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1.
J Hand Surg Am ; 36(8): 1294-302, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21715102

RESUMO

PURPOSE: New repair techniques for fragility fractures such as those of the distal radius require biomechanical justification. This study was conducted to investigate a technique using an expanding polymer bone cement to provide strength to a fracture repair. METHODS: Distal and proximal ends were isolated from 6 pairs of human radii (mean age 65). Transverse osteotomies were made near the head of each specimen. Paired specimens were repaired using 2 materials of differing polymer chemistries: polyurethane versus polymethylmethacrylate. Repaired specimens were subjected to failure tests in a cantilever beam configuration (distal, n = 6 per treatment) or pure tension (proximal, n = 5 per treatment). Cement penetration tests were conducted using a uniform open-cell model of cancellous bone. Baseline mechanical properties of the polyurethane cement were determined according to ASTM standards. RESULTS: Distal radii repaired with polyurethane bone cement withstood average shear stress 2.9 times as high as polymethylmethacrylate (0.91 vs 0.31 MPa). Peak tensile bending stress was 2.5 times as high in polyurethane (2.57 vs 1.02 MPa). Under pure tension, polyurethane-repaired samples failed at 0.83 MPa versus 0.74 MPa for polymethylmethacrylate. The polyurethane cement expanded to penetrate 49% farther into the trabeculae. The polyurethane cement had mean compressive yield stress of 20.3 MPa, compressive modulus of 754 MPa, ultimate tensile stress of 18.5 MPa, and tensile elastic modulus of 723 MPa. CONCLUSIONS: The biomechanical strength data indicate the potential of an expanding bone cement as a candidate strategy for fracture repair. Further evaluation might provide evidence for such an alternative repair strategy for fragility fractures, including those of the distal radius.


Assuntos
Cimentos Ósseos/química , Fixação Interna de Fraturas/métodos , Poliuretanos/química , Fraturas do Rádio/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Fenômenos Biomecânicos , Cadáver , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polimetil Metacrilato/química , Estresse Mecânico
2.
J Craniofac Surg ; 21(6): 1848-54, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21119438

RESUMO

PURPOSE: Development of alternatives to autologous bone has been served by many hypotheses and developments. Favorable properties of synthetic materials used currently in bone grafting support tissue differentiation without shielding capacity for integrated modeling. Ideally, new materials provide tissue compatibility and minimize patient morbidity and are attractive because of potential for in situ delivery, isothermal polymerization, porous structure, and nontoxic chemistry. For application in cranial bone, ability for materials to be laid adjacent to brain and offer postsurgical protection without neural risk is a critical asset. METHODS: Kryptonite Bone Cement (KBC) meets the property criteria for cranial bone repair with regard to adhesive, conductive, and biologic transparency and US Food and Drug Administration approval for cranial bone void repair. To better delineate the morphology effective in cranial bone repair, a comparison was made between KBC and BoneSource, another material approved for the same indication. After Institutional Animal Care and Use Committee approval, the study assessed 24 rabbits, each with 2 separate cranial implants, to evaluate integration and absorption of the biomaterial at defined time points of 12, 18, 24, and 36 weeks. RESULTS: The 36-week assessment demonstrated near-complete resorption/integration of the BoneSource graft material. Bone was present within the biomaterial as well as independent of contact. The KBC was similarly integrated throughout the mass of the material, and new bone was in contact with the grafting material and also seen as separate islands of new bone. The bone demonstrated lamellar bone architecture with clear trabecular morphology. At higher magnification, the bone architecture can be clearly delineated, and comparison between the graft fillers is not obvious relative to the bone that has formed. Despite microscopic similarities, the most striking difference was maintenance of scaffold anatomy during bone regeneration. CONCLUSIONS: Kryptonite Bone Cement meets the criteria described in the introduction; properties of biologic transparency, osteoconductivity, and ergonomic utility offer other potential uses in bone repair. Key tenets of bone tissue regeneration observed in this analysis included adequate cell differentiation and tissue support. Bone that formed demonstrated lamellar rather than woven bone to suggest response to loading strain rather than merely biochemical precipitation. Over the 36-week study, the graft showed progressive bioabsorbable potential with calibrated replacement.


Assuntos
Doenças Ósseas/cirurgia , Óleo de Rícino/uso terapêutico , Regeneração Tecidual Guiada/métodos , Osteogênese/fisiologia , Polímeros/uso terapêutico , Crânio/cirurgia , Implantes Absorvíveis , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/uso terapêutico , Cimentos Ósseos/química , Cimentos Ósseos/uso terapêutico , Regeneração Óssea/fisiologia , Óleo de Rícino/química , Hidroxiapatitas/química , Hidroxiapatitas/uso terapêutico , Masculino , Osseointegração/fisiologia , Polímeros/química , Coelhos , Distribuição Aleatória , Crânio/patologia , Propriedades de Superfície , Fatores de Tempo , Tecidos Suporte/química
3.
Ann Thorac Surg ; 90(3): 979-85, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20732527

RESUMO

BACKGROUND: Wire cerclage closure of sternotomy is the standard of care despite evidence of pathologic sternal displacement (> 2 mm) during physiologic distracting forces (coughing). Postoperative functional recovery, respiration, pain, sternal dehiscence, and infection are influenced by early bone stability. This translational research report provides proof-of-concept (part A) and first-in-man clinical data (part B) with use of a triglyceride-based porous adhesive to rapidly enhance the stability of conventional sternal closure. METHODS: In part A, fresh human cadaver blocks were subjected to midline sternotomy and either conventional wire closure or modified adhesive closure. After 24 hours at 37 degrees C, using a biomechanical test apparatus, a step-wise increase in lateral distracting force simulated physiologic stress. Sternal displacement was measured by microdisplacement sensors. In part B, a selected clinical case series was performed and sternal perfusion assessed by serial single photon emission computed tomography imaging. RESULTS: Wire closure resulted in measurable bony displacement with increasing load. Pathologic displacement (> or = 2 mm) was observed in all regional segments at loads 400 newton (N) or greater. In contrast, adhesive closure completely eliminated pathologic displacement at forces 600 N or less (p < 0.001). In patients, adhesive closure was not associated with adverse events such as adhesive migration, embolization, or infection. There was excellent qualitative correlation between cadaver and clinical computed tomographic images. Sternal perfusion was not compromised by adhesive closure. CONCLUSIONS: This first-in-man series provides proof-of-concept indicating that a novel biologic bone adhesive is capable of rapid sternal fixation and complete elimination of pathologic sternal displacement under physiologic loading conditions. A randomized clinical trial is warranted to further define the potential risks and benefits of this innovative technique.


Assuntos
Cimentos Ósseos , Fios Ortopédicos , Óleo de Rícino , Polímeros , Esterno/cirurgia , Cadáver , Humanos , Complicações Pós-Operatórias/prevenção & controle , Procedimentos Cirúrgicos Torácicos/métodos
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