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Updated: Mar 29, 2026
Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction
Published on: December 3, 2017
Diagnosis of spacer-associated infection using quantitative cultures from sonicated antibiotics-loaded spacers:
J Esteban1, I Gadea2, C Pérez-Jorge2
1Department of Clinical Microbiology, IIS-Fundación Jiménez Díaz, UAM, Av. Reyes Católicos 2, 28040, Madrid, Spain. jestebanmoreno@gmail.com.
Abstract:
Recent studies showed that a positive microbiological result from sonication of the PMMA spacer was associated with poor outcome of patients, but no quantitative analysis has yet been performed. For this purpose, a prospective analysis of 50 spacers (46 patients) was performed. All spacers were processed according to a previously described protocol, including centrifugation and quantitative culture. Clinical data and outcome were also analysed. A statistical relationship between the results of the cultures and the outcome of the patient was assessed. Sixteen patients were diagnosed with spacer-associated infection. Thirteen out of 50 spacers gave a positive culture. Nine of 13 presented with growth of an organism not isolated in the first-stage cultures, and in 7 out of 13 the organisms count was high (>10,000 CFU/ml). We have detected a significant statistical relationship between poor outcome and positive cultures, high colony counts, isolation of different organisms, positive periprosthetic cultures and spacer-associated infection. The detection in a sonicated, antibiotic-loaded PMMA spacer of organisms other than those isolated in the first surgical samples or high colony counts of any organisms is diagnostic with regard to spacer-associated infection.
Insights
Positive microbiological results from sonicated polymethyl methacrylate (PMMA) spacers indicate poor patient outcomes. High bacterial counts or different organisms detected in spacers are diagnostic for spacer-associated infections, guiding treatment decisions.
Area of Science:
- Orthopedic surgery
- Infectious disease diagnostics
- Biomaterial science
Background:
- Polymethyl methacrylate (PMMA) spacers are used in orthopedic surgery to deliver antibiotics locally.
- Positive microbiological results from explanted PMMA spacers have been linked to adverse patient outcomes.
- Quantitative analysis of sonication cultures from PMMA spacers is lacking.
Purpose of the Study:
- To perform a quantitative analysis of microbiological results from sonicated PMMA spacers.
- To assess the relationship between spacer culture findings and patient outcomes.
- To establish diagnostic criteria for spacer-associated infections based on sonication cultures.
Main Methods:
- Prospective analysis of 50 PMMA spacers from 46 patients.
- Quantitative culture of sonicated spacer samples after centrifugation.
- Analysis of clinical data and patient outcomes.
- Statistical assessment of correlations between culture results and outcomes.
Main Results:
- Sixteen patients were diagnosed with spacer-associated infection.
- 13 out of 50 spacers yielded positive cultures.
- Nine of 13 positive cultures showed organisms not found in initial surgical samples.
- Seven of 13 positive cultures had high bacterial counts (>10,000 CFU/ml).
- Significant statistical relationships were found between poor outcomes and positive cultures, high counts, different organisms, and positive periprosthetic cultures.
Conclusions:
- Positive sonication cultures from PMMA spacers are significantly associated with poor patient outcomes.
- Detection of organisms different from initial surgical samples or high bacterial counts in sonicated spacers is diagnostic for spacer-associated infection.
- Quantitative sonication cultures aid in diagnosing spacer-associated infections and predicting patient prognosis.
