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Joint Replacement: Less Is Sometimes More

Minimally invasive surgery offers an alternative for some patients

SUNDAY, Aug. 21, 2005 (HealthDay News) -- Every year in the United States, more than 325,000 aching knees and more than 172,000 painful hips must be replaced as age, arthritis and injuries take their toll.

Advances in orthopedics, however, also mean there's less hospitalization and a quicker recovery time for joint-replacement patients because more surgeons are performing what are known as "minimally invasive" or "less invasive" procedures.

While the newer techniques won't work for everyone, they can be a godsend, especially for busy people who can't take a lot of time off from work to recover from surgery.

Today, joint-replacement surgery is classified as "conventional," "less invasive" or "minimally invasive," according to Dr. Jay Mabrey, chief of orthopedic surgery at Baylor University Medical Center at Dallas. The minimally invasive procedures involve the smallest surgical incisions; the conventional, the largest.

Minimally invasive surgeries are performed with specially designed, smaller surgical instruments, and the instruments can also be used for the less invasive surgeries.

Doctors typically insert two small tubes into the incision site. One tube contains a fiber optic camera and a light source; the other usually contains miniaturized surgical instruments. The surgeons watch a TV monitor to guide them during the operation.

Total hip replacement involves removing the head of the thighbone. The ball-and-socket mechanism of the hip is then replaced with the artificial implants. Knee replacement involves resurfacing the worn-out surfaces of the knee and replacing the cartilage with metal and plastic, Mabrey said.

"Most surgeons have gone to a smaller incision," Mabrey said, "and a smaller group of them have gone to minimally invasive techniques."

In traditional hip replacement surgery, for instance, the incision is about 12 to 14 inches in length, he said, and the operation involves a significant amount of blood loss. In less invasive techniques, the incision can be 4 to 8 inches, and in minimally invasive procedures, about 4 inches, he said.

It's not just the incision size that has changed in joint replacement surgery, Mabrey said. "Newer types of anesthesia techniques allow some patients to get out of the hospital within 24 to 36 hours [after surgery]," he said. Because the incision is smaller, the trauma to muscles and tissues is less, and thus recovery time is faster.

With minimally invasive surgeries, some patients go back to work in as little as 10 days to two weeks, said Dr. Mack Lancaster, an orthopedic surgeon at Baylor who does minimally invasive techniques in about 10 percent of his joint replacement patients. With less invasive techniques, the back-to-work timetable tends to be three to four weeks. With conventional surgery, it's six weeks or more, he said.

Both Lancaster and Mabrey, who does "less invasive" but not "minimally invasive" techniques, acknowledged that there are downsides to minimal incision surgery.

"There is a much smaller surgical field," Mabrey said. "So instead of being able to see everything, such as alignment of the implant, the actual surgery is not done under direct vision."

And a minimal incision operation, Mabrey said, "almost always increases the length of the surgery time."

Lancaster said he does not recommend minimal incision surgery unless it is crucial for the patient to get back to normal functioning, such as their job, quickly.

The best candidates for minimally invasive surgery, Lancaster said, are otherwise healthy people of average body weight. Overweight individuals are not good candidates for minimal incision surgery, Mabrey said, because "so much fat overlies the hip, it makes it difficult to see what you are doing."

Older patients who have more osteoporosis and are more likely to fracture are not good candidates for minimally invasive techniques either, Mabrey said.

If your surgeon says you are not a good candidate for minimal incision surgery, ask why, both doctors agreed. If you are a good candidate, ask your surgeon if he has trained in the technique.

More information

To learn more about minimally invasive surgery, visit the American Academy of Orthopedic Surgeons.

SOURCES: Jay Mabrey, M.D., chief of orthopedic surgery, Baylor University Medical Center at Dallas; Mack Lancaster, M.D., orthopedic surgeon, Baylor University Medical Center at Dallas
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