Skin Flap Necrosis in Inguinal Lymph Node Dissection

Abstract

Inguinal skin flap necrosis (SFN) is a significant clinical problem associated with inguinal lymph node dissection (ILND). The aetiology of SFN is multifactorial, and its manifestations vary widely. Thermal damage caused by electrocautery during the elevation of the skin flap may contribute to this problem, which has not been studied previously. This prospective, observational study included patients undergoing ILND from January 2020 to July 2022. Based on the technique of raising the inguinal skin flaps, the patients were divided into two groups (cold knife or electrocautery). The remaining part of the procedure was the same. The inguinal wound was examined and photographed to assess the SFN. A total of 42 patients were included (21 in each group). Age, gender, body mass index (BMI), alcohol or tobacco consumption, immune compromised status, and serum albumin were comparable (p > 0.05). The average time required to elevate flaps was 13.14 vs. 11.47 min (p = 0.0231), and gauze soakage was 2.05 vs. 1.52 (p < 0.0001) with a cold knife compared to electrocautery. The incidence of SFN and surgical site infection (SSI) was significantly lower with the use of a cold knife [4.8% vs. 33.3% (p = 0.045) and 0% vs. 19% (p = 0.0378)]. Grade 3 necrosis was observed only with electrocautery use. Compared to conventional electrocautery, the cold knife technique lowers the incidence of SFN and SSI. Further research with a larger sample size and a standardized definition is needed to validate these results.

Introduction

Inguinal lymph node dissection (ILND) is an integral part of oncological resections for carcinomas of the penis, vulva, and skin of the pelvis and lower extremities. It provides disease staging and prognosis. In addition, it acts as a guide for any adjuvant treatment and serves a therapeutic purpose by removing regional nodal disease. Historically, ILND is associated with the greatest morbidity (up to 70%) among all types of lymph node dissections described for various cancers. The range of complications includes skin necrosis (7–70%), surgical site infection (SSI) (10–17%), seroma formation (5–15%), lymphocele (2–6%), chronic lymphedema (10–30%), and deep vein thrombosis (0–13%) [1]. Complications increase anxiety, treatment costs, and hospital stays. Furthermore, it may delay any adjuvant treatment and lower the quality of life.

Skin flap necrosis (SFN) is the most common complication that has worried surgeons and pushed them to look for innovative ways to decrease this problem. Modifications to reduce skin necrosis include altering the shape and size of the incision, elevating thick flaps, carefully handling skin flaps, revising skin edges at the end of the procedure, and using different methods to close the skin incision. Others recommend prophylactic use of the Tensor Fascia Lata (TFL) flap. Still, the incidence of this particular complication remains significant [2, 3]. The use of electrocautery and its concomitant thermal injury may be one of the factors responsible for this complication [4]. The thermal damage may be invisible to the surgeons but subsequently manifest as skin flap necrosis [5]. Once SFN sets in, it causes a varied amount of tissue loss, delayed wound healing, protracted hospitalization, and unsatisfactory cosmesis. Avoiding electrocautery may perhaps reduce the necrosis of the inguinal flaps. The study's primary objective is to determine the incidence of skin necrosis using either a cold knife or electrocautery for flap elevation during an inguinal lymph node dissection. The secondary objectives are to determine the factors associated with SFN, extent of necrosis, SSI rates and reinterventions for flap necrosis.

Materials and Methods

Study Design

We used a prospective, observational design for this pilot study. The study was conducted in the Department of Surgical Oncology at a tertiary care teaching and referral centre from January 2020 to July 2022. The study commenced after the approval of the Institutional Ethics Committee. All consecutive patients with squamous cell carcinoma of the penis, vulva, and cutaneous sites of the lower extremity planned for simultaneous resection of the primary tumor and inguinal lymph node dissection were considered for recruitment. Patients were excluded if any of the following were present: a) involvement of the overlying skin by the inguinal lymph node; b) simultaneous pelvic node dissection; c) inability to do primary closure of the ILND incision; d) previous scarring at the local site; e) history of previous surgery or radiation at the inguinal area; f) history of an autoimmune skin disorder or steroid therapy; and g) failure to give consent.

Methodology

The history (smoking, tobacco chewing, alcohol, diabetes), clinical details (diagnosis, age, height, weight, body mass index), and laboratory findings (HIV, hepatitis infection, preoperative serum protein, and albumin) were collected and entered into a structured format preoperatively. Electrocautery is used as a standard procedure for raising inguinal flaps. We designated one consultant surgeon to use the cold knife to elevate skin flaps, while others continued using electrocautery to raise flaps in all consecutive patients. A standard inguinal lymph node dissection was performed using an oblique incision made two fingers breadth lateral and below the pubic tubercle parallel to the inguinal ligament using a cold knife. Except for the flap elevation technique, the remainder of the procedure remained the same. The time taken to raise the flaps with both procedures was recorded. At the conclusion of the procedure, the skin was closed primarily after putting drains. The closed suction drain was removed once output was less than 20 ml over a period of 24 h. Perioperative thromboembolic prevention was not administered. Patients were encouraged to move the next day following surgery. Antibiotic prophylaxis was administered as per standard protocol.

The inguinal wound was examined daily and photographed at 48 h and on postoperative days 5 and 10. Observations regarding the wound were made by an observer (consultant surgeon) blinded to the identity of the patient and the surgical technique used. This was done to prevent measurement bias. The worst pattern of depth of cutaneous necrosis was recorded. The depth of skin necrosis was assessed in three grades as follows: Grade A: Color change of the skin flap as cyanosis or erythema suggestive of impaired perfusion of the flap; Grade B: Less than full thickness SN resulting in at least epidermal sloughing. Grade C: Full-thickness flap SN. The results of SFN from the two techniques were compared.

Statistical Analysis

The mean and standard deviation (SD) values were utilized for continuous, normally distributed variables, but median (Interquartile range) values were used for non-normal data. Comparisons between continuous variables were assessed using the independent samples t-test / Mann–Whitney test, whereas the Pearson chi-square test was used for comparisons between proportions. P-value < 0.05 was considered statistically significant. All statistical analyses were performed using SPSS version 23.0 (SPSS-23, IBM, Chicago, USA).

Results

A total of 42 patients participated in this study. Of them, inguinal flaps were raised with a cold knife in 21 (50%) patients and with electrocautery in the other half of patients. Table 1 shows the distribution of patients according to the primary tumor site. The mean age of patients in the cold knife and electrocautery groups was 54.7 and 50.8 years, respectively. Most of the patients were males (80.9%) and were equally distributed across both groups. The body mass index (BMI) of patients in both groups was similar, and both groups were in the normal range for BMI. Majority of the patients were non-alcoholic (95%), non-smoker (76%), and not habitual of tobacco chewing (59.5%) and were similarly distributed among both the groups, as shown in Table 2. There was no significant difference in the patient group when compared for comorbidity like diabetes mellitus (9.5% vs. 4.8%) or immunocompromised state (4.8% vs. 14.3%). The mean value of serum albumin was found to be 3.28 g/dL in the cold knife group and 3.44 g/dL in the electrocautery group (p = 0.257). There was no significant difference in baseline characteristics between the two groups (Table 2).

Table 1.

Distribution of patients according to the site of primary tumour

Site of Primary (n)	Cold knife (n = 21)	Electrocautery (n = 21)
Penis (22)	13 (61.9%)	9 (42.9%)
Vulva (3)	0 (0.0%)	3 (14.3%)
SCC lower limb (17)	8 (38.1%)	9 (42.9%)

n = total numbers, SCC = Squamous cell carcinoma

Table 2.

Baseline characteristics of the two groups

Variables	Cold knife (n = 21)	Cautery (n = 21)	p-value
Age (years)	54.76 ± 13.67	50.86 ± 11.42	0.321
Males (%)	18 (85.7)	16 (76.2)	0.697
Females (%)	3 (14.3)	5 (23.8)
BMI (kg/m2)	21.11 ± 2.81	21.26 ± 2.58	0.865
Alcohol
Yes	2 (9.5%)	0 (0%)	0.488
No	19 (90.5%)	21 (100%)
Smoker
Yes	6 (28.6%)	4 (19%)	0.719
No	15 (71.4%)	17 (81%)
Tobacco chewing
Yes	11 (52.4%)	6 (28.6%)	0.208
No	10 (47.6%)	15 (71.4%)
Diabetes Mellitus
Yes	2(9.5%)	1 (4.8%)	0.999
No	19 (90.5%)	20 (95.2%)
Immunocompromised (Hepatitis B/C or HIV)
Positive	1(4.8)	3 (14.3)	0.606
Negative	20 (95.2)	18 (85.7)
Serum Albumin	3.28 g/dl	3.44 g/dl	0.257

The average time required to elevate skin flaps with a cold knife was 13.14 min, compared to 11.47 min (p = 0.0231) when electrocautery was used. The average number of gauzes soaked during flap elevation was 2.05 with cold knife and 1.52 with the electrocautery (p =  < 0.0001) (Table 3).

Table 3.

Time taken and number of gauzes soaked while raising skin flaps

Variables	Cold knife (n = 21)	Cautery (n = 21)	p-value
Time taken (min)	13.14 ± 2.088	11.47 ± 2.478	0.0231
Gauze soaked	2.05 ± 0.344	1.52 ± 0.219	< 0.0001

Flap necrosis was observed in eight out of forty-two patients (19%), seven of whom were in the electrocautery group (33.3%) and one in the cold knife group (4.8%) (p = 0.045). In the electrocautery group, grade 2 and 3 necrosis developed in two (9.5%) and three (14.3%) patients, respectively, while only one patient in the cold knife group (4.8%) developed grade 2 necrosis. In total, SSI developed in four patients (9.5%). All of these patients belonged to the electrocautery group (4 out of 21), and only those who developed flap necrosis manifested SSI. Reintervention for flap necrosis (debridement and/or resuturing) was necessary for five patients (11.9%), with 4 (80%) in the electrocautery group and the remaining in the cold knife group. (Table 4) There were no postoperative deaths.

Table 4.

Skin flap necrosis and SSI distribution among two groups

Variables	Cold knife (n = 21)	Cautery (n = 21)	p-value
Flap necrosis	1(4.8%)	7(33.3%)	0.045
Necrosis grade
Grade 1	0	2
Grade 2	1	2
Grade 3	0	3
SSI	0 (0%)	4 (19.0%)	0.0378
Reintervention	1 (4.76%)	4 (19.0%)	0.158

SSI = Surgical site infection

Discussion

In this pilot study, the incidence of SFN and SSI in the entire sample was 19% and 9.5%, respectively. We discovered that using a cold knife compared to electrocautery resulted in an absolute reduction of 28% in the SFN as well as the grade of necrosis. As a result of using the former, reinterventions following the SFN were also reduced. The use of cold knives significantly decreased infection rates (19% vs. 0%). However, when using a cold knife to raise skin flaps, the required time increased by an average of two minutes, and the amount of blood loss during flap elevation was slightly more (by an average of half a gauze soakage).

The incidence of SFN has been reported in various ways in the literature, resulting in substantial heterogeneity (Table 5) [1, 2, 6–16]. This is due to the absence of a consistent definition of this complication. Most studies fail to specify in their methods what constitutes flap necrosis. Many consider only blackening with skin loss to be SFN [11]. Some consider a slight change in colour due to ischemia to be necrosis, while others may consider it to be entirely normal. The usage of ambiguous terms like "skin edge necrosis" (SEN) and "skin flap necrosis" also contributes to the problem because these two entities are technically distinct [13]. A skin edge necrosis would mean only necrosis along the incision line, whereas a SFN would mean a necrotic change in any area of the flap that has been raised during the procedure. Another word that can be confusing is "wound breakdown" or "dehiscence," which means that the skin has lost its internal integrity, leaving a gaping wound. Thirdly, the available studies do not explicitly state the time when necrosis should be reported. SFN is a dynamic process that may take some time to evolve after the surgery. A slight colour change can also eventually lead to full thickness loss. If this complication is reported prior to the complete establishment of the SFN, an underreporting of the outcome will occur. In our experience, it takes approximately 7 to 8 days for SFN to reach its maximum extent.

Table 5.

Comparison of the complications of open radical ILND in various studies

Author (Year of publication)	Study site	Primary site	Number of Groins	Inguinal skin flap necrosis (SFN)	Surgical Site Infection (SSI)
Ravi [6] et al. (1993)	India	Penile cancer	231	61%	18%
Gaarenstroom [7] et al. (2003)	Netherland	Vulva cancer	101	17%	39%
Bouchot [8] et al. (2004)	France	Penile cancer	58	12%	NA
Tobias [9] (2007)	Brazil	Penile cancer	10	30%	10%
Wang [10] et al. (2017)	China	Penile cancer	21	28.6%	14.3%
Faut [2] et al. (2017)	Netherland	Melanoma	240	13.6%	29.8%
Kumar [11] V et al. (2017)	United Kingdom	Penile cancer	35	Wound Debridement under GA 23%	NA
Yadav [12] et al. (2018)	India	Penile cancer	29	27.5%	13%
Singh [13] et al. (2018)	India	Penile cancer	100	Edge necrosis 23% SFN-13%	17%
Pontre [14] et al. (2018)	India	Vulva cancer	71		59.2%
Ye [15] et al. (2018)	China	Penile cancer	62	8% CD I & II grade
Yu [16] et al. (2019)	China	Penile cancer	10	45% (Necrosis & SSI combined)
Das [1] et al. (2021)	India	Penile cancer	79	17%	16%
Present study	India	Penile, vulva, SCC skin	42	19%	9.5%

CD = Clavien Dindo, GA = General anaesthesia, NA = data not available, SCC = Squamous cell carcinoma

The inguinal skin is highly susceptible to vascular compromise, contributing to the high incidence of inguinal SFN. Therefore, it is necessary to understand its potential mechanisms. The superficial fascia of the inguinal region consists of two layers, namely the outer fatty layer (Camper's fascia) and the inner membranous layer (Scarpa's fascia). Flaps are elevated in a plane just beneath the membranous layer. This ensures that the camper's fascia has been included and the flaps are thick, thereby increasing the likelihood of flap viability. Very thin flaps are less vascularised and more susceptible to necrosis.

The blood supply to the inguinal skin is extremely tenuous. The area is supplied by the superficial external pudendal artery, the superficial inferior epigastric artery, and the superficial circumflex iliac artery. All three originate in the femoral sheath from the femoral artery. After their origin, they penetrate the femoral sheath and fascia lata and then pass between fascia Scarpa and camper before ultimately supplying the skin. The venous drainage parallels the arterial supply and drains into the greater saphenous or femoral vein near the saphenofemoral junction. All of these vessels have a small calibre of 1 to 2 mm. They are highly susceptible to injury because of their long course and smaller diameter, vessel handling in the lymphadenectomy area, and poor anastomotic connections.

The traction applied while elevating skin flaps may cause compression of the small cutaneous vasculature, impeding blood flow and reducing tissue oxygenation. This contributes to the increased incidence of SFN. Some surgeons freshen the edges of the skin by 0.5 to 1 cm to remove the portion of the flap that is most susceptible to necrosis as a result of traction injury. Walker et al. discovered that the method of skin closure (subcuticular suture or skin stapler) had no effect on inguinal skin flap complications [17].

Another factor is the thermal injury that may result from overzealous electrocautery use. It may result from a direct injury to the skin flap or the tiny vascular branches. The key elements are the temperature generated at the dissection site, the lateral thermal spread, the voltage setting, and the precision with which the electrocautery instrument is utilized. Thermal damage causes tissue desiccation, eventually resulting in devascularization and epidermal necrosis [18].

Additionally, the moist nature of the inguinal region, the pathogenicity of the genital flora (staphylococcus, Pepto streptococcus, and diphtheroid), and inadequate hygiene all contribute to the increased risk of infection.1 The resulting inflammation impacts tissue oxygenation and promotes flap necrosis. The Sartorius muscle transposition method was first described for the protection of the femoral vessels in cases of inguinal wound breakdown [19]. Randomizing patients undergoing ILND with or without sartorius transposition, Judson et al. found no difference in the incidence of skin flap breakdown or infection [20].

The strength of our study comes from the fact that it was carried out in a single department where a defined group of surgeons routinely operated on patients with the same surgical steps. The definition of the outcome was standardized and established prior to the study. No patient had received radiation to the inguinal region, and all incisions were closed primarily without tension. The outcome assessment was blinded to reduce measurement bias. Furthermore, the statisticians were unaware of the patients and the technique. However, our pilot research is limited by its small sample size and observational design. A well-designed randomized clinical trial (RCT) would perhaps provide high-quality evidence supporting our hypothesis. We are currently planning to do such a trial, registered under the national clinical trial registry with number CTRI/2022/04/042283.

Conclusion

In conclusion, our pilot study comparing skin flap necrosis after inguinal lymph node dissection using a cold knife versus electrocautery reveals important insights. The findings indicate that the choice of surgical technique influences the incidence of skin flap necrosis substantially. While both methods have their merits, the cold knife technique appears to be associated with a lower risk of necrosis and subsequent reinterventions. Further research with a larger sample size is warranted to validate these results and explore potential contributing factors. Additionally, a standard definition of this particular complication is required to evaluate future studies effectively. Surgeons should carefully consider these findings when selecting a technique for inguinal lymph node dissection to optimize patient outcomes and minimize postoperative complications.

Funding

We also have no source of any external funding.

Declarations

Conflicts of Interest

We have no conflicts of interest to disclose.