As the American population ages, some of our parts naturally wear out. In particular, wear and tear on joints causes pain for millions of people, and knees are among the most common joints prone to age-related problems. Decades of force placed on our knees take a toll on the cushioning cartilage, and may result in enough discomfort to curtail daily activities and negatively affect quality of life.
“There are more people living longer, and they’re pushing themselves further along in athletics earlier in their lives,” says Dr. Donald Bassman, an orthopedic surgeon in Creve Coeur. “Our joints are being put to higher use, and that doesn’t necessarily cause arthritis, but joints that are more prone to it probably develop it a little bit earlier, so you’ll probably see more total joint replacements than in the past.”
In 2009, the last year for which figures are available from the U.S. Centers for Disease Control and Prevention, about 676,000 knees received artificial joints. Although the number of total knee replacements seems staggering, in most cases, the surgery was strictly a last resort.
“In patients with extensive cartilage loss, we will often try conservative approaches, such as anti-inflammatories, lifestyle modifications and sometimes injections to help reduce the symptoms of arthritis. If pain limits a person’s ability to perform activities of daily living despite conservative measures, then a knee replacement is indicated,” explains Dr. Jason Young, an orthopedic surgeon with Orthopedic Associates.
And when surgery is needed, today’s patients benefit from new technologies that make the artificial joints fit and move more like a natural knee. “Knee replacement has certainly come a long way in the last 20 years,” Young continues. “We’ve seen improvements on knee sizing, including gender-specific knee prostheses, which all serve to recreate an artificial knee with good motion and balance of the ligaments.”
Young thinks the most significant event in the evolution of knee replacement is the continued development of the artificial joints’ plastic liner (polyethylene). The newer materials allow shock absorption while resisting motion-induced stress. “This is important because the small micro-particles that are released as the liners wear out are typically what cause the body's inflammatory reaction, which then leads to loosening,” he says. “In addition, there are now partial knee replacements that can be used in selected patients who have just one localized area of arthritis. This allows the patient to maintain as much native joint surface as possible.”
Surgical techniques also evolve, notes Dr. Paul Lux, an orthopedic surgeon with the Orthopedic Center of St. Louis. “The latest technique for putting in a total knee is through a minimally invasive incision,” he says. “This involves sparing the quadriceps muscle, which in the past, was always cut. Also, newer surfaces to the implants allow for cementless implantation of the components. In the past, the implants were cemented in place and the glue does not last forever. Once the implants loosen, the entire knee has to be redone. The recovery is quicker and the stay in the hospital is shorter.”
For many people, knee replacements allow a return to an active lifestyle. “Most people will walk without a walker or cane and drive by three weeks post-op, and then have four to six weeks of outpatient therapy,” Lux says. “Patients can return to any activities that are normal for their age. I’ve had patients complete marathons, bike the MS 150 and compete in the Senior Olympics.”