Introduction

Primary augmentation mammoplasty in muscle splitting biplane is a partial submuscular pocket where an implant is placed behind and in front of the pectoralis major at the same time (Figs. 1, 2, 3) [1]. It is an extension of partial submuscular augmentation as the implant is not covered completely by the pectoralis (Figs. 1b, 2d, 3a) [2]. The concept allows better lower pole definition and closer breast cleavage without lateral displacement of the implant as the device gets locked at the lateral end of the intact pectoralis (Figs. 1b, 2c, 3a) [1,2,3]. The procedure has been used for primary [1, 4,5,6,7,8] and secondary procedures [9,10,11,12] including correction of animation or dynamic deformity [1, 3, 13,14,15] commonly seen following partial submuscular or its popular extension dual plane pocket (Fig. 3b) [16, 17]. The procedure is reproducible with longevity of results and acceptably low revision rate [3, 18,19,20] with no anatomical disruption of muscle activity or risk to its nerve supply [1, 3, 18, 21]. However, there is no detailed account, appraisal or nature of revision surgeries arising from the primary augmentation mammoplasties in muscle splitting pocket. As such, this is the first article, in which the number, distribution and nature of the revisionary surgeries are documented since the pocket was first described in 2007 [1].

Fig. 1
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a A diagrammatic and anatomical illustration of pectoralis major origin and extent along with the level of muscle split. The muscle split starts at the level of the middle and lower third of the sternum, outlined by blue dots. b Schematic illustration of an implant in muscle splitting biplane showing upper pectoralis covering the implant while lower pectoralis lies behind the implant

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Fig. 2
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a Intraoperative picture showing right split upper and lower pink and healthy pectoralis major held with silk sutures in a patient for implant replacement, who had her breast augmentation in muscle splitting biplane 12 years ago. b Silk sutures have been pulled apart to show lower subglandular pocket communicating through the split with submuscular space. Fourth rib and third intercostal space are clearly visible under the pectoralis major through an inframammary incision. c A schematic intraoperative drawing of muscle splitting pocket seen through inframammary incision marked in yellow outline as rectangle. For the sake of simplicity and understanding of the dissected pocket anatomy, total extent of pectoralis major split is shown from the junction of the lower and middle third of the sternum up to its joined lateral end in bright red. Lower subglandular pocket is communicating with the upper submuscular pocket through the gap in the split muscle, separated in the drawing by forceps below and breast retractor above, respectively. d Smooth cohesive gel silicone implant in place through the split pectoralis. Lower split pectoralis is visible through the implant with the silk suture in place to upper border of lower split pectoralis. The silk suture in the lower border of the upper split pectoralis delineates upper submuscular pocket from the lower subglandular pocket

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Fig. 3
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a Pectoralis major relationship to implant in muscle split technique as seen in front view. Upper split pectoralis major lies in front and lower split pectoralis major lies behind the implant. b An illustration showing implant in dual plane. Pectoralis major muscle in dual plane lies completely in front of the implant as shown in front view

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Materials and Methods

A retrospective data analysis for revision surgeries following muscle splitting primary augmentation mammoplasties performed between October 2005 and October 2018 was carried out.

Methods

All examinations, measurements, planning, surgeries and follow-ups were done by the author. All patients were marked preoperatively in the standing position, according to the procedure planned. Patients were operated under general anaesthesia with full muscle relaxation and arms extended less than 90°. The inframammary incision is generally used for revisionary surgery excluding those requiring mastopexy. All patients had nipple shields to minimize incision site contamination. Double gloves were used routinely of which the outer layer was changed before device handling; perioperative intravenous antibiotics were given and pockets irrigated with diluted povidone iodine before the insertion of devices. All procedures are performed as a day procedure, and drains are not used as a routine unless necessary. Pocket adjustments, using capsulotomies or capsulorrhaphies, are performed where necessary and to accommodate a smaller or larger implant. Also muscle splitting is extended, where necessary, to accommodate a larger implant diameter. Patients are followed for at least 2 years at 2 weekly, 3 weekly, 3 monthly and 6 monthly intervals.

Statistical Analysis

The data were analysed using the Statistical Package for the Social Sciences (SPSS), version 19.0. The results are presented in the text as frequency, percentage for qualitative/categorical variable (difference in implant size) and mean ± S.D for quantitative/continuous variables (age and implant size). The Chi-square test is used to compare the categorical variable, and t test for quantitative/continuous variables. In all statistical analyses, only p values < 0.05 are considered significant.

Results

A total of 1511 primary augmentation mammoplasties were performed by the author during the period specified. Of these 1511 patients, 93 (6.1%) had their revisionary or secondary surgery following primary augmentation mammoplasty in the muscle splitting pocket. The mean age of the patients was 33.8 ± 9 years (range 20–60). Of the 93 patients, 78 patients had the same size implants (mean 337 cc ± 53.5, range 230–495) and 14 had different size implants. Of these 14 patients, mean implant size on the right and left was 331 cc ± 59.4 (range 225–425) and 351 cc ± 61.7 (range 260–450), respectively (Table 1). Of the recorded texturing in 1495 patients, only 3.1% had smooth implants. All revisionary surgeries involved those patients who had textured implants. The leading causes for revision were implant exchange for various reasons and wanting larger implants in 33 (35.4%), 25 (26.8%) wanted to go for bigger implants and had no other associated problems, capsular contracture was seen in 18 (19.3%), implant rupture in 9 (9.6%), 4 (4.3%) patients had surgery for recurrent back-to-front flipping, 2 (2.1%) patients requested to smaller implants, 1 (1.07%) patient had fold flaw failure, and in 1 (1.07%) patient, the cause was not recorded (Table 2). Periprosthetic infection and wound healing issues were seen in 1 (1.1%) patient, and 5 patients presented with late seroma. No haematoma, breast implant-associated anaplastic large cell lymphoma (BIA ALCL) were recorded in the series.

Table 1 Preoperative size of the implants in the series, size of the explanted implants in revision cases, and size of the exchanged implants in revision cases
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Table 2 Breakdown of the preoperative size of the implants used in the revisionary surgery, size of the implants exchanged following revisionary surgery, and the time taken in each group, from initial surgery to the revision surgery
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Discussion

The quest for an ideal breast implant pocket is far from over. Various implant pockets and techniques have been described so far, but essentially, the pectoralis major remains the anatomical divide for all the techniques described so far, that is, prepectoral or subpectoral. An ideal breast pocket to enhance a breast should ideally be prepectoral, where the anatomical position of the breast gland is located. However, changes related to ageing, pregnancy, breast-feeding and weight loss bring a discord between the ever-changing breast gland and the permanent physical nature of the breast implants currently in use. The harmony between the filler and the target gland is likely to dissociate over a period of time and eventually break down in the majority of cases. A submuscular position of the implant, even though aesthetically less rewarding, does provide stability to the results and extends support to the ever-changing physical characteristics of the breast tissue. To improve the aesthetic appearance, to enhance the three-dimensional outcome of the breast and to bring harmony between the permanent nature of the device and often ever-changing breast tissue, various modifications have been introduced. Two such recent modifications are the dual plane pocket and subfascial techniques [16, 22]. Dual plane is a modified partial submuscular and subfascial being an extension of the subglandular technique, where pectoral fascia is incorporated into the breast gland. However, when the dual plane is used, animation or dynamic deformity can be distressing with high incidence [17, 18, 23,24,25] and may require repositioning of the implant in the prepectoral location [26] or conversion of the dual plane or partial submuscular plane to a muscle splitting pocket [9, 13,14,15, 23, 25]. On the other hand, the longevity of the subfascial pocket has not shown much advantage over a simple submammary pocket [27]. The muscle splitting pocket, another modification of partial submuscular, is unique in that the implant lies in front of and behind the pectoralis at the same time and a three-dimensional result is achieved without releasing the muscle; hence, there is no animation or dynamic distortion of the breast (Figs. 1a, 2b, 3a). The implant placement in this pocket gives a natural close cleavage due to the commencement of split above the cleavage hindering costal margin of the pectoralis and the locking effect of the device at the un-split lateral end of the pectoralis (Fig. 4a–f). The locking effect is produced when an implant is placed after splitting the muscle, a part of the muscle is over and a part of it behind the implant; however, the two split ends join laterally where the locking effect is created (Figs. 1a–b, 2c, 3a). The superior pole of the submuscular implant is prevented from being displaced or slipping out laterally, where the two ends of the split pectoralis meet together (Figs. 1b, 2c, 3a). Similarly, the lateral subglandular part of the implant, extending beyond and laterally to the confluence of the split pectoralis, disallows the implant to displace superiorly, and hence, no high riding breasts are seen or special bands or dressings are required to keep the implants down (Figs. 1b, 3a). The revision rate following muscle splitting augmentation mammoplasty was significantly lower when compared with submammary and partial submuscular pocket. In a large series with a follow-up of 6 years in subglandular, partial submuscular and muscle splitting pockets, the revision rate was reduced from 7.3% in submuscular and 6.0% in subglandular to 1.2% in muscle splitting pocket, respectively [3]. The longevity of the results in muscle splitting pocket has been documented [18], making the technique a useful option for augmentation mammoplasty.

Fig. 4
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a–c Preoperative views of a 32-year-old patient who had her augmentation mammoplasty 4 years ago. She had 340 cc cohesive gel silicone implants in the muscle splitting biplane pocket. She was not happy with her cup size and wanted to go larger. d–f Postoperative views showing results following revision surgery using 560 cc microtextured implants in muscle splitting biplane pocket

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The muscle splitting pocket, however, is not devoid or free of complications or revision surgeries. Surprisingly, the largest proportion of the revision surgeries (35.4%) comprised those patients who wanted to replace implants before the expiry of its presumed life expectancy of 10 years. Not surprising, most of these patients wished for larger implants and some required treatment for associated breast changes like ptosis requiring mastopexy [4, 6], sliding ptosis requiring internal lift with device size increment [5, 28], improvement of cleavage using multilayer lateral capsulorrhaphy or higher device repositioning requiring inframammary crease relocation using multilayer capsulorrhaphy [11]. Requests for smaller size implants were not frequently made. Smallest size implants used in revisionary surgery in the series were 230 cc. In such a scenario and to match the breast footprint, exchanging a high profile implant for a lower profile is extremely important. These patients may require lateral capsulorrhaphies and/or inframammary crease relocation to reduce the dimensions of the pocket and minimize skin excess issues. In some cases, mastopexy is strongly advised if the patient decides to have a significant drop in implant size or requests explanation altogether.

The second most common reason for surgery was a request for larger implants with no other associated problems (Fig. 4a–f). A good process of consultation, adequate information and simulation of breast cup size by preoperative trial of implants in a bra may reduce an early 3-year reoperation rate, but the long-term results in this study have shown that reoperation for bigger size, standing at 26.8%, constituted a large proportion of revision surgeries [18, 29, 30]. Two of the patients who requested a larger size and chose 800 cc implants had their implant pockets changed from muscle splitting to subglandular pocket in order not to disturb the medial and lateral pectoral nerves supplying the pectoralis major [21].

The incidence of capsular contracture and its treatment, with an incidence of 19.3% in this series, was the largest clinical reason for reoperation. Capsular contractures are treated according to the degree and symptoms at the time of presentation (Fig. 5a–f). In grade four capsular contractures, total or near total capsulectomies are performed, whereas in grade two and three capsular contractures, capsulotomies are performed. Capsulotomies are also performed in patients requiring larger implants, to accommodate the larger size implant [31].

Fig. 5
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a–c Preoperative pictures of a 40-year-old patient, who had her augmentation mammoplasty 13 years ago with 350 cc microtextured cohesive gel silicone implants in the muscle splitting biplane pocket. She had a little asymmetry, grade III capsular contracture with left implant sitting a little higher and wanted to go bigger. d–f Postoperative views 1 month following implant exchanged with 500 cc smooth cohesive gel silicone implants placed in the muscle splitting biplane pocket

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Implant rupture (9.6%) was the fourth largest group and formed a significant portion of revision surgeries in the current series.

The overall revisionary rate documented in this 13-year follow-up of 1511 mammoplasties stands at an acceptable 6.1%. In another recently published article, timings for these revisions were reported [18]. The mean times for surgeries for larger implants, for capsular contracture, implant rupture and to exchange implants were 2.7 years, 4.5 years, 6.2 years and 7.9 years, respectively. The average timing for revisionary surgeries suggests that the request time for larger implants (26.8%) was shortest, at 2.7 years, within the patients who had revisionary surgery. Surgeries performed for implant rupture constituted 9.6% of the revisionary surgery with an average time of 6.2 years following their first surgery. Most of the implant ruptures were silent, but some were symptomatic with loss of breast shape (Fig. 6a–f). Implant exchange (35.4%) for all reasons took an average time of 7.9 years (Fig. 7a–f). The mean time for capsular contracture surgery (19.3%) was 4.5 years (Table 2). Back-to-front flipping of implants resulting in flattening of the breast is not a well-recognized or reported complication. The condition was seen when microtextured, high profile, low gel fill ratio implants flipped 180° with the flat base lying on the front and round front facing backwards (Table 2) [32]. The flipping can be corrected using outpatient-based external manipulation; however, recurrence of the condition may require surgical intervention and was carried out in 4 patients in the series [32].

Fig. 6
figure 6

a–c Preoperative views of a 35-year-old patient, who had her augmentation mammoplasty 8 years ago. She had 340 cc smooth cohesive gel silicone implants placed in the muscle splitting biplane pocket. She noticed a change of shape of her left breast and had an ultrasound imaging. Her left implant was found ruptured. d–f Postoperative views 6 weeks following revision augmentation mammoplasty in the muscle splitting biplane pocket, using 375 cc round textured cohesive gel silicone implants

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Fig. 7
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a–c Preoperative views of a 37-year-old patient who had her augmentation mammoplasty 10 years ago using 260 cc and 300 cc round microtextured cohesive gel silicone implants in the muscle splitting biplane pocket on her left and right side, respectively. The patient had a little discomfort on her left side, wanted to replace old implants and go larger as well. d–f Postoperative views taken 3 months following revision surgery. She had 340 cc on her right and 375 cc on her left, textured cohesive gel silicone implants, in the muscle splitting biplane pocket

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The patients, who developed periprosthetic infections, had their implant removed and replaced after 6 months as a routine [33]. The surgery was not included as revisionary surgery as it was not related to the technique. The patients with wound breakdown were treated conservatively, and all experienced full recovery. Textured implants were involved in all five patients who developed late seroma, all of whom had appropriate investigations and none of whom showed CD 30 on ultrasound-controlled aspiration and immunohistochemistry [18]. No BIA ALCL was reported in the series.

Strength and Weaknesses of the Study

The current study is based upon a large number of augmentation mammoplasties consulted, examined, performed and followed up by a single surgeon. Even though a large number of the patients were followed up for a good period of time, the data on the majority of patients were not available for a more reliable or accurate conclusion, especially when the possibility of complications like capsular contracture and implant rupture is known to occur most. These difficulties are commonly experienced in other long-term follow-ups and are largely due to the patients moving to other areas, not coming for follow-up if all is well or possibly going to other surgeons for complications and further treatment.

Conclusion

The incidence for revisionary surgery following muscle splitting primary augmentation mammoplasty is acceptable and can be corrected using the described techniques.