Replaceable Parts: hip and knee surgery

Posted on 23 July 2016

 

Kalispell surgeon one of leaders in field 

 BY DAVID REESE, Montana Health Journal

Dr. James Blasingame held eight inches of plastic and metal materials in his hands that resembled some kind of machinery component.

But in his hands are an opportunity for someone. The titanium and plastic components are parts used in total knee replacements, and Blasingame, a Kalispell orthopedic surgeon, uses them to give people a new lease on life.

With nearly 100 million more people in the United States who have arthritis than in the 1950s, Blasingame said many of those people want to remain active. So their obvious choice is to replace old worn out hips and knees.

But it’s not always that simple.

dr blasingame

Dr. James Blasingame

Operations have become easier and the technology of the replaced joints themselves is better, Blasingame said, but still there can be problems. That’s why he tries to get people to wait as long as possible before they opt for surgery.

The process of a hip or knee replacement is “relatively straightforward,” he said, but knees take longer to recover.

Surgery requires a two- to three-day hospital recovery, followed by physical therapy, if needed. Three months is about the average length of time to completely recover, Blasingame said. They are artificial devices that can wear out, so activity level and weight of the patient needs to be addressed, according to Blasingame, who performs about 100 hip and knee replacements annually. “We wear on our joints a lot faster because we are heavier,” he said.

The ideal patient for a hip or knee replacement is someone who is “miserable with their discomfort,” he said. He often advises patients to delay surgery as long as possible, but “Americans don’t like pain and they expect to have something done about that,” he said.

With the combination of Americans weighing more and their desire to remain active into their later years, thousands of people each year are choosing partial or total hip and knee replacements.

“It used to be you wouldn’t touch someone 65 or older,” Blasingame said. “Now it’s not uncommon to see people in their 50s” choosing orthopedic surgery for hips and knees.

 As more people are active later in life, this leads to injuries that lead to arthritis — one of the leading causes of hip and knee replacements.

The problem with having a knee or hip replaced for someone in their 50s is that if they’re moderately or highly active, they could end up back in surgery in 12 to 15 years, Blasingame said.

Some of the dangers involved with a hip or knee surgery are infections or loss of blood, nerve injuries, persistent pain or stiffness, or prosthesis failure.

“If you don’t do the surgery, you don’t associate yourself with those risks,” Blasingame said.

The person who gets in trouble after a knee or hip replacement looks like this: someone who is younger, physically active, with isolated post-injury joint arthritis. “When you free him because the joint was painful, he has a tendency to do whatever he wants,” Blasingame said.

He recommends that people who have had surgery avoid keeping extra weight and refrain from pounding activities like running or treadmills, and opt for activities like swimming or bicycling. Hiking sticks also help when doing long hikes, he said.

Knees are some of the most amazing joints in the human body. The native human cartilage in knees has the lowest co-efficient of friction — meaning they are very slippery.

Knee-replacement surgery involves exposure of the front of the knee, with detachment of part of the quadriceps muscle from the patella. The femur and tibia are then accurately cut to shape using cutting guides oriented to the long axis of the bones. Metal components are then placed onto the bone or fixed using special cement. Alternative techniques may involve osseointegration, including porous metal prostheses.

A round-ended implant is used for the femur, mimicking the natural shape of the bone. On the tibia the component is flat, although it often has a stem which goes down inside the bone for further stability. A flattened or slightly dished high density polyethylene surface is then inserted onto the tibial component so that the weight is transferred metal to plastic not metal to metal. During the operation any deformities must be corrected, and the ligaments balanced so that the knee has a good range of movement and is stable.

“There’s quite an attention to detail,” Blasingame said. Securing the ligaments too tightly will restrict the knee’s natural movement, and securing the ligaments too loosely will allow instability in the knee.

It’s a fine line between a stable knee and a floppy knee. “You don’t leave the operating room without the full range of motion,” Blasingame said. “If you don’t have it in the operating room, you won’t have it when you leave.”

Hip replacement is a surgical procedure in which the hip joint is replaced by a prosthetic implant.

The prosthetic implant used in hip replacement consists of the acetabular cup, the femoral component and the articular interface.

Hip replacement surgery can be performed as a total replacement or a hemi (half) replacement. Such joint replacement orthopaedic surgery generally is conducted to relieve arthritis pain or fix severe physical joint damage as part of hip fracture treatment. A total hip replacement (total hip arthroplasty) consists of replacing both the acetabulum and the femoral head while hemiarthroplasty generally only replaces the femoral head. Hip replacement is currently the most common orthopaedic operation, but patient satisfaction varies widely.

A total hip replacement tends to provide the longest benefit to the patient, for the cost involved. “You get the best quality of life improvement for the longest time, and knee replacements are getting close to that,” Blasingame said.

With a new hip or knee — and a new lease on life — the patient might want to continue doing things he had been doing 20 years ago. Not a good idea, says Blasingame. “I spend a lot of time counseling people not to go overboard with their activities,” he said.

For people who get orthopedic surgery in their younger years, like in their 50s, Blasingame said he encourages them to stay away from high-impact sports and maintain a healthy body weight. “We spend a lot of time talking people out of operations or informing and encouraging them to delay,” he said.

He tries to find a solution that is simple and non-operative that can help the patient, “but if it’s inevitable and they’re miserable, we have to go ahead with the operation,” he said.

“The art is operating on the right patients.”

replacement knee part 

The replaceable hip is a titanium or chrome/cobalt ball with a liner. These are press-fitted into component in the femur. (Brenda Ahearn photo)

 



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