News
Emerson Hospital debuts computer-navigated knee replacement surgery
Orthopedic surgeon is the first in New England to perform “pinless” procedure with new system
(CONCORD, Mass., August 17, 2006)--A milestone occurred in an Emerson Hospital operating room when John McInnis, MD, chief of Emerson’s orthopedic surgery service, became the first surgeon in New England to use a leading-edge computerized navigation system to perform “pinless” knee replacement surgery. According to Dr. McInnis, the technology he used on June 26 to operate on Catherine Byron, a Concord resident, represents important progress in improving the overall function and longevity of the metal-and-plastic implants.
“With pinless knee replacement surgery, we avoid making extra small ‘pin’ incisions above and below the knee—something that was required by the earlier technology,” Dr. McInnis explains, noting that an infrared tracker attached to the main incision avoids the need for pins. “As a result, there is less risk of infection and fractures.”
That is a benefit any patient can appreciate. But Dr. McInnis says that use of sophisticated surgical navigation, which brings increased precision to how the knee implant is placed in the bone, is the real news. “One of the challenges in joint replacement surgery is achieving perfect alignment,” he explains. “Not only do we want the knee to be perfectly aligned with the ankle, but we need to ‘balance’ the soft tissues. Ligaments, which tend to become stretched on one side and tight on the other, need proper balancing.”
The new system, which was developed by Stryker Navigation, provides two-way communication between the computer and the surgeon’s instruments. In addition to three cameras, a sophisticated tracking system and monitor, the system includes an infrared wand that the surgeon uses to ‘paint’ the patient’s knee, which produces a highly detailed, computer-generated model of the patient’s anatomy. “This assists us in determining where to cut the bone and how to place the knee implant as precisely as possible,” says Dr. McInnis.
There are short- and long-term benefits. A patient whose implant is perfectly aligned and balanced will recover more quickly. This has been true for Mrs. Byron, 84, who along with family members was surprised at her steady progress. “My recovery has been remarkable,” she said four weeks after her surgery. “I’m able to walk without crutches and have no problem going up and down the stairs.”
The resulting precision leads to implant longevity, a key goal for patient and surgeon alike. “Research has shown that proper alignment can make the difference between an implant lasting ten years and lasting twenty years,” says Dr. McInnis. “When a joint replacement fails, it is usually because the alignment or balance was off by a few degrees.”
The navigation technology being used at Emerson Hospital, where more than 200 joint replacement surgeries are performed each year, is available in few hospitals. Other Emerson orthopedic surgeons using the system include John Blute, MD, Donald Driscoll, MD, and Dean Howard, MD. As they become experienced in using the new technology, they expect joint replacement surgery to become more minimally invasive. The navigation system’s ability to “see” the operating field may make surgery possible—and safe—through smaller incisions. Also, the surgery itself is likely to take a shorter amount of time.
The timing worked well for Mrs. Byron. She had planned to have Dr. McInnis perform knee replacement surgery in March but was delayed when she broke her hip on New Year’s Eve. By the time she was ready for her knee surgery, Dr. McInnis was ready with technology that has given her a quicker recovery than she would have experienced at an earlier date. “I’m glad how it turned out,” says Mrs. Byron, whose goal is to continue to live independently. “I am very pleased.”