Prosthetic joint infections (PJIs) present significant challenges in healthcare, impacting patient quality of life and with a significant impact on the financial health of the healthcare system. In the fight against these infections, surgical treatments like implant-retaining strategies or two-stage revision procedures are employed. One key development in infection control is the use of antibiotic-loaded poly(methyl methacrylate) (PMMA) spacers, which both act as drug delivery systems and facilitate prosthesis implantation.
A promising addition to these spacers is the use of microsilver, a well-known and well-researched antimicrobial agent. This study sought to assess the safety and effectiveness of microsilver-loaded PMMA spacers in patients undergoing revision surgery for infected total hip arthroplasty (THA). This blog post covers the critical points of the study and its implications.
Study Overview
This prospective cohort study involved 12 patients who underwent a three-stage revision surgery. All patients received gentamicin-loaded PMMA spacers, with one group having additional 1% microsilver loading. Microsilver spacers were swapped after 14 days, and revision prosthesis implantation occurred in the third surgery.
Key areas of the study included:
- Clinical observation
- Laboratory parameters
- Silver concentration analysis in blood, urine, and drainage fluids
- Histological analysis of perispacer tissue
The aim was to evaluate the biocompatibility of these spacers and ensure the silver concentration levels remained within safe limits.
Results and Key Findings
Of the 12 patients, 11 completed the study, and the findings were promising:
- No Serious Adverse Events: No instances of argyria (a condition causing skin discoloration due to silver) or other silver-related adverse events were observed.
- Low Silver Concentrations: Silver levels in blood and urine were generally low. In 10 out of 11 patients, the concentrations were below the detection limit of 1 part per billion (ppb). One patient showed a peak level of 5.6 ppb, still below the safety threshold of 10 ppb. No detectable silver was found in urine samples.
- Drainage Fluid Analysis: Silver levels in the drainage fluid ranged from 16.1 to 23.3 ppb at 12 hours post-implantation and from 16.8 to 25.1 ppb at 48 hours. These values align with the concept of local antimicrobial application.
- Histological Findings: No differences were found in the inflammatory response between microsilver-loaded and silver-free PMMA spacers. The tissue surrounding the implants did not show any signs of silver toxicity, such as necrosis.
Strengths and Limitations
Strengths:
The prospective collection of data in a target population made this study robust, giving valuable insights into spacer safety in real-world clinical settings.
Limitations:
The sample size was relatively small, with only 12 patients, which limits the generalizability of the findings. Additionally, the follow-up period was short, and the long-term efficacy of microsilver spacers in preventing infections was not assessed.
Conclusion
This study provided strong evidence for the safety of microsilver-loaded gentamicin-PMMA spacers. The low silver concentrations in blood and urine, alongside the lack of silver-related adverse events, suggest that microsilver offers a biocompatible solution with the potential for broader antimicrobial protection without concern that there is absorption of microsilver in the body.
Future research is needed to assess the effectiveness of microsilver spacers in reducing reinfection rates in PJIs. For now, the broad-spectrum antimicrobial activity of silver and its safe application in clinical settings make it a valuable tool in the ongoing fight against prosthetic joint infections, improving clinical outcomes while lowering hospital acquired infections (HAI’s).
