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Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction
Published on: December 3, 2017
Gentamicin concentrations in diagnostic aspirates from 25 patients with hip and knee arthroplasties
Matthew D A Fletcher1, Robert F Spencer, V George Langkamer
1Avon Orthopaedic Centre, Southmead Hospital, Bristol, UK.
Background:
There is little information on long-term release of antibiotics from impregnated bone cement.
Patients And Methods:
We assayed joint fluids obtained for diagnostic purposes from 25 patients for the presence of gentamicin. All patients had presented with failing or painful joints up to 20 years following primary hip or knee arthroplasty, using gentamicin-impregnated cement.
Results:
Gentamicin was detected in the joint fluids from 9 of 15 patients with knee prostheses and 4 of 10 patients with hip prostheses. The concentrations ranged from 0.06 mg/L to 0.85 mg/L with no significant differences in concentration between the patients with hip or knee prostheses, or the type of prosthesis. We found no relationship between the gentamicin concentration and the time after primary arthroplasty.
Interpretation:
Although most concentrations were below the levels required to inhibit susceptible pathogens, we conclude that gentamicin release around failing implants may lead to false negative cultures in some patients and provide selective pressure for the emergence of resistance where infection is present in others.
