探讨维持扩张期对扩张皮肤生物力学与胶原结构的影响

目的 以生物力学的方法探讨一种有效的缩短皮肤扩张时间的途径。方法 在6只成年大狗的背侧，对称设计6个术区，实验分为空白对照组、埋置扩张器不施行注水的对照组、注水2周和注水6周组，注水2周组和注水6周组又分为维持1周、2周和4周3组。每个术区取4个皮肤试件，分别测定极限应力强度、应力应变、应力松弛和蠕变，并测量单位面积的胶原含量和排列。结果 皮肤扩张后，极限应力强度下降；随着维持期的增加，应力应变、应力松弛和蠕变均逐渐接近正常，胶原含量增加，排列更加有序。结论 维持期对扩张皮肤的黏性和胶原的含量及其排列的恢复是不可少或缺的阶段，2周的维持期对扩张皮肤的黏弹性恢复致关重要。     

快速扩张皮肤生物力学特性的实验研究

本实验研究的目的在于观察皮肤软组织快速扩张后牲力学特性的改变，并与常规扩张，未扩张的皮肤进行对比研究，以了解扩张皮肤生物力学特性的改变与扩张速度的关系，即扩张皮肤２４小时应力松弛的程度和应力状态的平衡与一周应力松弛和平衡的区别，为床快速扩张提供生物力学的研究基础。取４只体重为１５ｋｇ左右的猪为实验动物，分为常规扩张组，快速扩张组和对照组；将容量为２４０ｍｌ矩形扩张器埋置于筋膜下，按分组要求定期给予     

快速扩张后皮肤生物力学特性的实验研究

本实验研究的目的在于观察皮肤软组织快速扩张后生物力学特性的改变，并与常规扩张、未扩张的皮肤进行对比研究，以了解扩张皮肤生物力学特性的改变与扩张速度的关系，即扩张皮肤２４小时应力松弛的程度和应力状态的平衡与一周应力松弛和平衡的区别，为临床快速扩张提供生物力学的研究基础。取４只体重为１５ｋｇ左右的猪为实验动物，分为常规扩张组，快速扩张组和对照组；将容量为２４０ｍｌ的矩形扩张器埋置于筋膜下，按分组要求定期给予扩张；扩张结束后取标本进行皮肤构关系、应力松弛特性、应变能密度和强度参数等生物力学指标的测定，结果表明扩张皮肤的粘弹性明显下降，有别于未扩张的皮肤，而快速扩张皮肤与常规扩张皮肤的粘弹性的下降则非常相似。因此，扩张可致皮肤粘弹性下降，但扩张皮肤粘弹性的下降除与扩张刺激的强度有明显的关系外，尚与扩张刺激的间隔时间有关，但后者的影响较小。临床上可以采用快速扩张的方法，以缩短疗程，提高疗效。     

快速扩张后皮肤生物力学特性的实验研究

本实验研究的目的在于观察皮肤软组织快速扩张后生物力学特性的改变,并与常规扩张、未扩张的皮肤进行对比研究,以了解扩张皮肤生物力学特性的改变与扩张速度的关系,即扩张皮肤24小时应力松弛的程度和应力状态的平衡与一周应力松弛和平衡的区别,为临床快速扩张提供生物力学的研究基础。取4只体重为15kg 左右的猪为实验动物,分为常规扩张组,快速扩张组和对照组;将容量为240ml 的矩形扩张器埋置于筋膜下,按分组要求定期给予扩张;扩张结束后取标本进行皮肤构关系、应力松弛特性、应变能密度和强度参数等生物力学指标的测定,结果表明扩张皮肤的粘弹性明显下降,有别于未扩张的皮肤,而快速扩张皮肤与常规扩张皮肤的粘弹性的下降则非常相似。因此,扩张可致皮肤粘弹性下降,但扩张皮肤粘弹性的下降除与扩张刺激的强度有明显的关系外,尚与扩张刺激的间隔时间有关,但后者的影响较小。临床上可以采用快速扩张的方法,以缩短疗程,提高疗效。     

扩张皮肤移植后的生物力学变化

目的:探讨扩张皮肤移植后的生物力学变化。方法:成年狗8只,每只背部置入4个150ml扩张器,两个不扩张作为对照。注水8周取出扩张器,扩张组:切取标本后形成和基底大小一致的皮瓣原位移植;对照组:一侧切取标本,另一侧取出扩张器后皮瓣原位缝合,以作远期观察。然后随机将8只狗平均分为4组,皮瓣移植后3周、6周、3个月、6个月时在实验部位取1cm×4cm大小的皮肤3块,分别进行应力-应变、应力松弛、极限抗拉强度测定。结果:扩张后皮肤的粘弹性及强度均下降,前者于移植后半年恢复,后者恢复较慢,移植后6个月仍未完全恢复。结论:皮肤扩张后的改变是一种暂时的现象,扩张皮肤于移植后6个月物理特性基本恢复正常。     

皮肤软组织重复扩张的微观研究

目的 探讨皮肤软组织重复扩张的微观变化，为临床应用提供理论依据。方法以6头小型猪为实验动物，并分为正常对照组、常规扩张组、重复扩张组，分别切取皮肤标本，进行光镜结构和超微结构的观察，以及碱性成纤维细胞生长因子（bFGF）含量的测定。结果重复扩张的皮肤软组织肉眼观察基本健康，其微观结构在常规扩张的基础上有进一步的变化。胶原纤维损伤明显，细胞损伤较轻并且进一步增殖和功能更加活跃。皮肤中bFGF含量进一步增高。结论重复扩张过程中，皮肤软组织虽然有进一步损伤，但通过进一步加强生长和修复功能，仍然能保持基本健康，因此，重复扩张安全可行。     

肋软骨生物力学性能及在耳廓再造手术时机选择中的意义

目的 探讨不同年龄组肋软骨的生物力学特性的变化,以期为肋软骨作为耳廓再造的支架材料应用于整形外科的最佳手术时机提供理论参考.方法 将5～25岁行耳廓再造的患者按年龄分为3组.对不同年龄组肋软骨的应力-应变、应力松弛、蠕变和极限抗拉强度等各项生物力学性能指标进行测试,对测试结果进行统计学分析处理.结果 儿童组肋软骨的极限抗拉强度、应力-应变、应力松弛及蠕变等生物力学指标明显优于青少年组和成人组,3组当中以青少年组的力学性能最差,经统计学分析,差异具有统计学意义(P＜0.05).结论 鉴于肋软骨的生物力学性能随年龄发生变化,综合各方面因素,在利用肋软骨进行耳廓再造手术时,应优先考虑在肋软骨生物力学性能最佳的儿童期进行.     

重复皮肤组织扩张术的临床、生物力学及病理观察

目的 总结重复皮肤扩张的经验,探讨其组织学和生物力学变化,为在临床的应用提供理论基础和实践经验.方法 对已扩张的皮肤进行重复扩张,分次修复缺损,首次扩张与重复扩张的时间间隔平均为8个月.将31例分为儿童组和成人组,对重复扩张术的治疗经验进行总结,测量首次和重复扩张后皮瓣的增长率,并做生物力学特性检测和病理观察,进行两组间的比较.结果 共治疗31例,第1、2次扩张过程中的并发症发生率分别为10%、17%,随访6～12个月,大部分治疗效果满意.重复扩张后两组的皮瓣增长率均下降、应力-松弛特性和断裂强度减弱、表皮增殖减少,尤以成人组较为显著.结论 皮肤重复扩张术是临床可行的手术方法,在儿童可取得比成人更加满意的手术效果,但因其风险增大、皮瓣质量下降,应用时应小心慎重.     

3种方法修复关节软骨缺损生物力学的研究

目的评价骨软骨柱镶嵌移植、骨-骨膜柱镶嵌移植和Ⅱ型胶原骨形态发生蛋白(BMP)复合物3种方法修复关节软骨缺损的生物力学变化,为临床应用提供实验依据。方法将20只成年新西兰兔制成膝关节缺损模型,修复1组在缺损局部镶嵌移植骨软骨柱,修复2组为骨-骨膜柱,修复3组为Ⅱ型胶原BMP复合物,空白组软骨缺损处不作处理,另取4只兔作为正常对照。术后12周取材制成宽3mm、长5mm、厚0·5mm的条状试件进行单向拉伸试验、黏弹性蠕变和松弛试验,所得数据结果进行统计学分析。结果3种方法对关节软骨缺损修复的修复物应力-应变曲线、时间-应力曲线和时间-应变曲线都具有一定的黏弹性表现,与对照组比较差异具有显著性(P<0·01),但较正常组仍有差距(P<0·05),其中修复1组标本力学性能强于修复2组和修复3组(P<0·05)。结论骨软骨柱镶嵌移植、骨-骨膜柱镶嵌移植和Ⅱ型胶原BMP复合物3种方法对关节软骨缺损具有良好的修复作用,骨软骨柱移植近期效果最佳,而Ⅱ型胶原BMP复合物来源广泛,适合修复大面积的关节软骨缺损。     

应用改良扩张器构建大鼠皮肤软组织扩张模型

目的应用改良设计的短注射导管枕形扩张器构建大鼠皮肤软组织扩张模型，并探讨其产生的扩张应力对大鼠皮肤细胞增殖分化的影响，验证扩张模型的扩张效果，为研究扩张皮肤新生机制提供一个稳定的动物模型。方法SD大鼠随机分为A、B两组（每组各30只），A组大鼠采用改良设计的扩张器，B组大鼠采用上海威宁公司生产的普通扩张器；选择SD大鼠近颈部切口，以注射壶外置的方式埋置扩张器，制作皮肤软组织扩张模型。分别采集A组在不同扩张时间点（1、2、3、4、5周）的扩张中心区域皮肤和正常皮肤组织作为标本；利用HE染色方法观察扩张后皮肤结构的变化；根据增殖细胞表达增殖细胞核抗原，采用免疫组织化学染色方法观察扩张皮肤中细胞增殖的情况。结果A组应用自行改良设计的扩张器，选择大鼠近颈部切口构建的皮肤软组织扩张模型，术后外置的注射壶不易被大鼠咬掉，且术后注水及护理更简单，模型稳定性显著高于B组。HE染色结果表明，扩张后皮肤的表皮层明显增厚，真皮层变薄；免疫组织化学染色结果显示，增殖细胞呈点状分布，主要集中于表皮基底层和毛囊鞘。结论自行改良设计的短注射导管枕形扩张器，是构建大鼠皮肤软组织扩张模型的良好实验材料；扩张应力对大鼠的皮肤结构和增殖产生了影响。     

Biomechanical comparison between conventional and rapid expansion of skin.

This study was designed to investigate the effects of different surgical expansion regimens on the biomechanical features of expanded skin. Two hundred and forty millilitres expanders were implanted on the backs of six adult dogs. Six flaps were designed on the dorsum of each dog. After serial expansion, the expander was left beneath the skin for a certain period of time, which is called the maintaining period. Rapid expansion and conventional expansion with various maintaining periods were compared. The experimental result shows that the area gain of expanded skin surface had no significant difference between the rapid and conventional expansion. Both the tension in vivo and the instant stretch-back ratio increased during the expansion, but fell almost to control values after four weeks' maintaining period. Biomechanical properties in vitro, such as tensile strength, stress-strain, stress-relaxation, and creep were tested by INSTRON material testing machine. Results show that the biomechanical properties of expanded specimens differ significantly from those of their controls immediately after expansion. However, the difference reduces with prolongation of maintaining time. With the same maintaining period, the biomechanical properties of rapidly expanded skin are similar to conventionally expanded skin. We conclude that rapid skin expansion did not demonstrate any deleterious effect when compared with the conventional expansion. Extension of the maintaining period can improve the biomechanical properties of expanded skin and effectively reduce the stretch-back ratio. Therefore, rapid expansion with an extended maintaining period is acceptable in clinical practice.     

A型肉毒毒素辅助额部皮肤软组织扩张的生物力学研究

目的:通过动物实验探讨A型肉毒毒素注射后额部扩张皮瓣的生物力学性能的变化规律,以期为临床应用提供理论依据。方法:选用白色实验小型猪,在其胸腹部两侧用作网格样标记,一侧注射A型肉毒毒素,对侧注射生理盐水对照,两侧置入200ml扩张器,注水完成后切取全层扩张皮瓣作为试件,在I ns t r on4302万能材料试验机上对皮瓣试件进行应力-应变、应力松弛和蠕变实验。结果:实验组皮瓣的粘弹性比对照组的好,更接近于未扩张皮瓣;在同样的松弛时间内,实验组皮瓣比对照组更容易松弛;在相同的应力作用下,相同的时间内,实验组皮瓣的蠕变量要小于对照组。结论:注射A型肉毒毒素后,可以使扩张皮瓣的粘弹性增强,更接近于未扩张皮瓣,扩张器注水量增加,注水间隔缩短,在相同注水量下扩张面积增加。     

Quantitative benefits provided by acute tissue expansion: a biomechanical study in human cadavers.

The aim of this study was to test the ex vivo biomechanical properties of acutely expanded cutaneous flaps to quantitatively assess the efficacy of intraoperative tissue expansion. A total of 14 fresh male cadavers were used for the study. In each cadaver, a rectangular (15 x 8 cm), proximally based flap was designed on each side of the body, in three different locations: lateral arm, anterior thorax, anterior thigh. In each cadaver, one randomly selected flap per each body region underwent acute-intermittent expansion, whereas the contralateral flap served as control. The biomechanical properties (stress/strain ratio, mean stiffness) of both expanded and control flaps were then assessed by means of a dynamometer and a force-transducer. The obtained data showed that the biomechanical benefits provided by acute tissue expansion were statistically different (P< 0.05) from those obtained by simple subcutaneous undermining. While no changes of length have been observed in the acutely expanded skin flaps as compared to control cutaneous flaps, a statistically significant gain in the compliance of the former has been recorded as compared to the biomechanical behaviour of the latter.     

Tensile and viscoelastic properties of human patellar tendon

The tensile and viscoelastic properties of fresh-frozen, nonirradiated human patellar tendon were investigated in two groups of 15 specimens: one group was from individuals 29–50 years old and the other group was from individuals 64–93 years old. The central portion of each patella-patellar tendon-tibia complex was subjected to cyclic preconditioning, stress-relaxation, cyclic stress-relaxation, and load to failure tests. For each age group, stress-relaxation and stress-strain curves were obtained, from which percentage relaxation, ultimate tensile strength, strain at failure, modulus, and strain energy density were determined. Viscoelastic behavior was described with use of quasilinear viscoelasticity. The younger group showed a 46 ± 9% (mean ± SD) decrease in stress after 15 minutes, whereas the older group exhibited a 50 ± 6% decrease. The values for ultimate tensile strength and strain at failure, respectively, were 64.7 ± 15.0 MPa and 14 ± 6% for the younger group and 53.6 ± 10.0 MPa and 15 ± 5% for the older group. Modulus values were 660 ± 266 MPa for the younger group and 504 ± 222 MPa for the older group. Except for ultimate tensile strength, which was 17% less for the older group than for the younger one, no statistically significant differences were found in tensile or viscoelastic properties. This study indicated that there were minimal differences in biomechanical properties of the substance of the patellar tendon between younger and older age groups.     

Intraoperative expansion of scalp flaps. Quantitative assessment

BACKGROUND: The aim of this study was to test the ex-vivo biomechanical properties of acutely expanded scalp flaps, in order to quantitatively assess the efficacy of acute scalp expansion. METHODS: A total of 14 fresh male cadavers were used for the study. In each cadaver, a rectangular (4 x 10 cm), laterally-based flap was designed on each side of the scalp, starting from the superior margin of the external auditory canal. One randomly-selected flap per each scalp underwent acute-intermittent expansion (3-minute expansion-3-minute rest cycle per three times with the maximal expansion achievable), while the contralateral flap served as control. After the expansion process, the acutely-expanded flaps were measured to assess if the applied biomechanical stress have determined any changes in their dimensions. The biomechanical properties (stress/strain ratio, mean stiffness) of both expanded and control flaps were then assessed by means of a dynamometer and a force-transducer. RESULTS: The obtained data showed that the biomechanical benefits provided by acute scalp expansion were not statistically different (p < 0.05) from those obtained by simple subgaleal undermining. Neither any change of length nor any gain in the compliance have been observed in the acutely-expanded flaps as compared to control scalp flaps. CONCLUSIONS: In our opinion, a possible explanation (to be further validated) for the lack of effect of acute scalp expansion might be that inelastic galea aponeurotica did not allow the mechanical creep to exploit the inherent elastic properties of the overlying scalp skin.     

每次反复注水快速皮肤扩张法的实验研究

目的　探讨最佳的皮肤扩张法,了解每次反复注水快速皮肤扩张法的效果及机理。方法　白色乳猪4只,在脊柱两侧各设计3个皮瓣组,分别为每次反复注水快速扩张组、常规扩张组、对照组,在监测囊内压的情况下定期扩张,扩张结束后分别测定和比较扩张总面积、时间、皮肤的即时回缩率以及囊内压的变化,并进行组织学及超微结构的观察。结果　每次反复注水快速扩张组扩张后总面积明显大于常规扩张组（P＜0.05）,皮肤即时回缩率与常规扩张组间无明显差异（P＞0.05）,扩张总时间短于常规扩张组,扩张前囊内压在每次反复注水快速扩张组与常规扩张组间差异无显著性（P＞0.05）,每次反复注水快速扩张组扩张后皮肤的超微结构及功能与常规扩张组无明显区别。结论　每次反复注水快速皮肤扩张法是一种有效的、安全的方法,可在临床上推广应用。     

扩张后皮肤挛缩动力环境的实验研究

目的　研究皮肤扩张后真皮内环境的变化及其与挛缩过程的关系。方法　采用兔头部扩张模型进行皮肤扩张实验,通过免疫组化、放射免疫测定等方法研究了真皮Ⅰ、Ⅲ型胶原以及透明质酸的变化。结果　Ⅰ型胶原在皮肤扩张后出现破坏和修复的现象,而Ⅲ型胶原有一过性增多。透明质酸的含量在皮肤扩张后由30ng/ml增加到80ng/ml,而且在相当长时间内呈增高状态,快速扩张变化较常规扩张明显。结论　扩张后真皮中的胶原结构发生重组,透明质酸的增加为扩张后皮肤挛缩提供重要的动力环境基础,快速扩张产生透明质酸多因此更易发生挛缩。