BackgroundImplant-related osteomyelitis (IRO) is recently controlled with local antibiotic delivery systems to overcome conventional therapy disadvantages. In vivo evaluation of such systems is however too little.Questions/purposesWe asked whether vancomycin (V)-containing poly-l-lactic acid/β-tricalcium phosphate (PLLA/β-TCP) composites control experimental IRO and promote bone healing in vivo.MethodsFifty-six rats were distributed to five groups in this longitudinal controlled study. Experimental IRO was established at tibiae by injecting methicillin-resistant Staphylococcus aureus (MRSA) suspensions with titanium particles in 32 rats. Vancomycin-free PLLA/β-TCP composites were implanted into the normal and infected tibiae, whereas V-PLLA/β-TCP composites and coated (C)-V-PLLA/β-TCP composites were implanted into IRO sites. Sham-operated tibiae established the control group. Radiological and histological scores were quantified with microbiological findings on weeks 1 and 6.ResultsIRO is resolved in the CV- and the V-PLLA/β-TCP groups but not in the PLLA/β-TCP group. MRSA was not isolated in the CV- and the V-PLLA/β-TCP groups at all times whereas the bacteria were present in the PLLA/β-TCP group. Radiological signs secondary to infection are improved from 10.9 ± 0.9 to 3.0 ± 0.3 in the V-PLLA/β-TCP group but remained constant in the PLLA/β-TCP group. Histology scores are improved from 24.7 ± 6.5 to 17.6 ± 4.8 and from 27.6 ± 7.9 to 32.4 ± 8.9 in the CV-PLLA/β-TCP and the V-PLLA/β-TCP groups, respectively. New bone was formed in all the PLLA/β-TCP group at weeks 1 and 6.ConclusionsCV- and V-PLLA/β-TCP composites controlled experimental IRO and promoted bone healing.Clinical relevanceCV- and V-PLLA/β-TCP composites have the potential of controlling experimental IRO and promoting bone healing.

Vancomycin-containing PLLA/β-TCP composites may be useful for controlling MRSA but will require in vivo confirmation.

Achieving the stable osteointegration of prosthetic implants is one of the great challenges of modern orthopedic surgery. The fixation of ceramic acetabular cups of hip joint prostheses is usually achieved using a metal shell provided with screws or pegs that penetrate into the host pelvic bone. The deposition of bioactive coatings on the implant surface to be put in contact with bone could be a valuable strategy to promote a more “physiological” osteointegration. In this work, bioactive glass porous coatings were manufactured on the top of alumina/zirconia composite implants by two different methods, i.e., sponge replication and laser cladding. The coated samples underwent immersion studies in Kokubo’s simulated body fluid (SBF) to assess in vitro bioactivity and were found to exhibit an excellent hydroxyapatite-forming ability, which is key to allow bonding to bone. Biological tests using mesenchymal stem and osteoblast-like cells revealed the good biocompatibility of both types of materials. Furthermore, a higher level of mineralization was induced by the sponge-replicated coatings at 10 days. Overall, these results are highly promising and encourage further research on these materials.

vVK100 polymer, as a local antibiotic delivery system, seems to be an effective method for the treatment of implant-related chronic MRSA osteomyelitis.

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Bone spacers are exclusively used for replacing the tissue after trauma and/or diseases. Ceramic materials bring positive opportunities to enhance greater osteointegration and performance of implants, yet processing of porous geometries can be challenging. Additive Manufacturing (AM) opens opportunities to grade porosity levels in a part; however, its productivity may be low due to its batch processing approach. The paper studies the biological responses yielded by hydroxyapatite with β-TCP (tricalcium phosphate) ceramic porous bone spacers manufactured by robocasting 2-layer meshes that are rolled in green and sintered. The implants are assessed in vitro and in vivo for their compatibility. Human bone marrow mesenchymal stem cells attached, proliferated and differentiated on the bone spacers produced. Cells on the spacers presented alkaline phosphatase staining, confirming osteogenic differentiation. They also expressed bone-specific COL1A1, BGAP, BSP, and SPP1 genes. The fold change of these genes ranged between 8 to 16 folds compared to controls. When implanted into the subcutaneous tissue of rabbits, they triggered collagen fibre formation and mild fibroblastic proliferation. In conclusion, rolled AM-meshes bone spacers stimulated bone formation in vitro and were biocompatible in vivo. This technology may give the advantage to custom produce spacers at high production rates if industrially upscaled.

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