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Updated: Aug 7, 2025
Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction
Published on: December 3, 2017
A prospective study to identify preoperative serum parameters for spinal implant infection detected by sonication
Daniel García-Pérez1,2, Guillermo García-Posadas3, Rafael San-Juan4
1Department of Neurosurgery, University Hospital, 12 de Octubre, Avda de Córdoba S/N, 28041, Madrid, Spain. dgp.neurosurgery@gmail.com.
Purpose:
Low-virulent microorganisms identified on pedicle screws by sonication fluid culture (SFC) are an important cause of implant loosening. While sonication of explanted material improves the detection rate, the risk of contamination exists and no standardized diagnostic criteria for chronic low-grade spinal implant-related infection (CLGSII) are stablished. Besides, the role of serum C-reactive protein (CRP) and procalcitonin (PCT) in CLGSII has not been adequately investigated.
Methods:
Blood samples were collected prior to implant removal. To increase sensitivity, the explanted screws were sonicated and processed separately. Patients exhibiting at least one positive SFC were classified in the infection group (loose criteria). To increase specificity, the strict criteria only considered multiple positive SFC (≥ 3 implants and/or ≥ 50% of explanted devices) as meaningful for CLGSII. Factors which might promote implant infection were also recorded.
Results:
Thirty-six patients and 200 screws were included. Among them, 18 (50%) patients had any positive SFCs (loose criteria), whereas 11 (31%) patients fulfilled the strict criteria for CLGSII. Higher serum protein level was the most accurate marker for the preoperative detection of CLGSSI, exhibiting an area under the curve of 0.702 (loose criteria) and 0.819 (strict criteria) for the diagnosis of CLGSII. CRP only exhibited a modest accuracy, whereas PCT was not a reliable biomarker. Patient history (spinal trauma, ICU hospitalization and/or previous wound-related complications) increased the likelihood of CLGSII.
Conclusion:
Markers of systemic inflammation (serum protein level) and patient history should be employed to stratify preoperative risk of CLGSII and decide the best treatment strategy.
Insights
Diagnosing chronic low-grade spinal implant infections is challenging. Higher serum protein levels and patient history are key indicators for identifying these infections, guiding better treatment strategies.
Area of Science:
- Spinal surgery
- Infectious disease diagnostics
- Biomarker research
Background:
- Low-virulent microorganisms on pedicle screws cause implant loosening.
- Sonication fluid culture (SFC) aids detection but risks contamination.
- Standardized criteria for chronic low-grade spinal implant-related infection (CLGSII) are lacking.
Purpose of the Study:
- To evaluate diagnostic markers for CLGSII.
- To investigate the role of serum C-reactive protein (CRP) and procalcitonin (PCT).
- To establish reliable criteria for CLGSII diagnosis.
Main Methods:
- Collected blood samples pre-implant removal.
- Used sonication fluid culture (SFC) on explanted screws.
- Defined CLGSII using loose (any positive SFC) and strict (≥3 implants or ≥50% positive SFC) criteria.
- Recorded factors potentially promoting infection.
Main Results:
- 50% of patients met loose criteria; 31% met strict criteria for CLGSII.
- Higher serum protein levels showed high accuracy (AUC 0.702-0.819) for CLGSII detection.
- CRP had modest accuracy; PCT was unreliable.
- Patient history (trauma, ICU, complications) increased CLGSII likelihood.
Conclusions:
- Serum protein levels and patient history are crucial for preoperative risk stratification.
- These markers aid in determining optimal treatment strategies for CLGSII.
- Further research needed to refine diagnostic protocols for spinal implant infections.
