Osteoarthritis of the knee affects more than 10 million Americans and has prompted many people to undergo total knee replacement surgery to alleviate pain and improve the joint's function. An implant system, however, may make things easier for some of these patients.
Osteoarthritis is the breakdown of cartilage that works as a shock absorber between bones where they meet at the joint. When this cartilage disintegrates, the cushion is gone and the bones rub together, which causes pain, swelling and a decreased range of motion in the joint.
If the knee does not respond to treatments such as over-the-counter pain relievers, braces, exercise, physical therapy or steroid injections, the patient's physician may recommend knee-replacement surgery to alleviate the pain and ensure full use of the knee. Traditionally, this meant a total knee replacement, but with the Oxford Partial Knee implant, many patients can benefit from a less-invasive procedure.
"Lots of patients who have been told they need a total knee replacement in fact only need a partial knee replacement," says Dr. R. William Junius III, an orthopedic surgeon at East Jefferson General Hospital. "Most patients develop knee osteoarthritis in the medial or inner portion of the knee joint. If the rest of the knee is healthy, we want to avoid a total knee replacement. That's where the Oxford implant comes in."
The implant requires less bone and cartilage to be removed from the knee than a total knee replacement does. It also is less painful, and the implant design allows more natural motion. The implant has been used in England for more than 20 years, but only received FDA approval in the United States in 2004.
"I use the Oxford because it's been proven to be extremely successful," says Junius, one of the first doctors in the New Orleans area to use the Oxford implant. "In the past, partial knee replacements didn't hold up very well, but the Oxford partial knee replacement has been shown to be successful in 95 percent of cases. This is comparable to total knee replacement."
Junius, who has used the Oxford implant for several years, says recovery times are shorter than with a total knee replacement, and the majority of patients go home the day after surgery. Most patients are able to walk several hours after surgery, he says, and within two weeks no longer need canes, walkers or crutches. Patients are also at lower risk for postoperative complications such as infections, blood clots or stiffness than those receiving total knee replacements, the doctor says.
"The difference between this type of knee replacement and other partial knee replacements is its mobile bearing design," Junius says. "The lining of the implant floats, rather than being fixed, so it can move more easily, leading to less wear and tear on the implant. As a result, only a fraction of a millimeter of wear occurs in 15 to 20 years. My patients love it."