Har-Shai Y, Sela E, Rubinstien I, Lindenbaum E S, Mitz V, Hirshowitz B
Plastic Surgery Unit, Carmel Medical Center, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
Plast Reconstr Surg. 1998 Dec;102(7):2466-70. doi: 10.1097/00006534-199812000-00033.
Recently, the superficial musculoaponeurotic system (SMAS) was found to be a composite tissue comprising collagen, elastic fibers, and fat cells in an extracellular viscous matrix. Both SMAS and facial skin tissues exhibit viscoelastic properties, but SMAS tissue has delayed stress relaxation. As a consequence, SMAS is viewed as a firmer elastic foundation for the more viscous facial skin. In some patients, a slackening effect of SMAS tissue takes place over a period ranging from weeks to months after tightening. To determine the relative quantity of viscoelastic components and better understand their biomechanical behavior, a quantitative morphometric study of the elastic and collagen fibers in the SMAS and facial skin was conducted. Thirty-four SMAS preparations were taken from 17 patients during either primary face lift operations (12 women) or reoperative face lift procedures (4 women, 1 man), which were performed 4 to 9 months after the original surgery, to examine the elastin and collagen content. For comparison, preauricular skin was also gathered from these patients. The specimens were stained with Weigert's staining to identify elastin and collagen fibers. Using a computerized morphometric analysis, 100 fields of each SMAS and skin specimen were examined. According to our findings, the average percentage of elastin and collagen fibers in SMAS and facial skin was as follows: (1) the percentage of elastin fibers in the SMAS was 4.71 +/- 1.2 (standard error of mean +/- 0.0291); (2) the percentage of elastin fibers in the skin was 6.1 +/- 1.8 (standard error of mean +/- 0.0436); (3) The percentage of collagen fibers in the SMAS was 38.7 +/- 5.9 (standard error of mean +/- 0.1430); and (4) the percentage of collagen fibers in the skin was 48.47 +/- 6.96 (standard error of mean +/- 0.1688). A statistical significance of p < 0.0001 was demonstrated between the collagen and elastin groups. A different percentage of elastin and collagen fibers was found among the 17 patients and within each of them separately. Neither gender nor age differences were found regarding elastin and collagen fiber content. No statistical differences were demonstrated between specimen sources, i.e., whether the operations were primary or reoperative face lift procedures. Findings from previous studies indicate that the cheek has two viscoelastic layers, the skin and the SMAS. The proportional similarity in average percentages of elastin and collagen in SMAS and facial skin cannot explain the relatively delayed stress relaxation effect of the SMAS. Therefore, the fat cells that are found exclusively in the SMAS probably lend a certain degree of firmness to this layer and play a significant role in the long-term efficacy of SMAS surgery.
最近发现，表浅肌肉腱膜系统（SMAS）是一种复合组织，由细胞外粘性基质中的胶原蛋白、弹性纤维和脂肪细胞组成。SMAS和面部皮肤组织均表现出粘弹性，但SMAS组织的应力松弛延迟。因此，SMAS被视为更具粘性的面部皮肤的更坚实弹性基础。在一些患者中，SMAS组织在收紧后的数周数月内会出现松弛效应。为了确定粘弹性成分的相对数量并更好地了解其生物力学行为，对SMAS和面部皮肤中的弹性纤维和胶原纤维进行了定量形态学研究。在初次面部提升手术（12名女性）或再次面部提升手术（4名女性，1名男性）过程中，从17名患者身上获取了34份SMAS标本，这些手术在初次手术后4至9个月进行，以检查弹性蛋白和胶原蛋白含量。为作比较，还从这些患者身上采集了耳前皮肤。标本用魏格特染色法染色以识别弹性纤维和胶原纤维。使用计算机化形态学分析，检查了每个SMAS和皮肤标本的100个视野。根据我们的研究结果，SMAS和面部皮肤中弹性蛋白和胶原纤维的平均百分比分别如下：（1）SMAS中弹性纤维的百分比为4.71±1.2（平均标准误差±0.0291）；（2）皮肤中弹性纤维的百分比为6.1±1.8（平均标准误差±0.0436）；（3）SMAS中胶原纤维的百分比为38.7±5.9（平均标准误差±0.1430）；（4）皮肤中胶原纤维的百分比为48.47±6.96（平均标准误差±0.1688）。胶原蛋白和弹性蛋白组之间的统计学显著性为p<0.0001。在17名患者之间以及每个患者内部，发现弹性蛋白和胶原纤维的百分比各不相同。在弹性蛋白和胶原纤维含量方面未发现性别和年龄差异。标本来源之间（即手术是初次面部提升手术还是再次面部提升手术）未显示出统计学差异。先前研究的结果表明，脸颊有两个粘弹性层，即皮肤和SMAS。SMAS和面部皮肤中弹性蛋白和胶原蛋白平均百分比的比例相似性无法解释SMAS相对延迟的应力松弛效应。因此，仅在SMAS中发现的脂肪细胞可能赋予该层一定程度的紧致度，并在SMAS手术的长期效果中起重要作用。
