Effects of PMMA spacer loaded with varying vancomycin concentrations on bone regeneration in the Masquelet technique
Jie Xie1,2, Wu Wang1,2,3, Xiaolei Fan1,2
1Department of Orthopedics, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China.
Abstract:
Whether antibiotics should be included remains greatly debated in Masquelet technique. This study intended to determine the effect of polymethyl methacrylate (PMMA) spacer loaded with different vancomycin concentrations on bone defect repair. Hollow cylindrical spacers consisting of PMMA and varying vancomycin concentrations (0, 1, 2, 4, 6, 8, and 10 g) were prepared. Critical bone defects of rabbits were created at the radial shaft, and spacers were implanted and subsequently intramedullary fixed with retrograde Kirschner's wires (n = 4 for each vancomycin concentration). After 4 weeks, the induced membranes were opened and cancellous allografts were implanted into the defects. Eight weeks post-operatively, the results of X-ray, histology, and micro-CT revealed that some cortical bone was formed to bridge the gap and the bone marrow cavity was formed over time. Quantitatively, there was more new bone formation in the groups with a relatively lower vancomycin concentration (1-4 g) compared with that in the groups with a higher vancomycin concentration (6-10 g). Our findings suggested that PMMA spacers loaded with relatively lower vancomycin concentrations (1-4 g) did not interfere with new bone formation, whereas spacers loaded with relatively higher vancomycin concentrations (6-10 g) had negative effects on bone formation.
Insights
Polymethyl methacrylate (PMMA) spacers with lower vancomycin concentrations (1-4 g) support bone defect repair in rabbits. Higher concentrations (6-10 g) negatively impact new bone formation, guiding optimal antibiotic use in bone reconstruction.
Area of Science:
- Orthopedics
- Biomaterials Science
- Regenerative Medicine
Background:
- The Masquelet technique is a widely used method for treating large bone defects.
- The role of antibiotics, specifically vancomycin, within polymethyl methacrylate (PMMA) spacers in this technique is still under investigation.
- Optimizing antibiotic elution from PMMA spacers is crucial for balancing infection prevention and bone healing.
Purpose of the Study:
- To evaluate the impact of varying vancomycin concentrations loaded into PMMA spacers on critical-sized bone defect repair in a rabbit model.
- To determine the optimal vancomycin concentration range that promotes bone regeneration without hindering the healing process.
Main Methods:
- Hollow cylindrical PMMA spacers were fabricated with vancomycin concentrations ranging from 0 to 10 g.
- Critical bone defects were created in the radial shafts of rabbits and treated with these vancomycin-loaded PMMA spacers.
- Bone healing was assessed over 8 weeks using X-ray, histology, and micro-computed tomography (micro-CT) analysis.
Main Results:
- New cortical bone formation was observed, bridging the defect and restoring the medullary cavity over time.
- PMMA spacers with lower vancomycin concentrations (1-4 g) showed enhanced new bone formation compared to higher concentrations.
- Higher vancomycin concentrations (6-10 g) demonstrated an inhibitory effect on bone regeneration.
Conclusions:
- PMMA spacers loaded with 1-4 g of vancomycin do not impede bone defect repair and may support healing.
- Higher vancomycin concentrations (6-10 g) in PMMA spacers adversely affect bone formation, suggesting a concentration-dependent inhibitory effect.
- These findings provide valuable insights for optimizing antibiotic selection and dosage in PMMA spacers for bone reconstruction procedures.
