.)
Additionally, there is little data regarding surgical outcomes in computer-assisted cases in comparison to more conventional methods. One recent JBJS meta-analysis of navigated knee surgery showed that, across 33 studies, there were few benefits over a conventional procedure and that surgery times were an average of 23% longer. Some specific endpoints, such as the similar alignment of mechanical axes between both navigated and conventional groups, could be addressed by a phantom knee - alignment precision is one of the NIST's goals with the phantom devices, and the precision of those measurements could be one way that CAOS can prove itself beneficial over conventional sugery.
