Diagnostics & Imaging Week Washington Editor

WASHINGTON An orthopedic specialist presented research on a new, non-invasive strategy for diagnosing, treating and monitoring osteoarthritis, during a scientific presentation at last week's American Academy of Orthopaedic Surgeons (AAOS; Rosemont, Illinois) meeting at the Washington Conference Center.

People with joint injuries due to sports, work-related activity or accidents may be at increased risk of developing osteoarthritis, a degenerative joint disease that contributes to the most common type of arthritis.

The new technique for orthopedic surgeons to detect cartilage degeneration earlier and more accurately was developed, and described at the AAOS session, by Hollis Potter, MD, director of research at the Department of Radiology and Imaging at the Hospital for Special Surgery (New York). Potter used MRI technology from GE Healthcare (Waukesha, Wisconsin) in a modality she described as a "non-invasive microscope."

"We're really excited about this," Potter told Diagnostics & Imaging Week. "For the first time, MR has the potential to act as a surrogate for interventional biopsies."

According to Potter, a radiologist specializing in musculoskeletal MRI since 1990, what's been missing in this field has been objective outcome measurement. She said that physicians traditionally monitor a patient's progress by asking how they're doing, how they're feeling or functioning measuring pain and how they perform daily activities.

The race to develop cartilage "is big business for pharmaceutical companies," she said, and "that's where imaging can act as a surrogate for biopsy."

"What these techniques do is allow for very early detection of arthritis, beyond anything we could see before," she added.

According to Potter, GE's 1.5 Tesla and 3 Tesla systems demonstrate greater detail of cartilage and soft tissue injury, permitting earlier detection of clinically significant lesions.

"This research shows MR provides reliable, consistent, accurate and non-invasive visualization of cartilage," she said. "It is a step beyond what the orthoscope doesn't show. These new techniques provide an objective measurement of when good cartilage starts to go bad, without always having to send the patient into surgery."

Potter also said the new techniques have been shown to be the most sensitive clinical imaging test in demonstrating bone loss adjacent to joint replacements.

According to the AAOS, particle disease is the No. 1 failure of joint replacement surgery. Potter said MRI has been effective in detecting early forms of particle disease, which occurs when bits of polyethylene and metal break off from implants, affecting the bone around the implants.

Potter described it as a case of the body reacting against its implants, which then can become loose. The morbidity is much worse for revision surgery than it is for the primary implant procedure.

"What's really exciting about this research is that we are offering the patient non-invasive cartilage imaging," said Potter. "After the patient undergoes surgery to replace cartilage, these new MR techniques can act as a surrogate for second-look arthroscopy. In other words, the patient will not have to undergo a second operation for purely diagnostic purposes."

She also said that MRI is better for patients because it uses radiation that is non-ionizing. "It's not an X-ray," she said. "Patients and the public are worried about that."

Even beyond being able to detect disease earlier and monitor its progression non-invasively, Potter said, these imaging techniques provide a better understanding of "the true biologic process" because clinical symptoms often don't follow arm-in-arm with what's happening biologically.

"Even if the patient is feeling better, the disease may be progressing," she explained. "We know that from a lot of previous data that has been reported on different disease states that though patients may feel better, their disease may be getting worse. You have to look at all stages of the disease."

Also at the AAOS meeting, a panel of surgeons discussed advances in the field of computer-assisted orthopedic surgery, which they abbreviated as CAOS.

According to the panel members, CAOS offers an adjunct to current joint replacement procedures, allowing for more feedback, instant information, more accurate decision-making and potentially fewer complications for patients.

Richard Berger, MD, assistant professor of orthopedic surgery at Rush Presbyterian-St. Luke's Medical Center (Chicago), said that CAOS enables better accuracy in the positioning of prosthetic components, but he added that its use is still a little "under the radar." He added: "As CAOS technology becomes easier to use and receives greater recognition in terms of how it enhances surgical procedures, it will be more widely adopted by the orthopedic community."

The presenters likened CAOS technology in the orthopedic surgery setting to a global-positioning system. CAOS systems use optical sensors, computers and infrared cameras to help map out joints for replacement and provide a guide to position implants with much more precision.

The technology fits in with the current trend of minimally invasive techniques. Computed tomography scans proved a complete 3-D view of the joint, helping to reduce the incision size and trauma to surrounding bone and tissue.

Cost is a drawback of the technology though. Systems can cost upward of $250,000.

Right now, according to panel members, because the technology is in its infancy, it actually adds time to the surgical procedure, and the longer surgery takes, the more blood is lost and the greater the risk of infection.

Anthony DiGioia, MD, director of The Western Pennsylvania Hospital (Pittsburgh), is considered one of the pioneers of CAOS, beginning work in the field in the early 1990s.

He said that time and cost factors will drop as the technology is more widely used. "We are just scratching the surface," he noted. "My predication is that minimally invasive procedures with CAOS will be combined with tissue engineering within about 10 years or less."

This will allow surgeons to perform biologic resurfacing of patients' joints using their own bone and cartilage as implants, instead of the metal, ceramic or plastic versions used today, DiGioia said.

Commenting on this strategy, William Hozack, MD, professor of orthopedic surgery at Thomas Jefferson Medical School (Philadelphia), said: "The only negative I see is when a surgeon thinks a computer is going to perform the operation forgetting that surgery is an art.

"The surgeon," he emphasized, "still makes the biggest difference."