PubMed · 8567318
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J P Choudhury, P Ghosh. Membrane based ethanol separation process.. https://pubmed.ncbi.nlm.nih.gov/8567318/
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STUDY DESIGN: A review of the literature concerning the use of interbody fusion devices and materials in anterior cervical surgery. OBJECTIVES: To examine the evidence supporting the use of interbody fusion devices as an alternative to autologous bone after anterior cervical discectomy. SUMMARY OF BACKGROUND DATA: Concerns over the morbidity associated with harvesting autologous bone and the risk of transmissible infectious from allografts and xenografts have prompted the search for alternative methods of achieving interbody fusion. Several of these methods have been associated with an unacceptable rate of complications. The clinical and health economic implications of the widespread introduction of interbody fusion devices in the absence of sound evidence cannot be ignored. METHODS: A systematic review of the literature relating to cervical interbody fusion was undertaken. Studies were assessed critically with respect to their methodology, results, and conclusions. RESULTS: Thirty-two clinical studies and 10 laboratory studies were analyzed. Methodologic weaknesses were identified in the majority. Only four clinical reports were either randomized or blinded or involved independent assessment of their outcomes. Fewer than half of the studies included a valid statistical analysis. Radiologic evidence of fusion was limited in many cases. There was little evidence that nonautologous fusion devices offered a reduction in the length of hospital stay. Autologous bone was as effective as, or superior to, many other fusion devices. The early results of some new fusion techniques used alone or in combination showed promise. CONCLUSIONS: There is limited evidence supporting the use of a cervical interbody fusion device in place of autologous bone. There is a need to standardize the testing of implants with good quality laboratory work preceding clinical use. Certain devices including cages, some forms of hydroxyapatite, and bone morphogenic proteins merit further study.
A glass and a rhenanite-wollastonite glass-ceramic were synthesized with the qualitative composition Na2O-CaO-SiO2-P2O5. Both materials were prepared by reaction sintering under isostatic pressure (RSIP) using powder mixtures. Solid state reactions were complete within a few hours at 950 degrees C under modest pressure. Formation of the glass and crystalline phases was driven by an intermediate, reactive, low viscosity Na2O-SiO2 phase. A reaction mechanism is suggested. Porous materials were obtained with two ranges of pore sizes: 100-200 microm and < or =5 microm in diameter. The glass and the glass-ceramic were corroded in simulated body fluid at 37 degrees C. The evolution of surface features was studied. Gel layers formed on both materials. Corrosion was fastest inside the pores. Microcrystals of apatite were identified by crystal structure analysis and by chemical analysis. During corrosion of the glass-ceramic, rhenanite most likely was converted into apatite. Comparison of these results with published information suggests that the glass and glass-ceramic are bioactive. We suggest that RSIP can be used (a) to control the surface porosity and pore size of bioactive implants, thereby increasing the stability of tissue/implant interfaces; (b) to make glasses and glass-ceramics with new properties; and (c) to make near net-shape materials.
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