Reimplantation following infected TKR provides the best function

KOHALA COAST, Hawaii — The use of a two-staged reimplantation for infection in a total knee replacement will provide the best functional outcomes but not the best eradication of the infection, according to an orthopedist from the Mayo Clinic.

“In our center like [in] others, the rate of infection after knee arthroplasty has decreased over the past three decades, but it remains a significant problem, especially with more patients undergoing the procedure,” Robert T. Trousdale, MD, said at Orthopedics Today Hawaii 2009.

“Of all complications to occur after knee surgery, with the exception of neurovascular complications, infection is probably one of the most problematic,” he said.

The goals of treatment are to eradicate the infection, alleviate the pain and restore the best function to the joint.

Of all the options for treating infected knee arthroplasties, amputation is probably the best way to insure that you have removed all of the infection.

“However, it also provides the worst functional results of all the options. On the other side of the spectrum, reimplantation provides the best function, but it may also have the highest reinfection rates,” said Trousdale, a member of the Orthopedics Today Editorial Board.

Arthrodesis is a little better at curing the infection than reimplantation, but the function is not as good. “Resection arthroplasty is pretty good at curing infection, but it provides miserable functional results,” he said.

Treatment with pure antibiotic suppression is rare and indicated for the patient who has a viable organism that you can treat with an oral antibiotic. Debridement and antibiotic suppression is more frequently used for healthy patients who present with symptoms of less than 2 or 3 weeks duration and have well-fixed and well-positioned implants.

“We give them debridement plus 4 to 6 weeks of IV antibiotics and oral suppression for a year. At 1 year, I check their SED rate and c-reactive proteins If they are still elevated and are mildly symptomatic, I will continue the antibiotics for life. If they are mildly symptomatic but their rates are normal, I discontinue the antibiotics,” he said.

“There are a lot of controversies and a lot of unknowns involved in how we treat an infected total knee. These include the optimal duration of staging, optimal duration and delivery of antibiotics, the efficacy of spacers and antibiotic cement, optimal fixation at time of reimplantation and the role of spacer blocks on functional outcome,” Trousdale said.

The gold standard treatment, and probably the most common at the Mayo Clinic in Rochester, is the two-stage revision.

“When a patient presents with a chronically infected total knee replacement, they get a resection arthroplasty with a spacer block with high-dose antibiotics,” he said. “Postoperatively they get a knee mobilizer for 4 to 6 weeks [and] IV antibiotics.”

After that time if the SED rates and c-reactive proteins are normal, he proceeds with the reimplantation. If they are elevated, he will re-aspirate the knee and proceed to surgery with probable re-debridement.

“I re-implant the patient with antibiotic cement with 1 bag of vancomycin and tobramycin per bag of cement,” he said.

Reference:

Trousdale RT. Prevention, diagnosis and treatment of infection. Presented at Orthopedics Today Hawaii 2009. Jan. 11-14, 2009. Kohala Coast, Hawaii.