Published: Oct. 17, 2006
Updated: July 2, 2010
Total joint replacement has come of age.
Since it was introduced in the U.S. in the mid '60s, steady improvements in materials and techniques have made the formerly rare surgical strategy a highly effective and increasingly common way to relieve pain and restore mobility to joints damaged by arthritis, trauma, and other debilitating conditions.
Today, nearly half a million Americans undergo total joint replacement surgery each year -- many of them not much older than the procedure itself.
But, despite the great progress joint replacement has made, it’s not yet a perfect science. And with younger, more active, and sometimes heavier patients now receiving joint replacements, the implants (referred to by surgeons as prostheses) sometimes wear out while their recipients still have decades of life ahead of them.
Of the 245,000 total knee replacement surgeries performed annually in the U.S., 8 percent are repairs or replacements of worn-out prostheses. Such “re-do’s” also account for 17 percent of all hip replacements.
So surgeons at Duke’s Total Joint Center are actively seeking ways to make joint replacement even more effective and long-lasting.
An important factor in the success of any joint replacement is careful selection of an implant, based on discussions with the patient and personal characteristics such as age, weight, and activity level.
"There is a large list of different implants we offer," says Michael P. Bolognesi, MD, director of adult reconstruction at the center. "What surgical approach is most appropriate is based on the size and anatomy of the patient."
Because returning to an active, pain-free lifestyle is what joint replacement is all about, it’s no surprise that demand for the surgery is on the rise, especially among younger patients.
"As we develop prostheses that last longer, it makes more sense to implant them at a younger age," says James Nunley, MD, chair of orthopaedic surgery. "So, with life expectancies rising, we have to come up with prostheses that last 30 or 40 years."
According to Nunley, a key strategy to enhance the durability of prostheses is to design them so that they more closely reflect the real thing. "There is no simple hinge joint in the human body," Nunley points out.
"Yet all the original joint prostheses were highly simplified -- consisting, for example, of simple hinges for elbows. We’ve realized that, to get good results, we have to better reproduce the anatomical features of actual joints."
For elbow replacements, that insight has led to the recent development by Durham surgeon Ralph Coonrad, MD (who collaborates with Duke surgeons on elbow replacements) of a so-called "sloppy" artificial joint that better duplicates the elbow’s natural mobility.
For shoulders, former Duke surgeon Carl Basamania, MD, created a revolutionary prosthesis for the surgical treatment of cuff tear arthropathy (CTA), a condition in which the rotator cuff -- a key shoulder structure -- is missing. Basamania designed the new CTA prosthesis with an overhang that prevents bone from rubbing together, a problem with standard prostheses. All of the CTA patients who have received the new replacement reported satisfaction with the results.
Perhaps the single most complicated joint to replace is the ankle. "Past ankle replacement designs have not been all that good," says Nunley, "and it’s quite easy for an ankle joint implant to get out of alignment. Then, just like a misaligned front end of a car, it will wear out more quickly."
Over the past several years, Nunley and colleagues Mark Easley, MD, and James DeOrio, MD, have conducted clinical trials of four new ankle joint designs, with excellent results. "We’ve had patients come in and say, in tears, ‘You’ve changed my life,’" Nunley says. "That makes a physician feel very, very good."
In their hip and knee implant operations, Bolognesi and colleague David Attarian, MD, are developing new techniques to minimize the length of incisions and preserve bone.
In one such technique, rather than removing the worn ball of the hip (done in most hip replacements), the surgeons shape it into a cylinder, which is then capped with a new ball. In another example, patients with only partially damaged knees can undergo partial knee replacement -- a less invasive procedure that reduces recovery time and conserves more natural knee tissue.
In addition, Scott Kelley, MD, has been performing hip replacement surgery using an technique that dramatically cuts down on recovery time. The anterior approach uses a specialized table that allows the surgeon to position the leg so that he doesn't have to cut any muscle.
The method also allows patients more freedom of motion during their recovery period and minimizes the risk of hip dislocation. Kelley began using the approach several years ago. "The patients really like it because it frees them up and gives them a good hip," he says.
Duke orthopedic surgeons and their anesthesia colleagues have played a pioneering role in refining anesthesia techniques for several procedures, including total joint replacement.
"Our anesthesiologists can now use very specific regional blocks for certain operations that were previously done under general anesthesia," says Bolognesi. "Now they can numb just the limb using directed blocks and give sedation so that patients sleep through the operation, but are breathing on their own and easily wakened when it’s over. In many cases these blocks are administered via catheters that are left in place for added pain control following the surgery. If a patient is having a lot of pain, the catheters can be re-dosed. This helps patients avoid using excessive amounts of oral and intravenous pain medications during the early post-operative period."
In joint replacement, as in many other surgical disciplines, studies show that experience is indeed the best teacher -- and that patients treated by more experienced surgeons have better outcomes.
Performing almost 700 hip and knee replacement procedures each year, Duke’s Total Joint Center offers patients an unusual depth of experience and expertise.
"There's no question that there are improved outcomes associated with a higher volume of surgeries," Bolognesi says. "Anything you do in repetition, you're more able to perfect that technique."