The LDMF is contraindicated in women who have large skin requirements for immediate or delayed breast reconstruction. In these situations, abdominal wall tissue is preferred. The LDMF can be used for chest wall coverage in cases of inflammatory breast cancer in which the mastectomy flaps are unable to be closed, and the patient will receive adjuvant radiotherapy. However, in standard breast reconstruction, this flap should not be used if the skin requirements are greater than the proposed dimensions of the LD skin paddle.

The LDMF is relatively contraindicated in patients who have previously undergone axillary lymph node dissections followed by radiation therapy. It can be extremely difficult to perform an appropriate dissection of the neurovascular pedicle in these situations. Vascular injury or insufficiency can result from a previously dissected axilla. There are certain situations when it is known that the thoracodorsal pedicle has been previously transected. Although the LDMF can potentially be harvested on the serratus branch, this has been shown to result in an increased incidence of flap necrosis.

Additional relative contraindications to using the LDMF are patients who have undergone posterior thoracotomies where the LD muscle has been transected. In addition, patients who have a known preexisting shoulder dysfunction or athletes who require the use of this muscle should not be considered candidates for this pedicle transfer.

In order for the LDMF to be utilized for breast reconstruction, certain patients must be willing to undergo the insertion of a prosthetic device. The volume of the standard LDMF is most often not sufficient to create an appropriate reconstructed breast. The extended LDMF can be considered to replicate the shape and volume; however, donor site seromas are higher in the flap technique. Patients must be clearly advised of this.

The LD muscle is responsible for extension, adduction, and internal rotation of the shoulder joint. It also plays a role in assisting with extension and lateral flexion of the lumbar spine. The LD muscle has a type V Mathes and Nahai vascular supply classification, meaning it has a dominant blood supply from the thoracodorsal artery and vein, a branch of the subscapular vessels, and secondary blood supply belonging to perforators

from the posterior paraspinal system. The axillary vessels give rise to the subscapular vessels that give rise to the thoracodorsal vessels (Fig. 30.1). The serratus branch splits from the thoracodorsal vessels as it enters the LD muscle. The thoracodorsal pedicle enters the deep surface of the LD muscle approximately 10 cm below the axillary vessels and 2 to 3 cm inside the lateral edge of the this muscle. This vessel then splits into two terminal vessels within the LD muscle. By taking advantage of this vascular pattern, the LD muscle can be harvested separately on these branches to potentially limit the use of the muscle and move these segments independently, especially when a skin paddle is not required. Several musculocutaneous perforators supply the skin paddle, which is usually centered over the muscle. As long as the skin paddle is centered over the muscle, there is typically no concern that it will not capture a musculocutaneous perforator and have an adequate blood supply.

Nerve supply to the LD muscle is the thoracodorsal nerve. The nerve is a branch of the posterior cord of the brachial plexus, deriving its fibers from C6, C7, and C8. The nerve follows the course of the subscapular artery where it can be traced along the lower border of the muscle. The nerve is typically found in a medial position relative to the vascular bundle. The nerve is typically transected to prevent postoperative contraction of the muscle. Some surgeons do not transect the nerve because of concern that
the muscle will atrophy and the resultant effect of transferring the muscle to the chest wall or mastectomy site will be ameliorated. We prefer transaction of both the insertion (floor of intertubercular groove of the humerus) and its origin (spinous processes of thoracic T7–T12, thoracolumbar fascia, iliac crest, and inferior three or four ribs) but sparing the nerve creates a clinical situation that does not lead to postoperative muscle contraction and does not cause significant atrophy (Fig. 30.2).

Determining the status of the thoracodorsal pedicle to the LD muscle must be confirmed prior to surgery. Information can be readily attained by reading prior operative notes if the patient has previously undergone an axillary lymph node dissection. The status of the pedicle is typically discussed, and this information can often be useful. However, there is no substitute for clinical evaluation. In the preoperative setting, patients are asked to place their hands at their sides and push inward. If the patient has a denervated LD, the scapula will pull upward and outward, appearing almost “winged.” This is secondary to the anatomical orientation of the LD in how it drapes across the tip of the scapula, keeping it fixed to the chest wall. In addition, having patients abduct their arm and push against resistance while the LD muscle is palpated can reveal functional status. If there
has been a history of a prior axillary lymph node dissection, it is critical to consider that the pedicle to the LD flap has been compromised. If this is the case, the vascular branch to the serratus muscle can be used in a retrograde fashion for blood supply to the muscle. However, in this situation, there are reported incidences of flap necrosis when the LDMF is solely based on the serratus pedicle. It is, therefore, critical that the LD muscle be assessed intraoperatively. If there is evidence of atrophy, then the neurovascular pedicle was most probably compromised during the lymph node dissection or has intimal damage from radiotherapy. In this instance, even though it can be harvested on the serratus anterior branch, the volume of the LD muscle and integrity of the skin paddle can be affected. Another autologous flap would be recommended in this situation.

The patient is marked in a well-lit room in the standing position at both the recipient (mastectomy) and the donor (LDMF) sites. First, the breast markings are made, which include the sternal notch, midline, bilateral inframammary folds, and the superior borders of the breast. In the operating room, the inframammary folds are reinforced with a sterile marker as often these marks become faded following surgical preparations or from the mastectomy procedure.

The patient’s back and lateral chest wall is marked to delineate the LD muscle, the skin paddle used for breast reconstruction and the pathway for which the LDMF will be placed under the axilla and into the partial or complete mastectomy defect (Fig. 30.3 A and B).
First, the tip of the scapula is marked, along with the iliac crest and the posterior midline. These are critical marks and should be performed only in the standing position to allow proper delineation of anatomical landmarks. It is helpful to have the patient abduct and adduct the shoulder complex to appropriately confirm the tip of the scapula. In obese patients, it is often difficult to palpate this key anatomical landmark. If this landmark is not established, the potential for inappropriately setting the skin paddle on the LD muscle becomes greater. Next, the anterior lateral and inferior borders of the LD muscle are marked. Having patients adduct their arm against resistance to feel the anterolateral edge of the LD muscle is extremely helpful when marking this border. The upper border of the muscle is marked as it extends from the axilla across the tip of the scapula. The trapezius muscle is then marked as it overlaps the upper medial portion of the LD muscle. This marking is meant to be a reminder during surgical dissection of this critical landmark. Often times, the trapezius muscle can be elevated inadvertently during the LD muscle harvest, and this anatomical boundary should not be violated.