Breast reconstruction with the latissimus dorsi flap

Introduction

Breast reconstruction has undergone a transformation over the past 40 years. Techniques in soft tissue management and improvements in tissue expander and implant design have advanced to the point where the subtle and artistic forms that define the female breast can be preserved and even improved upon after mastectomy. Central to the development of these techniques, and in particular, the management of soft tissue, has been the description and subsequent refinement of the latissimus dorsi musculocutaneous flap (LDMF). This chapter will outline the basics of latissimus dorsi flap breast reconstruction and describe in detail how the flap can be used to obtain outstanding results in both immediate and delayed breast reconstruction after mastectomy.

Operative strategy

To understand the important role the latissimus flap has played in helping define the current results and expectations associated with modern breast reconstruction, it is helpful to organize the goals inherent in achieving an aesthetic result.

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  Volume – One of the most powerful visual criteria that defines breast beauty is volume. The creation of proportional and symmetric breast volume is paramount when performing breast reconstruction. Volumes that either fall short of aesthetic or conversely exceed the desired amount can adversely affect the quality of the result, particularly when any degree of asymmetry is created.

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  Skin envelope – To accommodate a desired volume, it is imperative that a proportional skin envelope be either preserved or reconstructed. Failure to create a skin envelope of either adequate surface area or shape will adversely affect the final result as the volume of the reconstructed breast will fall short of ideal.

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  Contour – An aesthetic breast presents smooth and even contours across the medial, superior and lateral borders that flow away from the chest wall. Any element of sudden contour change or sharp step-off appears artificial and can be a hallmark of an unsatisfactory breast reconstruction.

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  NAC – The nipple–areola complex (NAC) presents as a defining element of an aesthetic breast. When absent, a breast mound can be perfectly reconstructed; however, the missing NAC is immediately noticed. The addition of a symmetrically placed NAC of the proper size and shape that preserves symmetry enhances the quality of the aesthetic result in a very significant manner.

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  Symmetry – Central to any successful breast reconstruction is the creation of symmetry in every aspect of breast appearance. This includes the position of the breast footprint, volume, shape, inframammary fold location, breast base diameter, projection and position of the NAC. Each of these aesthetic elements can be properly reconstructed; however, if symmetry with the opposite breast is lacking, the quality of the result is adversely affected.

The great advantage afforded by the addition of the LDMF is that each of these elements of an aesthetic breast can be reconstructed using the skin, fat and muscle of the flap to add missing volume, replace missing skin, soften peripheral contours, create a reconstructed breast that can accommodate the addition of a significant amount of volume, and provide appropriate symmetry. Additionally, secondary to the thickness of the dermis on the back, using the skin island of the flap to reconstruct the NAC results in the most reliable and long-lasting projection of the reconstructed nipple of any technique currently described. Such results are often lacking when using traditional techniques based on thin mastectomy skin flaps. While the technical versatility of the LDMF is of great advantage, perhaps even more important is the reliability of the vascular supply to the flap. Due to the robust thoracodorsal pedicle that supplies the flap, it is very unusual to experience any degree of ischemia in either the muscle, skin or fat of the flap, even in patients with complex medical conditions such as diabetes, connective tissue disease, or even in patients who smoke. The dissection of the flap is straightforward and the anatomy is constant, which facilitates easy elevation and rotation of the flap into the mastectomy defect. Taken together, all of these factors combine to make the LDMF an excellent option for patients seeking either immediate or delayed breast reconstruction.

Anatomy

The latissimus is one of several muscles that cover the upper portion of the back ( Fig. 29.1 ). Of these muscles, it is the largest and takes origin from the medial thoracolumbar fascia, posterior iliac crest, and lateral fibers of the external oblique before inserting via a thick tendon into the intertubercular groove of the humerus. The anterior border of the muscle defines the posterior border of the axilla. The superior border of the muscle takes origin from under lower medial origin of the trapezius before coursing over the tip of the scapula. As the muscle passes into the axilla, there is a variable fusion of muscle fibers with those of the teres major that must be correctly identified and released to allow proper access to the axilla.

The dominant vascular pedicle to the LDMF is the thoracodorsal artery, which is a branch of the subscapular artery, which comes off the axillary artery ( Fig. 29.2 ). The thoracodorsal artery gives off an important serratus branch approximately 10 cm below the tendinous insertion of the muscle. This branch can maintain vascular viability of the flap via reversal of flow when the thoracodorsal pedicle has been previously ligated. A secondary blood supply is provided by perforators off the posterior intercostal arteries laterally and the lumbar arteries medially. These perforators enter the under surface of the muscle directly from the chest wall in the mid-substance of the muscle and must be directly controlled during flap elevation. Within the substance of the muscle, the thoracodorsal artery then bifurcates into a transverse and a lateral branch that then extensively arborizes within the muscle, passing multiple perforators to the overlying skin and fat. The venous return parallels the artery as two evenly spaced comitantes before emptying into the axillary vein.

The innervation to the latissimus muscle comes from the C6 to C8 ventral nerve roots that coalesce into a well-defined thoracodorsal nerve. The nerve enters the muscle separately from the vascular pedicle and can be positively identified by pinching the substance of the nerve and observing the intense contraction that results in the muscle. Once the nerve enters the muscle, several different portions of the muscle are innervated independently, which has led some surgeons to adopt a partial muscle harvest strategy when using the LDMF and yet still leave behind functional muscle mass.

Patient marking

The marking sequence in LDMF breast reconstruction is important as it identifies the specific landmarks that guide the surgical procedure ( Video 29.1, Video 29.2 ). This marking procedure is performed preoperatively with the patient standing comfortably with the arms at the sides. Initially the midline is marked along with the palpable tip of the scapula. A line is drawn from the posterior border of the axilla curving medially across the tip of the scapula. This represents the upper border of the latissimus muscle. The estimated inferior margin of the trapezius is drawn as it covers the superomedial corner of the latissimus muscle. With the arm raised up over the head, the anterior border of the muscle is marked by identifying the edge of the muscle in the axilla and drawing this landmark inferiorly toward the iliac crest. The origin of the muscle from the thoracolumbar fascia is drawn estimating this to be 2–3 cm off the midline and this muscle origin is followed as it curves inferolaterally along the iliac crest. In this fashion, the surface area of the latissimus muscle is outlined in such a way that the skin island can now be centered over the muscle, adjusting the exact position of the skin island as needed.

Skin island orientation requires thoughtful consideration of several factors depending upon whether the reconstruction is immediate or delayed and how much skin is required to restore the breast skin envelope.

Historical perspective

With the introduction of silicone gel breast implants in the 1960s came the first attempts to reconstruct the missing volume of the breast after mastectomy. These early results were plagued with complications secondary to poor implant engineering in addition to a difficult patient population who presented with severe mastectomy defects including those patients with a significant soft tissue defect after radical mastectomy. In the 1970s, the recognition of the importance of musculocutaneous perforator anatomy and its effect on flap design resulted in the re-discovery of the LDMF, which had been originally described and used for chest wall reconstruction in the early 1900s. It was soon realized that using the LDMF in conjunction with an implant could together address some of the complications seen when implants were used in isolation. These early results were promising and provided some of the best results ever seen in breast reconstruction. This experience was then followed closely by the description of the transverse rectus abdominus musculocutaneous (TRAM) flap, which then became the preferred method of reconstruction for many surgeons, both as a pedicled or a microvascular free flap, due to the fact that a completely autogenous reconstructive result was created that obviated the need for an implant. As a result, the use of the LDMF was limited to special circumstances when anatomy or patient co-morbidity issues made the TRAM flap a less attractive option. Further recent advances in implant design and, in particular, the introduction of acellular dermal matrices (ADM) and fat grafting to the breast has pushed the LDMF further down the list of available reconstructive options. Recent experience has documented that less aggressive mastectomy techniques including widespread use of the nipple-sparing mastectomy has created a reconstructive environment where a stable soft tissue envelope can be filled with an implant supported by ADMs and supplemented with fat grafting to provide outstanding results. As a result, while the LDMF is an excellent option for many patients, it is now used predominantly in patients who are not otherwise candidates for tissue expander/implant reconstruction or who for any reason cannot, or should not, undergo TRAM flap reconstruction.

Surgical technique

When using a LDMF in immediate breast reconstruction, there are important sequencing factors that must be taken into account to allow the operation to flow smoothly but at the same time afford proper exposure for easy flap dissection and elevation and still allow for an accurate and aesthetic flap inset.

Patient positioning

Because LDMF reconstruction requires operative dissection on both the ventral and dorsal sides of the torso, a wide area of exposure is required to provide adequate access to both the mastectomy defect as well as the back donor site. To avoid a position change during the procedure, many surgeons will place the patient in the lateral decubitus position for a unilateral reconstruction, such that both the chest wall and the back will be exposed in one surgical field ( Fig. 29.3 ). This allows the mastectomy defect to be developed at the same time as LDMF elevation if two surgical teams are used. As well, the flap can be passed anteriorly once it is fully elevated and the back donor site closed without the need for patient repositioning. Typically, at this point the patient is then rotated into the supine position in preparation for flap inset while still maintaining the sterile surgical field. This approach shortens the operative time as a full position change with a re-prep and redrape of the patient is avoided. The disadvantage is that it can only be used with a unilateral reconstruction. Additionally, the lateral decubitus positioning places the anatomic landmarks of the mastectomy defect as well as the back donor site in a forced position that can distort the natural borders of the breast and the back donor site leading to inaccurate or excessive dissection of these two surgical spaces. For these reasons, it is the authors preferred approach to separate the procedure into a ventral – dorsal – ventral sequence with two position changes being used. Initially the patient is placed in the supine position for either a unilateral or a bilateral delayed breast reconstruction. This allows the mastectomy defect to be accurately recreated and, very importantly, facilitates accurate and symmetric positioning of the inframammary fold (IMF). As well, initial creation of the axillary tunnel designed to facilitate flap transfer from the back is easily and accurately performed. It is recommended that the mastectomy defect be recreated first in every instance so that appropriate adjustments in flap design and position can be made as needed. In addition, the dimensions of the mastectomy defect could dictate that a larger or even smaller flap might be required, which is information that should be developed prior to flap design and elevation. The patient is then rotated into the prone position with the chest and abdomen appropriately padded to lift the patient off the operative table sightly. This allows the arms to be secured slightly above the shoulders with the elbows flexed. This position prevents undue stress from being placed on the shoulders and avoids any chance for position related injury. After the flap has been elevated and passed anteriorly through the axillary tunnel, accurate closure of the donor defect can be performed will little risk of soft tissue misalignment. Finally, the patient is rotated back into the supine position where flap inset and tissue expander or implant placement is performed. At this point, the ability to sit the head of the bed up anywhere from 60° to 90° allows intraoperative adjustments to be performed that ensure accurate setting of the IMF and aesthetic breast mound creation. This sequence is particularly applicable to cases of bilateral breast reconstruction where the lateral decubitus position is not practical. The disadvantage of this approach is that two position changes are required, each with a separate prep and drape of the patient. However, the enhanced control and accuracy of flap development and inset has led over time to it being used in both unilateral and bilateral reconstructive cases, simply as a means to simplify the entire operative approach and create consistency in patient positioning for the operative staff.

Defect preparation

Preparation of the mastectomy defect is an important part of the overall process of LDMF breast reconstruction. After a mastectomy, the skin flaps become adherent to the underlying pectoralis major muscle and chest wall by scar. This mastectomy flap plane must be redeveloped by separating the skin flaps from these underlying structures in such way that all possible scar is left attached to the muscle and chest wall and only soft and pliable skin and fat are left on the mastectomy flaps. The scar layer is then debrided off the deeper chest wall tissues. Very often an old seroma cavity is encountered during this dissection and the walls of this cavity must be removed in the manner of a capsulectomy in order to prepare for the subsequent introduction of the LDMF. During this dissection, the borders of the mastectomy defect must be carefully constructed such that the medial and lateral extent of the dissection will create the desired breast base diameter. In particular, it is mandatory that the level of the IMF be set and secured to achieve the optimal result. This can be accomplished by simply controlling the amount of dissection that is performed or, alternatively, the fold can be set with sutures once the lower mastectomy flap has been elevated. Dissection of the superior flap is of less importance as long as it is released enough to allow it to redrape without tethering over the latissimus flap/device construct once it is in position. Lateral dissection of the mastectomy defect and setting the lateral breast contour must be performed in a manner that preserves this important landmark as correcting an over-dissected lateral border can be a technical challenge. Due to the fact that these tissues can be quite thin after mastectomy, it can be difficult to place sutures that restore this contour smoothly and without visible notching in the skin. As well, any degree of over-dissection can predispose to postoperative lateral migration of the tissue expander or implant into the back donor site. To prevent this, great care must be taken to set the lateral breast contour according to the marks made preoperatively making every effort to keep these lateral attachments intact. Finally, a preliminary development of the high axillary tunnel is made once the limits of the pocket dissection are set. By carefully dissecting along the lateral chest wall according to the limits of the axillary tunnel marked preoperatively, the anterior border of the latissimus dorsi muscle is identified, care being taken not to undermine the muscle at this point to avoid inadvertent injury to the vascular pedicle. This part of the eventual communication between the mastectomy defect and back donor site can be difficult to fully develop from the back. However, with preliminary dissection done at the time of mastectomy defect development, creation of an accurate tunnel once the patient is rotated into the prone position can be more easily accomplished without inadvertent over-dissection of the lateral chest wall tissues.