Plastic Techniques For Wound Coverage: Do You Need To Pull The Trigger?
When wounds fail to heal by conventional methods, plastic surgery techniques can offer viable alternatives for wound closure. Accordingly, these authors discuss the reconstructive ladder/pyramid and various types of techniques ranging from bilobed and double Z rhomboid flaps to split-thickness skin grafts and distant pedicle flaps.
Wound closure is a challenging process, especially when dealing with multiple comorbid risk factors. When treating wounds, consider a holistic approach, focusing on issues including patient lifestyle, comorbidities, likelihood of success, the anatomy and physiology of the wound, functional outcome and the risks of surgery and anesthesia.1 Other factors that affect wound healing include diabetes control, normal nutrition status, infection control, mechanical stress avoidance and nursing care.2
Wound closure starts with a simple approach and the surgeon uses more sophisticated techniques as deemed appropriate. Decisions for wound closure require sound preoperative planning and depend on the location of the wound along with host risk factors of tissue extensibility and potential for healing.3 The reconstructive ladder/pyramid is the fundamental step in wound closure using plastic surgery techniques.4 Starting from bottom to top, this pyramid includes primary/secondary wound closure with negative pressure wound therapy and split-thickness skin graft (STSG); local random flaps; muscle flaps; pedicle flaps; perforator flaps; and free flaps.
Proper wound bed preparation is the key step in wound healing before proceeding to wound closure techniques. It is vital to ensure the wound has enough perfusion for healing, removal of biofilm, appropriate debridement and infection control as well as proper offloading to avoid any hindrance to the healing process. Primary closure is not always an option for wound closure due to the size, location and proximity of neurovascular structures and inelasticity of the skin, especially the plantar skin and the diabetic foot.
One can consider secondary intention as the next option but it often results in unstable scars that are prone to repeated ulceration, especially in neuropathic plantar wounds.5 In those situations, it becomes imperative to consider the more sophisticated plastic surgery techniques from the reconstruction ladder/pyramid to attempt a successful wound closure. There are many plastic surgery techniques available but some are in wider use than others in the field of podiatry.
According to the literature, physicians can manage 90 percent of the diabetic foot pathology with simple surgical reconstructive approaches while only 10 percent of pathology requires the complex muscle, pedicle or free flap approach.6 As Gillies and Millard mentioned, “the next best skin is the nearest skin” for wound closures.7 When primary and secondary intention wound healing fail, local flaps are the next best reliable option for coverage of defects, especially on the weightbearing surfaces.
Skin grafting is not optimal on plantar surfaces.8,9 However, STSG can either cover the secondary defect where the local flap was raised or cover the primary defect when flaps are not feasible. When one uses these simple methods, the chance of healing diabetic wounds increases substantially, even with a patient’s immunocompromised state of health. The idea is to target isolated pathology with minimal sacrifice of healthy tissue.10 Reserve the complex reconstructive approaches such as local muscle, pedicle and free flaps for when simple reconstructive approaches such as local flaps and STSG fail.
A Guide To The Types Of Local Random Flaps
Local flaps are the flaps that include the epidermis, dermis, subcutaneous tissue and, in some cases, the fascia and underlying muscle. These flaps are random in nature as there is no specific arterial blood supply. However, knowledge of anatomy and angiosomes is crucial for appropriate surgical planning. These flaps are vascularized by a cutaneous artery, a musculocutaneous perforating artery or a septocutaneous perforating artery.
Local flaps are typically based on geometric designs, the mobility of soft tissues, nature of their movement and the angiosomes of the foot. There are various types of local random flaps and the safest design of a local flap is where the movement of the flap occurs over the area of greatest skin elasticity or lines of maximum extensibility, and toward the nearest dominant perforating artery.5 One can close the flaps using primary intention but if necessary, the clinician may utilize STSG or bioengineered tissue allograft to cover the non-weightbearing donor site. In certain clinical scenarios that require one to simultaneously address the underlying deformity and equinus at the time of surgical reconstruction, the physician can offload the site with external fixation.4
Rotational. Surgeons usually use rotational flaps to close triangular or circular defects where there is a pivot point and the flaps move in an arc motion to eliminate the tension from the primary defect and transfer it to the donor site.3 The rotational flap circumference usually has to be five to eight times the width of the defect or the flap area has to be three to four times the area of the defect for primary closure of the donor site. At times, with larger defects, the use of orthobiologics or STSG is required to close the donor site. Primary movement is rotating the flap to the defect in an arc whereas secondary movement is rotating the surrounding tissue in an opposite direction of the flap to close the donor site.
Transpositional. Transpositional flaps are similar to rotational flaps but differ in shape. They are tongue-like and have narrower bases than rotational flaps. Transpositional flaps incorporate both rotation and advancement of the adjacent intact skin to close a defect. Surgeons have used several modifications of the transpositional flaps in the foot, including rhomboid, bilobed and Z-plasties.10
Bilobed. The bilobed flap consists of two flaps that share a common pedicle and are separated by an angle. A bilobed flap is designed to move more skin over a larger distance than is possible with a single lobe flap and it works well in regions where skin mobility is limited. The indications for this type of flap include closure of excisions for digital cysts, metatarsal head ulcerations, osteomyelitis, plantar forefoot or rearfoot ulcerations, and correction of heel defects. This flap can close defects 1 cm to 3 cm in diameter on the plantar aspect of the foot. The first lobe closes the original defect while the second lobe is for the first flap donor site. Then the surgeon closes the second flap donor site primarily. Typically, the lobes are designed to be 90 degrees from the defect and from each other, but this angle may vary. On the plantar aspect of the foot, we recommend that the angles be no greater than 60 degrees.
While there are different recommendation for the size of the lobes, a general rule for lobe creation is that the first lobe can be 75 percent of the width of the original defect while the second lobe is 50 percent of the original defect. The rotating base should be undermined.
Close the two apices first. Then utilize circumferential sutures along the lobes. The advantage of the bilobed flap is the ability to recruit large amounts of tissue by borrowing from different areas and opposing directions. The disadvantages of bilobed flaps are the length and varying directions of the incisions required.
Rhomboid. Rhomboid flaps cover rhomboid or circular defects with similar dimensions as the defect. Draw two parallel lines in the same direction as the lines of maximum extensibility and draw two additional lines to complete a rhombus with 60 and 120 degree angles. Four possible flaps can be raised. By using the pinch test, one can choose the best flap for transposition.3 Transpose the raised flap 60 degrees into the defect, covering only about 50 percent of the total defect. Close the rest of the defect with either primary intention, redistributing the tension from donor to recipient site in 90 degree fashion.3 Rhomboid flaps are versatile and one can use them in multiple wound defects on weightbearing and non-weightbearing surfaces.
Double Z rhomboid. The double Z rhomboid flap can correct a rhomboid defect with the use of two Z-plasties. Draw two parallel lines in the direction of the resting skin tension line enclosing the defect. Then, in order to complete a 60- and 120-degree rhombus, draw a second set of parallel lines. Proceed to draw two Z-plasties on opposing sides of the rhombus in such a way that their central lines are continuations of the original two parallel lines of the rhombus. Then transpose the flaps in a similar fashion as a Z-plasty, resulting in an incision shaped like two Zs end-to-end.10
What You Should Know About Split-Thickness Skin Grafts For Wound Closure
Split thickness skin grafts consist of the entire epidermis and varying portions of dermis. We can further divide STSG into thin (0.008-0.012 inches), intermediate (0.012-0.016 inches) and thick (0.016-0.020 inches) grafts depending on the size of the dermis.3 The main prerequisites for STSG are the presence of a granular wound bed with no drainage, malodor, periwound erythema or edema, which keeps the bacterial burden lower.5 Choose the donor site preoperatively, keeping in mind the size of the defect and skin extensibility. One can prep the donor site with povidone-iodine solution but wash it off with sterile water prior to using the dermatome to avoid sticking to the instruments. Set the dermatome blade thickness set to 0.015 inches and advance the instrument forward with constant pressure on the skin.3
After harvesting the graft, soak it in the sterile water and keep gauze on it. If meshed graft is desirable, we recommend not exceeding the meshing ratio over 1.5 to 1.0 to promote adherence of the graft to the wound bed.3 Secure the graft to the wound bed from the graft to surrounding skin with either suture material or surgical staples. The wound dressing is the surgeon’s preference with the most common one being a bolster dressing or negative pressure VAC therapy (Acelity) for less friction against the graft site. One may utilize a dry sterile dressing over the donor site. The indications for STSG are sterile ulcerations including burns, donor site defect from other flaps, traumatic tissue loss, post-removal of oncologic lesions, defects from debridement of soft tissue and bone infection, etc.3 If there is a defect deeper than 5 mm in a wound with exposed bone/joint, adipose tissue or the wound is on the weightbearing areas, STSG use is contraindicated.5
Key Insights On The Use Of More Complex Flaps
Local muscle flaps are indicated when the area of defect is large due to wide osseous or joint resections in cases of osteomyelitis.4 One can use local muscle flaps on weightbearing surfaces as well. The healing potential is high due to the vascularity of the covering soft tissue. Preoperative arterial testing is required to analyze the viability of the vascular structure.4
Local and distant pedicle flaps are the flaps with at least one area of attachment to the donor site, and have a unique distinguishable neurovascular bundle. They may be raised adjacent to the soft tissue defect or from a distant site to a soft tissue defect.5 However, it is crucial to have an intimate understanding of angiosomes and pre-designed analysis of retrograde and anterograde vascular inflow with Doppler ultrasound mapping in pedicle flaps.3 These flaps offer a wide variety of reconstructive options to treat the soft tissue defects in the foot.
A free flap is a unit of tissue with its own vascular supply that one transfers surgically from its native location to a distant site, restoring vascular continuity with microvascular anastomosis. It is indicated when local pedicle flaps are not appropriate to cover a large defect with or without bone,vessel or nerve exposure.2 The risks of free flaps include prolonged patient exposure to anesthesia, the presence of medial calcinosis, arterial disease and increased large wound comorbidities from the donor site in high-risk patients. Perforator flaps in the foot are usually based on a patent peroneal artery. Check patency of the artery preoperatively with vascular medical imaging. One may offload the surgical site with external fixation to prevent motion and weightbearing.3
Wound closure is a challenge that podiatrists face on a day to day basis. There are many techniques for wound closure including primary intention with direct closure and secondary intention using biological allografts and other modalities. If those techniques fail or are not feasible, the surgeon can decide to pull the trigger to incorporate plastic reconstructive techniques for wound healing.
Researchers cite many ladders, pyramids and “elevators” for wound coverage. However, the key is to start with simple reconstructive procedures such as local flaps and skin grafts, and use complex procedures such as muscle and pedicle flaps as necessary for difficult cases. Evaluate each case based on many factors, such as wound size, location, quality of surrounding skin, surgeon preference, etc.
The crucial part for any plastic technique to work is proper preparation of the wound bed. Wound healing is multifactorial and one needs to appropriately consider these factors before selecting an optimal option to facilitate proper wound coverage.
Dr. Dhatt is a first-year resident in the Department of Podiatric Surgery at Yale-New Haven Hospital.
Dr. Jariwala is a first-year resident in the Department of Podiatric Surgery at Yale-New Haven Hospital.
Dr. Blume is an Assistant Clinical Professor of Surgery, Anesthesia and Orthopedics and Rehabilitation at the Yale School of Medicine. He is the Codirector of Limb Preservation/CLI/HVC at Yale New Haven Health.
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