RESUMO
An intervertebral titanium tumour cage was implanted in a 2-year-old-girl after T11 spondylectomy due to Ewing sarcoma. After 2-years' follow-up without evidence of recurrence, the titanium cage was explanted to correct spinal deformity and to allow normal spinal growth development. Radiological follow-up and surgical exploration at the time of retrieval suggested fusion of the segment. Histologic evaluation, however, demonstrated ingrowth of trabecular bone, but without bridging trabecular bone. The distance between the opposing bone fronts measured 1.5 mm and the viable bone volume (BV/TV) within the cage was 36%. Histologic evaluation demonstrated that bone formation was still an ongoing process in the fusion zone 2 years after implantation.
Assuntos
Fixadores Internos/normas , Sarcoma de Ewing/cirurgia , Fusão Vertebral/instrumentação , Vértebras Torácicas/cirurgia , Titânio/uso terapêutico , Pré-Escolar , Feminino , Humanos , Fixadores Internos/tendências , Imageamento por Ressonância Magnética , Osteogênese/fisiologia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/fisiopatologia , Complicações Pós-Operatórias/prevenção & controle , Radiografia , Compressão da Medula Espinal/etiologia , Compressão da Medula Espinal/patologia , Compressão da Medula Espinal/fisiopatologia , Fusão Vertebral/métodos , Vértebras Torácicas/diagnóstico por imagem , Vértebras Torácicas/patologia , Titânio/normas , Falha de Tratamento , Resultado do Tratamento , Cicatrização/fisiologiaRESUMO
We show the use of a dimensionless parameter alpha h, in properly downscaling a parallel-plate flow chamber system for flow stimulation of bone cells under microgravity. The proper experimental regime for exposing cells to predictable levels of dynamic fluid shear stress requires: 1) alpha h < 2, based on the consequent quasi-parabolic form of the velocity profile in this regime, and 2) fo m
RESUMO
Determination and quantification of anisotropy is of great interest in research fields dealing with physical structures or surface textures. In this paper, a volume-based method is presented, which essentially determines the mean object length in a certain direction for a typical point within a structure or texture. The mean object lengths for all orientations together form the so-called star length distribution (SLD). The validity and the accuracy of the SLD method are investigated, and illustrated by applying it to trabecular bone. By using a line sampling algorithm, the relation with other anisotropy measures could be studied analytically. Preliminary tests suggest that with SLD a more exact description of the mechanical properties of porous structures may be obtained than with other anisotropy measures. However, due to possible secondary orientations that become apparent with SLD, a fabric tensor must be of rank higher than two in order to properly describe an orthogonal structure mathematically.
