Pre-expanded Intercostal Perforator Super-Thin Skin Flap

This article introduces pre-expanded super-thin intercostal perforator flaps, particularly the flap that has a perforator from the first to second intercostal spaces. The key techniques, advantages and disadvantages, and complications and management of this flap are described. At present, the thinnest possible flap is achieved by thinning the pre-expanded flap that has a perforator from the first to second intercostal spaces. It is used to reconstruct large defects on the face and neck, thus restoring function and cosmetic appearance.

Key points

  • When the intercostal perforator flap is thinned after expansion, it is slightly thicker than a full thickness skin graft and can be used to repair face and neck defects, thereby simultaneously restoring function and cosmetic appearance.

  • Its benefits include a surgical delay after expansion, which allows the flap to be trimmed into a thinner flap while avoiding necrosis and reducing the risk of long- and short-term skin contracture.

  • Pre-expanded intercostal perforators enhance the blood flow of the flap and yields a flap with an above-average length-to-width ratio. However, it is a time-consuming three-stage procedure that is difficult for elderly patients and patients with cervical problems.

Video content accompanies this article at www.plasticsurgery.theclinics.com .

Introduction

The pre-expanded super-thin perforator flap was developed by combining the super-thin flap with a perforator and expansion. Alternatively, it is seen as a perforator flap that has been processed by super-thinning and pre-expansion. The super-thin flap, or the subdermal vascular network flap, was first reported by Situ in 1986. Thereafter, it gained wide attention in P.R. China, thus resulting in the late 1980s and early 1990s in the publication of many experimental and clinical studies in Chinese journals.

Surgeons have sought to develop thin flaps for many decades. In 1966, Colson and Janvier trimmed the distal end of a flap, thus forming a flap-graft. In 1980, Thomas also reported a thin flap. However, this thin flap was still a conventional flap because it required a delay of 3 weeks to achieve flap transposition and another 3 weeks before the pedicle could be divided after flap transposition. Unlike the conventional thin flap, the super-thin flap reported here is revolutionary in that a delay in flap transposition is not required and the pedicle division occurs about 1 week postoperatively. Later, the free thin flap and the narrow pedicled super-thin flap without an axial vessel were also developed. In 1992, Gao and coworkers (one of the authors of this article) introduced a super-thin (intercostal) perforator flap with a perforator from subcutaneous vessels. It was later improved as the perforator-supercharged flap with vessel anastomosis at its distal end and, as reported here, the pre-expanded super-thin (intercostal) perforator flap. These developments in perforator flap design enlarged and stabilized the dimension of flaps.

The perforator flap was initially introduced by Kroll and Rosenfield in 1988, whereas the expansion technique started in 1957. Perforators increase the blood supply to the super-thin flap, whereas expansion enhances the tolerance of the flap to ischemia and hypoxia, thus augmenting the subdermal vascular plexus and reducing the risk of flap failure. The pre-expanded super-thin perforator flap is thinner than the regular flap and has a larger survival area: the length-to-width ratio is 1.5 to 2:1. Thus, it improves the viability of the distal flap. Other advantages of the procedure are that the donor site requires only primary suture and that there is no secondary thinning of the flap. However, this flap also has several disadvantages, including its time intensiveness, the need for staged procedures, and that the patients must adopt an uncomfortable position during healing.

Theoretically, any donor site with a known perforator can be used to generate a pre-expanded super-thin perforator flap, especially those sites with large and stable perforators. The chest and abdomen are often used to generate super-thin perforator flap designs because they are conventional donor sites and are usually covered by clothes. In clinical practice, perforators from the first to third intercostal spaces are frequently used to reconstruct defects on the face and neck, whereas perforators from the fourth to the twelfth intercostal spaces are used to reconstruct the hands. The chest and abdomen have abundant skin that is suitable for transposition, and the donor sites can be easily closed primarily. For this reason, pre-expansion is rarely required when the perforators are from the fourth to the twelfth intercostal spaces. Therefore, this article mainly discusses the pre-expanded super-thin perforator flap whose perforator comes from the first to third intercostal spaces.

Introduction

The pre-expanded super-thin perforator flap was developed by combining the super-thin flap with a perforator and expansion. Alternatively, it is seen as a perforator flap that has been processed by super-thinning and pre-expansion. The super-thin flap, or the subdermal vascular network flap, was first reported by Situ in 1986. Thereafter, it gained wide attention in P.R. China, thus resulting in the late 1980s and early 1990s in the publication of many experimental and clinical studies in Chinese journals.

Surgeons have sought to develop thin flaps for many decades. In 1966, Colson and Janvier trimmed the distal end of a flap, thus forming a flap-graft. In 1980, Thomas also reported a thin flap. However, this thin flap was still a conventional flap because it required a delay of 3 weeks to achieve flap transposition and another 3 weeks before the pedicle could be divided after flap transposition. Unlike the conventional thin flap, the super-thin flap reported here is revolutionary in that a delay in flap transposition is not required and the pedicle division occurs about 1 week postoperatively. Later, the free thin flap and the narrow pedicled super-thin flap without an axial vessel were also developed. In 1992, Gao and coworkers (one of the authors of this article) introduced a super-thin (intercostal) perforator flap with a perforator from subcutaneous vessels. It was later improved as the perforator-supercharged flap with vessel anastomosis at its distal end and, as reported here, the pre-expanded super-thin (intercostal) perforator flap. These developments in perforator flap design enlarged and stabilized the dimension of flaps.

The perforator flap was initially introduced by Kroll and Rosenfield in 1988, whereas the expansion technique started in 1957. Perforators increase the blood supply to the super-thin flap, whereas expansion enhances the tolerance of the flap to ischemia and hypoxia, thus augmenting the subdermal vascular plexus and reducing the risk of flap failure. The pre-expanded super-thin perforator flap is thinner than the regular flap and has a larger survival area: the length-to-width ratio is 1.5 to 2:1. Thus, it improves the viability of the distal flap. Other advantages of the procedure are that the donor site requires only primary suture and that there is no secondary thinning of the flap. However, this flap also has several disadvantages, including its time intensiveness, the need for staged procedures, and that the patients must adopt an uncomfortable position during healing.

Theoretically, any donor site with a known perforator can be used to generate a pre-expanded super-thin perforator flap, especially those sites with large and stable perforators. The chest and abdomen are often used to generate super-thin perforator flap designs because they are conventional donor sites and are usually covered by clothes. In clinical practice, perforators from the first to third intercostal spaces are frequently used to reconstruct defects on the face and neck, whereas perforators from the fourth to the twelfth intercostal spaces are used to reconstruct the hands. The chest and abdomen have abundant skin that is suitable for transposition, and the donor sites can be easily closed primarily. For this reason, pre-expansion is rarely required when the perforators are from the fourth to the twelfth intercostal spaces. Therefore, this article mainly discusses the pre-expanded super-thin perforator flap whose perforator comes from the first to third intercostal spaces.

Treatment goals and planned outcomes

The pre-expanded super-thin flap with an intercostal perforator from the first to the third intercostal spaces is suitable for the following: (1) reconstruction of a large defect or scar on the face and neck, (2) compulsory transposition of a local flap or a pre-expanded local flap, and (3) patients who have zero tolerance to a scar caused by an additional local incision ( Fig. 1 ). This flap is preferable to other conventional flaps for reconstructing face and neck defects for the following reasons. First, the color of the flap is similar to that of the face and neck: the color differences between the donor and recipient sites are small. Second, this flap does not require secondary thinning and is not bulky. Third, this procedure is less invasive than others because the perforator can supply blood to a large flap and the donor site is closed primarily. Most importantly, the flap is pliable and does not readily contract. Given its promising long-term outcomes, it is now the flap of choice for reconstruction of large defects on the face and neck in our institution.

Fig. 1
The pre-expanded super-thin perforator flap (3c). ST, super-thin.

Preoperative planning and preparation

Clinical Anatomy

The intercostal perforators derive from the internal mammary artery. This artery arises from the first part of the subclavian artery, travels along the medial scalenus anterior muscle, and crosses the clavicle to enter the thorax. It then descends 1 to 1.5 cm laterally off the lateral sternum with intercostal perforating branches running in parallel to the intercostal plane. The perforators end at the inner margin of the thoracoacromial artery. They are subcutaneous arteries and many anastomose with the thoracoacromial artery and with subcutaneous branches of the cervical part of the transverse cervical artery. These anastomoses constitute wide blood supply sources. The intercostal perforators from the second intercostal spaces are the most commonly used perforators because they have a relatively large diameter of 1.2 mm and their perforating points in the deep fascia are relatively fixed. In this case, the second intercostal perforator serves as the axial vessel of the flap, whereas the accompanying perforating vein, in which the blood flows back to the internal thoracic vein, serves as the vein of the flap ( Fig. 2 ).

Fig. 2
Anatomy of the perforators from the second intercostal space. (a) Perforators from the second intercostal artery of the internal thoracic artery. (b) Perforators from the transverse cervical artery of the thyrocervical trunk. (c) Perforators from the thoracoacromial artery.
( From Dang R, Zhang C. Object atlas of human regional anatomy[M]. Shanghai: Second Military Medical University Press, 2011:183; with permission.)

Surgical Planning

Three-stage procedure

Stage 1 is insertion of an expander subcutaneously in the chest and shoulder region. After the patient is discharged, the expander is inflated with saline solution for 3 months in the outpatient department. Stage 2 is flap transposition. Stage 3 is pedicle division about 10 days after flap transposition.

Flap dimensions

The upper margin of the flap reaches the lower clavicle. The inner margin is 2 cm off the lateral sternum. The outer margin touches the deltoid. The lower margin is at the fifth rib level. The rotation point is at the intercostal space between the first and second ribs, 2 cm off the lateral sternum. The expander should be placed in the area described previously (10 cm × 12 cm). The width of the flap doubles after expansion, which is sufficient for reconstructing defects on the face. Primary closure at the donor site is also feasible.

Expander selection

Cylindrical and crescent-shaped expanders (range, 350–600 mL) are commonly used in clinical practice, but the crescent-shaped expander (usually 400 mL) is the most frequently used expander because it matches the curve of the lower clavicle and the anatomic shape of the chest and shoulder. The volume of the crescent-shaped expander depends on the cervical length of the patient and the coverage required.

Other considerations

Measure the coverage and arc of flap rotation required, determine the appropriate inflation of the expander, and decide whether the flap should have one or two perforators.

Patient positioning

The patient takes a supine position. In stage 2, when the flap is transposed to the face and neck, a pillow should be given to elevate the patient’s head and neck and the patient should tilt his or her head toward the involved side to relieve tension on the pedicled flap. After pedicle division, the patient must again adopt the supine position with a pillow under the shoulder and the head falling backward to relax the contracted neck.

Procedural approach

Stage 1: Expander Placement

Flap design

Mark the surface projection of the perforators in the first and second intercostal spaces with methylene blue. The incision should be parallel to the axillary folds on the medial wall of the axilla and approximately 7 cm in length. After sterilization and draping, leakage of the 400-mL crescent-shaped expander should be checked by filling it with air. Then empty the expander, flatten it, and place it on the operating field with its base plate downward and the injection port pointing toward the axilla. Mark the expander with methylene blue ( Fig. 3 ).

Fig. 3
Designing the incision and separation areas. Solid red line, the incision; dashed red line, the perforators; dashed blue line, the separation area.

Tissue separation and expander placement

Make an incision to the muscle fascia and separate the tissue by blunt dissection to avoid impairing the perforators, especially those from the second intercostal space and the transverse cervical artery. After meticulous hemostasis and irrigation, place the expander flat into the cavity with its base plate downward and the injection port at one side of the incision near the anterior axillary line. Routinely install a negative pressure drain and then inject air into the expander to check the folding of the fill tube and the roll-over of the expander. Finally, evacuate all air from the expander.

Postoperative inflation

Place pressure on the expander area with a sandbag and maintain the negative pressure drain after the operation. When the drain fluid is dark red or yellow serum-like in color, and the drainage is less than 5 mL, remove the drain tube. Remove the incision suture on Day 7 and start to slightly inflate the expander with saline solution. The expander should be inflated once every 3 days in the early stage and will be filled in a month. Maintain the inflated expander by injecting saline solution once every 7 days for 2 more months. Thus, the inflation takes about 3 months in total and the total volume that is injected is 800 to 1000 mL. When the skin in the center of the expander area is expanded and thin enough that small blood vessels that stretch parallel to the longitudinal axial of the flap are visible, it is time to perform the second operation.

Precautions

Do not overinflate at each injection because it can cause excessive tension and/or pain and result in dermis tearing and “stretch marks,” or even ulceration and exposure of the expander. The inflation process should be aseptic to prevent infection. In the late stage of expansion, the expander reaches a certain volume and is likely to slip downward because of gravity. In this case, an elastic bandage should be placed underneath the expander to fix it in place and preparations for the stage 2 operation should be started.

Stage 2: Expander Removal and Flap Transposition

Flap design

Identify the candidate pedicled vein using the transillumination test and mark the artery branches in the flap in red and blue using Doppler flowmetry ( Fig. 4 ). Based on the preferred candidate pedicle vessels and the coverage required, decide on the number of perforators, direction of flap, and dimensions of the flap to be transposed in the stage 2 operation. Generally, the intercostal perforator from the second intercostal space serves as the pedicle. Perforators from the transverse cervical artery can also be included if necessary. The flap should be more than large enough to cover the defect with a redundant rim of about 1 cm. Stimulate flap rotation with a cloth, then decide the arc of rotation.

Fig. 4
Transillumination test ( circle indicates the light source direction) before ( A ) and during ( B ) surgery.

Flap elevation

Elevate the flap from the middle and distal periphery to elevate half or two-thirds of the total flap. The incision should be made to the capsule of the expander. Then open the capsule with scissors and remove the expander. Maintain the intactness of the flap vascular plexus as much as possible. During surgery, if part of the flap periphery cannot be transposed because of excessive tension, consider cutting through the epidermis only but leaving the subcutaneous vascular plexus as it is.

Flap thinning

Flip the flap over and remove the expander capsule with blunt straight scissors to expose the subcutaneous adipose tissue of the flap, where the adipose globules among the fibrous septa bulge if gently pressed with scissors. Prick the globule capsules and remove the entire adipose globules. This thinning strategy guarantees maximal adipose removal while protecting the vascular plexus in the fibrous septa. After trimming off the deep subcutaneous adipose tissue, the subdermal vascular plexus becomes visible. It is important to maintain the intactness of the subdermal vascular plexus because this ensures favorable flap blood supply. Use low-energy electrocoagulation or multiple clamping to achieve hemostasis after thinning. Thereafter, pack the flap with wet gauze ( Fig. 5 ). Slightly cut through the epidermis along the markings in the pedicle area using the back of the scalpel and stain the incision with gentian violet. It marks the incision that is to be used in pedicle division ( Fig. 6 ).

Nov 21, 2017 | Posted by in Dental Materials | Comments Off on Pre-expanded Intercostal Perforator Super-Thin Skin Flap
Premium Wordpress Themes by UFO Themes