Sinclair T M, Kerrigan C L, Buntic R
Microsurgical Research Laboratories, Royal Victoria Hospital, Montreal, Quebec, Canada.
Plast Reconstr Surg. 1993 Nov;92(6):1003-13; discussion 1014.
Although it is generally accepted that polyurethane-covered breast implants have decreased the incidence of clinical capsular contracture, there remain many unanswered questions regarding the physical and chemical degradation of the polyurethane foam covering itself. We have systematically studied the fibrous capsule and polyurethane foam recovered from human breast "explants" in an effort to characterize more precisely the biodegradation of polyurethane foam in the human body. Seventy-five freshly retrieved polyurethane-covered implants and surrounding capsule from 47 patients have been analyzed. Capsular tissue from several sampling sites around the surface of the implants was digested in a collagenase solution until foam was recovered or all tissue was digested. Additional samples were fixed in 10% formalin. Scanning electron microscopy was used to look for structural changes in the recovered intact foam and to determine the foam strut widths. Fourier transform IR spectroscopy and x-ray photoelectron spectroscopy were used to analyze the chemical composition of the polyurethane. The formalin-preserved capsule samples were examined histologically for further evidence of foam degradation. Of the 75 prostheses analyzed, 36 (48 percent) were removed because of capsular contracture and 10 (13 percent) because of infection or exposure of the prosthesis. The remaining 29 (39 percent) implants were removed for various other reasons. Visibly intact foam was recovered from 36 (48 percent) prostheses after enzymatic digestion of capsule tissue. There was a progressive decline in the ability to recover intact foam as the total implantation time increased. Scanning electron microscopy revealed fractures and fissures in the foam structure and thinning of the polyurethane struts. The mean strut width of control, unimplanted foam was 49 +/- 1.5 microns (+/- SEM). Retrieved foam from implants which developed capsular contracture and the infected implants had strut widths of 30 +/- 3.1 and 32 +/- 3.1 microns, respectively. In implants removed for other reasons, the polyurethane foam strut width was 41.2 +/- 2.3 microns. Despite an inability to recover visibly intact foam from 39 specimens, standard light microscopy of 37 of these same specimens showed residual polyurethane still present in the capsule. Various degrees of scalloping and fracturing of the foam were seen in the histologic sections. There is convincing evidence by scanning electron microscopy and histology that polyurethane is degrading. It was not possible to quantitate accurately the rate of degradation, but factors such as capsular contracture, infection, and time appear to have a role in the biodegradation of polyurethane in the human body. These relationships require further study.
尽管人们普遍认为聚氨酯包膜乳房植入物降低了临床包膜挛缩的发生率，但关于聚氨酯泡沫包膜本身的物理和化学降解仍有许多问题未得到解答。我们系统地研究了从人类乳房“切除物”中回收的纤维包膜和聚氨酯泡沫，以更精确地表征聚氨酯泡沫在人体内的生物降解情况。对47例患者的75个新取出的聚氨酯包膜植入物及其周围包膜进行了分析。将植入物表面几个采样部位的包膜组织在胶原酶溶液中消化，直到回收泡沫或所有组织都被消化。另外的样本用10%福尔马林固定。使用扫描电子显微镜观察回收的完整泡沫的结构变化并确定泡沫支柱宽度。使用傅里叶变换红外光谱和X射线光电子能谱分析聚氨酯的化学成分。对用福尔马林保存的包膜样本进行组织学检查，以获取泡沫降解的更多证据。在分析的75个假体中，36个（48%）因包膜挛缩而取出，10个（13%）因感染或假体暴露而取出。其余29个（39%）植入物因各种其他原因被取出。在对包膜组织进行酶消化后，从36个（48%）假体中回收了外观完整的泡沫。随着总植入时间的增加，回收完整泡沫的能力逐渐下降。扫描电子显微镜显示泡沫结构中有裂缝和裂隙，聚氨酯支柱变薄。对照未植入的泡沫的平均支柱宽度为49±1.5微米（±标准误）。从发生包膜挛缩的植入物和感染的植入物中回收的泡沫的支柱宽度分别为30±3.1微米和32±3.1微米。在因其他原因取出的植入物中，聚氨酯泡沫支柱宽度为41.2±2.3微米。尽管无法从39个样本中回收外观完整的泡沫，但对其中37个相同样本进行的标准光学显微镜检查显示，包膜中仍存在残留的聚氨酯。在组织学切片中可见泡沫有不同程度的扇贝状和断裂。扫描电子显微镜和组织学有令人信服的证据表明聚氨酯正在降解。无法准确量化降解速率，但包膜挛缩、感染和时间等因素似乎在聚氨酯在人体内的生物降解中起作用。这些关系需要进一步研究。
