Introduction

Primary augmentation mammoplasty, using breast implants, is a commonly performed procedure by plastic surgeons. Since the report of the use of the first breast implant in 1964 in a subglandular pocket [1], the plane for breast implants has been primarily referred to by its position in relation to the pectoralis major (PM) muscle. Regardless of the name given to the technique, a breast implant almost lies in front of or behind the PM with the exception of the muscle splitting biplane pocket where the implant lies in front of and behind the pectoralis at the same time. The concept of muscle splitting technique in combination with subfascial augmentation was first given by Baxter for the correction of dynamic deformity or its selective use in primary subfascial augmentation in 2005 [2]. The muscle was split at varying levels and was used in conjunction with the subfascial technique [2, 3]. The muscle splitting biplane technique was fully described later as a separate technique with well-defined anatomical landmarks and was reported for its use in primary augmentation mammoplasty in 2007 [4]. The technique and the concept have been extended for their use in other implant-related primary procedures such as mastopexy with augmentation [5, 6] and multiplane internal mastopexy with augmentation [7]. The technique also has been reported for secondary corrective procedures following subglandular and submuscular augmentation mammoplasties [8,9,10,11,12]. The technique has been used and reported by various other authors, for its use in primary as well as secondary procedures [13,14,15,16,17]. Follow-up and review articles of muscle splitting biplane technique have been frequently reported and published at regular intervals and have shown acceptable results and outcomes [18,19,20]. The current article is a 13-year data analysis of 1511 consecutive muscle splitting biplane primary augmentation mammoplasties carried out by a single surgeon.

Materials and Methods

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

Surgical Procedure

All patients had their procedures done using general anaesthetics with complete muscle relaxation as a day case, and all patients had perioperative intravenous antibiotics. Arms were placed and supported on an arm board at an angle less than 90°. A line is marked from mid-suprasternal notch to xiphoid process. A pocket is approached through an inframammary incision 5 cm wide and starting about 6 cm from midline. With nipple as the central point, a 2.5–3-cm-wide cleavage is marked bilaterally as the medial boundary. Measurements from the nipple to marked medial boundary are taken and transposed laterally as the lateral margin of the pocket. Lateral boundary of the pocket is limited by anterior axillary line, and implant base is always selected corresponding to the footprint of the breast. Vertical boundary is normally about 14.5 to 15 cm measured from inframammary incision upwards. Medial and lateral boundaries are joined together in a circumferential manner with special reference to inframammary crease. All patients have their nipple covered using a transparent sticky dressing. Subglandular pocket is created using cutting diathermy, extending from the junction of the middle and lower third of the sternum to the anterior axillary fold and crossing just below the level of nipple-areolar complex (NAC). Muscle splitting is commenced from the junction of middle and lower third and extends up and laterally to the anterior axillary point and crossing just below the NAC (Fig. 1a, b). Lateral third of the muscle split is done slowly using electro-cautery on coagulation mode as branches of thoracoacromial axis are often encountered. Irrigation of the pocket is performed using saline and diluted povidone-iodine. Implants are placed in the pocket, haemostasis rechecked before closure. Wounds are closed in three layers using 2–0, 3–0 and 4–0 absorbable sutures. Light adhesive dressings are placed, and a support brassiere is put on. Patients are discharged 3–4 h post-operatively with a supply of oral antibiotics (co-amoxiclav 500 mg/125 mg 8 hourly for 5 days or a substitute, if allergic to penicillin) and analgesia (Diclofenac 50 mg 8 hourly for 3 days followed by paracetamol 60 mg 4–6 hourly for 5 days). Wounds are checked in 2 weeks’ time.

Fig. 1
figure 1

a A diagrammatic and anatomical illustration of the pectoralis major origin and extent along with the level of muscle split. The muscle split starts at the level of middle and lower third of the sternum, outlined by blue dots. Reprinted with permission from Khan [20]. b Schematic illustration of a side view of an implant in muscle splitting biplane showing upper pectoralis covering the implant, while lower pectoralis lies behind the implant. Reprinted with permission from Riaz M, Khan UD. 2015. Use of multiplane internal mastopexy for ptosis correction revision-augmentation mammoplasty. Plast Aesthet Res 2:120–6

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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 patients had their primary augmentation mammoplasties consecutively performed in muscle splitting biplane pocket. The mean age of the patients was 29.4 ± 8.56 years (range 18–67). Of the 1502 patients with documented implant sizes, 1272 patients had same-size implants, mean 340 cc ± 58.3 (range 170–700), and 230 patients had two different-size implants for correction of asymmetry. Of these 230 patients, mean implant size on right and left was 341 cc ± 61.5 (range 200–655) and 345 cc ± 67.4 (range 200–605), respectively (Table 1). Of the 1495 recorded surface texturing, only 3.1% patients had smooth-surface implants (Fig. 2). Periprosthetic infection was seen in 10 (0.6%) patients, 38 (2.51%) had wound-healing issues and 5 had late seroma. A haematoma was seen in 10 (1.5%) out of recorded 1501 patients (Fig. 3). The presence of capsular contracture (CC) was recorded at three monthly, six monthly, one yearly and two yearly or a longer period. Of the recorded follow-up in 1260 patients at three-months, three had grade III/IV CC. At six-month follow-up recorded in 360 patients, three patients showed grade III/IV CC. A one-year follow-up recorded in 216 patients showed Grade III/IV CC in another three patients. Of the 133 patients followed up for two years or longer (range 2–12 years, median 6) another nine patients were found to have Grade III/IV CC (Fig. 4). Secondary procedures were performed for various reasons in 93 (6.15%) of the 1511 patients. The leading reasons for revisions in 93 (6.1%) patients were:  25 (1.65%) for bigger implants, 33 (2.2%) wanted to replace implants for various reasons and wished for bigger implants as well. Of these 93 revision cases, 18 (1.2%) patients were treated for capsular contracture and 9 (0.6%) cases for implant rupture (Table 2 and Fig. 5). Average time between primary and revision surgery was 5.4 ± 3.5 years (range 0.3–11.0) (Table 2).

Table 1 Size of the implants used in primary muscle splitting biplane augmentation, size of the implants removed in revision mammoplasties and the size of the re-implants in both symmetrical and asymmetrical breasts
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Fig. 2
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Make of the implant in primary procedures and their relative distribution to revision mammoplasty, capsular contracture and implant rupture

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Fig. 3
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Early post-operative complications following muscle splitting mammoplasty and their distribution for surgical or conservative management

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Fig. 4
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Reasons for revision mammoplasties and their relative distribution (N = 93)

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Table 2 Relative distribution of the size of the implants in four main types of revision surgeries and the timescale of their presentation
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Fig. 5
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Relative distribution of the causes for replacement in patients who exchanged their implants for various reasons and went bigger at the same time

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Smoking status was recorded in 1491 primary augmentation mammoplasty patients, and of these, 438 (29.4%) were smokers. Smoking status also was recorded in 85 revision surgeries, and of these, 16 (18.8%) were smokers. Drain was used in 79 (5.3%) and 7 (7.5%) of primary and revision groups, respectively.

There was no anaplastic large cell lymphomas (ALCL) or deep venous thrombosis recorded in the series.

Discussion

An ideal pocket for augmentation mammoplasty procedure is challenging. All techniques described so far may have certain advantages over the other procedures, and despite the fact that how meticulously or carefully these techniques are performed, the element of individual variations of breast at the time of presentation of surgery and its natural history later on in each patient make it extremely difficult to declare which can fit and suit all individuals. Anatomically, the breasts lie in front of the PM and for an ideal and most natural three-dimensional result, an augmentation should be performed using an ideal filler material in the subglandular or prepectoral plane and hence the reason for implant placement in this pocket when first described [1]. The subglandular pocket yields a three-dimensional natural result when compared to an implant placed in a two-dimensional total submuscular pocket. The subglandular pocket has various advantages because of its easy and quicker pocket dissection along with its reproducible, predictable and natural results in suitably selected patients. However, the marriage between the consistent filler material of the implant and the inconsistent physical characteristics of the breasts may not remain in harmony for too long, and the initial good results cannot be relied upon in the long term, requiring revision surgeries in many patients [21]. The initial subglandular pocket introduced in 1963 was quickly changed to total submuscular augmentation [22], not for the lack of appearance but due to a high and unacceptable rate of capsular contracture [23]. The submuscular technique has been evolved since then to render the submuscular results into more three-dimensional results comparable to subglandular pocket and to bring harmony in the outcome between its early and long-term results [24]. One such commonly used partial submuscular technique is dual-plane technique [25]. The technique is very commonly used but is not without an avoidable complication generally known as dynamic breast deformity or breast animation deformity (BAD).

Dynamic deformity or animation deformity is generating a lot of interest and concern among surgeons and patients alike and merits special consideration in this follow-up article. The complication is totally due to PM release from its fixed point on the sternum, costal margins, ribs and rectus fascia, allowing freed muscle to retract, reposition and reattach to the breast envelope and later to the implant capsule. The released muscle leads to the creation of a panniculus-carnosus muscle effect, which eventually results in breast skin envelope distortion and deformity when the muscle is activated [9, 10]. This disfiguring deformity is well described [2, 26], its grading system well outlined [26, 27] and its incidence well reported in primary augmentation mammoplasty as well implant-based breast reconstructions as 53% and 75.6%, respectively [27, 28]. However, a well-researched meta-analysis of the topic suggests that the incidence could be higher in primary augmentation mammoplasty as the response rate of the questionnaire was low of a small sample. The research article also reports that breast animation deformity or dynamic deformity is not only a cosmetic problem but also a functional problem which may eventually affect patient’s quality of life [29].  The deformity can be reversed either converting dual plane to the muscle splitting biplane technique [9, 10, 30–32], combining the muscle splitting technique with the subfascial technique [2, 3], or converting retropectoral to prepectoral position of the implant in breast reconstructions cases [30,31,32].

Another meta-analysis on animation deformity concluded that animation deformity was treated by muscle splitting biplane technique with least complications [9, 10] when compared with conversion of dual plane to prepectoral or subfascial plane in terms of skin envelope viability, capsular contracture and excessive rippling.[32] In selected group for subglandular and subfascial conversion, patients often needed advanced skin viability tests, acellular dermal matrix or auto-fat grafting in breast reconstruction group-related animation deformities.[32] However, the critique of the muscle splitting technique in this meta-analysis article erroneously reported the technique as being “excessively destructive” citing a reference in which Scott Spear referred excessive destruction, thinning and depression of the lower pole to the Pelle-Ceravolo technique [27, 32]. In the Pelle-Ceravolo technique, the pectoralis was bisected vertically, transecting the lower half of the pectoralis major as opposed to pectoralis splitting along the muscle fibres with no release in muscle splitting biplane technique [4, 26, 32]. In the current series, revision rate including bottoming down was well within the acceptable range (Fig. 5). Alnaif’s meta-analysis also has referenced the limitation of the size of the implants (greater than 400 cc) used in muscle splitting biplane. There was no such limitation or size restriction in earlier or current series (Table 1).

The muscle splitting biplane technique itself is an evolution of partial submuscular where the technique gives very natural lower pole fullness along with adequate muscle cover superomedially. There is no release of the muscle and hence no animation deformity as reported in the original article with a follow-up of 1.2 years [4]. Subsequent 6- and 9-year follow-up articles did not report this deformity either [8,9,10,11,12,13,14,15,16,17,18,19,20]. Similarly, there was no animation or dynamic deformity reported by other authors to date [13,14,15,16,17, 33]. The muscle splitting technique gives a natural and longer-lasting stable results (Figs. 6, 7 and 8). The muscle splitting biplane procedure is reproducible with a quick learning curve, and the safety of dissection has been established with no risk to the innervation of the pectoralis major muscle [33]. Lack of animation deformity prevents physical or chemical denervation [26, 28, 31, 34]. However, the dynamic movement of the implant resulting from muscle contraction that displaces the implant laterally but without a pull or distortion of breast or breast envelop skin can still happen [35]. This lateral mild displacement is a Grade II of the Spear [27] type and clinically not noticeable in the muscle splitting biplane technique due to the locking of the implant superolaterally at the anterior axillary fold where the muscle split ends (Fig. 1a) [4].

Fig. 6
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a, b Preoperative pictures of a 24-year-old patient following childbirth. c, d Post-operative pictures taken 4 months following augmentation mammoplasty in muscle splitting pocket using 300 cc round cohesive gel silicone implants. e–g Pictures showing results 13 years following augmentation mammoplasty. Patient had two more children following her mammoplasty

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Fig. 7
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a, b Front and side views of a 20-year-old nulliparous female with breast hypoplasia. c, d Front and side view six weeks following augmentation mammoplasty in muscle splitting biplane pocket, using 300 cc round microtextured cohesive gel silicone implants. e–g Front and side views 13 years following augmentation mammoplasty showing good and stable results

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Fig. 8
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a, b Preoperative pictures of a 25-year-old nulliparous patient presenting with hypoplastic breasts. c, d Post-operative pictures taken two months following augmentation mammoplasty using 300 cc cohesive silicone gel microtextured implants in muscle splitting biplane. e–g Pictures taken 13 years following augmentation mammoplasty showing stable results

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Following the report of absence of animation deformity, in the first original article [4], no animation deformity evaluation was carried out in the later part of the series [19, 20, 33]. Similarly, no animation deformities have been reported by other authors as well [13,14,15,16,17, 32]. Another recent development is the concept of the triple-plane technique, a submuscular pocket approached through its lateral edge [36]. After the creation of the submuscular pocket, the pectoralis is incised from its lateral edge to its sternal insertion at the nipple level, with no muscle release and no animation deformity noted in 524 patients [36].

Many authors have reported various revision rates in their follow-ups depending on the timescale the patients were followed up. In early follow-up of 1 to 3 years, revision rates of 0% to 1.97% were reported [4, 37, 38]. Follow-ups ranging between 6 and 7 years showed a revision rate of 3.7% and 4.2%, respectively [39, 40].

However, compiling long-term results following primary breast augmentation mammoplasty can be daunting and challenging, and for this reason, these reports are not frequently reported and often involve more than one operating surgeon, more than one technique, more than one type of implant used for various types of breast procedures. Even though there is an advantage that a good mix of surgeons, techniques or implants can allow us to expect a range of acceptable results, the lack of uniformity in execution of a surgical technique, variation of surgical techniques employed or diversity in behaviour of physical characteristics of implants may sway the results between broad ranges [20, 41,42,43,44,45]. One such report of a 25-year-old follow-up performed by Dr Handel showed a reoperation rate of 15.5% in primary augmentation mammoplasties [43]. Results following primary augmentation mammoplasty by a single surgeon are not frequently published and may still have different types of implants or different techniques used [45, 46]. In one such study, where a single surgeon operated on all patients, the overall results showed a 9.4% revision rate in all types of implants and 11.9% of reoperation in round implants alone following 6-year follow-up [46].

A longer follow-up almost always shows a rise of revision surgeries, even when all surgeries are performed by the same surgeon, using the same type of implants with the same technique. In a report of first 125 bilateral primary cases in muscle splitting augmentation mammoplasties with a follow-up of more than a year, there was no reported revision [4]. At six years, the revision rate in 914 muscle splitting primary augmentation mammoplasties rose to 1.2% [20]. An 8-year follow-up in 1298 muscle splitting primary mammoplasties showed a revision rate of 1.4% [18]. However, there was a sharp increase in revisionary procedures, from 1.2% at 6 years to 6.15% at 13 years in the current series.

Early post-operative emergency procedures, whether requiring surgical intervention or not, are not of implant origin and were not included as revision surgeries. There were 10 (0.66%) cases of haematomas, 10 (0.66%) periprosthetic infections and 38 (2.5%) had wound-healing issues (Fig. 3).

Breast implant-associated anaplastic large cell lymphoma (BIA ALCL) is a hot topic and is a serious condition; luckily, the incidence of the condition is rare and acceptable risk is 1 in 30,000 patients and may take up to 8 to 10 years to develop. The condition is predominantly related to textured implants, especially the macrotextured variety (Allergan, Inamed, McGhan, etc.) [47]. Of the 1495 patients in the current series, 700 patients had smooth or microtextured/nanotextured implants, 215 had macrotextured implants and the rest had varying degrees of texturing (Fig. 2). Late seroma was seen in five patients, and all patients had macrotextured implants [48]. These seromas routinely have an ultrasound examination, ultrasound-guided aspiration and immunohistochemistry for CD30 to exclude BIA ALCL. There was no BIA ALCL diagnosed so far in the series probably due to the low incidence of the condition and low number of macrotextured implants used in the series. The author also uses diluted povidone-iodine for pocket irrigation and implants immersion before insertion. Povidone-iodine is quite effective against gram-negative bacteria, which may possibly be involved in the development of BIA ALCL, as proposed in the gram-negative bacteria biofilm pathway [49]. There is a possibility that some patients in the current series may have developed the condition and were treated elsewhere, but no request for release of clinical notes and pictures has been requested by any other physician or an attorney.

Request for change of implants for a bigger size only was the most common reason for the revision (Fig. 5). The author’s earlier report for preoperative breast implant size selection, on a 3-year reoperation rate in 507 patients, was noted at 0.2%. However, the current larger data and longer follow-up show that 25 (26.95%) patients of the 93 revision mammoplasties requested bigger implants, forming a total of 1.65% of 1511 patients. The mean duration between surgery and request for reoperation was shortest in this group (Table 2). Of these 25 patients who requested larger implants, 10 patients wanted 800 cc implants with a round fake look and the muscle splitting biplane pocket was changed to a subglandular pocket. Even though the author has used up to 700 cc extra high-profile implants in primary augmentation mammoplasty, larger than 700 cc implants with wide bases are not recommended for primary or secondary mammoplasty as these may interfere with pectoralis innervation [33]. Capsular contracture was the second most common reason for revision seen in 93 revisionary surgeries. As one would expect, there was a sharp rise in capsular contracture when follow-up was carried out for two years or longer. It must be noted that this 6.8% CC was seen in only 133 patients, forming 8% of the 1511 patients (Table 2, Fig. 9). Exchange for implant was performed in patients presenting with various problems and most of them requested larger implants at the same time. In this group, the mean time between surgery and reoperation was longest (7.9 years, range 4–11), reflecting the stability of results (Table 2 and Fig. 5).

Fig. 9
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Distribution and timescale of cases of capsular contracture in muscle splitting mammoplasty (N = 18)

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Of the 93 revision surgeries performed by the author in this series, nine implants were found ruptured and constituted 9.6% of the 93 revisions or an overall incidence of 0.6% (Fig. 2). True implant rupture, just like capsular contracture, is difficult to estimate in any long-term follow-up as the patient may not be aware of it or may have moved out of the area for various reasons or may have gone to another surgeon. Other 6-year-old and 25-year-old studies showed a similar rupture rate of 1.5 [43] and 1.6%, respectively [42].

The make of the implants also was looked into for their distribution and involvement in revisionary surgeries relative to the number of the implants used (Fig. 2).

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. All patients had round silicone gel implants with 97% having varying degrees of textured surfaces and using the single muscle splitting biplane technique. As the data presented in the article suggest, the follow-up number gradually decreased over a period of time, from 83% at three months, 23% at six months, 14% at one year to 8.8% for two years or more. Even though 133 patients were seen for two years or more, with a mean of 6 years and a range of 2–12 years, still 91.2% of patient data were not available for a more reliable or accurate conclusion, especially when the possibilities of complications like capsular contracture and implant rupture are known to occur most. These difficulties are commonly experienced and reported in other long-term follow-ups and largely due to the patients moving to other areas, not coming for follow-up if all is well or may have gone to other surgeons for complications and further treatment [43].

Conclusion

The muscle splitting pocket for primary augmentation mammoplasty is a reliable and reproducible procedure with an acceptable low revision rate.