“Soap Scrap” Technique: A Tissue-Preserving Approach to Treating Wounds With Undermining or Pockets : Advances in Skin & Wound Care

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Soap Scrap” Technique: A Tissue-Preserving Approach to Treating Wounds With Undermining or Pockets

Melnychuk, Igor MD, CLT; Juriga, Julia MBS

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Advances in Skin & Wound Care ():10.1097/01.ASW.0000931584.75689.df, May 1, 2023. | DOI: 10.1097/01.ASW.0000931584.75689.df
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Even perfectly debrided wounds may not heal due to unfavorable edges, wound undermining, or wound pockets. Wound remodeling may need to be performed in such cases. Edge remodeling typically involves edge resection at a 45% angle to prevent epiboly formation and facilitate closure. When this is not possible to debride vertical edges at a 45%-degree angle or when the wound base is not connected to the wall, an "edge trenching" technique can be used.1 The technique involves excavating a trench at the point of merger of the wound base and the wound wall. This allows tissues in the wound base to connect to the vertical edge and creates a favorable transitional angle. However, some wounds have significant undermined areas or pockets preventing closure. Here the authors describe this approach for wound closure when they have undermined areas or pockets. The three components include debridement of all surface areas, compression, and immobilization.


Wound bed preparation is an essential component of wound healing. It consists of the TIME (Tissue, Inflammation/Infection, Moisture imbalance, Epithelial edge advancement) concept.2 This article presents a new approach to solving a common clinical problem of unfavorable edges. It is axiomatic that wound edges need to be attached to the wound base and be sharply angulated at 45% degrees or less to facilitate keratinocyte migration toward the center of the wound. Unfortunately, many wounds have so-called rolled or epibolic edges. Epibolic edges form when the wound contracts while keratinocytes migrate from the edges and follow the wall.3 The edge creates an awning. The inner part of the wall gets fully epithelialized and fails to grow together with the tissue in the wound base. Typically, it is recommended to either resect the rolled edges at a 45%-degree angle or cauterize them with silver nitrate. Undermined areas or wound pockets are usually either resected or unroofed if the wounds are refractory to negative-pressure wound therapy (NPWT), or when NPWT cannot be used. Complete resection of the lesion and reconstruction using a flap are considered the treatment of choice for an ulcer with a pocket.4 Yamamoto et al5 proposed to perform a parallel pocket incision to treat pressure injuries with pockets. His approach allowed necrotic tissue removal in pockets up to 20 cm deep.5 However, sometimes these approaches may not be possible or practical in other types of wounds. This case series aimed to introduce a methodology that may serve as the initial approach to treating these challenging wounds.


This case study was conducted in Charles George VA Medical Center with 11 patients displaying poor wound closure treated between 2015 and 2022. All undermined or pocket wound areas that were in contact with each other underwent sharp mechanical debridement. These included all epithelized portions of the rolled edges, undermined areas, or internal sides of the wound pocket. If part of the wound base was open, it was sharply debrided as well. To ensure that all areas were debrided, debridement followed an imaginary clock to not leave gaps of undebrided tissues. Debridement converted chronic wound into acute wound, and restarted the healing cascade. One needed to be cautious when debriding wounds in the vicinity of neurovascular bundles. None were present in these cases. After debridements, undermined areas or wound pockets were packed with absorbable oxidized regenerated cellulose/collagen dressings.6 In 3 out of 10 cases, placental grafts were used to facilitate healing. The topical treatment of the wounds was the same as it would have been when treating them without use of the “soap scrap” technique. Two upper and three lower extremity cases were treated with compression therapy alone. Providers used NPWT in two cases and NPWT along with compression wraps were used in four cases.

Providers should assess the use of either multilayered compression alone, modified NPWT, or both. Wounds on the lower extremities without moderate to severe peripheral disease could be initially treated with multilayered compression alone. Wounds of the upper extremities are compressed with short-stretch bandages that are typically used to treat lymphedema. Decrease in size of undermined areas or wound pockets was usually seen within the first two weeks of therapy. If this approach was not successful, then providers applied NPWT with or without multilayered compression therapy.7–11 If there was an open wound, the NPWT foam was placed inside of the wound (and overlapped up to 3 to 4 cm outside of the wound pocket or wound undermining), thus combining application techniques of conventional and closed incision negative pressure therapy. Occasionally NPWT needs to be used with compression wraps which can have an additive effect by compressing all of the wound tissues together. Compression wraps are not used on the trunk or on ischemic wounds. Only NPWT was used in such cases. The concept was to approximate edges by bringing them closer to one another to facilitate closure. This method used the negative pressure range of 125 to 175 mm Hg of continued suctioning. Typically, extremity wounds received standard pressures (125-150 mm Hg) and trunk wounds received higher pressures (150-175 mm Hg). The use of compression wraps on the extremities prevented edema of the periwound or treated extremity edema. Compression also helped to approximate wound edges effectively decreasing the size of the wound. When debrided areas are compressed against one another, diffusion of molecules from the debrided upper part of the wound to the base results in the subsequent merging of tissues following Fick's law of diffusion. It is assumed that collagen fibers from the two compressed areas would develop cross-linking and cause the tissues to “glue” together.

The tissues must be immobilized to prevent any shearing forces. Immobilization allows the tissues to move “en block,” and is especially crucial when the wound base visibly moves or “pistons” with extremity or trunk movement. This technique used arm braces or removable Cam Walkers on the extremities and back braces on lower back wounds. This methodology worked very well on wounds located on the extremities.

It was less successful when applied to lower back wounds likely due to increased depth or inability to immobilize tissues well. However, all postoperative lower back wounds showed improved closure rate with debridement of all surface areas and negative pressure therapy used as a combination of conventional and closed incision techniques. This approach may be considered as the initial first step in treating unfavorable wound edges and wound pockets (Figure 1).

Figure 1:

Informed consent for treatment and publication was obtained from all patients treated at Charles George VA Medical Center that were incorporated into this case study.


Case 1

An 84-year-old veteran with a history of atrial fibrillation and venous insufficiency sustained a traumatic injury to his right leg. A large boulder rolled down a hill fracturing his tibia and fibula and causing an extensive right lower extremity hematoma. The hematoma was evacuated and all necrotic soft tissues were debrided. The fracture was repaired via open reduction and internal fixation. The patient was left with a large post-operative wound measuring 7.7 x 6.3 x 0.5 cm with rolled edges and undermining of 0.4 cm between 7 and 11 o’clock. Ankle brachial indices (ABIs) were within normal limits at 1.24. The wound base and undermining was debrided, and a combination NPWT was used to collapse the undermined area and build granulation tissue. A multilayered Profore compression wrap was used with the NPWT to keep leg edema down. Once the fascia was covered with granulation tissue, NPWT was discontinued. A split-thickness graft was placed using Xpansion micro-autografting technology. A removable Cam Walker was used to immobilize wound edges when walking and an offloading heel boot, locking the foot in the dorsiflexed position, was used when the patient was in bed. The site closed within 8 weeks.

Case 2

An 83-year-old veteran with a history of diabetes mellitus type 2, peripheral artery disease, and left above-the-knee amputation, was presented for evaluation of medial malleolar pressure injury stage 4. His malleolar ulcer did not heal after 8 months of conventional debridement, collagen dressings, and placental grafting, and the patient was then referred to the wound care clinic. Evaluation of arterial status of the extremity revealed moderate ischemia (ABIs of 0.66) but his toe pressures were 99 mm Hg indicative of good healing potential. The ulcer measured 1.5 x 1.7 x 0.4 cm with some undermining of 0.4 cm between 9 and 1 o’clock (Figure 2). The site was debrided. A derma scaffold (Primatrix) was sutured in the wound base. A combination of conventional and closed incision NPWT was continued (Figure 3). A multilayered Profore Lite compression wrap was used to treat leg edema and underlying venous insufficiency. The edges of the ulcer were mobile with foot movement. A combination of a removable Cam Walker when walking and an offloading heel boot was utilized to immobilize the malleolar ulcer, and allow the periwound to grow together with the tissues in the base. The ulcer closed in 15 weeks.

Figure 2:
Figure 3:

Case 3

An 80-year-old veteran with a history of cardiomyopathy, chronic obstructive pulmonary disease, and peripheral artery disease was referred to the wound care clinic for a nonhealing heel ulcer. It was ischemic and did not respond to 8 months of debridement and grafting therapy. At the time of evaluation, the ulcer measured 1 x 0.9 x 0.4 cm with undermining of up to 0.8 cm towards 6 o’clock. The ABI of the left lower extremity was 0.43. Transcutaneous oxygen measurements were obtained showing 42 mm Hg in the lateral foot. The patient had non-operable peripheral artery disease that was managed using arterial pumps to improve blood flow to the area. The base of the ulcer was fibrotic and necrotic. Debridement of the ulcer and all undermined areas was performed. A removable Cam Walker was used for walking and an offloading heel boot was used in bed to offload the ulcer. Closed incision NPWT was initiated to collapse the undermining and rolled edges. Abdominal pads were used to lift up the arch to provide additional offloading of the heel since it had a NPWT foam. The edges collapsed after a little over 3 weeks. The ulcer closed completely within 10 weeks.

Case 4

A 71-year-old-veteran with a history of diabetes type 2, cerebrovascular accident, peripheral artery disease, venous insufficiency, and bilateral lower extremity lymphedema, sustained a traumatic injury to the left lower extremity with a sharp metallic object. The injury created a 10 cm long vertical laceration at the subcutaneous level of the anterolateral shin. The wound measured 10 x 2.8 x 0.5 cm with undermining of 0.7 cm at 12 o’clock (Figure 4). When the patient was presented to the emergency department, the site was glued and sutured. The laceration dehisced within two weeks. When he presented to the wound care clinic, ABIs and a wound culture were obtained. Arterial evaluation demonstrated moderate peripheral arterial disease (ABIs of 0.8). The wound was debrided and a multilayered Profore Lite compression wrap was applied. Closed Incision NPWT was initiated. The foam was overlapping the pocket by 3 to 4 cm. A combination of a removable Cam Walker and a heel offloading boot was used to immobilize wound layers. The pocket collapsed within 4 weeks and NPWT was discontinued. It took 14 weeks for complete closure (Figure 5).

Figure 4:
Figure 5:

Case 5

A 73-year-old-veteran with a history of hypertension, chronic heart failure, and severe peripheral artery disease developed left hallux gangrene and underwent amputation of the left great toe. The site did not heal and he underwent transmetatarsal amputation of the forefoot. Postoperatively, he developed a wound measuring 4.3 x 2.7 x 1.8 cm with undermining of 3.3 cm between 5 and 6 o’clock (Figure 6). He underwent revascularization of the extremity. His postoperative arterial evaluation showed moderate peripheral disease (ABIs of 0.76). The wound and all walls of the pocket were debrided. A combination of classical and closed incision NPWT was initiated to collapse the pocket and grow some granulation in the wound base. The foam overlapped the contours of the pocket by 3 to 4 cm on each side (Figure 7). The patient had a non-weight bearing status initially. A combination of a removable Cam Walker and a heel offloading boot was used to immobilize wound layers after that. A multilayered Profore Lite compression wraps were used to assist with the treatment of venous disease and to control dependent leg edema. The undermining on the plantar surface closed within 7 weeks. A Cam Walker was utilized with 2 layers of abdominal pads to lift the arch to prevent any pressure injuries from the NPWT foam. The site closed completely within 10 weeks.

Figure 6:
Figure 7:

Case 6

A 67-year-old veteran with a history of diabetes mellitus type 2 and recurrent diabetic foot ulcer developed a right foot abscess with methicillin-resistant Staphylococcus aureus. The abscess was drained and the site was debrided. The resultant postoperative wounds measured 10.7 x 2.7 x 1 cm with undermining of 1.3 cm between 6 and 11 o’clock. The undermining communicated between two postoperative wounds. A combination of traditional and closed-incision NPWT was initiated to close all undermined areas. All undermined areas closed within 6 weeks of application of negative pressure therapy. The patient was initially of non-weight-bearing status. When NPWT was discontinued, providers switched to TCC EZ total cast system for further offloading. The wound closed within 12 weeks.

Case 7

A 68-year-old-veteran with a history of chronic obstructive pulmonary disorder sustained a traumatic anterior shin degloving injury when a heavy boulder fell on his leg. The site was repaired surgically. However, it became infected and dehisced within 2 weeks after repair. It was then debrided in the wound care clinic. It measured 5 x 9.2 x 1 cm and had 2 cm deep undermining at 7 o’clock and a 0.5 cm undermining at 11 o’clock. The wound and undermined areas were debrided. Providers obtained ABIs, which did not reveal any peripheral arterial disease. Multilayered compression wraps Profore were then used. A combination of a removable Cam Walker and a heel offloading boot was used to immobilize wound layers. The pocket closed a week after. The wound closed in 9 weeks. Only compression with multilayered compression wraps was used to close this 2 cm deep undermining.

Case 8

A 70-year-old veteran with a history of morbid obesity (body mass index, 50.5 kg/m2), diabetes mellitus type 2, and atrial fibrillation presented for evaluation of leg cellulitis. Computed tomograpy of the extremity revealed an abscess measuring 10.9 x 8.8 x 3.8 cm. The leg abscess was initially aspirated and then formally drained. The cavity measured 4 x 2.2 x 3 cm and it was down to femoral fascia. Circumferential undermining was up to 5 cm. His arterial studies did not reveal peripheral arterial disease. All undermined areas were debrided using curettes. Multilayered compression wraps Profore were initiated to collapse the cavity. A combination of a removable Cam Walker and a heel offloading boot was used to immobilize wound layers. The patient continued with weekly debridements and compression therapy. The cavity closed within 6 weeks.

Case 9

A 73-year-old veteran with a history of diabetes mellitus, fell and sustained a traumatic laceration of the left olecranon bursa with subsequent hematoma accumulation. Hematoma was drained and bursectomy was performed in the wound clinic. The walls of the cavity were gently debrided. Post procedure wound measured 1.7 x 0.6 x 0.8 cm with undermining of up to 2 at 12 o’clock and 1 cm in all other areas (Figure 8). The arm brace was provided to immobilize the elbow. Providers also initiated compression wraps to collapse the cavity. The wound closed in 5 weeks (Figure 9).

Figure 8:
Figure 9:

Case 10:

A 75-year-old veteran got bitten by a dog on his left hand. He developed purulent tenosynovitis and underwent debridement. All wounds healed but a 2.4 cm tunneled wound between his second and third metacarpophalangeal joints persisted. His hand developed postoperative lymphedema. The tunnel was debrided using a 2 mm curette and collapsed using short-stretch lymphedema bandages. The second and third fingers were immobilized using a splint. The site closed within 3 weeks. A compression glove was used to treat postoperative hand lymphedema.

Case 11

A 61-year old veteran with a history of uncontrolled diabetes mellitus type 2 presented for evaluation of the necrotizing soft tissue of the right forearm caused by grade A Streptococcal infection. After surgical debridement at the muscle level, his wound measured 4 x 4.7 x 1.2 cm with a periwound ulcer measuring 0.8 x 0.3 x 1 cm that was connected to the main ulcer (Figure 10). There was undermining of 2.5 cm at 12 o’clock and 1.6 cm at 6 o’clock. There was also evidence of postoperative lymphedema. Serial debridements along with compression with compression using short-stretch lymphedema bandages were initiated (Figure 11). His undermining closed within 4 weeks. The wound closed at 8 weeks (Figure 12).

Figure 10:
Figure 11:
Figure 12:


The average patient age was 73 years old, including wounds of the upper and lower extremities. The average wound depth was 1.12 cm. The average undermined area was 1.7 cm, undermined areas ranging from 0.2 to 5 cm. Wounds healed on average in 9.1 weeks, all wounds healed between 3 and 15 weeks.


Wounds with unfavorable epibolic edges, undermining, and pockets pose to be a significant obstacle in the healing of chronic wounds. The traditional approaches to these obstacles (silver nitrate cauterization, resection and unroofing) can be damaging to the tissues. The tissue-preserving approach presented here has been successfully used in many wounds with undermining and/or pockets. This methodology consisted of debriding contact wound surfaces, immobilizing tissues in areas where tissues move and shear, and using multilayered compression alone, modified NPWT or both, to collapse undermining and wound pockets. This approach follows an old thrifty practice of reusing two left-over soap bars. One needed to soften up both soap bars (ie, perform debridement), compress them against each other (apply NPWT, compression wrap or both), and then to leave them alone for some time (immobilize) until they become one.

This technique has been largely used on upper and lower extremities. It was also used on a long-standing postoperative tunneled wounds in the lumbar area and wounds with significant undermining after below- and above-the-knee amputations. However, the other instances were not as thoroughly documented as the ones presented here in this case series. Blind debridement may be an occasional limitation of this method as there needs to be careful consideration for of possible neurovascular bundles. No excessive bleeding occurred in this series. Postprocedure compression helped control minor bleeds. It is possible that using multilayered compression alone or modified NPWT with compression could be a confounding variable-although it is often necessary to use these two modalities together to prevent periwound edema or treat extremity edema. This methodology also uses a concept that compression causes wound edge approximation and effectively decreases the size of the wound. If one finds a way to immobilize the wound, it will heal in the compressed shape. After the wound heals, compression can be removed. This study was limited to the use of shallow and moderately deep wounds (up to 1.5 cm); this methodology has not been tested on deeper wounds. It is suspected that deep wounds may not reliably respond to this methodology due to the dissipation of pressure in the surrounding tissues. This novel tissue-preserving approach using multilayered compression alone, modified NPWT or both, demonstrated to be an excellent initial treatment for extremity wounds with undermined areas and wound pockets.


Wounds with undermined areas and wounds with pockets are very challenging. Providers typically need to resect undermined areas and unroof pockets. This tissue preserving approach presents another option for treatment of wounds with undermining and pockets. The new methodology is based on Fick's diffusion principle and consists of three steps: debridement, immobilization, and compression.

Truncal or gluteal wounds may be difficult to immobilize. It is suspected that using modified NPWT helped keep wound edges immobile to a certain extent. It is unknown if the immobilization component may be achieved by suturing the layers of the wound together after thorough debridement. It was noticed that even wounds that are not completely immobilized, showed significant improvement with partial immobilization, debridement of all contact areas, and compression. Immobilization was felt to be of crucial significance when there was a visible movement of the wound base vis-a-vis periwound area or other wound layers.


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undermining; wound pockets; wound edge; epibole; multi-layered compression; negative pressure wound therapy; closed incision negative pressure therapy; modified negative pressure therapy; Fick’s diffusion principle; soap scrap; edge trenching

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