Pre-expanded Muscle-sparing Latissimus Dorsi Flaps for Reconstruction of Severe Scar Contractures on the Anterior Chest

Zhichao WANG ,Dujuan LIU ,Shuchen GU ,Baoxiang TIAN ,Tao ZAN,* ,Bin GU,*

Affiliations of all authors:1 Department of Plastic and Reconstructive Surgery,Shanghai Ninth People's Hospital,Shanghai Jiaotong University School of Medicine,Shanghai,China,200011 2 Department of Burn & Plastic Surgery,Jilin City Hospital of Chemical Industry,Jilin Province,China,132021

ABSTRACT Objective To investigate the utility of pre-expanded muscle-sparing latissimus dorsi flaps in the reconstruction of deformities secondary to severe scar contractures on the anterior chest.Methods The function of the latissimus dorsi was preserved with blood supply from the main or lateral branch of the thoracodorsal artery.The entire treatment period was divided into two stages,during which segmental latissimus dorsi flaps were pre-expanded in stage I and anterior chest scar deformities were reconstructed in stage II.During stage I,the musculocutaneous perforators arising from the lateral branch of the thoracodorsal artery were determined by ultrasound preoperatively; the flap design included the anterior segment of the latissimus dorsi supplied by the musculocutaneous perforators from the lateral branch; and a tissue expander was placed following flap dissection and then infused with saline intermittently for 4-6 months.In stage II,the chest scars were excised,and breast tissues were repositioned; the continuity of the medial branch of the thoracodorsal nerve to the muscle was preserved when reconstruction was performed using the segmental latissimus dorsi flaps supplied by the main or lateral branch of the thoracodorsal artery.Results From October 2010 to October 2019,21 patients (on 24 sides) underwent reconstructive procedures for extensive scar contractures on the anterior chest.All flaps survived,and their donor sites were sutured directly.During a follow-up of 3 months to 8 years,the flaps became soft and exhibited color similar to that of the adjacent tissues.The limited neck and shoulder movements improved,and postoperatively,all female patients were satisfied with the shape of their breasts.Additionally,neither apparent weakening on the adduction,internal rotation,or extension strength of the shoulder joint on the affected side nor marked depression deformity in the back was observed.Conclusion Pre-expanded muscle-sparing latissimus dorsi flaps with blood supply from the main or lateral branch of the thoracodorsal artery proved to be a desirable option for the reconstruction of extensive scar contractures on the anterior chest.

KEY WORDS Latissimus dorsi flaps; pre-expansion; muscle-sparing; thoracic scars

Serious burn injuries involving the anterior chest skin often give rise to severe scarring,leading to significantly limited neck and shoulder movements,and the breasts are usually affected in females.The scar tissues in and around the breasts invariably contribute to severe breast deformity,which may distort the appearance and disturb the function of the chest in female patients and even hinder the growth and development of the breasts in young girls during puberty.Regarding the management options for thoracic scars,conservative treatments hardly result in satisfactory outcomes; hence,surgical reconstructive procedures are often required.However,extensive anterior chest scars,especially extensive scar contractures between the breasts,remain a great challenge for plastic and reconstructive surgeons.

Under these circumstances,we utilized pre-expanded muscle-sparing latissimus dorsi flaps supplied by the thoracodorsal artery for the treatment of extensive scar contractures on the anterior chest since October 2010,and satisfactory outcomes were obtained in terms of appearance,function,and reduction of donor site deformities.Our clinical experience with this method may offer a novel,useful reconstructive option to deliver tangible benefits to patients afflicted by extensive scar contractures on the anterior chest.

CLINICAL DATA

From October 2010 to October 2019,21 patients (24 sides:3,bilateral; 18,unilateral) with extensive scar contractures on the chest and between the breasts underwent reconstruction using the pre-expanded musclesparing latissimus dorsi flaps with blood supply from the thoracodorsal artery.Five of the 21 patients were males and 16 were females,with an age range of 12-48 years.Among these adults with burn scars on the anterior chest or around the breasts,9 cases presented with limited neck and shoulder mobility and 12 female cases presented with breast deformities.Moreover,there were 5 cases of severe scar deformities on and around the breasts,and 3 females presented with severe breast dysplasia resulting from breast burn scars in childhood.The features shared by all the cases were the presence of scars on the anterior chest and/or between the breasts,while the skin on the back and lateral chest on the affected side (unilateral or bilateral)was normal (Fig.1).

SURGICAL METHODS

Stage I Surgery

Preoperative preparation

Ultrasound Doppler was used to localize the anterior border of the latissimus dorsi on the affected side,detect the main thoracodorsal artery and vein and their medial and lateral branches,and identify the locations where the lateral branch produced musculocutaneous perforators to the skin along the anterior edge of the muscle.The entire range was marked with dots on the body surface.Additionally,a 400-or 500-mL expander was prepared for later use.

Surgical procedures

Under general anesthesia,the patient was placed in the lateral decubitus position with the affected side facing upward.The surgical design was drawn on the body surface (Fig.2):The anterior border of the latissimus dorsi,thoracodorsal vessels,and medial and lateral branches,and the location of the skin perforators,as well as the extent of dissection of the expander cavity,were marked.The skin and subcutaneous tissues were incised 2 cm anterior to the anterior edge of the latissimus dorsi(depending on the skin condition) toward the direction of the anterior edge.Approximately 4 cm from the edge of the muscle,an incision was made from the deep surface to subcutaneous tissues until the dissection scope of the expander cavity marked preoperatively was reached.The entire procedure resulted in the harvest of a muscle bundle of about 4 × 8 cm at the top of the cavity without detachment from the skin (Fig.3).After complete hemostasis was achieved,a 400-or 500-mL expander was placed together with a drainage tube,and then,the incision was closed.Postoperative prevention of infection and saline injection into the expander were performed intermittently for 4-6 months.

Stage II Surgery

Four to six months postoperatively,the anterior chest scars were released and excised,the breast tissue was repositioned,and flap reconstruction was performed with the expanded latissimus dorsi segment after sufficient expansion (Fig.4 and 5).During the operation,the expander was removed and the position of the lateral branch of the thoracodorsal vessel entering into the flap was then determined by the transillumination test.The tissue surrounding the flap was incised for maximum flap harvest,provided the donor site could be sutured primarily,leaving the lateral branch vessels entering the flap.

A portion of the muscle sleeve could be attached at the entry of the lateral branch.In some cases when pedicle extension is required,the surgeon may dissect the main thoracodorsal vessels in the axilla by cutting off the lateral branch of the thoracodorsal nerve at the bifurcation of the medial and lateral branches,ligating the medial branch of the thoracodorsal vessels,and then dissecting the vessels to the proximity from the thoracodorsal nerve in the vascular bundle.

Finally,the expanded flap was pedicled with the main or lateral branch of the thoracodorsal vessels and tunneled through the axilla to the anterior chest and medial breast.

RESULTS

Twenty-one patients with 24 sides were included in this study.All flaps survived; the donor sites were sutured directly and subsequently healed by first intention.During a follow-up period of 6 months to 8 years,the limited neck and shoulder movements improved,and the breast deformities relieved or even disappeared in some cases.All female patients were satisfied with the shape of their breasts,and their flaps became soft,with the color and texture similar to those of adjacent tissues.Additionally,neither apparent weakening of the adduction,internal rotation,and extension strength of the shoulder joint on the affected side nor any marked depression deformity in the back was noted.

Case 1

A 14-year-old girl presented with a 5-year history of boiling water burns to the anterior chest.Physical examination indicated large hypertrophic scars on both sides of the chest and upper abdomen,coupled with local hypopigmentation.With a flat chest,the patient's areolae were absent,and both nipples were buried in scars; the abduction of her shoulders was slightly limited on both sides (Fig.1).Under general anesthesia,two expanders(rectangular,400 mL) were placed below the muscle bundles of the latissimus dorsi segments supplied by the bilateral thoracodorsal arteries and veins.After a 4-month conventional expansion (Fig.4 and 5),the expanders were removed,and the thoracic scars were excised under general anesthesia,followed by a pre-expanded flap reconstruction procedure.The flaps achieved good survival postoperatively (Fig.6,7,and 8).On a follow-up after 8 years,the flaps were soft,with their color similar to that of the adjacent thoracic skin; breast development was observed,and both shoulder joints of the patient had good mobility (Fig.9,10,and 11).Moreover,no depression was noted at the donor sites (Fig.12,13,and 14) (during this time,the upper chest scars were reconstructed with the expanded tissue of the adjacent locoregional normal skin).

Case 2

A 28-year-old man presented with a 2-year history of high-temperature cement burns to the anterior chest.He experienced scar contractures to the lower neck and left anterior chest with limited mobility of the neck and left shoulder (Fig.15 and 16).An expander was placed below the muscle bundles of the latissimus dorsi segments supplied by the thoracodorsal artery and vein on the same side.After a 4-month conventional expansion(Fig.17),the expander was removed,and the neck and shoulder scars were released and excised,followed by a pre-expanded flap reconstruction procedure.Six months postoperatively,the limited neck and shoulder movements were restored,and the anterior chest scars improved aesthetically (Fig.18 and 19),without any depression found at the donor sites (Fig.20 and 21).

DISCUSSION

Superficial scars on the chest are conventionally believed to have a little impact on the motor movement of human body,and thus surgical interventions are generally not advocated.However,hypertrophic scars secondary to severe skin burns on the chest can often limit the neck and shoulder mobility and lead to severe breast deformity and displacement as well as interfere with thoracic movement.Notably,the breasts are paired organs overlying the chest muscles predominantly in females and bear the major function of lactation.Indeed,the breasts serve as a characteristic feature of women's physical appearance as well as a vital source of self-confidence in this gender.Among minors,chest scars may also impede further development of the thorax and breasts.Hence,appropriate treatment of chest scars is important.The current surgical options for chest scars generally fall under two categories:skin grafts and skin flaps.However,extensive anterior chest scars,especially extensive scar contractures between the breasts,remain challenging for plastic and reconstructive surgeons.The postoperative outcomes of skin grafts rarely meet patients' expectations or satisfaction in terms of color,texture,thickness,and late contraction,regardless of using autologous skin transplantation or a combination of acellular dermis and autologous skin transplantation.

Adjacent expanded flaps are not preferred due to the limited supply of the surrounding normal skin and impractical flap expansion on female breasts,which severely limits the application of adjacent soft tissue expansion.With impressive advances in microsurgical and breast reconstruction techniques,the latissimus dorsi flaps supplied by the thoracodorsal artery have been widely utilized for chest deformity correction and breast reconstruction[1-2].Nevertheless,the latissimus dorsi flaps are relatively bloated with regard to superficial skin defects because of breast scar contractures with intact chest wall scars and breast tissue,which necessitates multiple postoperative thinning procedures.Furthermore,skin graft repair is often required for the donor sites,leaving visible scars and depression deformity after the procedure[3-4].Free flaps,which are another alternative,require sophisticated microsurgical techniques and are associated with high surgical risks and donor site deformities.

In the past few decades,perforator flaps have become ubiquitous in the field of plastic and reconstructive surgery.The latissimus dorsi perforator flaps have drawn great attention because they are not as bloated as the original myocutaneous flaps.Moreover,they preserve most of the functions of the latissimus dorsi[5,6].Previous anatomical studies revealed that direct cutaneous perforators from the thoracodorsal artery were found in 81% cases.The lateral branch of the thoracodorsal artery was noted to have two constant myocutaneous perforators:one located approximately 8-12 cm below the posterior axillary fold and the other located 2-3 cm medial to the anterior border of the muscle.There may be another perforator located 2-4 cm below the muscle in 80% cases[7].Therefore,most of the latissimus dorsi perforator flaps are based on musculocutaneous perforators.Given that the muscle perforators obliquely traverse through 3-5 cm of the muscle,a prolonged sophisticated operation is required,and there is a potential risk of damaging the perforating vessels[8-10].

To address this concern,we employed the pre-expansion technique with the muscle-sparing latissimus dorsi flaps.The musculocutaneous perforators from the lateral branch of the thoracodorsal artery medial to the anterior border of the latissimus dorsi were identified on the body surface preoperatively with ultrasonography.The muscle bundle with musculocutaneous perforators was then harvested.The distal and medial ends of the muscle bundle were incised from the deep surface; the proximal end was continuous with the main thoracodorsal artery or its lateral branch; the surface of the muscle bundle was connected with the subcutaneous tissue,ensuring structural continuity of the main trunk,lateral branch,and musculocutaneous perforators of the thoracodorsal artery.

When dealing with the vascular pedicle,we dissected the lateral branch at the thoracodorsal nerve bifurcation to preserve the integrity of the medial branch,leaving the remaining latissimus dorsi to retain its original function.This technique substantially reduces the operation time,decreases the risk of perforator injury,and has various advantages of perforator flaps,such as flap thinness and preservation of most of the functions of the latissimus dorsi.

This procedure also involves a flap expansion technique.Pre-expansion of the segmental latissimus dorsi flaps can provide large flaps without the need for donor site skin grafting considering that extensive skin defects often remain after the thoracic scars are released and excised and direct suture of the donor site after harvesting the latissimus dorsi flap is about 8-10 cm wide.Indeed,the expanded flaps function in the same way as a delayed surgery,and the delay mechanism of mechanical expansion promotes further remodeling of blood vessels in the flap[11],thereby remarkably improving flap vascularity.The expansion also contributes to considerable lengthening of the harvested flaps,allowing the transferred flaps to be extended to the intermammary region,which is a great challenge for reconstruction with non-expanded latissimus dorsi flaps.Therefore,the reconstructed flaps tend to appear more natural morphologically via selection of the color and texture that matches the dorsal region in combination with the tissue expansion technique.

This surgical procedure,however,has several limitations:(1) the procedure needs to be performed in two stages with a prolonged treatment duration; (2) surgical risks may increase as various complications of the expander are likely to occur during flap expansion.However,with appropriate care taken regarding the indications,pre-expansion of muscle-sparing latissimus dorsi flaps may be a desirable treatment option for extensive scar contractures on the anterior chest.