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Joint Replacements on the Rise

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If a knee or hip joint is painful and limiting your mobility, you’re probably considering joint-replacement surgery. You’re hardly alone. Every year, more than one million Americans have a knee or a hip joint replaced. And that number is growing as baby boomers join the ranks. In the past, joint replacement surgery was mostly for the elderly, in part, because the prostheses had a functional lifespan of only about 10 or 15 years. If you didn’t want to repeat the ordeal, you soldiered through the pain.

But times have changed. In 2010, 39 percent of the 453,663 patients who received hip replacements in the U.S. were under 65, according to the Agency for Healthcare Research and Quality. And 42 percent of that year’s 721,443 knee replacements were performed on patients ages 45 to 64. Those numbers are expected to rise dramatically in the next 15 years. Researchers anticipate a 17-fold increase in the number of total knee replacements in this age group by 2030. The demand for total hip replacements in the same age category is expected to grow six-fold during the same period.

“We’re still seeing patients 65 and up, but the volume is increasing among those under 65,” says Dr. Brian Galinat, chair of Christiana Care’s Department of Orthopedic Surgery. The reason may be the boomers’ never-say-die approach to life. They are 76 million strong and showing no signs that they’re ready to adopt the sedentary lifestyle of their parents’ generation. They view advances in medical technology as a means to keep on running, cycling, skiing and engaging in other activities.

But those are the same activities that often bring on osteoarthritis, one of the leading reasons for joint-replacement surgery. “A lot of activities cause injuries like ACL tears, which, even if repaired, increase the risk of arthritis down the road,” says Dr. Gregory Daut of Bayhealth Orthopaedics of Dover. Another factor that’s driving the demand for knee and hip replacements is obesity.  For each pound of weight gained, pressure on those joints increases by three pounds. It’s no surprise that the obese account for more than half of patients having joint surgery.


Photograph by Kevin Fleming
 

Dr. Steven M. Dellose of Delaware Orthopaedic Specialists with patient Coo Murray. 

Another reason is that the surgeries themselves have improved. Knee and hip replacements are among the most successful and cost-effective interventions in medicine. Both boast a success rate of 90 percent to 95 percent after 10 years and 80 percent to 85 percent after 20 years, according to the American Academy of Orthopaedic Surgeons. Changes in surgical techniques as well as advances in instruments, pre- and post-operative care, pain management and the administration of anesthesia have made for a less painful and quicker recovery.

“Eighty percent of my patients who have a knee replacement go home after a two- night stay in the hospital,” says Dr. Leo Raisis, medical director of Christiana Care’s Center for Advanced Joint Replacement at Wilmington Hospital. “Fifteen years ago, it used to be five days in the hospital, and 80 percent went to a nursing facility.” Prosthetics are also getting better. A new kind of plastic, called highly cross-linked or irradiated polyethylene, has greatly slowed the wearing out of the implant and changes to the bone. The newest generation of this plastic blends the cross-linked polyethylene with vitamin E, further cutting down on wear and increasing long-term stability.

“The plastics we have now are even better than the ones we had five years ago,” says Dr. Steven Dellose of Delaware Orthopaedic Specialists. Metals have improved as well. Some implant designs combine cross-linked polyethylene with oxidized zirconium, a metallic alloy that provides the wear
resistance of ceramic without its brittleness. Simulation tests in newer knee implants showed an 81 percent reduction in wear, a leading cause of knee-implant failure. Surgeons are also using smaller instruments and less invasive techniques that minimize trauma to the patient, resulting in less post-operative pain and faster rehabilitation. “Thirty years ago, incisions measured 12 inches,” says Raisis. “Now, depending on the patient, the incisions can be as small as four inches.”

In the knee-replacement arena, several new technologies have been introduced. One is patient-specific cutting blocks. With this technology, patients have a CT scan or an MRI. The results are then sent to a manufacturer, where technicians measure certain anatomical features of the patient’s knee. These measurements generate a computerized plan, containing detailed information regarding the size of the implant and the location of the bone cuts. The manufacturer then creates specialized cutting blocks for that particular patient, allowing optimal fit and better alignment. Theoretically, this could lead to longer implant life and improved range of motion.

Another emerging technology involves patient-specific implants. In this case, not only are the cutting blocks tailored to the patient’s anatomy but the implant as well. This is the cutting edge of patient-specific prostheses, but the technology is not yet widely available. Advancements in shoulder replacement surgery have made the procedure accessible to a greater number of patients. The two most common techniques are the anatomic shoulder replacement and the reverse shoulder replacement. As its name suggests, the anatomical shoulder replacement mimics the natural workings of the shoulder: A plastic cup is fitted to the shoulder socket and a metal ball is attached to the upper arm bone.

But not all patients are eligible for this procedure. A newer procedure, called the reverse shoulder replacement, works better for those with torn or severely compromised rotator cuffs. In this procedure, the socket and metal ball are switched: The metal ball is fixed to the socket, and the plastic cup is fixed to the upper end of the upper arm bone. This allows the deltoid muscle, rather than the rotator cuff, to power and position the arm. The reverse shoulder replacement provides relief from pain and restores some mobility to the arm, but not as much as the conventional shoulder replacement.

“We try to use the conventional replacement whenever possible,” says Galinat, who performs about 100 shoulder replacements a year. Also, coming to the fore are developments in replacement procedures for smaller joints, including elbows, ankles, wrists, knuckles and even big toes. All of this is good news for baby boomers, but as always, the details are in the fine print. While successful joint replacement surgeries provide excellent relief from pain and restore mobility, surgeons stress the procedures do not give patients a “normal” hip. Most patients can and do resume regular activities, but high-impact activities like running are not recommended. Riskier activities like skiing are possible but may place the new joint at risk.

“A joint can last 15-20 years if it’s taken care of,” says Dellose. “It’s like a car. If you buy a brand new car, and you put 100,000 miles on it every year, it’s not going to last you 10 years.” Indeed, surgeons often find they need to temper patients’ expectations. “You’re not going to be 20 years old again,” says Dellose. Patients also need to realize that joint replacement surgery is major surgery and presents certain risks, including heart attack, stroke and blood clots as well as loosening of the new joint over time.

Surgeons recommend that patients exhaust all other pain-management remedies before considering joint replacement. Says Daut, “I still think of
it as a final step.” 
 

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