Oxford, United Kingdom; and Atlanta, Ga. From the Department of Plastic and Reconstructive Surgery, Nuffield Department of Surgery, and the Nuffield Department of Anesthesia, University of Oxford, John Radcliffe Hospital; Department of Materials, University of Oxford; and Materials Science and Engineering, Georgia Institute of Technology.
Plast Reconstr Surg. 2012 Jan;129(1):79-88. doi: 10.1097/PRS.0b013e3182362100.
The advent of self-inflating hydrogel tissue expanders heralded a significant advance in the reconstructive potential of this technique. Their use, however, is limited by their uncontrolled isotropic (i.e., uniform in all directions) expansion.
Anisotropy (i.e., directional dependence) was achieved by annealing a hydrogel copolymer of poly(methyl methacrylate-co-vinyl pyrrolidone) under a compressive load for a specified time period. The expansion ratio is dictated by the percentage of vinyl pyrrolidone content and the degree of compression. The expansion rate is modified by incorporating the polymer within a silicone membrane. The in vivo efficacy of differing prototype devices was investigated in juvenile pigs under United Kingdom Home Office Licence. The devices were implanted within a submucoperiosteal pocket in a total of six porcine palates; all were euthanized by 6 weeks after implantation. A longitudinal volumetric assessment of the expanded tissue was conducted, in addition to postmortem analysis of the bony and mucoperiosteal palatal elements.
Uncoated devices caused excessive soft-tissue expansion that resulted in mucoperiosteal ulceration, thus necessitating animal euthanasia. The silicone-coated devices produced controlled soft-tissue expansion over the 6-week study period. There was a statistically significant increase in the volume of expanded soft tissue with no evidence of a significant acute inflammatory response to the implant, although peri-implant capsule formation was observed. Attenuation of the bony palatal shelf was noted.
A unique anisotropic hydrogel device capable of controlled expansion has been developed that addresses a number of the shortcomings of the technology hitherto available.
自膨式水凝胶组织扩张器的出现标志着该技术在重建潜力方面取得了重大进展。然而，它们的使用受到其不可控各向同性（即各个方向均匀）扩张的限制。
通过在压缩载荷下对聚（甲基丙烯酸甲酯-co-乙烯基吡咯烷酮）水凝胶共聚物进行退火处理一定时间来实现各向异性（即方向依赖性）。膨胀比由乙烯基吡咯烷酮含量和压缩程度决定。通过将聚合物纳入硅树脂膜中来修改膨胀率。在英国内政部许可下，在幼年猪中研究了不同原型设备的体内功效。将设备植入总共六只猪的黏膜下-骨膜袋中；所有动物在植入后 6 周内被安乐死。除了对骨和黏膜下骨膜腭元素进行死后分析外，还对扩展组织进行了纵向体积评估。
未涂层的设备导致过多的软组织扩张，导致黏膜骨膜溃疡，因此需要对动物进行安乐死。硅酮涂层的设备在 6 周的研究期间产生了可控的软组织扩张。扩展软组织的体积有统计学意义的增加，没有证据表明对植入物有明显的急性炎症反应，尽管观察到了植入物周围胶囊的形成。腭骨架的衰减也得到了证实。
已经开发出一种独特的各向异性水凝胶装置，能够实现可控扩张，解决了迄今为止可用技术的许多缺点。
