HEALTH: The Thigh Bone’s Connected to the Hip Bone …
Knee Model courtesy of Wright Medical
According to a report from the Centers for Disease Control (CDC), the most common reason for joint replacement is pain and a decreased quality of life … often caused by osteoarthritis, which occurs when cartilage in your joints wears down over time.
Recent advances in surgical techniques, such as computer-assisted and minimally-invasive procedures, have allowed patients to recover quickly and experience reduced levels of pain. This may account for the increase in the number of joint replacements — the demand for total hip replacements has increased by an astounding 60 percent and for total knee replacements by 70 percent in a 10-year period. Doctors performed 543,000 total knee replacements and 230,000 total hip replacements in 2007 (CDC).
In fact, the CDC estimates that by 2030 this demand will increase six-fold for total knee replacements and by a whopping 175 percent for hip replacements.
Baby boomers, because they are more active than previous generations, are fueling this increase. An article published by Banner Health, points to boomers’ refusal to scale back on their active lifestyles or to accept the pain that may result from wear-and-tear or injuries. Natural joints as well as prosthetics become worn with more use, and Americans, on the whole are living longer, thus replacements — and replacements of the replacement — will become more common.
Physicians suggest replacing some high-impact activities, such as running, racquetball, tennis and basketball with low-impact activities, such as swimming, cycling or golf.
The Basic Information
Hip replacement surgery, technically hip arthroplasty, is also performed to relieve pain and increase/restore mobility and function as well as to treat fractures. While many hip replacements are performed as a result of osteoarthritis or rheumatoid arthritis or a fracture, tumors or a condition known as osteonecrosis may cause the need for replacement. Osteonecrosis occurs when there is an inadequate blood supply to the ball portion of the hip.
This procedure has also become more common; partial hip procedures, most often used to treat fractures, increased by 60 percent during a 10-year period, total hip replacements by one-third. Artificial hips consist of a ball component (made of metal or ceramic) and a socket (plastic, metal or ceramic); the hip may be cemented, held in place with bone cement, or uncemented, with a textured surface that allows new bone to grow into the implant and secure it. Patients can generally expect a six- to eight-week recovery time.
Knee replacement surgery, technically knee arthroplasty, is most often performed to relieve pain and restore function in diseased knee joints. The procedure is surprisingly routine — if any surgery can be called routine — and involves the removal of damaged bone and cartilage from the thigh and shin bones and the kneecap and the insertion of an artificial knee that replicates the movement and function of a natural knee.
The first knee replacement surgery was performed in 1968, according to the American Academy of Orthopaedic Surgeons; of course, the artificial knee has become more advanced, with various models that are chosen based on patients’ gender, height and weight and other factors. Patients can generally expect a two- to six-week recovery time.
An Innovation In Knee Replacement
As reported, more than 500,000 total knee replacements are performed in the United States each year. Dr. C. Lowry Barnes specializes in 
hip and knee replacement, and recently, with a team of five other surgeons and Wright Medical, developed the Evolution knee. The Evolution knee is, according to Barnes, a better implant as it is designed to mimic the normal motion pattern of a natural knee.
“Previous knees were somewhat rudimentary from a kinematic standpoint,” Barnes said, referring to the motion of the knee. “The inside or medial part of the articulation between the femur (thigh bone) and tibia (shin bone) act differently in the normal knee, and we have recreated this in the Evolution knee replacement. The medial part of the Evolution knee is more conforming, much like part of a ball and socket mechanism, and the lateral side of the knee is where most of the translation occurs. The normal [or natural] knee rotates as it bends — the tibia, rotates on the femur. This new knee mimics that motion. The Evolution therefore feels more like a ‘normal’ knee and feels more stable … something patients really appreciate.”
The team worked on the development of the Evolution knee for several years, and Barnes said they offer better sizing options based not only on gender — men’s and women’s knees have different ratios from top-to-bottom and side-to-side — but also based on stature and height as well.
While there is no statistical data regarding the longevity of this new knee — it was introduced last August — Barnes estimates the average “life” of the knee to be about 15 years or more. There is no difference in the cost of the Evolution, and Barnes’ amazing surgery time of 45 minutes to an hour remains the same. “We have patients who have one type of [artificial] knee and have received an Evolution knee on the other side, and they have recovered more rapidly with this new knee and report that they prefer the Evolution’s mobility and stability.
For more information about the Evolution knee, log onto wmt.com; for more information about Barnes, log onto arspecialty.com.
