Related Experiment Video
Updated: Oct 24, 2025
Animal Model of Implant-Associated Infections in Mice
Published on: June 27, 2025
Active rheumatoid arthritis in a mouse model is not an independent risk factor for periprosthetic joint infection
Rishi Trikha1, Danielle Greig1, Troy Sekimura1
1University of California, Los Angeles, Los Angeles, CA, United States of America.
Introduction:
Periprosthetic joint infection (PJI) represents a devastating complication of total joint arthroplasty associated with significant morbidity and mortality. Literature suggests a possible higher incidence of periprosthetic joint infection (PJI) in patients with rheumatoid arthritis (RA). There is, however, no consensus on this purported risk nor a well-defined mechanism. This study investigates how collagen-induced arthritis (CIA), a validated animal model of RA, impacts infectious burden in a well-established model of PJI.
Methods:
Control mice were compared against CIA mice. Whole blood samples were collected to quantify systemic IgG levels via ELISA. Ex vivo respiratory burst function was measured via dihydrorhodamine assay. Ex vivo Staphylococcus aureus Xen36 burden was measured directly via colony forming unit (CFU) counts and crystal violet assay to assess biofilm formation. In vivo, surgical placement of a titanium implant through the knee joint and inoculation with S. aureus Xen36 was performed. Bacterial burden was then quantified by longitudinal bioluminescent imaging.
Results:
Mice with CIA demonstrated significantly higher levels of systemic IgG compared with control mice (p = 0.003). Ex vivo, there was no significant difference in respiratory burst function (p = 0.89) or S. aureus bacterial burden as measured by CFU counts (p = 0.91) and crystal violet assay (p = 0.96). In vivo, no significant difference in bacterial bioluminescence between groups was found at all postoperative time points. CFU counts of both the implant and the peri-implant tissue were not significantly different between groups (p = 0.82 and 0.80, respectively).
Conclusion:
This study demonstrated no significant difference in S. aureus infectious burden between mice with CIA and control mice. These results suggest that untreated, active RA may not represent a significant intrinsic risk factor for PJI, however further mechanistic translational and clinical studies are warranted.
Insights
This study found no increased risk of periprosthetic joint infection (PJI) in mice with collagen-induced arthritis (CIA), a model for rheumatoid arthritis (RA). These findings suggest active RA may not intrinsically elevate PJI risk.
Area of Science:
- Orthopedics
- Rheumatology
- Infectious Diseases
Background:
- Periprosthetic joint infection (PJI) is a severe complication of joint replacement surgery.
- Rheumatoid arthritis (RA) may be associated with a higher incidence of PJI, but evidence and mechanisms are lacking.
Purpose of the Study:
- To investigate the impact of collagen-induced arthritis (CIA), an animal model of RA, on infectious burden in a PJI model.
Main Methods:
- Compared CIA mice to control mice using a Staphylococcus aureus PJI model.
- Assessed systemic IgG, ex vivo bacterial burden, and in vivo bacterial bioluminescence and CFU counts.
Main Results:
- CIA mice had higher systemic IgG but no significant differences in ex vivo or in vivo bacterial burden or biofilm formation.
- No significant difference in bacterial load was observed on implants or surrounding tissue between groups.
Conclusions:
- Active, untreated rheumatoid arthritis (RA) may not be an intrinsic risk factor for periprosthetic joint infection (PJI).
- Further translational and clinical studies are needed to confirm these findings.
