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S U P P L E M E N T T O O U T P AT I E N T S U R G E R Y M A G A Z I N E O N L I N E | A U G U S T 2 0 1 4
Permanente South Bay Medical Center in Harbor City, Calif., who specializes in
adult reconstruction of the hip and knee. Here's a review of some of what's avail-
able.
• Computer-assisted navigation.
With fluoroscopy-based navigation systems, you
tap metal markers into the knee to serve as bony anatomical landmarks,
explains Dr. Navarro. A small series of fluoroscopic images capture these
markers. A software program synthesizes these images to relate the surgical
area in space, and identify the position of the instruments and implants. A step
up from this is 3D fluoroscopy-based navigation, which lets you visualize the
surgical area in the axial plane as if you had an intraoperative CT scanner.
Imageless (radiation-free) navigation systems construct a model that fits the
registered surface points from its many stored CT scans.
"The computer can map the coordinates of this bone in my system so I see
what the true axis of the bone is with respect to the ends of the tibia and
femur," says Dr. Navarro. "I can do surgery in a way that is enhanced. I get a bet-
ter understanding of the angles and directionality when I'm making my guided
cuts."
Few question whether computer navigation improves axial limb alignment
and implant positioning in total knee arthroplasty (TKA) over conventional sur-
gery. And there's anecdotal evidence that it leads to more efficient and faster
surgery. Yet orthopods are still waiting for the evidence that clinical outcomes
are appreciably better when you reduce TKA alignment outliers. Most naviga-
tion system studies show improved accuracy and better post-operative imaging,
but the proof that patients are experiencing less pain and better functionality is
lagging. "Does this make a difference in the patient's outcome? That's still being
debated, but I think you can assume that if you align the knee more consistently,
outcomes probably will follow that," says Dr. Peters.
• Robotics.
The surgeon uses patient-specific 3D computer mapping and an
interactive, handheld robotic arm system to resurface the diseased portion of the
knee joint and replace it with an artificial implant. The robot technology guides
S U R G I C A L N A V I G A T I O N
