Opinion Mixed on 'Minimally Invasive' Joint Surgery : Some praise the cosmetic results and the sparing of muscles, but others worry about malpositioning.

Alfred J. Tria, M.D., of St. Peter's University Hospital at Robert Wood Johnson Medical School, New Brunswick, N.J., reported that those of his patients who had minimally invasive knee replacements (about 300) have recovered three times faster, have one-third less pain, one-third less time in the hospital, 30% less blood loss, and an increased range of motion, compared with patients who underwent standard procedures.

Other physicians presented cohort studies and case studies, most of them published, that provide short-term outcome data. Some showed benefits in terms of early recovery and cosmetics, but others showed no differences in any factor—from functional recovery to complications.

“That's not better, but if you're an advocate, it's not worse either. If you're not having more complications, perhaps it's not an unreasonable thing to continue doing,” said William Hozack, M.D., of Thomas Jefferson University Hospital, Philadelphia.

Long-term durability remains a key question for many physicians. “If we are malpositioning components even slightly, are those implants going to last as long?” Dr. Gross asked. “If it's an 80-year-old lady, it wouldn't matter. But if it's a 50-year-old male or female … it does.”

Criticism and Complications

Several speakers cited a retrospective study published last year showing no difference in blood loss and hospital stay between small-incision and conventional hip replacement surgery, and a higher risk of soft-tissue complications and component malposition with the “mini” incisions.

Richard Rothman, M.D., of the Rothman Institute and the Thomas Jefferson University Hospital in Philadelphia, argued in a pro-con session that many recent reports have shown complication rates with minimally invasive hip replacement surgery that are three times higher than with the conventional approach.

“There's no demonstrable advantage, and there's increased risk to your patients,” Dr. Rothman said. “So, when I look at the facts, the nails are in the coffin.”

He and other critics of the new techniques argue that the high rate of success with traditional hip and knee replacement surgery renders the newer techniques unnecessary.

Patients are being bombarded, however, with information about the minimally invasive techniques from hospitals, companies, and some surgeons. They also find plenty on the Internet.

“I did a Google search on minimally invasive total knee placement and found 66,000-plus sites. I did a Medline search and found 13,” said Thomas Thornhill, M.D., who still uses a traditional-length incision for many of his knee replacements at Brigham and Women's Hospital in Boston.

Ryan S. Labovitch, M.D., an orthopedic resident at the University of California, San Francisco, reported at the meeting that much of the online information about minimally invasive hip replacement surgery is marketing oriented and often incomplete or inaccurate. Only 13% of Web sites described the potential risks with either the standard or the minimally invasive surgery, he said.

Patients' expectations and satisfaction with the outcome—even if that outcome is scar size—are important, however, as long as surgeons are up-front and honest, others argued.

“I tell patients, I will do what I can to make the operation as minimally invasive as possible, but I will prioritize the long- and short-term results over the cosmetics,” Dr. Rosenberg said. “I also tell them, your scar size will be different if you're a size 3 than if you're a size 14.”

Complications, Dr. Rosenberg told his colleagues, are an inevitable part of any new surgical technique. “No doubt, minimally invasive [joint replacement] surgery has introduced a whole raft of complications,” he said. “But they will decrease with experience, better patient selection, implant selection, and [physician] training.

“Progress comes at a price,” he added.

The challenge in future research, he and others said, will be to accurately tease out the effects of less invasive surgical techniques from other changes—such as new protocols for anesthesia, pain management, rehabilitation, and patient education—that have been introduced at the same time as minimally invasive joint replacement surgery.

One incision, over the femoral neck, allows for placement of the femoral component; the other, the acetabular component. Courtesy Dr. Richard A. Berger