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Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 165 - 165
1 Dec 2013
Russo A Panseri S Shelyakova T Sandri M Ortolani A Meikle S Lacey J Tampieri A Dediu V Santin M Marcacci M
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Introduction

Diaphyseal bone defect represents a significant problem for orthopaedic surgeons and patients. Bone is a complex tissue whose structure and function depend strictly on ultrastructural organization of its components: cells, organic (extracellular matrix, ECM) and inorganic components. The purpose of this study was to evaluate bone regeneration in a critical diaphyseal defect treated by implantation of a magnetic scaffold fixed by hybrid system (magnetic and mechanical), supplied through nanoparticle-magnetic (MNP) functionalized with Vascular Endothelial-Growth-Factor-(VEGF) and magnetic-guiding.

Methods

A critical long bone defect was created in 8 sheep metatarsus diaphysis: it was 20.0 mm in length; the medullary canal was reamed till 8.00 mm of inner diameter. Then a 8.00 mm diameter magnetic rod was fitted into proximal medullary canal (10 mm in length).

After that a scaffold made of Hydroxyapatite (outer diameter 17.00 mm) that incorporates magnetite (HA/Mgn 90/10) was implanted to fill critical long bone defect. A magnetic rod (6.00 mm diameter) was firmly incorporated at proximal side into the scaffold. Both magnets had 10 mm length. To give stability to the complex bone-scaffold-bone a plate was used as a bridge; it was fixed proximally by 2 screws and distally by 3 screws.

Scaffolds biocompatibility was previously assessed in vitro using human osteoblast-like cells. Magnetic forces through scaffold were calculated by finite element software (COMSOL Multiphysics, AC/DC Model).

One week after surgery, magnetic nanoparticles functionalized with VEGF were injected at the mid portion of the scaffold using a cutaneous marker positioned during surgery as reference point in 4 sheep; other sheep were used as control group. After sixteen weeks, sheep were sacrificed to analyze metatarsi. Macroscopical, radiological and microCT examinations were performed.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 97 - 97
1 Mar 2009
MEROLLI A Santin M Ambrosio L Nicolais L
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INTRODUCTION. A new class of soybean-based bio-materials has been presented to the scientific community (patent PCT/GB01/03464) which shows good mechanical properties and an intrinsic anti-inflammatory potential, probably related to the phyto-hormone Genistein. This plant isoflavone is also reported to inhibit osteo-clastic activity.

MATERIALS AND METHODS. De-fatted soybean curd was prepared into granules which were subsequently implanted in a cylindrical cavity drilled into the femural canal of New Zealand White rabbits. Retrieved femurs were embedded in poly-methyl-meta-acrylate and samples were analyzed by back-scattered electron microscopy (BSEM).

RESULTS. Retrieved operated femurs showed a macroscopic appearance similar to the non-operated controls. BSEM showed that granules were still present at the site of implantation after 8 weeks, but a clear progressive degradation took place from the periphery to the centre of the femural canal already after 3 weeks. The degradation of the granule was accompanied by the production of new trabeculae apposed to the surface of the material.

CONCLUSIONS. It can be hyothesised that the released Genistein shifts the metabolic balance towards bone production by inhibiting the macrophagic and osteo-clastic activities and that the material degrading surface supports the apposition and mineralization of the newly-formed bone.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_II | Pages 190 - 190
1 Apr 2005
Merolli A Santin M Ambrosio L Nicolais L Gabbi C Leali PT
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A new class of soybean-based biomaterials has been presented to the scientific community (patent PCT/GB01/03464) that shows good mechanical properties and an intrinsic anti-inflammatory potential, probably related to the phyto-hormone Genistein. This plant iso-flavone is also reported to inhibit osteoclastic activity.

De-fatted soybean curd was prepared into granules which were subsequently implanted in a cylindrical cavity drilled into the femoral canal of New Zealand White rabbits. Retrieved femurs were embedded in polymethyl-meta-acrylate and samples were analysed by back-scattered electron microscopy (BSEM). Retrieved, operated femurs showed a macroscopic appearance similar to the non-operated controls. BSEM showed that granules were still present at the site of implantation after 8 weeks, but a clear progressive degradation took place from the periphery to the centre of the femural canal already after 3 weeks. The degradation of the granule was accompanied by the production of new trabeculae apposed to the surface of the material.

It can be hypothesised that the released Genistein shifts the metabolic balance towards bone production by inhibiting the macrophagic and osteoclastic activities and that the material degrading surface supports the apposition and mineralisation of the newly formed bone.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_II | Pages 190 - 191
1 Apr 2005
Merolli A Santin M Ambrosio L Cannas M Giannotta L Leali PT
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Coatings for endo-osseous implants have been developed based on phospholipids. Such coatings promote the formation of a very thin superficial rim which is highly enriched with calcium phosphates.

Two phospholipid-based preparations have been compared with a standard hydroxyapatite coating. Preparation S was based on phosphatidyl-serine; preparation C was based on a mixture of phosphatidyl-serine, phosphatidyl-choline and cholesterol. Titanium cylinders spammed with titanium foam were the metallic substrate for the coatings; they were implanted in the femoral canal of New Zealand White rabbits and retrieved after 4, 8 and 26 weeks. A back scattered electron microscopy analysis followed.

Both phospholipid preparations were shown not to have any inhibitory action on bone apposition and growth and did not elicit any adverse fibrous reaction. Pictures of bone in-growth into the cavities of the titanium foam are present. A truly tight apposition between bone and coating was evident only in the comparative group sprayed with hydroxyapatite, but this latter coating was often fragmented and its constituent granules were evident. The phospholipid-based coatings did not show inhibitory action on bone apposition and growth and did not elicit any adverse fibrous reaction.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_II | Pages 190 - 190
1 Apr 2005
Merolli A Gabbi C Locardi B Santin M Giannotta L Leali PT
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The rationale for a degradable bioactive glass coating is to lead the bone to appose gradually to the metal without the release of non-degradable particles. Two formulations of bioactive glasses, already described in the literature, have been studied: bg A and bg F. A non-bioactive glass (glass H) was sprayed as a control. Glass-coated Ti6Al4V cylinders were implanted in the femoral canal of New Zealand White rabbits. Samples were analysed by back scattered electron microscopy (BSEM) and electron dispersive analysis (EDX).

Bone was in tight apposition with the coating. As time progressed, images were found where bone showed features of physiological remodelling (newly formed bone filling areas of bone resorption) close to the coating. At the interface the apposition was so tight that it was not possible to discern a clear demarcation, even at higher magnification (more than 2500x). There was a gradual degradation during time and at 10 months bone was found apposed directly to the metal in more than half of the samples. In contrast, the non-bioactive glass coating showed complete integrity at any time examined and a clear demarcation with the coating was evident. Two peculiar features of the behaviour of bioactive glass coatings in vivo are: (a) degradation during time; and (b) promotion of a tight apposition with the newly formed bone.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_I | Pages 65 - 65
1 Mar 2005
Merolli A Santin M Ambrosio L Gabbi C Leali PT
Full Access

Aims: A new class of soybean-based biomaterials has been presented (patent PCT/GB01/03464) which shows good mechanical properties and an intrinsic anti-inflammatory potential, probably related to the phyto-hormone Genistein. This plant isoflavone is also reported to inhibit osteoclastic activity. Aim of this study is to evaluate in-vivo the bone response to such soybean-based biomaterials.

Methods: De-fatted soybean curd was prepared into granules which were subsequently implanted in a cylindrical cavity drilled into the femural canal of New Zealand White rabbits. Retrieved femurs were embedded in poly-methyl-methacrylate and samples were analyzed by back-scattered electron microscopy (BSEM).

Results: Retrieved operated femurs showed a macroscopic appearance similar to the non-operated controls. BSEM showed that granules were still present at the site of implantation after 8 weeks, but a clear progressive degradation took place from the periphery to the centre of the femural canal already after 3 weeks. The degradation of the granule was accompanied by the production of new trabeculae apposed to the surface of the material.

Conclusions: It can be hypothesised that the released Genistein shifts the metabolic balance towards bone production by inhibiting the macrophagic and osteo-clastic activities and that the material degrading surface supports the apposition and mineralization of newly-formed bone.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_I | Pages 60 - 60
1 Mar 2005
Merolli A Santin M Ambrosio L Cannas M Giannotta L Leali PT
Full Access

Aims. Coatings for endo-osseous implants have been developed based on phospholipids. Such coatings promote the formation of a very thin superficial layer which is highly enriched with calcium phosphates. Aim of this study is a comparison of such coatings with an hydroxyapatite coating.

Methods. Two phospholipid-based preparations have been compared with a standard hydroxyapatite coating. Preparation S was based on phosphatidyl-serine; preparation C was based on a mixture of phosphatidyl-serine, phosphatidyl-choline and cholesterol. Titanium cylinders wrapped with titanium foam were the metallic substrate for the coatings; they were implanted in the femural canal of New Zealand White rabbits and retrieved after 4, 8 and 26 weeks. A Back Scattered Electron Microscopy analysis followed.

Results. Both phospholipid preparations showed to have no inhibitory action on bone apposition and growth and did not elicit any adverse fibrous reaction. Pictures of bone in-growth into the cavities of the titanium foam were present. A tight apposition between bone and coating was evident only in the comparative group sprayed with hydroxyapatite, but this latter coating was often fragmented and its constituent granules were evident.

Conclusion. Phospholipid-based coatings showed no inhibitory action on bone apposition and growth and did not elicit any adverse fibrous reaction.