Effect of the Layered Fasciocutaneous Flap in the Repair of Complex Wounds of the Lower Extremity

Repair of complex wounds of the lower extremity remains challenging for clinicians.^1,2 Complex wound reconstruction requires the use of customized flap designs. While repairing a superficial tissue defect wound, it is also necessary to fill the deep dead space.² Advances in the field of microsurgery prompted the development of a variety of chimeric free flaps for use in repairing complex wounds of the lower extremity.^3,4 However, this type of surgical repair usually requires the surgeon to be proficient in micromanipulation techniques.^1,3,4 When repair of a complex wound of the lower extremity does not involve the need for functional reconstruction (eg, a small bone defect cavity with soft tissue defect, or a deep tissue defect cavity with soft tissue defect), the authors of the present study propose the use of a layered fasciocutaneous flap with pedicled perforator. Flap design and surgical procedure are described herein.

Patients and treatment

Three cases (2 female, 1 male) with complicated wounds of the lower extremity at presentation subsequently underwent repair using a layered fasciocutaneous flap. The mean patient age was 45.7 years (range, 27 years–64 years). Skin and soft tissue defects ranged in size from 3.5 cm × 2.5 cm to 7 cm × 3.5 cm, and dead space wounds ranged in size from 3.5 cm × 1 cm × 1.5 cm to 6 cm × 2 cm × 1.5 cm after debridement.

Patient characteristics, including sex; age; cause of injury; defect site; size of the soft tissue defect, deep dead space defect, main part of the flap and the skin paddle, and adipofascial flap; initial bacterial culture result; perforator artery; donor site closure; complications of flap or skin graft; and follow-up data, are shown in the eTable.

Bacterial cultures of the wounds were performed prior to antibiotic administration and at the beginning of each debridement procedure. Empiric broad-spectrum antimicrobial therapy was initiated first and later modified, if necessary, based on the bacterial culture results. Radical debridement of all necrotic and devitalized tissues was performed. If the wound required serial debridement, NPWT was applied for 3 to 5 days between debridement procedures until a good wound bed was achieved, that is, until part of the cavity was covered by a thin layer of granulation tissue and the bacterial culture was negative, and the wound was ready for coverage. All patients underwent computed tomographic angiography to confirm that the blood vessels supplying the tissue flap to be selected were unobstructed.

Flap design and surgical procedures

First, the perforating sites of cutaneous branches of the lateral circumflex femoral or peroneal artery were detected using Doppler ultrasound. These sites were marked and the surgical area disinfected with iodophor. Second, the pedicled perforator flap was excised. Third, starting at the distal end (or lateral aspect) of the primary flap, the flap was dissected using a surgical blade and surgical scissors from the fat level (approximately 2 mm beneath the superficial fascia). This sharp separation measured approximately 3 cm to 4 cm lengthwise (or, if started at the lateral aspect, in a transverse orientation).

The primary flap was then divided into 3 parts: the main part, the skin paddle, and an adipofascial flap. The skin paddle contained the epidermis, dermis, superficial fascia, and shallow fat layer, which was located approximately 2 mm below the superficial fascia. The adipofascial flap included the deep fascia and the deep fat layer, which extends from about 2 mm beneath the superficial fascia to the interface of the deep fascia (Figure 1A).

The adipofascial flap was either gently curled up (Figure 1B) or not curled up (Figure 1C), and then it was used to fill the deep dead space. Subsequently, the skin paddle was shifted to the lateral edge of the wound to cover and seal the exposed wounds. A large STSG was transplanted to repair the donor site wound.

Complete survival of the layered flaps was achieved in cases 1 and 3. In case 2, venous congestion measuring 1 cm × 1 cm occurred at the distal end of the skin paddle, resulting in superficial skin ulceration, which healed after a dressing change. Dressing change was performed every interval day until the wound healed. In cases 1 and 2, the skin grafts at the donor sites survived as well. In case 3, the grafted skin in the wound showed slight de-epidermized changes, and the wound healed after 2 weeks of dressing changes. At a mean follow-up of 9 months, both the donor and the recipient sites had healed successfully. All patients demonstrated good long-term coverage, flap pliability, and contour without significant tendon adhesion at the flap site.

Case 1

A 64-year-old male patient sustained a fracture of the left tibial plateau in a car accident. He underwent internal fixation surgery in another hospital. Infection occurred at the surgical incision site, which led to removal of the internal fixation device 1 month postoperatively. Subsequently, a skin sinus tract formed at the surgical incision site, and the tract had remained unhealed for 2 months prior to the patient presenting to the institution of the authors of this manuscript.

When the patient was admitted to the hospital of the authors of the present study, the outer opening of the sinus tract, located on the lateral aspect of the upper calf, measured approximately 3 cm × 2 cm (Figure 2A). The sinus tract was approximately 15 cm long and extended to the middle calf (Figure 2B). After debridement was performed and NPWT applied, the sinus tract wall and exposed tibialis anterior muscle were covered by a thin layer of granulation tissue (Figure 2C). The portion of the sinus tract located in the middle calf was filled and sutured with the tibialis anterior muscle bundle after separation. The remaining sinus tract in the upper calf measured approximately 3.5 cm × 1 cm × 1.5 cm. A layered fasciocutaneous flap with pedicled peroneal artery perforator was created. The main part of the flap and the skin paddle measured 6 cm × 4 cm, and the adipofascial flap measured 4 cm × 2 cm × 1 cm. The adipofascial flap was used to fill the sinus tract, and the skin paddle was used to cover the wound. An STSG was transplanted to repair the donor site wound (Figure 2D). At 6-month follow-up, there was no sign of recurrence at the wound repair site (Figure 2E).

Case 2

A 27-year-old female patient sustained an extensive injury to her right lower extremity in a car accident, resulting in tibial and fibular fractures with skin and soft tissue necrosis. She underwent surgical debridement at another hospital, at which time incisions were made in the posteromedial tibia and posterolateral fibula to relieve compartment syndrome. The patient subsequently underwent open reduction for tibial fractures, internal fixation for fibular fractures, and external fixation reduction for metatarsal fractures, and NPWT was applied.

The patient was admitted to the hospital of the authors of the present study with skin and soft tissue defects on the dorsum of the foot, the anterior tibia, the posterior tibia, and the posterior fibula. On the lower anterior tibia, a portion of fractured tibia measuring approximately 3 cm × 1 cm was exposed, and a cavity was visible next to the exposed bone. The extensor hallucis longus tendon was partially exposed, and the wound bed was covered with fresh granulation tissue (Figure 3A). After debridement, the fractured tibia along with the extensor hallucis longus tendon were exposed. The soft tissue defect of the lower extremity measured 7 cm × 3.5 cm, and the deep dead space measured 4 cm × 2 cm × 1 cm (Figure 3B). A pedicled peroneal artery perforator layered fasciocutaneous flap was harvested to cover the exposed wound and obliterate the deep dead space. A large STSG was transplanted to repair the donor site wound (Figure 3C). At 13-month follow-up, there was no sign of recurrence at the wound repair site, and there was no local venous reflux disturbance in the leg (Figure 3D).

Case 3

A 46-year-old female patient was bedridden for 10 months owing to Parkinson disease, which resulted in the formation of pressure ulcers in multiple anatomic areas, including the sacrococcygeal region, left and right lateral thigh, and left and right heel. The pressure ulcers had been present for 2 weeks before the patient presented to the authors' institution. When the patient was admitted to the authors’ hospital, the pressure ulcer wound on the outer aspect of the left thigh measured approximately 6 cm × 4 cm, and the necrotic skin showed crust-like changes (Figure 4A). After debridement was performed and NPWT applied, a soft tissue defect measuring approximately 6 cm × 4 cm was created, and a cavity of approximately 6 cm × 2 cm × 1.5 cm was created at the lateral edge of the femur (Figure 4B). A layered fasciocutaneous flap with a pedicled perforator of the descending branch of the lateral circumflex femoral artery was harvested. The main part of the flap and the skin paddle together measured approximately 8 cm × 6 cm, and the adipofascial flap measured approximately 8 cm × 3.5 cm × 1.5 cm (Figure 4C). The adipofascial flap was used to fill the cavity, and the skin paddle was used to cover part of the wound. An STSG was transplanted to repair the residual wound. The donor site wound was sutured directly (Figure 4D). At 8-month follow-up, there was no sign of recurrence at the wound repair site (Figure 4E).

Complex wounds often manifest as compound soft tissue defects; these defects involve the presence of 2 or more types of tissue defect simultaneously. Repair of complex wounds has always proved challenging for clinicians.^1,2

An improved understanding of perforator and vascular anatomy, coupled with advances in microsurgery, has resulted in the recent development of the chimeric flap technique. The chimeric flap has separate components with separate vascular supplies attached to a common pedicle.⁵ These flaps can be used to reconstruct complex or extensive defects while maintaining effective and economical tissue usage and low donor site morbidity. Chimeric flaps have been applied in the reconstruction of complex wounds of the lower extremity, such as thoracodorsal artery perforator chimeric free flap,¹ latissimus dorsi-
serratus anterior chimeric free flap,⁶ anterolateral thigh perforator chimeric free flap,² deep inferior epigastric artery perforator chimeric free flap,^7,8 peritoneal-deep inferior epigastric perforator chimeric free flap,⁹ and fabricated chimeric free flaps consisting of multiple separate flaps.^3,4

The aforementioned chimeric free flaps can be used to repair complex wounds of the lower extremity, especially those with large, complex soft tissue defects.^3,4 However, this type of repair surgery usually requires advanced proficiency in micromanipulation techniques.^1,3,4 When repair of a complex wound does not require functional reconstruction (eg, small bone defect cavity with soft tissue defect, deep tissue defect cavity with soft tissue defect), the authors of the present study propose the use of a layered fasciocutaneous flap with pedicled perforator. With such repair, unlike in chimeric free flap surgery, it is not necessary for the pedicled perforator vessel to be freed and anastomosed. Thus, the pedicled layered fasciocutaneous flap procedure is relatively simple and safe.¹⁰

To the knowledge of the authors of the present study, there is no precise definition of a pedicled layered fasciocutaneous flap, nor has a consensus been reached.¹⁰ There are reports in the literature regarding the use of a pedicled layered fasciocutaneous flap for wound repair. Chen et al¹¹ used a pedicled abdominal double-layer fasciocutaneous flap in the repair of complex hand injury. The abdominal fasciocutaneous flap was separated at the level of the superficial fascia to form a double-
layer fasciocutaneous flap, which contained the skin paddle and the adipofascial flap. The adipofascial flap was placed between the tendon and metacarpal bone, and the skin paddle was used to cover and seal the soft tissue defect. Deng et al¹² used a pedicled abdominal layered fasciocutaneous flap combined with allogeneic tendon transplantation in the repair of complex hand injury. The fasciocutaneous flap was divided into 2 layers, with the superficial layer comprising a skin paddle preserved with the subdermal vascular network and the deep layer comprising an adipofascial flap containing either the superficial abdominal artery or the superficial iliac circumflex artery. Good results were achieved in 15 cases. Lu and Zhou¹³ used pedicled abdominal layered fasciocutaneous flap combined with autologous skin transplantation to repair 12 cases of degloving injury of the hand. The abdominal fasciocutaneous flap was divided into 2 layers. The skin paddle, which was supplied by a subdermal vascular network, was used to repair the skin defect on the dorsal aspect of the hand, and the adipofascial flap combined with autologous skin graft was used to repair the palmar aspect of the wound. Satisfactory results were achieved.

Because corresponding tissues supplied by separate branches of the same blood vessel attach to a common pedicle, a fasciocutaneous flap could then be divided into a double-layer flap consisting of a superficial skin paddle and a deep adipofascial flap. As such, the double-layer flap could be used to repair a skin defect wound and deep dead space wound simultaneously.

The posterior tibial artery perforator flap and peroneal artery perforator flap are the most widely used flaps in the repair of lower extremity wounds.^14-16 The perforator branches of the posterior tibial artery and peroneal artery in the lower extremity musculature are relatively constant.^16,17 The cutaneous branches of the perforator artery enter the subdermis immediately after passing through the deep fascia and form a subdermal vascular network.^16,17 Previous literature has found that the blood supply of the ascending and horizontal cutaneous branches was not obviously reduced when the deep fat and/or deep fascia under the flap were stripped off.¹⁷ The skin paddle is rich in subdermal vascular network consisting of ascending and horizontal branches of the perforator artery. Because the blood supply to the deep fascia and deep fat is independent of the blood supply to the superficial fascia, after careful and acute separation of the skin flap from the fat level (which lies approximately 2 mm beneath the superficial fascia) the adipofascial flap retains its blood supply from the preserved subfascial plexus.¹⁷

The design of the layered fasciocutaneous flap discussed in this case series has several potential advantages. The pedicled flap is relatively easy to obtain because it does not require vascular anastomosis. The flap is nourished by the perforating artery, and the main vessel is preserved when the flap is harvested.¹⁵ The surgical procedure does not affect the original physiological function of the lower limb muscles.¹⁴ After achieving good wound bed preparation, a single flap surgery is performed to repair the deep dead space and soft tissue defects simultaneously.

Attention should be paid to several aspects of treatment. The limb must have relatively rich adipose tissue. When designing a layered flap, the skin paddle should retain 2 mm of superficial fat, and the thickness of the adipofascial flap should not be too thin (preferably, > 0.5 cm).¹¹

This case series has several limitations, one of which is the small number of patients treated. In addition, the flap procedure described in this paper is better suited for complex wounds that do not require functional reconstruction (eg, small bone defect cavity with soft tissue defect, deep tissue defect cavity with soft tissue defect) and in which the volume of the deep dead space is not too large. The ratio of length to width of the primary flap in these cases did not exceed 1.5:1 (thus far, the maximum is 1.7:1).

In the cases discussed herein, the use of a layered fasciocutaneous flap with pedicled perforator to repair complex wounds of the lower extremity provided a relatively simple, safe, and effective method for the repair of small soft tissue defects with deep dead space. It should be noted that although the pedicled perforator flap can optimize wound repair, it is also necessary to use the vascular anastomosis technique in conjunction if intervention failed to achieve a pedicled perforator flap. Larger randomized controlled clinical trials with long-term follow-up are necessary to support the recommendation of the pedicled perforator layered fasciocutaneous flap for patients with complex wounds of the lower extremity. In addition, the scope of supply of blood vessels at each level of the layered fasciocutaneous flap and the design ratio of the layered flap need to be further clarified.