The role of RANKL/RANK/OPG system in the canine model of hip periprosthetic infection osteolysis

Experimental study of radial extracorporeal shock wave therapy for periprosthetic osteolysis induced by wear particles

Radial Extracorporeal Shock Wave Therapy (rESWT) is applied as a conservative treatment modality in orthopedics, yet its effectiveness in addressing aseptic loosening of cementless joint prostheses remains unclear. Through animal experimentation, we have revealed that in a titanium particle-induced osteolysis rat model, rESWT intervention significantly increased periprosthetic bone density compared to untreated controls, concurrently reducing osteolytic lesion area and lowering serum IL-1β levels. Histological analyses demonstrated a relative decrease in osteoclast counts within the treatment group versus non-treated controls. These findings indicate that rESWT, through mechanisms involving anti-inflammatory actions and suppression of osteoclastogenesis, may serve as a non-invasive therapeutic strategy for preventing and managing periprosthetic bone loss, demonstrating clinical potential to delay or eliminate the necessity for revision surgeries.

Investigation of the medium-term effect of osteoprotegerin/bone morphogenetic protein 2 combining with collagen sponges on tendon-bone healing in a rabbit

BACKGROUND

Osteoprotegerin (OPG) and bone morphogenetic protein-2 (BMP-2) could be administered sequentially to promote tendon-bone healing. There remain several unresolved issues in our previously published study: a) the release kinetics of OPG/BMP-2 from the OPG/BMP-2/collagen sponge (CS) combination in vitro remained unclear; b) the medium-term effect of the OPG/BMP-2/CS combination was not analyzed. Hence, we design this study to address the issues mentioned above.

METHODS

30 rabbits undergoing anterior cruciate ligament reconstruction (ACLR) with an Achilles tendon autograft randomly received one of the 3 delivery at the femoral and tibial tunnels: OPG/BMP-2, OPG/BMP-2/CS combination, and nothing (blank control). At 8 and 24 weeks post-surgery, the biomechanical tests and histologic analysis were used to evaluate the tendon-bone healing.

RESULTS

In mechanical tests, the OPG/BMP-2/CS group showed a higher final failure load and stiffness than the other groups at 8 and 24 weeks. Additionally, the maximum stretching distance showed a decreasing trend. The mechanical failure pattern of samples shifted from a tunnel pull-away to a graft midsubstance rupture after OPG/BMP-2/CS-treated. From histological analysis, the OPG/BMP-2/CS treatment increased the amount of collagen fibers (collagen I and II) and promoted fibrocartilage attachment.

CONCLUSION

CS as a carrier promotes the medium-term effect of OPG and BMP-2 on tendon-bone healing at the tendon-bone interface in a rabbit ACLR model. OPG, BMP-2 and CS were already applied in several clinical practice, but a further study of clinic use of OPG/BMP-2/CS is still needed.

Multifunctional antibiotic- and zinc-containing mesoporous bioactive glass scaffolds to fight bone infection

Bone regeneration is a clinical challenge which requires multiple approaches. Sometimes, it also includes the development of osteogenic and antibacterial biomaterials to treat the emergence of possible infection processes arising from surgery. This study evaluates the antibacterial properties of gelatin-coated meso-macroporous scaffolds based on the bioactive glass 80%SiO₂-15%CaO-5%P₂O₅ (mol-%) before (BL-GE) and after being doped with 4% of ZnO (4ZN-GE) and loaded with both saturated and the minimal inhibitory concentrations of one of the antibiotics: levofloxacin (LEVO), vancomycin (VANCO), rifampicin (RIFAM) or gentamicin (GENTA). After physical-chemical characterization of materials, release studies of inorganic ions and antibiotics from the scaffolds were carried out. Moreover, molecular modelling allowed determining the electrostatic potential density maps and the hydrogen bonds of antibiotics and the glass matrix. Antibacterial in vitro studies (in planktonic, inhibition halos and biofilm destruction) with S. aureus and E. coli as bacteria models showed a synergistic effect of zinc ions and antibiotics. The effect was especially noticeable in planktonic cultures of S. aureus with 4ZN-GE scaffolds loaded with VANCO, LEVO or RIFAM and in E. coli cultures with LEVO or GENTA. Moreover, S. aureus biofilms were completely destroyed by 4ZN-GE scaffolds loaded with VANCO, LEVO or RIFAM and the E. coli biofilm total destruction was accomplished with 4ZN-GE scaffolds loaded with GENTA or LEVO. This approach could be an important step in the fight against microbial resistance and provide needed options for bone infection treatment. STATEMENT OF SIGNIFICANCE: Antibacterial capabilities of scaffolds based on mesoporous bioactive glasses before and after adding a 4% ZnO and loading with saturated and minimal inhibitory concentrations of levofloxacin, vancomycin, gentamicin or rifampicin were evaluated. Staphylococcus aureus and Escherichia coli were the infection model strains for the performed assays of inhibition zone, planktonic growth and biofilm. Good inhibition results and a synergistic effect of zinc ions released from scaffolds and antibiotics were observed. Thus, the amount of antibiotic required to inhibit the bacterial planktonic growth was substantially reduced with the ZnO inclusion in the scaffold. This study shows that the ZnO-MBG osteogenic scaffolds are multifunctional tools in bone tissue engineering because they are able to fight bacterial infections with lower antibiotic dosage.