A Three-Tiered Approach To Improving Joint Implants

Dr. Roger Greenberg, an orthopedic surgeon at Sky Ridge Medical Center, says the improvements for total joint replacements fall within three areas: materials, design and surgery techniques.

Better Materials

Through the years, the materials in replace- ment joints have improved and replaced the weaker plastic in previous models.

The hip joint is composed of a ball that rotates in a cup-like socket. Today, it can be made from a metal ball and socket, a ceramic ball and socket, or one of those materials in combination with an upgraded plastic. The surface plastic has improved in knee replacements as well. The knee joint has a metal upper bone which articulates with a polyethylene (plastic) lower bone and knee cap.

“These newer surfaces are wearing down at a much lower rate than previous materials,” Dr. Greenberg says. “There- fore we’re expecting a longer lifespan for each implant.”

Modified Design

Design considerations continue to improve for both hip and knee. Dr. Greenberg explains there is a tendency to use a larger ball for more stability in hip replacements. This allows for increased activity, and it is less likely to slip out of the socket.

Knee replacements have been designed to account for differences in gender. “We can give men and women a more specific implant depending on the size and function of that knee,” Dr. Greenberg says. These specialized joints have been designed for extended mobility. In fact, the artificial knees can bend greater than 120 degrees. “The replacements can better mimic normal knee function. Now, patients can even kneel down and lineup a golf putt.” As aging genera- tions remain active, the advancements in artificial joint design can help them stay in the game.

Advanced Techniques

While the materials and design of total joint replacements continue to advance, so does the approach surgeons are tak- ing toward the procedure. Recently, reduced tissue trauma surgery has helped speed up recovery time. Dr. Greenberg explains, “We have reduced the size of the incision, and we cause less surgical trauma to surrounding tissues, which translates into a more rapid recovery and earlier return to active function. These new techniques focus on lessening the pain associated with joint replacement surgery recovery.”

Surgeons also are beginning to use computers as assist- ing devices during joint replacement. Dr. Greenberg says,

“The idea is that if we can take advantage of this technology to more accurately place a hip or knee joint in a person’s body, we will get a longer life out of the implant.”