June 4, 2014 | Revolution in the operating room: A combination of novel navigation and positioning, using infrared light instead of x-radiation, offers a high degree of minimal invasiveness. The patient benefits can be striking.
Text: Eric Johnson
Photos: Anna Schroll
Lose a limb or lose a life – this was the worst-case dilemma confronting Georg M., a 47-year-old man from Stuttgart, Germany. His pelvis had become riddled with a rare, malignant tumor – an osteosarcoma – which threatened to kill him. Conventional surgical procedure would require removal of nearly half his pelvis, which would likely ward off imminent death, but at the same time possibly render it incapable of proper function.
Finding The Best Approach
Faced with the choice of avoiding the grave to end up potentially in a wheelchair, most patients would have to accept this quasi-Faustian bargain. But Georg M.’s doctor instead referred him to the University Clinic of Ulm, a sprawling medical center to the south of Germany, with 1,100 beds, over 5,000 staff, and a world-class department of orthopedic traumatology, hand, plastic, and reconstructive surgery. There, thought the referring physician, lay the patient’s best chance of beating both perils: death or a destroyed pelvis.
And sure enough, everything changed when Georg M. was put in the care of the department’s chief. Dr. Florian Gebhard came forward with a radically different approach to handling the patient’s problem: “I thought we could eliminate the cancer and still keep the patient walking.”
The Operating Room of the Future
If anyone were to have foresight into complex surgeries, it ought to be Gebhard. The MD and PhD was already famed as a pioneer before he became Department Director in 2007. His specialty: the hybrid operating room (hybrid OR).
Of course it has some features standard to a conventional OR such as surgical and instrument tables, an anesthesia work-station, and ventilation equipment. But it also hybridizes into an imaging center that is used for positioning (and monitoring) during actual surgeries. Even more high-tech is the addition of a navigator – a machine that maps out body internals and surgical kit in three-dimensional detail.
High-Tech Advantages
The brilliance of the positioner-navigator combination is three-fold. First, it allows the positioning of the patient and the operating instruments to be determined within a tolerance of 1 millimeter. Second, it allows any given position to be stored and recalled, as many times as might be required. Third, it executes positioning and re-positioning with the use of infrared light (IR) rather than x-radiation.
The Hybrid Operation Room – Set-up and Potential for Clinical Use
What it is: Filled with tricked-out versions of conventional items (such as operating tables made largely of carbon, so as to not to leave artifacts in images) plus real-time scanner/positioners and navigators.
What it can do: Conduct surgery within a tolerance of 1 millimeter, which is especially valuable in sensitive areas such as the brain, spine, and pelvis, with both minimal invasiveness and minimal radiation to patients and staff.
What it means for patients and healthcare providers: Less time spent in the operating room, fewer operations, and more success from any necessary procedures – resulting in more value for money and higher patient satisfaction.
Maximized Minimalism
The benefits are all about minimalism. Due to ultra-precise positioning, hybrid ORs offer a high degree of minimal invasiveness. By relying on IR and fluoroscopy when possible, they make the most out of three-dimensional scanning, but with minimal exposure to radiation. Finally, by bringing sophisticated scanning directing to the OR, they minimize the length and the number of procedures required. If, say, a screw were to be placed improperly, this can be detected and corrected immediately, rather than in a post-op scan that would lead to a further session under the knife.
Weighing Costs and Benefits
These kind of medical results come at a cost. Gebhard concedes that hybrid ORs are expensive, but contends that they can well justify their value. First, minimizing duration and numbers of procedures is a direct reduction in hospital operating costs. Second, in complex cases, increased precision in itself can deliver better – thus more valuable – results. Third, as he puts it: “A hybrid OR can be a strong draw in an increasingly competitive market.”
Playing Now, at an (Operating) Theater in Ulm
The University Clinic in Ulm is the first to have both an Artis zeego® positioner and a Brainlab Curve™ Navigator in one operating room. The typical workflow is described in the following steps.
Click on the boxes below to read more on each step.
Positioning
The patient is placed with his feet facing the anesthesiologist (face down for spine and posterior pelvis), on an operating table specially designed to minimize scanning artifacts. Foam cushions with openings below for ventilation and anesthesia tubes allow the patient to lie comfortably. Then, the surgical team goes through a ‘dry run’ of all pending procedures, Gebhard notes, making sure that all required positions can actually be reached in reality. Two-dimensional fluoroscopy is used to locate the surgical targets initially. Gebhard likens this use of the fluoroscope to the use of a ‘scout’ in CT scanning to deliver preliminary images of an area of interest. Particularly beneficial in this step is the size (30x40 cm/15x17 inches) of the detector screen: the entire thoracic spine can be visualized in a single fluoro-shot.
Collision Check
Again this is a dry-run; this time for the c-shaped robotic arm that holds the imaging equipment. The arm is put through all the paces of the upcoming surgery in a non-scanning mode to ensure that it will not bump into the patient, the table or any of the associated kit around it. During this step, the patient is still un-scrubbed and un-draped, allowing any repositioning to be done at this point with the minimum complication. This saves potential time loss and worse. Gebhard notes that if a scrubbed and draped patient must be repositioned (then re-scrubbed and re-draped), this can take an extra half hour. In extreme cases – for example, if the skin has already been opened so the patient can no longer be moved – the entire procedure might need to be aborted.
Patient Preparation and Referencing
To keep all avenues clear for the scanner, patients are wrapped in drapes similar to a mummy or an egg-roll. After an initial incision, the dynamic reference base (DRB) is clamped firmly to the patient’s bone. The DRB, an array of three marker spheres linked by metal rods, is a ‘rigid body’ by which the navigator plots positions. The navigator’s IR camera triangulates (also attached in a further step to the navigation tools) exact locations of all the critical items from the spheres – namely the patient’s internals and the surgical implements. During surgery, the reflective markers need to be visible to the infrared camera, because highest precision can be achieved only when all markers are clearly detected.
3D-Run and Automated Data Transfer
Now the robotic arm of the angiography system goes into action with 3D mode turned on, usually in a 5- or 6-second protocol. The data is then shipped to the navigator in less than a minute without any manual intervention. “The speed and simplicity are remarkable,” Gebhard notes, adding that less-sophisticated systems require a complicated sequence of computer coding. In such cases, because the surgeon is already sterile, he or she must dictate that coding to an assistant. This can take five or even ten minutes longer.
Accuracy Check and Referencing of the Navigation Tools
This is where the surgeon lines up his “top-gun shots,” as Gebhard puts it. Using its IR camera and the DRBs mounted on the patient and the tools, the navigator plots all important locations on the map provided by the 3D scan.
Operation and Verification
With everything in position, the real surgery begins. In procedures involving multiple screws, these can be placed in rapid succession, one after the other. Positions already stored can be simply recalled, holes drilled, screws placed, and onto the next one. This is in sharp contrast with conventional procedure, Gebhard points out, where scanners need to be re-run periodically to get positioning just right. Before suturing, the robotic arm takes a verification pass over the patient, letting the team check whether all positions were in fact accurate – and giving a chance to re-work any that were not.
Have Your Cake and Eat it, too
The applications of this cutting edge positioning-navigation duo are numerous. In neurosurgery, it is especially useful in treating cerebral aneurysms and arteriovenous malformations. In complex spinal repairs – for instance, insertion of pedicle screws – the combination system is unparalleled. Facial reconstructions and oral biopsies are another key area of use, along with pelvic surgery and tumor resection – which is precisely the dual challenge faced by Georg M. “It is very useful,” says Gebhard, “when the work has to be very, very precise.”
Right to the Point with Ultra-Precise Surgical Navigation
His solution was elegantly simple. After imaging and positioning ultra-precisely with the navigator, he slotted a single screw to pin together the ilium to the sacrum, thereby reinforcing two of the key ‘ring’ bones in the pelvis. The tapped cylinder added strength to what would ultimately be a weakened pelvic structure.
Then, after prepping with the same set-up tools once again, he carefully carved out the diseased bone from the ilium, right down to the 1-centimeter safety margin prescribed in such cases. Without such an exact set-up, he notes, such a precise cut would not have been possible.
Less Stress for the Patient
The stability of the post-op pelvis would have been too compromised for the patient to walk. Reconstruction of the pelvis would have required additional surgery – perhaps even multiple operations – that would not only have pushed the budget, but have taken many months more to heal, with a considerable risk of afterwards walking with a painful limp or perhaps not walking at all. Instead, Georg M. went from the hybrid OP straight to rehabilitation. After intensive physical therapy, he emerged with full use of his leg.
Next-Level Surgery
Hybrid OR, with its double team of positioning and navigation, takes surgery to the next level. As Gebhard puts it, “the hybrid OR integrates optimally all steps in a surgery: planning, transmission of planning data to the OR and the navigator, navigation itself, and post-operative documentation – all without leaving the table. This eliminates time-consuming data-transmission steps and avoids possible incompatibility. At the same time, documentation for all the steps and measures taken is completed seamlessly, without requiring even more time.”
For patient Georg M., the value of the hybrid OR is much more personal. It allowed him to beat bone cancer, while keeping both life and limb intact.
About the Author
Eric Johnson writes about business, the environment, medicine, and technology from Zurich, Switzerland. He studied chemistry, and prior to working independently, headed what is now a Thompson-Reuters bureau and corresponded for McGraw-Hill World News.
