Newspaper article The Florida Times Union

Replacing the Replacement; Problems with Older 'New' Knee Call for a 'Revision'

Newspaper article The Florida Times Union

Replacing the Replacement; Problems with Older 'New' Knee Call for a 'Revision'

Article excerpt

Byline: Roger Bull, Times-Union staff writer

And so it begins all over again.

As Don Mathis stretched, bent, pushed and grunted his right leg into usefulness, it was time for his left. Just six weeks after Mathis had his right knee replaced, it was time to have his left replaced.

He'd already had that done nine years ago. But it's been giving him trouble ever since. That's not supposed to happen.

David Heekin, the orthopedic surgeon who replaced Mathis' replacement last month, said that artificial knees should last at least 20 years. Studies of knee replacements done in 1982 found 90 percent to 95 percent were intact and fully functional.

Mathis' left knee was not. It's been hurting for years, pretty much since he got it done. He thinks it was probably from all the complications he had in the days and weeks right after the operation. The blood clot, the hematoma that swelled up and started leaking blood through the new incision that hadn't had time to heal.

Heekin thought it might have been the time Mathis fell out of tree. That might have jarred everything loose.

It was a fall from a ladder in the front yard. Mathis was trimming a palm tree, was on the last frond and doing fine until he hit the wasps' nest. They weren't happy. Next thing he knew he was on the ground with a shattered right ankle. But he doesn't think his left leg took much of the impact.

Either way, that left knee has been hurting, and it was time to get it done. Mathis' usual orthopedic surgeon, Steven Lancaster, couldn't do it because he's with Jacksonville Orthopaedic Institute, which stopped doing elective surgery in early May when other surgeons stopped working. They've since gone back.

In the meantime, Mathis found Heekin.

"When an implant fails," Heekin said, "it's almost like a bearing in a wheel."

The implants start to shed tiny, almost microscopic pieces of the polyethylene. The body thinks those are bacteria, Heekin said, and sends enzymes to attack them. But those enzymes damage the bone, a process called osteolysis.

Artificial knees are supposed to be pain free. There are, after all, no nerve endings in the metal and plastic pieces. But those little pieces of plastic start floating around, and some end up between the implant and the bone, grinding the bone on every step.

And that hurts.

A revision, that's what replacing a replacement is called, is more complicated operation. Mathis was in the operating room for about five hours for the revision. The replacement of his right knee took less than two.

The problem, Heekin said, is that those pieces of plastic settle in the dozens of natural cavities in the bones there. The enzymes also collect there and eat at the bone, enlarging each cavity. The bones around Mathis' knee, he said, looked "moth-eaten. …

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