BACKGROUND & AIMS: :The purpose of this study is to compare the effects of spinal and epidural anesthesia on a rat transverse rectus abdominus myocutaneous flap ischemia-reperfusion injury model.Forty Sprague-Dawley rats were divided into 4 experimental groups: group I (n = 10), sham group; group II (n = 10), control group; group III (n = 10), epidural group; and group IV (n = 10), spinal group. After the elevation of the transverse rectus abdominus myocutaneous flaps, all groups except for the sham group were subjected to normothermic no-flow ischemia for 4 hours, followed by a reperfusion period of 2 hours. At the end of the reperfusion period, biochemical and histopathological evaluations were performed on tissue samples.Although there was no significant difference concerning the malonyldialdehyde, nitric oxide, and paraoxonase levels in the spinal and epidural groups, the total antioxidant state levels were significantly increased, and the total oxidative stress levels were significantly decreased in the epidural group in comparison to the spinal group. The pathological evaluation showed that findings related to inflammation, nuclear change rates and hyalinization were significantly higher in the spinal group compared with the epidural group.Epidural anesthesia can be considered as a more suitable method that enables a decrease in ischemia-reperfusion injuries in the muscle flaps.

背景与目标： : 本研究的目的是比较脊髓和硬膜外麻醉对大鼠腹直肌横肌肌皮瓣缺血再灌注损伤模型的影响。将40只Sprague-Dawley大鼠分为4个实验组: I组 (n = 10)，假手术组; II组 (n = 10)，对照组; III组 (n = 10)，硬膜外组; IV组 (n = 10)，脊髓组。腹直肌肌皮瓣抬高后，除假手术组外，所有组均进行常温无血流缺血4小时，然后再灌注2小时。在再灌注期结束时，对组织样本进行生化和组织病理学评估。尽管脊髓和硬膜外组的丙二醛，一氧化氮和对氧磷酶水平没有显着差异，但总抗氧化状态水平显着增加，与脊髓组相比，硬膜外组的总氧化应激水平显着降低。病理评估表明，与硬膜外组相比，脊柱组与炎症，核改变率和透明化有关的发现明显更高。硬膜外麻醉可以认为是一种更合适的方法，可以减少肌肉皮瓣的缺血再灌注损伤。

BACKGROUND & AIMS: BACKGROUND:High-risk patients undergoing prophylactic mastectomy (PM) may have unsuspected cancers identified on pathology. The optimum way to identify and manage them is controversial. Magnetic resonance imaging (MRI) may identify occult cancer preoperatively. Sentinel lymph node biopsy (SLNB) allows intraoperative staging and axillary dissection during the same operation. We determined the efficacy and cost of MRI and/or SLNB in managing high-risk PM patients. METHODS:We reviewed 192 PMs in 173 patients from 1999 to 2005. Costs were estimated for MRI and SLNB during PM by the 2005 Medicare Resource-Based Relative Value Scale. We also estimated costs and procedures for the four strategies in a larger hypothetical cohort. RESULTS:A total of 19 (10%) of 192 PMs contained occult cancers, 14 ductal carcinoma-in-situ (DCIS) and 5 invasive ductal carcinoma (IDC). In 59 patients, MRI detected an IDC but missed two DCIS and an IDC. Positive MRIs generated an additional average cost of $1,207 per patient. In 56 PMs with SLNB, 6 occult cancers were found, 5 DCIS and 1 IDC, all with negative SLNBs. Adding a SLNB costs an additional average of $644. A theoretical analysis demonstrated that PM alone costs $808 per patient, PM with SLNB costs $1,420, PM with MRI and selective SLNB costs $1,774, and PM with routine MRI and SLNB costs $2,379. CONCLUSIONS:MRI adds great cost and misses most occult cancers in PMs. SLNB allows the rare patient with occult IDC to avoid axillary dissection but adds cost. Given the low rate of unsuspected invasive cancers and the costs of MRI and SLNB, neither is recommended as standard practice for PM patients.

背景与目标：

BACKGROUND & AIMS: :A scar flap is formed with the pedicle at the lateral part of the columella base at the cleft side, that is, in the center of the affected region. It enables flap placement according to individual need. A prospective evaluation was performed in a group of 76 patients with cleft lip and palate, all operated on by the same plastic surgeon. The flap was used to improve the height of the columella and the extent of nasal mucosa on the frontal septum and on the nostril base in the vestibule. In the lip, the flap raised its height and improved proportionality. The average area of flap used in a unilateral deformity was 42 mm. Both flaps in a bilateral deformity were 77 mm. The average follow-up was 22.4 months. Neither local nor general complications were noted apart from a recurrence of the deformity of the nasal septum in 7.9% of patients. The nasal passage was improved in 59.9% of patients and normalized in 19.6% upon follow-up rhinomanometry, but nevertheless, only one third of patients overcame their dynamic stereotype of breathing by the mouth. Anthropometric measurements showed an absence of statistically significant differences between patients after surgery and healthy individuals in crucial parameters (nasal tip projection, length of columella, nasolabial angle, nasal angle, and lip angle). The loss of the stigmatizing deformity is based on rotation of the nasolabial angle in relation to the aesthetic axis of the face. Direct examination proved aesthetic and functional improvement as statistically significant in 92.1% of patients.

背景与目标： : 疤痕皮瓣在裂隙侧的小柱基部的外侧部分 (即在受影响区域的中心) 形成。它可以根据个人需要放置襟翼。对76例唇腭裂患者进行了前瞻性评估，所有患者均由同一位整形外科医生进行手术。皮瓣用于改善前庭额隔和鼻孔基部的小柱高度和鼻粘膜的程度。在嘴唇上，皮瓣提高了高度并提高了比例。用于单侧畸形的皮瓣的平均面积为42毫米。双侧畸形的两个皮瓣均77毫米。平均随访22.4个月。除了7.9% 患者的鼻中隔畸形复发外，均未发现局部或一般并发症。59.9% 患者的鼻腔通道得到改善，并在随访的鼻腔测量后在19.6% 中恢复正常，但是，只有3分之1的患者克服了通过口腔呼吸的动态刻板印象。人体测量显示，手术后患者与健康个体之间在关键参数 (鼻尖投影，小柱长度，鼻唇角，鼻角和唇角) 上没有统计学上的显着差异。污名化畸形的丧失是基于鼻唇角相对于面部美学轴的旋转。直接检查证明在患者92.1% 中具有统计学意义的美学和功能改善。

BACKGROUND & AIMS: :Old and frail patients with advance breast malignancy require mastectomy which often results in large defects requiring soft tissue cover. We present three cases of large fasciocutaneous perforator based V-Y advancement flaps for reconstruction of large post-mastectomy wounds in older patients with large tumours. This technique reduces the morbidity of patients who have severe co-existing morbidity factor in addition to the advance breast disease.

背景与目标： : 患有晚期乳腺恶性肿瘤的年老体弱患者需要进行乳房切除术，这通常会导致大量缺损，需要软组织覆盖。我们介绍了3例基于大型筋膜皮肤穿孔器的v-y推进皮瓣，用于重建患有大肿瘤的老年患者的大型乳房切除术后伤口。除了晚期乳腺疾病外，该技术还可以降低具有严重并存发病率因素的患者的发病率。

BACKGROUND & AIMS: :A technic for total mastectomy with complete axillary dissection has been described. The procedure utilizes division of the pectoralis major muscle between its clavicular and sternal portions, perservation of its innervation, and reconstruction after completion of the dissection. The pectoralis minor muscle is resected. This modification facilitates a thorough axillary dissection, particularly at the apex, while preserving the cosmetic and functional benefits of the Patey operation.

背景与目标： : 已经描述了一种完全腋窝清扫全乳房切除术的技术。该程序利用胸大肌在锁骨和胸骨部分之间的划分，保留其神经支配，并在解剖完成后进行重建。胸小肌被切除。这种修饰有助于彻底的腋窝解剖，尤其是在顶点处，同时保留了Patey手术的美容和功能益处。

BACKGROUND & AIMS: :To establish a risk scoring system for predicting locoregional recurrence (LRR) and explore the potential value of radiotherapy in T1 to T2 node-negative breast cancer patients treated with mastectomy. From January 2001 to February 2008, a total of 353 node-negative T1 to T2 breast cancer cases treated with mastectomy without adjuvant radiotherapy were retrospectively analyzed. Preliminary screening of the prognostic factors was accomplished by Kaplan-Meier univariate analysis, and survival curves between different groups were compared by log-rank test. Risk factors were determined using Cox proportional hazards model. A categorical risk scoring system was generated according to the Cox model, weighing the relative importance of each risk variable. Median follow-up was 115.7 months (range, 1.2-238.4 months). The overall 5-year locoregional recurrence-free survival (LRFS) was 89.8% (95% confidence interval [CI] = 86.7%-92.9%). Chest wall (53.8%) was found to be the most common site of LRR, followed by supraclavicular nodes (48.7%). Age ≤40 years, primary tumor size ≥4.5 cm and number of nodes resected ≤10 were found to be independent factors for poor prognosis of LRR. Two risk stratifications based on the scoring system were subsequently obtained. The 5-year LRFS was 91.6% (95% CI = 88.5%-94.7%) with low risk (score <2) and 75.7% (95% CI = 61.8%-89.6%) with high risk (score ≥2), respectively (χ = 7.544, P = .006). In addition, significant differences in overall survival (P = .045) and disease-free survival (P = .019) were presented between them. Patients with T1-2N0M0 breast cancer achieved favorable prognosis in general. Those with risk factors, including age ≤40 years, primary tumor size ≥4.5 cm and number of nodes resected ≤10, were at higher risk of LRR. The established scoring system could help to distinguish the subgroups that might potentially benefit from postoperative radiotherapy.

背景与目标： : 建立预测局部复发 (LRR) 的风险评分系统，并探讨放疗在接受乳房切除术的T1至T2淋巴结阴性乳腺癌患者中的潜在价值。回顾性分析2001年1月至2008年2月353例T1至T2淋巴结阴性的乳腺癌患者，行乳房切除术而不进行辅助放疗。通过Kaplan-Meier单因素分析完成了对预后因素的初步筛选，并通过log-rank检验比较了不同组之间的生存曲线。使用Cox比例风险模型确定危险因素。根据Cox模型生成了分类风险评分系统，并权衡了每个风险变量的相对重要性。中位随访时间为115.7个月 (范围为1.2-238.4个月)。总体5年无局部复发生存率 (LRFS) 为89.8% (95% 置信区间 [CI]  =   86.7%-92.9%)。胸壁 (53.8%) 是LRR最常见的部位，其次是锁骨上淋巴结 (48.7%)。年龄 ≤ 40岁、原发肿瘤大小 ≥ 4.5  cm、切除淋巴结数目 ≤ 10是LRR预后不良的独立因素。随后获得了基于评分系统的两个风险分层。5年LRFS为91.6% (95% ci   =   88.5%-94.7%) 的低风险 (得分 <2) 和75.7% (95% ci   =   61.8%-89.6%) 的高风险 (得分 ≥ 2) (χ  =   7.544，p   =  .006)。此外，两者之间的总生存期 (p   =  .045) 和无病生存期 (p   =  .019) 存在显着差异。T1-2N0M0乳腺癌患者总体上获得了良好的预后。具有危险因素 (包括年龄 ≤ 40岁，原发肿瘤大小 ≥ 4.5  cm和切除的淋巴结数目 ≤ 10) 的患者发生LRR的风险较高。建立的评分系统可以帮助区分可能从术后放疗中受益的亚组。

BACKGROUND & AIMS: :Flap endonucleases (FENs) catalyse the exonucleolytic hydrolysis of blunt-ended duplex DNA substrates and the endonucleolytic cleavage of 5'-bifurcated nucleic acids at the junction formed between single and double-stranded DNA. The specificity and catalytic parameters of FENs derived from T5 bacteriophage and Archaeoglobus fulgidus were studied with a range of single oligonucleotide DNA substrates. These substrates contained one or more hairpin turns and mimic duplex, 5'-overhanging duplex, pseudo-Y, nicked DNA, and flap structures. The FEN-catalysed reaction properties of nicked DNA and flap structures possessing an extrahelical 3'-nucleotide (nt) were also characterised. The phage enzyme produced multiple reaction products of differing length with all the substrates tested, except when the length of duplex DNA downstream of the reaction site was truncated. Only larger DNAs containing two duplex regions are effective substrates for the archaeal enzyme and undergo reaction at multiple sites when they lack a 3'-extrahelical nucleotide. However, a single product corresponding to reaction 1 nt into the double-stranded region occurred with A. fulgidus FEN when substrates possessed a 3'-extrahelical nt. Steady-state and pre-steady-state catalytic parameters reveal that the phage enzyme is rate-limited by product release with all the substrates tested. Single-turnover maximal rates of reaction are similar with most substrates. In contrast, turnover numbers for T5FEN decrease as the size of the DNA substrate is increased. Comparison of the catalytic parameters of the A. fulgidus FEN employing flap and double-flap substrates indicates that binding interactions with the 3'-extrahelical nucleotide stabilise the ground state FEN-DNA interaction, leading to stimulation of comparative reactions at DNA concentrations below saturation with the single flap substrate. Maximal multiple turnover rates of the archaeal enzyme with flap and double flap substrates are similar. A model is proposed to account for the varying specificities of the two enzymes with regard to cleavage patterns and substrate preferences.

背景与目标： : 皮瓣核酸内切酶 (FENs) 催化钝端双链DNA底物的核酸外切水解和在单链和双链DNA之间形成的连接处的5 '-分叉核酸的核酸内切裂解。使用一系列单寡核苷酸DNA底物研究了来自T5噬菌体和古细菌的FENs的特异性和催化参数。这些底物包含一个或多个发夹圈，并模拟双链体，5 '悬垂双链体，伪Y，刻痕DNA和皮瓣结构。还表征了具有螺旋外3 '-核苷酸 (nt) 的刻痕DNA和皮瓣结构的FEN催化的反应特性。噬菌体酶在所有测试的底物上产生了长度不同的多个反应产物，除非截短了反应位点下游的双链DNA的长度。只有包含两个双链体区域的较大dna才是古菌酶的有效底物，当它们缺乏3 '-外螺旋核苷酸时，它们会在多个位点发生反应。然而，当底物具有3 '-外螺旋nt时，与双链区域中的反应1 nt相对应的单个产物发生在fulgidus FEN中。稳态和预稳态催化参数表明，噬菌体酶受所有测试底物的产物释放的速率限制。单转换最大反应速率与大多数底物相似。相反，T5FEN的周转数随着DNA底物大小的增加而减少。比较使用瓣和双瓣底物的A. fulgidus FEN的催化参数表明，与3 '-外螺旋核苷酸的结合相互作用稳定了基态FEN-DNA相互作用，从而在DNA浓度低于饱和时刺激了比较反应。单瓣底物。具有瓣和双瓣底物的古菌酶的最大多次周转率相似。提出了一个模型来说明两种酶在裂解模式和底物偏好方面的不同特异性。

BACKGROUND & AIMS: INTRODUCTION:Soft tissue reconstruction around the knee is challenging from a functional and aesthetic perspective. While locoregional options remain limited, free flaps produce additional scarring and longer hospitalization. We describe the most distal "D-perforator" of ALT-axis and present our 4-year experience with a distal perforator-only propeller anterolateral thigh (D-POP ALT) flap for reconstruction around the knee. METHODS:Seventeen patients (7 males, 10 females, mean age 57 years), had distal perforator-only propeller (D-POP) ALT flap reconstruction of defects following the wide local excision of melanoma around the knee joint between May 2014 and December 2018. The most distal perforator in the line between spina illiaca anterior superior (SIAS) and the upper lateral border of patella was identified and marked with audible-Doppler and perforator-only propeller ALT (POP-ALT) flap, which was designed around it. Perforators were dissected intramuscularly or intraseptally to allow adequate flap mobilization, but no division of main pedicle was ever performed to ensure anterograde blood supply. Flaps were rotated into defects while all donor-sites were closed directly. RESULTS:The largest flap measured 25 × 6 cm. The perforator was found between 4 and 9 cm proximal to the upper lateral border of patella in all cases. It was found to be septal in 10 cases and intramuscular in 7 cases. Healing was uneventful in all cases, and patients were ambulatory immediately postoperatively. All patients were discharged on postoperative day 1. Excellent long-term outcomes were observed on follow-up by the senior author. CONCLUSIONS:In our experience, this technique is simple, reliable, and versatile. Thin and pliable flaps can be safely raised based on the most distal (D-POP) ALT perforator. In addition, sizeable flaps can be performed while still preserving the main ALT pedicle, if free flap is required for the same patient in the future.

背景与目标：

BACKGROUND & AIMS: PURPOSE:To evaluate locoregional control and survival after mastectomy, as well as toxicity, in patients irradiated by a previously described postmastectomy highly conformal electron beam radiation therapy technique (PMERT). METHODS AND MATERIALS:We included all women irradiated by postmastectomy electron beam radiation therapy for nonmetastatic breast cancer between 2007 and 2011 in our department. Acute and late toxicities were retrospectively assessed using Common Terminology Criteria for Adverse Events version 3.0 criteria. RESULTS:Among the 796 women included, 10.1% were triple-negative, 18.8% HER2-positive, and 24.6% received neoadjuvant chemotherapy (CT). Multifocal lesions were observed in 51.3% of women, and 64.6% had at least 1 involved lymph node (LN). Internal mammary chain, supraclavicular, infraclavicular, and axillary LNs were treated in 85.6%, 88.3%, 77.9%, and 14.9% of cases, respectively. With a median follow-up of 64 months (range, 6-102 months), 5-year locoregional recurrence-free survival and overall survival were 90% (95% confidence interval 88.1%-92.4%) and 90.9% (95% confidence interval 88.9%-93%), respectively. Early skin toxicity was scored as grade 1 in 58.5% of patients, grade 2 in 35.9%, and grade 3 in 4.5%. Concomitant CT was associated with increased grade 3 toxicity (P<.001). At long-term follow-up, 29.8% of patients presented temporary or permanent hyperpigmentation or telangiectasia or fibrosis (grade 1: 23.6%; grade 2: 5.2%; grade 3: 1%), with higher rates among smokers (P=.06); 274 patients (34.4%) underwent breast reconstruction. Only 24 patients (3%) had early esophagitis of grade 1. Only 3 patients developed ischemic heart disease: all had been treated by anthracycline-based CT with or without trastuzumab, all had been irradiated to the left chest wall and LN, and all presented numerous cardiovascular risk factors (2-4 factors). CONCLUSIONS:This study demonstrated the good efficacy of this technique in terms of locoregional control and survival, and good short-term and long-term safety. Longer follow-up is required to analyze chronic cardiac events.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:Pectoralis major muscle flaps (PMMFs) and fasciocutaneous free flaps (FFFs) are commonly used for reconstruction of the surgical defect after salvage total laryngectomy. This study compared swallowing function in patients who underwent reconstruction with either PMMF or FFF. METHODS:This study was based on a retrospective cohort of patients treated at the CHU de Québec between January 2000 and March 2015. Demographics, chemoradiation data, surgical protocol, pathologic results, complications, evolution, esophageal dilation, diet intake, and feeding tube dependence were documented. RESULTS:A total of 126 patients were analyzed (93 PMMFs and 33 FFFs). Of the patients who received PMMFs, 38.7% had a limited oral intake compared to 15.2% of patients who received FFFs (odds ratio [OR] 3.54; 95% confidence interval [CI] 1.25-9.99; P = .02). The need for esophageal dilation tended to be greater for PMMF patients (25% vs 9%; OR 3.38; 95% CI 0.94-12.13; P = .06). Complication rates were similar. CONCLUSION:The FFF reconstruction led to better results in terms of swallowing function than PMMF reconstruction.

背景与目标：

BACKGROUND & AIMS: -2

背景与目标： -2

BACKGROUND & AIMS: BACKGROUND:New surgical innovations of nipple-sparing mastectomy (NSM), such as endoscopic NSM (E-NSM) or robotic NSM (R-NSM), were emerging. However, there was a lack of evidence comparing the effectiveness and safety in the management of breast cancer. METHODS:A case-control comparison study was conducted for patients with breast cancer underwent E-NSM or R-NSM with immediate prosthesis breast reconstruction (IPBR) from July 2010 to February 2019 at a single institution to compare the clinical outcomes, learning curve, patient-reported cosmetic results, and medical cost. RESULTS:A total of 91 E-NSM and 40 R-NSM procedures were retrieved and analyzed. The surgical margin involvement rate in both R-NSM (2.5%) and E-NSM (4.4%) procedures were relatively low (P = 0.52). The R-NSM group was associated with higher satisfaction rates in terms of scar appearance, scar length, and surgical wound position compared with the E-NSM group. Compared with E-NSM, the R-NSM operation time took longer (241 ± 61 vs. 215 ± 70 min, P = 0.01), less blood loss (32 ± 29 vs. 79 ± 62 ml, P < 0.01), and higher medical cost (10,587 ± 554 vs. 6855 ± 936 U.S. dollars, P < 0.01). There was no statistically significant difference in nipple ischemia/necrosis or overall complication between R-NSM and E-NSM. In the learning curve analysis, it took the 27th procedure in E-NSM and 10th procedure in R-NSM to decrease operation time significantly. CONCLUSIONS:R-NSM was associated with higher wound-related satisfaction, lesser blood loss, and shorter learning curve compared with E-NSM, however, at the price of longer operation time and higher medical cost.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:The management of chronic pulmonary aspergillosis remains a challenge for thoracic and reconstructive surgeons. Different management options have been proposed with no consensus regarding the best treatment modality. The goal of this study is to report our experience with the use of intrathoracic muscle flaps for the management of pulmonary aspergillosis. METHODS:We retrospectively reviewed all patients who underwent intrathoracic muscle flap transposition for the management of pulmonary aspergillosis between 1990 and 2010. Demographics, surgical characteristics, and treatment outcomes were collected and analyzed. RESULTS:A total of 39 patients who underwent 48 muscle flaps were identified. The majority were classified as ASA 3 (n=30, 77%) or ASA 4 (n=8, 21%). Serratus anterior was the most common flap used (n=34), followed by latissimus dorsi (n=6) and pectoralis major (n=5). Flap loss was encountered in three (8%) patients (2 partial, 1 total). Bronchopleural fistula and empyema comprised the two most common intrathoracic complications (26%, 29% respectively). Median follow-up was 33 months (range, 0-216). Successful treatment was achieved in 77% of patients, while operative mortality was 23%. CONCLUSION:The use of intrathoracic muscle flaps can be a helpful adjunct to surgical resection in the treatment of chronic pulmonary aspergillosis with low rates of flap loss.

背景与目标：

BACKGROUND & AIMS: OBJECTIVE:to assess the haemodynamic effect of a free muscle flap on the midterm success of a pedal bypass. DESIGN:prospective consecutive study. MATERIALS:a pedal bypass (autogenous vein graft) combined with a free muscle flap was performed in 13 patients with critical leg ischaemia. The feeding artery of the flap was anastomosed end-to-side to the bypass. METHODS:blood flow was measured in the bypass before and after transplanting the flap. Doppler was used postoperatively to assess the patency. RESULTS:the bypass and flap pedicle were patent in 11 cases six months postoperatively. Two grafts were thrombosed and the legs amputated. In the successful group the median (range) blood flow in the bypass was 50 (10-100) ml/min. It increased (p<0.05) after transplantation to 64 (20-113) ml/min, being 44 (14-97) ml/min distributed to the foot. Blood flow through the flap was 20 (6-37) ml/min. The two failing grafts had a flow of 30 and 51 ml/min before and 48 and 52 ml/min after transplantation, respectively. Blood flow through the flap was 47 ml/min and 36 ml/min, respectively. In the failure group the free flap received most of the blood supply through the bypass. CONCLUSIONS:a free muscle flap connected to an infrapopliteal bypass increases the distal outflow bed and thus decreases the outflow resistance and increases graft flow.

背景与目标：

BACKGROUND & AIMS: :We treated a case with left tibial adamantinoma by use of a contralateral fibular osteoadiposal flap. The donor site of conventional fibular osteocutaneous flap must be covered with a skin graft because if we close the donor skin defect directly, compartment syndrome might occur. We were able to close the donor skin defect because this combined type flap included only a small monitoring skin paddle. We present herein the utility of the osteoadiposal flap and show the value of a skin-sparing approach with a minimal aesthetic defect.

背景与目标： : 我们使用对侧腓骨成骨瓣治疗了一例左胫骨成骨瘤。常规腓骨皮瓣的供体部位必须覆盖皮肤移植物，因为如果我们直接关闭供体皮肤缺损，可能会发生筋膜综合征。我们能够关闭供体皮肤缺损，因为这种组合型皮瓣仅包括一个小的监视皮肤桨。我们在此介绍了骨脂瓣的实用性，并显示了具有最小的美学缺陷的皮肤保留方法的价值。