Technology Makes Strides In Knee Replacement


Unicondylar is the latest orthopedic knee replacement technique to arrive in the United States from Europe.

Payson's own Dr. Charles A. Calkins was the first orthopedic surgeon in Arizona to perform the surgery.

"A lot of people think that knee replacement is just taking a knee out and putting a new one in, but it is really more a resurfacing of the knee," Calkins said.

The knobs of the knee at the end of the femur and the tibia are called condyles. These are the rounded surfaces of bone that allow the joint to move or articulate.

It may be helpful to understand total knee replacement (TKR) first.

In a TKR, "all the articular surfaces are resurfaced," Calkins said. "These are surfaces that are raw, down to bone, painful, cause swelling and the patient can't walk on them very well."

Metal or polyethylene plastic on metal is used on the articular surfaces. The kneecap gets a little button underneath to cushion it.

A thinner, 8-millimeter polyethylene was used 15 years ago and Calkins said surgeons in general are seeing fewer patients again who have had surgery performed more recently with 10-millimeter polyethylene.

Wear of the replacement surface can be seen in an X-ray, then a small incision can be made and the plastic exchanged.

"This is still a very good knee, but it is an older design. The advantage of the total knee is we can correct a lot more angulation," Calkins said.

"When we can diagnose a patient early enough, we only need to replace one condyle, one half of the knee," he said. That is a unicondylar knee replacement surgery (UKR).

"The difference between the standard (bone cushions) that are being used almost everywhere else and this one is the fact that it has the polyethylene slides," Calkins said. The cushion is called a mobile meniscal bearing.

UKR has been in Europe for about 12 years. It took a while to matriculate here and the government, in an unusual ruling, told surgeons they couldn't perform the surgery unless they went to a class.

Calkins went to a class at Biomet in Texas in June 2004 to learn the procedure.

Since then, he has performed the surgery 58 times, more than the other five surgeons trained in the procedure combined, said Brad Skousen, a representative for Biomet.

Carol Shear has checked groceries in Payson for 32 years, and standing took its toll on her legs. She was faced with quitting work or having knee surgery.


A knee replacement is really a cartilage replacement. The knee itself is not replaced, only the cartilage on the ends of the bones. The replacement implants include a metal alloy on the bottom of the thighbone and polyethylene (plastic) on the top of the tibia and underneath the kneecap. The implant is designed to create a new, smoothly functioning joint that prevents painful bone-on-bone contact.

"When I would get off work, my knee would hurt so bad that I would have to lift my leg to put it in the car."

She had knee pain for more than six years. After having shots that didn't help and wearing a brace for a year, a friend recommended Calkins.

Shear said her recovery wasn't bad at all. She had nine sessions of physical therapy after the surgery, then she did a great many exercises at home. She quit taking pain medication two weeks after the surgery.

"I walked with a cane for a little over a month and would have been able to return to work in two months rather than three if I had had a job off my feet.

"I live alone, so I had to get up and do things for myself," Shear said. She believes that fact speeded her recovery.

Shear is able to be more active, than she was before the surgery because she is not in pain and on painkillers.

"Now I walk, and I go to Curves," she said. "I feel so much better."

Rehabilitation varies tremendously with the person and their willingness to do the exercises prescribed.

"It's half of the outcome, as far as I am concerned," Calkins said.

"With UKR, we have to have all the ligaments in place. We have to have no arthritis in the opposite side and not much in the knee cap," Calkins said.

Stress films are taken.

An examination is done to make certain all the ligaments are intact so the knee is stable enough for the UKR.

"All we can do is reconstruct this to the alignment God originally made it in," Calkins said.

If the replacement plastic Calkins is using wears out, the wear can be seen on an X-ray, and a small incision can then be made and the plastic exchanged.

He even has UKR in one of his own knees.

"The other style of the unicondylar has the plastic actually fixed to the plate." When a patient goes to bend their knee, the plate does not match the curvature of the bone, which causes wear. Wear means it won't last as long.

UKR hospital stays are two to three days versus four or five for TKS. Incisions are several inches less than TKRs, depending upon the size and amount of deformity in a patient's knee. Physical therapy lasts about a month.

As with any orthopedic surgical procedure, there can be risks to UKR. A sudden drop in blood pressure during surgery due to the use of bone cement or formation of extra bone in the joint could happen.

The only problem Calkins said he has seen was a fracture of the shinbone, which has done well.

Calkins obtained his medical degree from the University of Arizona in 1972. He served his internship and residency at Vanderbilt University Hospital in Tennessee and Emory University in Georgia.

He practiced orthopedics in his hometown of Scottsdale until moving to Payson in 1998.

He has had privileges since 1978 at what is now Payson Regional Medical Center.

Calkins can be reached at Payson Regional Bone and Joint, 126 E. Main St., Suite D, Payson, (928) 472-5260.

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