JOINT REPLACEMENT EASES PAIN, DISCOMFORT FOR MANY PATIENTS

Artificial joints made of plastic and titanium metal replace worn human joints in, from left, the hip, knee and shoulder.

Rose Walter's left knee had been bothering her for years when she finally decided it was time to replace it.

"I almost got to the point where I couldn't walk," the 60-year-old Cape Girardeau woman said. "The cartilage was completely gone."

On Nov. 11, Walter's left joint was replaced. These days, she does exercises at home to keep the joint flexible, and she's able to get around without too many problems, she says.

"I don't have the pain I had before the surgery," she said. "Hopefully I'll get around better after a few months."

Joint replacement surgery as we now know it began in Great Britain in 1960s, said Dr. William Wester, an orthopedic surgeon.

"The idea of replacing a joint has been around since the turn of the century," he said.

Joints are formed by the ends of two or more bones which are connected by thick tissues. A ball at the end of one bone fits into a socket at the end of the other bone.

The bone ends of the joint are covered by a layer of cartilage, which is smooth tissue.

Most joint replacements involve the knee, hip and shoulder joints, Wester said, although any joint can be replaced.

He said the indications for replacement "are relatively similar" for any joint: Pain that can't be controlled by medication, braces, physical therapy or other non-surgical means.

Usually that pain is caused by arthritis damaging a joint until it no longer glides smoothly through its range of motion.

The cartilage helps the joint move smoothly with almost no friction. Cartilage diseased by arthritis makes for stiff, painful joint motion.

"People that get to a point where their pain will not allow them to participate in normal activities may be candidates for total joint replacement," Wester said.

Joint prostheses are made in two pieces: One of metals like alloys of cobalt or chrome, stainless steel and titanium, and the other of a plastic called polyethylene.

The design is straightforward: The metal piece fits into the plastic piece to allow the full range of motion of a natural joint. Both pieces are fused into the bone, sometimes with bone cement, sometimes with other prostheses.

In an arthritic hip, for example the damaged ball at the upper end of the thigh bone, or femur, is replaced by a metal ball that is attached to a metal stem fitted into the femur. The metal ball is fitted into a plastic socket implanted into the pelvis.

Surgeons don't always replace the entire joint -- the ball and the socket.

In some knee replacements, the surgeon essentially resurfaces the joint, "kind of like capping a tooth," Wester said.

And since shoulders aren't weight-bearing joints, usually only the ball end of the joint is replaced.

"We don't replace the socket," he said.

Southeast Missouri Hospital and St. Francis Medical Center both have joint replacement programs integrating the actual surgery and the follow-up care, which consists of physical therapy to keep the joint flexible.

Physical therapy, and then regular exercise, after joint replacement surgery are crucial, Wester said, "especially in shoulder and knee surgery. For the hip, it's not as important, because normal walking usually exercises it enough."

Without proper physical therapy and exercise, the joint becomes stiff and may not move through its full range of motion, he said.

Joint replacement is major surgery. Patients may be in the hospital for four or five days, and full recovery may take three months or longer.

"It takes six weeks pretty much to get over a joint replacement to the point where you are starting to function normally," Wester said.

Total joint replacement isn't without complications. Infection is a risk with any surgery, and in some cases, the replacement joint may loosen or slip.

And it's not unheard of for a prosthesis to wear out, just like the original did.

"Joints are mechanical devices and you can't expect them to last forever," Wester said.

Because prostheses do wear out, not everyone is an ideal candidate for total joint replacement surgery.

"They used to not approve these for anyone under 65," Wester said. "That's not the case anymore, but we try not to put them in anyone terribly young."

Someone in their 40s, for example, may be better suited for other options, such as a cartilage transplant, than a joint replacement because they'll need a second replacement 10 or 15 years after the first.

"The more wear somebody can get out of their own joint, the better," Wester said.

If a joint loosens or slips, or if only one part of it is worn, the surgeon may go in for "revision" surgery to fix the problem.