Treiser Matthew D, Lahair Tracy, Carty Matthew J
Harvard Combined Plastic Surgery Residency Program, Brigham & Women's Hospital, Boston, Mass.; and Division of Plastic Surgery, Brigham & Women's Faulkner Hospital, Jamaica Plain, Mass.
Plast Reconstr Surg Glob Open. 2016 Feb 5;4(2):e612. doi: 10.1097/GOX.0000000000000594. eCollection 2016 Feb.
Overfill of tissue expanders is a commonly used modality to achieve customized dimensions in breast reconstruction. Little formal study of the dynamics of hyperexpansion of these devices has been performed to date, however.
Overfill trials were performed using both Natrelle 133 MV and Mentor 8200 tissue expanders of indicated capacities ranging from 250 to 800 mL. Each expander was initially filled to its indicated capacity with normal water and then injected in regular increments to 400% overfill. Measurements of each expander's width, height, and projection were made at indicated capacity and with each successive incremental overfill injection, and these results were then recorded, collated, and analyzed.
Over the first 50% overfill, all expanders demonstrated a logarithmic increase in projection (mean increase, 143 ± 9%) while maintaining essentially stable base dimensions. Overfill levels in excess of 50% were accompanied by linear increases in height, width, and projection, during which projection approached, but never equaled, base dimensions. Stress versus strain analyses demonstrated nonlinear biomechanical dynamics during the first 50% overfill, followed by standard elastic dynamics up to 400% overfill. At no point during the study, did expander tensions outstrip elastic properties, thereby explaining the lack of device rupture.
Through overfilling, tunable geometries of tissue expanders can be accessed that may provide for increasing customization of reconstructions, particularly at overfill volumes up to 50% over indicated capacity. This study should serve to guide tissue expander selection and fill volumes that surgeons may implement in obtaining ideal reconstructed breast shapes.
组织扩张器过度填充是乳房重建中用于实现定制尺寸的常用方法。然而，迄今为止，对这些装置过度扩张动力学的正式研究很少。
使用容量范围为250至800 mL的Natrelle 133 MV和Mentor 8200组织扩张器进行过度填充试验。每个扩张器最初用普通水填充至其标称容量，然后以规则增量注射至400%的过度填充。在标称容量以及每次连续增量过度填充注射时测量每个扩张器的宽度、高度和突出度，然后记录、整理和分析这些结果。
在最初50%的过度填充过程中，所有扩张器的突出度呈对数增加（平均增加143±9%），同时基本尺寸保持稳定。超过50%的过度填充水平伴随着高度、宽度和突出度的线性增加，在此期间突出度接近但从未达到基本尺寸。应力与应变分析表明，在最初50%的过度填充过程中存在非线性生物力学动力学，随后在高达400%的过度填充过程中呈现标准弹性动力学。在研究过程中的任何时候，扩张器的张力都没有超过弹性性能，从而解释了装置未破裂的原因。
通过过度填充，可以获得组织扩张器的可调几何形状，这可能有助于增加重建的定制性，特别是在过度填充量高达标称容量的50%时。这项研究应有助于指导外科医生在获得理想的重建乳房形状时选择组织扩张器和填充量。
