The LD flap is a commonly used technique in reconstructive surgery. The LD flap is an autologous tissue that can cover a large area, for defects due to trauma, wide excision, or tumors. The LD flap was first reported in 1906, by Tansini and was used for the first time in breast reconstruction in 1970 [14–16]. It is one of the most commonly used flaps in reconstruction of small to moderate breast volumes. In a recent study, the transfer of the unilateral LD muscle to the breast, with an extended LD flap, did not interfere with shoulder function or daily life [17]. Mastectomy is a surgical treatment for breast cancer, which includes the aim of performing immediate breast reconstruction, simultaneously, after confirmation of oncological safety. When patients have small breast volumes, total mastectomy, followed by reconstruction, is a viable option. However, in most cases, recent reports demonstrate equivalent oncological safety in breast reconstruction after partial mastectomy and total mastectomy, with shorter operation times and better esthetic outcomes [18–20]. Therefore, deciding on total mastectomy, to avoid radiotherapy, does not secure superiority in oncological safety or esthetic outcome.
Various oncoplastic breast surgery techniques have been reported after partial mastectomy and breast-conserving surgery. Algorithms select reconstruction methods, such as the TDAP, AICAP, LICAP, mini LD flap, and omental flap, for the volume replacement technique, according to the size, shape, and location of the breast cancer [21, 22]. However, as there are limitations, differences, and personal preferences in the training of reconstructive surgeons, the adequate use of all reported techniques is challenging. In addition, the use of a perforator flap requires an advanced surgical technique and may be difficult due to anatomical variation. Therefore, this study reports a useful technique that can control the distance according to the defect, by designing an LD flap pedicle of the thoracodorsal artery to the anterior border (mid-axillary region).
Our technique provides easier access for the surgeon than perforator flap surgery. It can properly reconstruct the breast, even if the location and range of the cancer change slightly. First, elevation is started after checking the border of the axillary area, from where the thoracodorsal artery branches off, followed by incision of the flap design. This design is upward and downward undermining, releasing the thoracodorsal artery in the axillary direction, and cutting the thoracodorsal nerve to prevent jerking and extension of the range of flap movement.
With reference to the macroscopically visible pedicle, the LD flap was marked and descended downward; the route that entered the muscle was marked as thoroughly as possible using Doppler ultrasound. A previous study investigated the vascular pattern of the LD in cadavers [23]. To separate only the descending branch, more volume was required, and in some cases, the pedicle distance was sufficient [23]. While minimizing damage to the pedicle, the inferior part was cut to secure enough distance and the necessary muscles separated. Once the pedicle was visible with the naked eye, the flap was exfoliated while preserving the pedicle with minimal detachment of the uppermost humoral attachment area. This limits effects on shoulder function or limitation of motion. The flap was designed with a planarian head shape because an oval design of the flap may cause extra remnants of bulging skin in the axillary area; as the LD muscle passes through, these extra remnants may seem more prominent. Therefore, the flap was designed with a planarian head shape with the uppermost vertex pulled down in the inferior direction, according to the principle of an advancement flap, thereby relieving any axillary bulge and concealing possible axillary scars behind the brassiere’s inner area. Additionally, the lower part of the flap was designed to allow the linear scar of the donor site to maintain the S-line from the waist to the buttocks. As such, reconstruction can be conducted only through the incision of the LD muscle flap, without designing the skin flap. However, more muscle elevation is required to resolve the same volume of skin flap, and skin flap design is important, as atrophy may occur in future. Fat injection may be considered; however, the engraftment rate varies depending on the patient, and multiple re-operations may be necessary if insufficient amounts of fat are injected [24–26]. Furthermore, when the nipple or breast skin is excised due to involvement of cancer cells, simultaneous nipple reconstruction can be performed, and breast skin defects can be adequately covered [27, 28].
In this study, the mini LD flap group that underwent partial breast reconstruction using only a portion of the LD flap was used as the control group for comparison. Our findings showed that the vertical LD flap group required significantly less total operative time and flap elevation time than the mini LD flap group. This finding may be attributed to the following reasons: first, the surgery was conducted in the supine position without changing the patient's position, reducing the operation time. A vertical LD flap operation can be initiated without waiting for negative frozen biopsy results of the specimen. If cancer cells remain, additional excision can be performed by breast surgeons while prioritizing oncologic safety, and this can be compensated by further elevation of the vertical LD flap. Second, reconstruction with the vertical LD flap is easy to perform, as the long axis of the flap design coincides with the direction of the surgical field, whereas a classical mini LD flap may have the skin flap long axis perpendicular to the direction of the surgical approach. Thus, the operative field of view may be limited, affecting the total operative time. Finally, a vertical LD flap was used for smaller defects, which would have reduced the operation field. The transverse long linear scar at the back, covered by the underwear, may not be visible to the patient; however, the surgical scar may be visible when the patient wears a swimsuit or summer clothing. In contrast, the donor site scar of the vertical LD flap could not be seen when the arm was lowered, and no scar was visible on the back. Moreover, restoration of the original muscle position by undermining the remnant LD muscle on the back side, after transfer of the vertical LD flap to the breast defect region, cannot be performed with the transverse design.
Breast volume analysis by Volpara™ readings showed a strong correlation with actual mastectomy volume measurements in a previous study [29]. The volume difference analysis between the affected and unaffected sides of the breast demonstrated fewer differences in the vertical LD group at the 1-year postoperative follow-up, although the difference was not statistically significant. These objective data are considered to correlate deeply with breast symmetry, which is one of the most important factors in breast surgery and requires further analysis (Table 1).
However, these advantages do not lead to the complete replacement of partial reconstruction techniques, including the mini LD flap. If more than one-third of the breast volume is removed, a moderate volume of the flap is needed. In such cases, a mini LD flap is required. Patients must be fully informed about these possible intraoperative variations prior to surgery, to determine the most suitable surgical technique. Although a longitudinal extension of the vertical LD flap design may allow the use of an extended LD flap, a scar that is visible to the patient may be formed. In addition, the medial part can only be reached after changing the patient’s position to the decubitus position in the middle of the operation. This eliminates the advantages of the vertical LD flap, and longitudinal extension of the vertical LD flap design is not considered an appropriate indication. Therefore, a vertical LD flap can reconstruct defects in all breast regions and is very useful as a replacement reconstruction technique that requires a rather small flap volume, especially in patients with a small breast volume. The statistical results showed relatively fast recovery, high postoperative patient satisfaction, and high total patient satisfaction (Table 3). As such, a vertical LD flap is a pedicled flap among partial breast reconstruction techniques and has the same pedicle as an extended LD flap with great accessibility. A vertical LD flap may have positive effects on the algorithm of breast reconstruction using the LD flap, which allows reconstruction regardless of tumor location in the breast. Although less than one-third of the total breast volume was incised, a vertical LD flap may be an appropriate indication when the volume displacement technique is not feasible with the remaining tissues of small breast volumes if the nipple and the breast skin are excised. Herein, we report a vertical LD flap modified from an ordinary mini LD flap, which is a useful technique, capable of being used for all partial breast reconstructions. Small breast cancer in the upper lateral region is the best indication for the use of a vertical LD flap, and this technique allows excision of the excised breast skin (Figs. 4, 5). Reconstruction of defects in the lower medial parts, which requires the longest flap to reach the defect, also showed good long-term esthetic outcomes after the operation (Fig. 6). Partial mastectomy in the inframammary fold line, for defects of the lower lateral part, was also associated with a good outcome and no scars on the breast mound (Fig. 7). If the nipple is also involved, simultaneous nipple reconstruction can be performed using the skin flap of the vertical LD flap (Fig. 8). These advantages are considered reasons for superior patient psychological satisfaction (Table 3) and subsequent high patient satisfaction.
However, our study has the following limitations: first, as breast-conserving surgery becomes increasingly popular, long-term locoregional recurrence rates must be monitored, and the potential need for completion mastectomy and whole breast reconstruction (down the line in the event of a local recurrence) is a disadvantage of using an LD flap for partial breast reconstruction; however, our study only had a brief follow-up period. In the reconstruction of defects in the medial part of the breast, vertical flap designs may be slightly downward, such that the donor site may not be hidden under the bra, and as a result, the scar may be visible to the patient. Although a vertical LD flap is more applicable for defects regardless of their location, it has limitations in replacing the classic LD flap technique or a mini LD flap, in cases of moderate to large breast defects. Lastly, mild bulging is observed in the axillary area where the pedicle muscle has passed, although bulging is less than that with the mini LD flap or the extended LD flap techniques. Bulging is improved after six months in most cases; however, delicate procedures may be required to minimize muscles close to the pedicle. Furthermore, if the descending and transverse branches of the thoracodorsal artery diverge in the distal region, separation may not be possible with only the descending branch.