Introduction

Breast reconstruction after mastectomy is regarded as an integral part of breast cancer management that can positively impact patients’ quality of life [1]. The number of patients undergoing breast reconstruction after mastectomy is increasing. In the USA, in 2019, 107,238 patients underwent breast reconstruction after mastectomy, representing a 5% increase compared with the previous year, and a 36% increase compared with the year 2000 [2].

Breast implants are used for breast reconstruction after mastectomy. Subpectoral implant-based breast reconstruction following mastectomy commonly severs the inferior border of the pectoralis major muscle for better projection of the lower pole. This can affect a patient’s postoperative motor function and result in animation deformity.

Increasingly, implant-based breast reconstruction uses partial muscle coverage with an acellular dermal matrix (ADM). This approach provides greater soft tissue coverage than traditional implant-based breast reconstruction, which uses a submuscular expander and full muscle coverage [3, 4]. ADM provides an inferolateral coverage of the implant, reducing the need for rectus abdominis and serratus anterior muscle coverage. Partial muscle coverage with ADM allows increased lower pole expansion and enhanced breast aesthetics. Additionally, the risk of capsular contracture is reduced in ADM compared with non-ADM procedures [5,6,7]. Large ADMs may not be affordable for patients in regions where breast reconstruction is not covered by medical insurance, limiting access to breast reconstruction for these patients. New techniques that substantially reduce the size and thickness of the ADM would be beneficial.

The objective of this study was to develop a novel technique for submuscular implant-based breast reconstruction following mastectomy, utilizing the serratus anterior muscle fascia connected to the lateral margin of the pectoralis major muscle to form a lateral tissue pocket for implant coverage. This approach extends submuscular coverage laterally without undermining the serratus anterior muscle (Fig. 1). It improves the shape of the breast and maintains the implant in position, while avoiding animation deformities due to pectoralis contractions that can occur after subpectoral implant-based breast reconstruction. As this technique utilizes a minimally sized ADM, it requires less time and is less costly than more conventional surgical methods. Patient satisfaction and complications 12 months after surgery were assessed in patients who underwent implant-based breast reconstruction after mastectomy with our novel technique using a pectoralis-serratus musculofascial sling and ADM.

Fig. 1
figure 1

Surgical technique. a The pectoralis major muscle was incised. The pectoralis major and pectoralis minor muscles were separated, ensuring that the attachment point of the inferior border of the pectoralis major muscle was consistent with the inframammary fold. b, c The inside surface of the pectoralis major muscle was dissected to create a retropectoral lateral pocket for the implant. The integrity of the serratus anterior muscle and fascia were preserved (black dotted line). d An implant was placed in the implant pocket and covered with ADM, which was clipped and affixed to the pectoralis-serratus musculofascial sling

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Material and methods

Patient population

Patients who underwent mastectomy and implant-based reconstruction at Guangdong Provincial People’s Hospital between March 2015 and November 2020 were eligible for this study.

Inclusion criteria were (1) age > 18 years; and (2) underwent total mastectomy; or had multiple bilateral cystic breast masses; or had BRCA1/2 mutation, underwent bilateral total mastectomy, and required breast reconstruction; or required breast reconstruction immediately after surgical removal of breast wih previous injection for augmentation. Exclusion criteria were (1) patients with missing data relevant to our outcomes; or (2) patients who were lost to follow-up.

Patient selection was nonrandomized and uncontrolled. Patient suitability for our technique using a pectoralis-serratus musculofascial sling and ADM was assessed by Dr. Zhang and Dr. Liao. Patients were followed up for a minimum of 12 months.

This study was approved by the Ethics Committee of Guangdong Provincial People's Hospital. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Written informed consent was obtained from all individual participants included in the study.

Operative technique

All implant-based reconstructions were performed by a single surgeon (Dr. Zhang).

Pre-operatively, each patient was marked in the standing position. Marks included delineation of the planned mastectomy incision lines, the inframammary folds, and the midline; the sternal notch to nipple (S–N), nipple to midline (N–M), suprasternal notch to nipple (SN–N), and nipple to inframammary fold (N–IMF) distances; and breast width (BW), breast height (BH), and intermammary distance (IMD) to determine the volume and shape of the intended implant. After either nipple and skin sparing surgery or total mastectomy, the lateral margin of the pectoralis major muscle was marked. The pectoralis major muscle was incised with an electroscalpel (Fig. 1a). The pectoralis major and pectoralis minor muscles were separated (Fig. 1b). The inside surface of the pectoralis major muscle was dissected to create a retropectoral lateral pocket for the implant. The integrity of the serratus anterior muscle and fascia were preserved, and a continuous lateral musculofascial sling of pectoralis major and serratus anterior muscles was maintained (Fig. 1c). After confirming hemostasis, two high vacuum wound drainage systems (10 mm flat, PFM Medical, Inc) were inserted into percutaneous sites inferolateral to the breast, with one placed beneath the pectoralis major muscle and the other placed superficial to the pectoralis-serratus musculofascial sling.

Allograft sheets of ADM (Beijing Jayyalife Biological Technology Co., Ltd.), measuring 6 × 5 cm were rinsed and steeped in a solution of cefuroxime and gentamicin for 15 min. The ADM was affixed to the margin of the pectoralis major muscle with interrupted absorbable sutures (3-0 Vicryl, Ethicon, Inc., Somerville, NJ). The shape of the breast was adjusted to prevent excessive skin tension. An implant was placed in the implant pocket and covered with the allograft, which was clipped and affixed to the pectoralis-serratus musculofascial sling (Fig. 1d). The mastectomy flap was closed with interrupted deep dermal sutures (3-0 Monocryl, Ethicon, Inc.) and intradermal mono-filament absorbable sutures (4-0 Monocryl, Ethicon, Inc.). Patients were administered intravenous antibiotic as prophylaxis for 24 h postoperatively. We have included an edited video clip of the surgical procedure on one of the patients in the electronic supplementary material for more details.

Outcomes

Patient satisfaction and complications associated with breast reconstruction were recorded after 12 months of follow-up.

Patient satisfaction was determined using the BREAST-Q Reconstruction Module (postoperative), a patient reported outcomes instrument that measures quality of life (psychosocial, sexual and physical well-being) and satisfaction (with breasts, nipples, abdomen, back, and care) in patients undergoing breast reconstruction. Scores are converted to linearized measurements using the Q-score program, with higher scores meaning greater quality of life or satisfaction (http://www.breast-q.org).

Complications associated with breast reconstruction included incidences of major (resulted in implant loss) and minor (resolved with antibiotic treatment) infections, skin necrosis, hematoma, implant exposure, seroma, capsular contracture, and revision surgery.

Results

Patient population

A total of 117 patients (163 breasts) underwent mastectomy and implant-based reconstruction between March 2015 and October 2020. Of these, 105 patients (147 breasts) underwent single-stage breast reconstruction with a pectoralis-serratus musculofascial sling and ADM, and 12 patients (16 breasts) underwent two-stage breast reconstruction with tissue expander placement prior to use of a pectoralis-serratus musculofascial sling and ADM (Fig. 2).

Fig. 2
figure 2

Flow chart of patient selection

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Patients’ demographic and clinical characteristic are provided in Table 1.

Table 1 Patients’ demographic and clinical characteristics
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Outcomes

Among the 117 patients, mean satisfaction with breasts was 61 ± 4.7 (range, 48–73), mean psychosocial well-being was 66 ± 10 (range, 50–93), and mean sexual well-being was 47 ± 7.8 (range, 27–70) (Fig. 3). Complications included two (1.7%) patients with infections, which were treated by washout and exchange of the implant, resulting in successful salvage at the end of the surgery; nine (7.6%) patients with poor incision healing, which were resewn when the patients received chemotherapy 2 weeks after surgery; four (3.4%) patients with seromas, which were aspirated under ultrasonic guidance; and three (2.7%) patients with hematoma. Six (5.1%) patients experienced capsular contracture; of these, four patients underwent revision surgery with fat grafting, and two patients refused revision surgery.

Fig. 3
figure 3

a, b, c Preoperative images of a 46-year-old woman with multiple breast cysts who underwent breast reconstruction, d, e, f Postoperative images 12 months after reconstruction

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Discussion

This study describes a novel method for submuscular implant-based breast reconstruction following mastectomy. The technique utilizes a pectoralis-serratus musculofascial sling and ADM. The approach is easy for surgeons to perform and is associated with high levels of patient satisfaction and low complication rates. The method uses a minimally sized ADM, which lowers patient costs, making breast reconstruction more accessible to patients in low-income countries.

Another approach to breast reconstruction involves creation of a retropectoral pocket by incising the inferior border of the pectoralis major muscle and releasing all inferior attachments of muscle fibers, with allograft ADM sheets measuring 6 × 16 cm [8]. Although effective, this technique has several disadvantages, including greater injury to the pectoralis major muscle, increased risk of bleeding, and higher costs due to the use of large ADM sheets. Our technique has overcome these disadvantages. First, separation was performed along the pectoralis major muscle, reducing tissue damage and shortening recovery time. Second, the incision made in the pectoralis major muscle was much closer to the sternum, providing a far better visual field for tissue dissection and hemostasis. Third, the inferior attachments to the muscle fibers were dissected and only partially cut off, preserving the natural curvature of the breast lower pole and achieving moderate remediation of mastoptosis with a very small sized ADM sheet. Finally, the implant was inserted into the soft tissue pocket formed by the pectoralis major muscle and serratus anterior fascia, limiting lateral displacement and enhancing lateral protection.

Capsular contracture is a common complication associated with implant-based breast reconstruction. Although the cause of capsular contracture remains unclear, a local inflammatory response is regarded as the primary pathogenic mechanism in the formation of a fibrous capsule [9]. Breast implants can induce aggregation of inflammatory cells, leading to fibrosis. The application of ADM [10,11,12], especially human-derived ADM (HADM) [13], may reduce capsular contracture by decreasing levels of inflammatory parameters, including reducing the numbers of myofibroblasts, fibroblasts, macrophages, vascularity, and EndoMT in capsule tissue; reducing the expression of TGF-β1 and platelet-derived growth factor B (PDGF-B); and inhibiting the activities of interleukin (IL)-1, IL-6, IL-8, and vascular endothelial growth factor (VEGF) [10, 14,15,16]. Consistent with this, transforming growth factor-β1 (TGF-β1) and leukotriene inhibitors have negative effects on capsule formation [17]. Other complications of breast implant surgery include seroma and hematoma. A retrospective review [18] reported that the incidence of seroma in patients undergoing breast reconstruction with ADM ranged from 1.5% [19] to 24.3% [20], and blood-related lesions, including hematoma and seroma, have been associated with capsule formation and the recurrence of contracture [21].

In our study, the use of a small ADM to cover the implant rarely resulted in capsular contracture or seroma formation. The use of a retropectoral lateral pocket with ADM may apply sufficient pressure to the implant, reducing the incidence of hematoma and seroma, and avoiding implant compression and deformation. Alternatively, the location of the pectoralis major muscle incision close to the sternum may be beneficial for hemostasis of the internal mammary artery perforator and reduce postoperative hematoma.

This study had several limitations. First, this surgical method cannot be utilized in patients where the inferior border of the pectoralis major muscle is positioned higher than the inframammary folds. An alternative technique for these patients is to make a horizontal incision across the inferior border of the pectoralis major muscle followed by insertion of ADM or TiLoop® Bra to maintain the shape of the breast and provide better aesthetic results [8, 22]. Second, this was a retrospective review of operations performed by a single surgeon on 163 breasts in 117 patients that mainly resided in developed coastal areas of China; consequently, selection bias was unavoidable. Last, the small sample size from a single institution suggests findings from this study may not be generalizable to other populations.

In conclusion, submuscular implant-based breast reconstruction using a pectoralis-serratus musculofascial sling and ADM can achieve good aesthetic outcomes with high patient satisfaction. This technique, including the construction of a lateral pocket for implant coverage, was easy, rapid, and safe, with low rates of revision, postsurgical seroma and long-term capsular contracture. Prospective multi-center cohort studies with much larger sample sizes are warranted to confirm these findings.