Treatment of TKA infection should stress eradication of infection, alleviation of pain, restoration of function
 

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1st on the web (January 17, 2008)
January 2008

LAHAINA, Hawaii - Of the several treatment options for infections in total knee replacements, reimplantation may offer the best functional outcome along with a high degree of infection control.

"The infection rate [in total knee replacement] over the past three decades has diminished, but I think it remains one of the most difficult problems to manage. Once a patient has a periprosthetic infection, the outcome for that patient - both in the infection [cure] rate and overall patient functionality - is nothing like a primary TKR," said Robert T. Trousdale, MD, of the Mayo Clinic in Rochester, Minn.

The goals of infection management should include the eradication of the infection itself, alleviation of patients' pain, and restoration of function at the highest level possible.

"These should be the goals no matter what treatment approach you ultimately decide to use," he said.

Amputation is used in about 4% of infected knee replacements, according to Trousdale. While it offers the highest degree of infection control, "it also produces the worst functional results. These patients live their lives in wheelchairs, on crutches or with prostheses, and many them are miserable," he said.

Fusion also has a reasonably good infection cure rate, but not as good as amputation because it leaves some scar tissue. Although the functional outcomes with fusion are acceptable, many patients are not happy with the end result, Trousdale said.

As another option, resection arthroplasty demonstrates a slightly higher infection cure rate than arthrodesis but extremely poor functional results, he said.

Debridement can be good for patients who have acute infection, including those presenting with symptoms lasting less than 2 or 3 weeks, and those who are immunocompetent hosts. "We stopped doing our debridements arthroscopically, so we do them all open with antibiotic suppression," Trousdale said.

Antibiotic suppression alone is viable for patients who are too sick for an operation but can tolerate an oral antibiotic, he added.

While reimplantation may not offer the same high rate of infection control that amputation offers, "it is the best option for optimal functional outcome," he said.

One of the current controversies surrounding infection control concerns the timing of staging prior to performing reimplantation when the components are debrided or resected.

"Should it be 1 month, 6 weeks, 3 months or 1 year? There is a lot of disagreement about the optimal time," he said. "There is also a subset of patients who would benefit from a primary exchange, or performing a resection and putting the implants back at the same time."

Likewise, the optimal duration and route of antibiotic delivery is a hotbed of discussion.

"At the Mayo Clinic, we often use antibiotics for 4 to 6 weeks, then a 2- to 3-week antibiotic 'holiday,' followed by a restaging to make sure that there isn't an infection. When that's done, we do the reimplantation," he said.

Antibiotic spacers can be effective for select patients, according to Trousdale. "We also use cement with antibiotics in all of our revision cases," he said.

For more information:

Trousdale RT. Prevention, diagnosis and treatment of infection. Presented at Orthopedics Today Hawaii 2008. Jan. 13-16, 2008. Lahaina, Maui, Hawaii.