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Does computer navigation make life easier?
Bulky devices, rotating trackers and jumpy images may cause problems in the OR.
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Proponents of navigated surgery argue that computer-assisted systems improve implant positioning, but for the everyday surgeon, the technology may sometimes bring more confusion to the operating room.
Martin Sparmann, MD, an orthopaedic surgeon with the Immanuel Hospital in Berlin, has used navigation systems for six years. He said that problems often stem from device quality, software and workflow. Some computer-assisted orthopaedic surgery systems consist of bulky parts.
“Do you need 15 hands to bring the navigation device in the right position, and how do you perform the surgery then?” Sparmann said during his presentation at the 7th European Federation of National Associations of Orthopaedics and Traumatology Congress.
Limited choices
During an operation, surgeons’ hands are occupied, leaving orthopaedists with limited choices to operate navigation systems. Ironically, the worst choices in systems, according to Sparmann, are those that use foot pedals.
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![Martin Sparmann, MD [photo]](/~/media/images/news/print/orthopaedics-today-europe/2005/09_september/sparmann_70_90_3896.jpg)
“A foot pedal is a catastrophe in our way of surgery because we are constantly moving back and forth in the operating room,” Sparmann said.
Bone or instrument trackers can also create headaches. When touched, the trackers rotate, which negate their purpose.
“Is the issue to fix the tracker or is the issue to perform a knee arthroplasty?” Sparmann said. Consequently, he advises using removable trackers.
Computer-assisted orthopaedic surgery (CAOS) systems that require extensive instrument calibration waste precious operating room time and money, according to Sparmann.
“Many of you, when you spend your time calibrating your instruments and the tourniquet is on the patient for 30 minutes, understand that this is not the way you would like to perform and navigate the surgery,” Sparmann said.
He also cited passive optical systems as “very dangerous” because they can deflect and lose contact with cameras.
In addition to hardware issues, surgeons may experience trouble interpreting software data or controlling workflow. Navigational software produces a complex kinematic analysis that may prove difficult to understand.
“All of these numbers [distract] surgeons because they are not able to concentrate on the patient’s knee, and they are not able to concentrate on all the analysis the computer is providing,” he said.
Many CAOS systems also include screens that are so complex, “they resemble helicopter consoles,” he joked.
The numerous diagrams and readings make it tricky to determine anatomic parts and differentiate between medial and lateral positions.
Workflow problems can occur when systems drive operating procedures, placing surgeons in the backseat.
“Workflow is, in the end, the most important question because workflow means, ‘Is the computer system forcing you to do things you don’t want to?’” Sparmann said.
For example, systems may have software that advocate starting with a distal femoral cut, while the surgeon may, in fact, prefer to start with an interior femur incision. Consequently, it is critical that surgeons can manipulate and set system settings, he said.
Fluoroscopic methods
Fluoroscopic navigation systems may also prove cumbersome for some orthopaedic surgeons.
“We worked with [fluoroscopic devices] for one year and we are happy that we could quit them,” Sparmann said.
The devices require surgeons to wear heavy coats that protect from radiation.
Given the number of daily arthroplasties a surgeon performs, such a heavy coat becomes impractical, he said.
The hefty C-arm used in procedures can also be a problem. “And when you use the C-arm, you lose contact between your trackers and the camera system,” Sparmann said. “That means, when you’re working with the fluoro system, one of your assistants has to run around the OR with a camera. That’s not always practical.”
The software for these systems can produce “jumpy” images because the instruments are sensitive, Sparmann said.
Unstable connections between system handles and instruments could result in inaccurate guidance.
“The problem is that the connection between the handle and the instrument is a little bit weak, and that means that the computer is analyzing the tip of your instrument somewhere else,” he said. “In our hospital the Stryker navigation device is in clinical practice nearly every day.”
Sparmann said the system was developed between 1996 to 2001. Sparmann’s team supported the development of this “active, working system” that can be used in revision surgeries.
“The instruments are smart, they are cableless, the screen is easy to understand, the mathematics are easily explained and show you clearly the intraoperative measurements,” he said. “Prospective, randomized and externally evaluated studies could show that there is a big improvement in total knee arthroplasty with the support of this navigation device.”
For more information:
- Sparmann M. Are all CAOS systems equal? Symposium #23. Presented at the 7th European Federation of National Associations of Orthopaedics and Traumatology Congress. June 4-7, 2005. Lisbon, Portugal.