Artificial joint infections prove stubborn to treat

When Bob Wightman's leg swelled up like a red balloon in the summer of 2013 following a knee replacement he had to make a choice: take a daily dose of penicillin or go under the knife again.

​Now nearly two years after being diagnosed with Periprosthetic Joint Infection (PJI), the 78-year-old remains on antibiotics hoping he won't have to return to the operating room.

"If it doesn't come around in a couple of years you decide to stay on penicillin for the rest of my life — or go in, open it up, actually replace the joint and try again," Wightman said.

Infections can be as much as four to five times that cost, so you can see the burden of the disease can be quite significant.- Dr. Paul Beaulé, Ottawa Hospital

Infections at artificial joints are rare — developing in one per cent of artificial joint patients — but they are difficult and expensive to treat. Since the bacteria is attached to an artificial joint — made of plastic, ceramic or metal — instead of bone, the body's natural defences are less equipped to attack them.

Doctors at the Ottawa Hospital perform about 1,200 joint-replacement surgeries each year. If one in a hundred patients has an infection, that would result in about 12 patients with potentially costly complications, including risky follow-up surgeries, said Dr. Paul Beaulé, the hospital's head of the orthopedic surgery.

 "If you think about it gross numbers numbers, a primary artificial joint will cost between $8,000 and $10,000 in terms of the overall patient experience — in terms of hospital stay, implant, all those things," Beaulé said. "Infections can be as much as four to five times that cost, so you can see the burden of the disease can be quite significant."

Beaulé said the Ottawa Hospital is now conducting a detailed analysis of the PJI cases that have come through the hospital, and the various outcomes that can range from complete recovery to amputation — even death.

"We're looking at these patients' journey. How were they diagnosed, when did they have it, how did we treat them and what was their outcome," Beaulé said.

Infection difficult to trace, treat

The source of a PJI infection is difficult to trace because it can enter through a cut somewhere else on the body or during surgery. Despite the hospital's best efforts to sterilize the operating room and equipment, doctors can never guarantee a patient undergoing surgery won't get the infection.

"It can't be zero because the bacteria are on our skin, they live in us, so there always a potential of that contaminating our surgical area," he said.

Most cases are diagnosed within the first few days or weeks of surgery. Wightman's case was unusual because the infection didn't flare up until eight years after his knee surgery.

He was initially told surgeons would have to cut open his knee — again.

"You've got to really go in and open it up and seriously rinse it and replace the cap — and cross your fingers," he said.

Though Wightman ended up taking daily penicillin pills instead to keep the infection at bay, so far he hasn't been able to beat the infection.