New Ways to “See”

Thursday, July 1, 2010

Illustration by Stephen Sauer.

More Info

New Hampshire NeuroSpine Institute: www.nhneurospine.com
Core Orthopaedics: www.corephysicians.org

But now, just as pilots can consult navigation instruments for guidance, orthopaedic surgeons can do the same, says Thomas J. Kleeman, M.D., orthopaedic spine surgeon at the New Hampshire NeuroSpine Institute in Bedford and Catholic Medical Center in Manchester. In fact, the latest advances in orthopaedic technology enable doctors to pinpoint surgical targets with better precision and efficiency than ever before.

O, a better cure for my aching back!

Back surgery, given the spine’s complex structure and inaccessibility, can be tricky, says Kleeman. “To get to it, you have to go through something. You have to work around blood vessels, you have to work around intestines if you’re going from the front.”

Traditionally, surgeons have relied on fluoroscopy for guidance, which provides limited imaging of the spine and “a lot of radiation,” Kleeman says, particularly for the repeatedly exposed members of the surgical team. In contrast, new imaging technology called the O-arm Surgical Imaging System provides real-time, three-dimensional pictures and virtually eliminates radiation exposure for the surgical team. “It doesn’t eliminate it for the patient, but for the patient, it’s a one-shot deal, so the risk isn’t as high,” Kleeman says.

The O-arm system — so named because it encloses around the patient during surgery, making a complete circle — “sees” the surgeon’s surgical instruments and superimposes them on scanned images of the patient, which the surgeon can refer to during the operation. “You can actually see your instruments where they are in relation to the spine, so you can make a tiny little incision and work your way down to the spine without risking injuring nerves and other structures because you can see and know exactly where you are,” Kleeman says. The O-arm “shows you where you want to be and where you are.”

Because the O-arm enables surgeons to better visualize the spine and surrounding tissues, it supports minimally invasive surgery, helping the surgeon to work through a small incision and avoid cutting muscle, resulting in less patient scarring and strength loss. Patients often heal more quickly, leaving the hospital after an overnight stay rather than three to five days. “They’re able to return to work faster, they’re able to return to normal activities faster, there’s less scar tissue, [and] there’s less need for additional surgery,” Kleeman says.

The O-arm is used for a variety of spinal procedures, including spinal fusions, which are often performed to remedy spinal instability brought on by a slipped disk. The O-arm can also help in treating fractures, worn-out disks, spinal deformities such as scoliosis and osteoperosis-related compression fractures. Kleeman says he’s also relied on the O-arm to save the day in cases where the patient is so obese that regular x-rays fail to show the spine. Without the O-arm, spine surgery on these patients “could not have been done at all,” he says.

Likely future applications of O-arm technology include ears, nose and throat surgery, brain surgery and catheter surgery.

“This is just the beginning of a whole new era of surgery,” Kleeman says. “We’re just evolving surgery — right now spine surgery, but eventually all types of surgery — to the next generation of application where you don’t have to open everything up in order to see where you are.”

Fine tuning a new set of wheels

Navigation technology is also bringing marked improvements to joint replacement surgery. About 700,000 hip and knee replacements are performed in the United States each year, primarily due to osteoarthritis, says Thomas F. McGovern, M.D., an orthopaedic surgeon specializing in joint replacement at Core Orthopaedics in Exeter and director of Orthopaedics at Exeter Hospital.

That number is expected to rise as baby boomers age, and, with the average American lifespan now stretching well beyond seven decades, joint replacement parts need to last longer. Traditionally implanted manmade joints usually last about 15 years, says McGovern, and experts have learned that performance, as well as longevity, of implants can suffer if their placement is not ideal. “Even if one of the metallic components is tilted as little as three to five degrees to one side or the other, it could lead to premature wear in the life of the implant,” McGovern says.

Computer-assisted orthopaedic surgery addresses this concern head-on, with the technology in the operating room acting “almost like a GPS,” McGovern says. “Just like a navigation system in your car knows exactly where you are at any time, the navigation system in the OR knows exactly where my instruments are and exactly where the implants are going to go, so I can measure things to within a few degrees and a few millimeters, which are measurements that we didn’t have available with our traditional instruments,” he says.

During surgery, an orthopaedic physician using computer-assisted technology can refer to a computer screen for real-time guidance and feedback. Infrared cameras positioned over the patient track the surgeon’s electronic instruments and provide three-dimensional imaging and numeric displays that help the surgeon place the implants in the best possible position while working through a short incision and avoiding muscles. “It seems that if we leave the muscle alone, people recover a lot faster,” McGovern says.

Making really good even better

An even newer iteration of computer-assisted orthopaedic navigation called “custom knee replacement” goes a step further in minimizing risk for the patient by enabling the surgeon to perform an entire operation on a three-dimensional image of the knee joint before surgery. The virtual surgery allows the doctor to complete surgery-related measurements and planning that used to take place in the operating room — before anyone even brings the patient into the operating room. “We do the whole operation on the computer and then the manufacturer creates what we call custom patient instruments that are designed just for that patient. They fit that patient’s anatomy only,” McGovern says.

Custom knee replacement offers the precision of computer-assisted surgery, but also enables surgeons to work out the kinks before surgery, which shortens the length of the surgery, lessens the patient’s exposure to anesthesia and eases the pressure on the surgeon to make decisions in the operating room. Instead, McGovern says, “we can make decisions before we even enter” the operating room. NH