Introduction

Due to the recognition that texturization increases the risk of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) [1, 2], and especially after the Allergan recall in July 2019 with the removal of Biocell® implants [3, 4], the use of textured devices has diminished worldwide and is expected to continue to decline [5,6,7]. In contrast, no global databases have reported confirmed cases of BIA-ALCL from smooth breast implants.

Several studies demonstrate that with proper device handling, anatomical and round breast implant clinical results are practically indistinguishable, even to experienced plastic surgeons [8,9,10,11,12,13,14]. This is believed to be the case because all saline implants for example, especially when underfilled, take similar teardrop shapes in vivo with patients upright but no research has verified this statement in silicone gel implants. To date, no published articles have focused on SRSG devices in particular. Even the largest multicenter cohort study of breast implant outcomes [15] did not discuss in detail the properties of and the aesthetic outcomes that could be achieved with those devices.

This study aims to investigate how SRSG breast implants change their shape depending on implant profile and degree of filling and how those changes correlate to a range of aesthetic outcomes.

Materials and methods

A simple and reproducible experimental model was designed to investigate how SRSG devices changed their shape when switched from horizontal to vertical position and vice versa. SRSG implants of five different implant profiles with two degrees of filling were selected for that aim as follows: moderate, moderate plus, moderate plus extra filled, high, and high extra filled. The implants were last-generation devices with silicone gel cohesiveness type I—the softest cohesive gel [16], of the same manufacturer (Mentor Corp.), and all possessed similar or identical base diameters. Each device was consequently fixed on a specially-created holder with a transparent cling film. Same single piece of wrap was used in order to avoid any differential distortions of individual devices. This permitted the investigator to observe the shape and implant surface changes (Fig. 1).

Fig. 1
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An experimental model designed to study the shape changes of low cohesive SRSG implants in relation to their position. The devices were fixed vertically with transparent kitchen foil, which allowed direct observation from distance without touching the implant. In such an experimental setting, only gravity — the main forces impacting every single process on the earth — was acting on the devices. The figure presents the compared shape changes of a slightly underfilled (column A) and an extra filled high-profile implant (column B) when put vertically. Even with high profile, these devices still take more or less anatomical shapes. The underfilled implant expresses less pronounced upper pole convexity in comparison with its extra-filled counterpart with slightly more vertically orientated shell wrinkles showing the distribution of the gel inside the elastomer. The orientation of the surface wrinkles could help to predict a rippling effect depending on the degree of filling in cases with poor soft tissue coverage, for example in prepectoral BA in thin patients or even in post-mastectomy prepectoral breast reconstruction where a paucity of soft tissue exists

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A retrospective, descriptive analysis based on clinical records and photographic documentation was conducted, recruiting patients of the author’s practice with primary retropectoral breast augmentation (BA) with SRSG cohesive I implants. All patients were counseled following the Declaration of Helsinki guidelines; both verbal and written informed consent were obtained preoperatively. During the informed consent process, special attention was paid to the risks of texturization, such as BIA-ALCL, double capsules, increased bacterial growth, and increased rate of late seromas.

Demographic and medical information for 51 consecutive cases was collected, including age, regular habits, childbirth and breastfeeding, comorbidities, anatomical features, applied operative technique, and type of implant used. In general, patients with thin upper pole tissues and little breast parenchyma who chose smooth devices were advised to consider underfilled implants if seeking a more natural appearance. The patients were operated between August 2018 and March 2020. Considered for inclusion in the study were cases who met the following criteria: primary BA cases with no additional breast procedures performed (e.g., round blocks, mastopexy and breast lift procedures, fat grafting), no additional device used (e.g., acellular dermal matrices (AMDs), synthetic meshes), with the same type of implant used bilaterally, and at least 12 months of follow-up. Patients who did not fulfill at least one of these criteria (n = 5) were excluded from further analysis.

All surgeries were performed by the author in a hospital setting. The same surgical protocol was applied in all cases: procedures performed under general anesthesia via an inframammary incision and the implants were placed in a retropectoral plan. In some cases, a dual plan technique was applied. Redon drains were used in all the cases. Patients stayed overnight, and on the next day, after removing the drains, were discharged. During the postoperative period, patients used sports bras with strong support and were advised to abstain from excessive physical activities for 6 to 8 weeks. No additional massages or compression garments had been recommended to the patients.

The follow-up included clinical examinations at 3 to 12 days after the surgery, 1 month, 6 months, 12 months postoperatively, and once per year after that. In the second year after the augmentation, a magnetic resonance imaging (MRI) study was recommended to all the patients. Photographs were taken before the intervention, on the first month, 12 months, and every year afterward at the time of the regular follow-up. During the analysis of the results, special attention was paid to changes of the breast contour and shape over time, along with the control of the upper pole fullness.

At the 12-month follow-up visit, patient satisfaction was evaluated with a standardized patient satisfaction questionnaire about the facility, medical services, and surgical outcome. The questionnaire was anonymous and was completed by every patient on a tablet computer device under the supervision of the chief nurse who was responsible for maintaining the facility and patient-care standards.

Results

When switched from horizontal to vertical position experimentally, every underfilled implant, regardless of its profile, tended to form a more anatomical shape with less pronounced upper pole convexity compared to a filled one, which still maintained its upper pole fullness even though it was filled with the less cohesive gel. This observation was also registered in high profile devices where the anatomic conformation was even more visible compared with their lower profile counterparts (Fig. 1). Implant surface wrinkles, which indicated gel distribution inside the elastomer shell, were orientated slightly more vertically in the underfilled devices compared to the filled ones where they were more oblique.

Clinical outcomes of 92 breasts (46 augmented patients) were meticulously studied. The mean age of the patients at surgery was 31.8 years (range: 19–56 years). The mean SRSG implant volume was 345.4 cc (range: 225–490 cc) (Table 1). The most frequently used type of implant in the series was the moderate plus profile device (n = 48 breasts). Nearly all patients enrolled in the study demanded correction of the upper pole. All but two patients desired a natural look and maximal natural feeling when touching the breast. The vast majority of the patients were not prone to accept anatomical implants because of the texturization-related risks.

Table 1 Types of smooth round breast implants studied
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The patient analysis revealed a full scope of aesthetic outcomes (Figs. 2, 3, 4, 5, 6 and 7). Desired anatomical correction and natural appearance of the breast were achieved in thin individuals (Fig. 3), patients with significant glandular ptosis (Fig. 4), in women with thoracic outlet deformities (Fig. 5), and cases with constricted lower poles (Fig. 6). The upper pole fullness appeared to be predictable with reliable and stable control over time. In the clinical setting, the upper pole fullness was less pronounced and the contour was more concave than predicted with the experimental model.

Fig. 2
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Undesirably excessive upper pole fullness and upper pole stability over time are main concerns when round implants are being used. The first row depicts three women with relatively similar upper chest contours but with different desires that required different types of SRSG implants for their respective desired results. The middle row shows clinical outcomes after retropectoral breast augmentation with different SRSG low-cohesive implants (depicted below, on the third row). Different color lines show different changes in upper pole contours. Column A demonstrates a case of a 35-year-old patient, para 1, (also depicted in Fig. 4) who desired a natural look without big enhancement and possibly no décolletage changes. Moderate profile slightly underfilled implants of 375 cc were placed in the dual-plane II retropectoral position. The appearance at two years postoperatively is shown. Column B is the case of a 27-year-old patient, nulliparous, who demanded breast enhancement with pronounced but not excessive décolletage. For that aim, high projecting slightly underfilled implants of 300 cc, (same as the one depicted in Fig. 1A) were used. The postoperative picture was taken eighteen months after the surgery. Column C shows a 30-year-old nulliparous patient who desired enlarged, rounded breasts. High-profile, extra-filled 355-cc implants (same as the depicted one in Fig. 1B) were used. The postoperative picture demonstrates the clinical outcome at two and a half years’ follow-up. As in the rest of the case, the upper pole showed to be stable over time

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Fig. 3
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(Above) A 40-year-old thin patient with small breasts (para 1 with breastfeeding) who demanded visible breast enhancement with a natural look. She rejected anatomical devices because of concerns regarding BIA-ALCL. Moderate profile slightly underfilled 275-cc implants were used bilaterally. (below) Appearance 12 months postoperatively shows a nice shape of the breast with gentle take-off at the upper pole

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Fig. 4
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(above) A 35-year-old patient who wanted a very natural look with no additional fullness of the décolletage. She was a para 1 with breastfeeding with a lateralized position of her breast on the thoracic outlet and remarkable glandular ptosis. Moderate-profile, slightly underfilled 375-cc implants were placed in dual-plane II submuscular position and a benign melanocytic nevus over the sternum was removed during the same surgical session according to the patient’s wish. (below) Postoperative results at two years’ follow-up show a moderate change of the breast footprint cranially, aesthetically appealing linear or even slightly concave upper pole (see also Fig. 2, column A), tight and convex lower pole, and diminished intermammary distance. The patient also had lost six kg of body weight since her augmentation surgery

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Fig. 5
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(above) A 32-year-old patient (para 1 with breastfeeding) with empty breasts who desired visible enlargement with shaped but not prominent décolletage and no “round boobs.” She was not prone to accept anatomical devices because of the negative experience of a friend. She had a clinical history of rickets during childhood, presented with thoracic scoliosis with visible asymmetry of the position of the shoulders (the blue lines), and deformation of the thoracic outlet with significant bone prominence of the distal half of the sternocostal junction on her right side (the red arrow). (below) Clinical outcome two years after augmentation with underfilled moderate plus profile implant, 325 cc. Although the breasts look slightly asymmetrical due to the patient’s thoracic scoliosis, a good anatomical shape was achieved

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Fig. 6
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(above) A 32-year-old patient (para 1, no breastfeeding) with breast asymmetry and tuberosity with constricted lower pole and poorly defined inframammary fold, especially on her left breast. Note the asymmetrical position of her shoulders. The patient wanted a breast correction and augmentation with the least possible amount of scarring. She rejected textured devices. (below) Postoperative result 13 months after augmentation with slightly underfilled moderate plus profile 300-cc implants and modification of the parenchyma with radial and cross incisions. Good aesthetic breast shape was achieved with tight and expanded lower pole and linear upper one. No correction of the nipple-areolar complex was made

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Fig. 7
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(above) A 30-year-old patient (para 0) presented with dense glands that offered good soft tissue coverage and small intermammary space. The patient wanted a visibly augmented look. High-profile extra-filled 355-cc implants were used on both sides. (Below) Appearance at two and a half years postoperatively. Because of the excessive breast enlargement, the intermammary sulcus looks even more narrowed. The upper pole was quite stable in time and its fullness was not hampered even cohesive I devices were used. Such an augmented look with pronounced upper pole fullness (see also Fig. 2, column C) could be achieved only with high-profile round implants. Even not fitting the contemporary concepts for aesthetic breast and not common in the author’s practice, sometimes it is simply what the patient wants

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In the series, five patients out of 46 (10.9%) developed postoperative complications (Table 2). One breast had become harder without visible deformation and was interpreted as unilateral capsular contracture Baker Grade II. This change was registered at the second-year follow-up. The patient had no complaints and was left under observation with no progression and no treatment at this time, one year later. A “double bubble” deformity was registered in one patient (2.2%) at 12 months of follow-up, and in one patient (2.2%) one of the implants “bottomed out” 18 months after augmentation. In two patients (4.3%), rippling was registered. No postoperative hematomas, seromas, or implant failures were observed in the series.

Table 2 Postoperative complications
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At their 12-month follow-up appointments, all 46 patients (100%) marked on their surveys that they were “very satisfied” with their surgical results and stated that they would repeat the procedure and recommend it to others.

Discussion

There has been much speculation about the aesthetic superiority of the results that could be achieved with anatomically shaped breast implants. However, no randomized controlled trials of SRSG implants versus anatomical textured implants have been published in the past 20 years.

This study analyzed exclusively the smooth round low cohesive silicone gel breast implants to clarify their properties, shape changes, and their ability to achieve certain clinical outcomes.

Given that the shell of every implant (anatomical and round) folds and wrinkles regardless of surface and fill level, it is worthwhile to be familiar with this deformation and to leverage this knowledge in daily practice [10, 17,18,19]. The last-generation silicone elastomer shells that are currently on the market are more wear resistant and tend to fold less than in the past, which increases their longevity [20,21,22,23].

The vast majority of the patients in the series were not prone to accept anatomical devices because of the texturization and mostly its relation to the BIA-ALCL. The lack of established pathway programs for treating patients with BIA-ALCL in Bulgaria was likely a primary reason for the patients’ concerns. This is an issue in many other European countries too and increasingly determines both patients’ and surgeons’ choice of prosthesis.

In 1999, Robert S. Hamas published a clinical study conducted to evaluate the postoperative shape of saline round implants and compare it with the shape of saline teardrop implants in vivo. Hamas used postoperative radiographs and concluded that round implants are more “anatomical” because they are teardrop-shaped with patients upright and they settle back evenly with patients recumbent, as do normal breasts [12]. Hamas’s study, however, did not examine SRSG implants. In the current study, the findings and clinical observations on implant deformation and shape changes corroborate with the findings of Hamas et al. with the added value of some other advantages that SRSG implants offer, namely reliable and stable over time upper pole filling, medial fullness, lateral protrusion, and greater longevity [6, 10, 13, 24]. Furthermore, silicone low cohesive implants offer a maximal natural touch feeling and avoid the unpleasant clocking sound caused by the moving of saline inside the shell that occurs when the patient changes her body position.

Another clinical study compared highly cohesive silicone round and shaped implants and concluded that, in the hands of an experienced surgeon, the aesthetic result may not be differentiable when using round versus shaped implants in well-selected patients [9]. In the cited study, only low projecting fully-filled textured round implants were explored and no focus was put on the significance of the gel cohesiveness, the implant profile, or the degree of filling, all of which could significantly impact the outcome as has been demonstrated [25]. Aesthetic results could be achieved not only with low profile devices but also with moderate, moderate plus, or even with high profile underfilled devices, depending on the patient anatomy.

To the author’s knowledge, no previous studies had conducted experimental analyses on SRSG implant shape changes. When comparing the experimental and clinical findings of the same types of implants, they tended to have slightly more anatomical shape in vivo compared to on the table. This finding could be attributed to the in vivo compression forces of the pectoralis major muscle and overlying soft tissue: they further impacted the implant shape, affecting mostly its upper half. This was especially remarkable when the dual-plane technique with underfilled moderate-profile or moderate plus profile devices were applied (Fig. 4).

What one appreciates in a clinical setting is the final cumulative outcome of the above-mentioned forces, implant properties, patient anatomy, and factors such as precise surgical technique, the healing process, and response to the implant [26]. The skillful handling of all of those variables is the reason why results obtained by using round or anatomical implants could be practically indistinguishable. However, it is the author’s conviction that the implant type itself plays a leading role in the final aesthetic outcome. When natural-looking and natural-feeling results are desired, low cohesive underfilled smooth round moderate or moderate plus projecting silicone implants would be the optimal choice and the present study confirmed that assumption.

Concerns regarding the uncontrolled upper pole fullness are common but largely unjustified [27]. In this study, the upper pole fullness showed to be predictable and stable over time, which contradicts the assertion of some authors that filling material of round devices tends to descend within the shell and thus hampers maintenance of the upper pole fullness [27].

In summary, with SRSG low cohesive devices, we could achieve any desired breast shape with stable and reliable control of the upper pole fullness. At the same time, we avoid the risks of texturization-associated BIA-ALCL, double capsules, increased bacterial growth, late seromas, increased firmness (which often is unacceptable for the patients and their partners in the author’s practice), malrotation, and increased cost when anatomical devices are used [28,29,30].

Regarding complications, the overall rate of the series was 10.9%, which is comparable to other previous studies [15, 31, 32]. The most common complication was rippling, which was observed in two patients augmented with underfilled SRSG implants to achieve more anatomical outcome. In both patients, the rippling was palpable but not visible, located in the lower outer quadrant – Grade 1a according to the classification of Pantelides and Srinivasan [33]. This location was expected, considering the wrinkle orientation that was observed experimentally. It is well known that textured devices that become adherent to the overlying soft tissue typically manifest a greater degree of rippling than their smooth surface counterparts. However, rippling could happen in smooth implants too and underfilled devices tend to ripple more as explained by Nahabedian MY [34]. Nevertheless, rippling tends to be less noticeable when implants are placed retropectorally due to the cushioning effect and compressive forces of the pectoralis major muscle [33, 34]. This may explain why the incidence of rippling is still lower than those of other studies [33, 35, 36]. Since there was no visible deformation of the breast contour, the two registered cases in this study had no concerns regarding the status of their breasts and no additional treatment has been done. However, ADMs, synthetic meshes and autologous fat grafting are a reliable solution for camouflage and additional support when needed [33,34,35, 37, 38].

Capsular contracture (CC) is a specific implant complication. In this study, there was only one case of Baker II CC, which was registered during a regular follow-up clinical exam palpation with no patient complaints. This complication would have likely been considered a normal status had a form-stable anatomical implant with a textured surface been used. It may be challenging to conduct an accurate assessment of the presence of a CC in a form-stable implant through breast palpation because the prosthesis is firm to begin with. Thus, it likely begins, at best, as Baker grade II in every single case on the physical exam [30]. This fact is particularly important for young plastic surgeons and for those who have no experience with shaped implants, but it is not an issue when SRSG low cohesive devices are being used where an earlier clinical diagnosis is easier and more reliable.

The case with double-bubble deformity was a woman with tuberous breast who denied any scarring or aggressive manipulation on her breast tissue because of concerns about her ability to breastfeed in the future. At the same time, she was not prone to accept an anatomical implant because of the texturization. Thus, only an augmentation with smooth high profile, slightly underfilled implants with minimal modification of the inferior border of the parenchyma with radial incisions was performed. The postoperative double-bubble deformation was expected and the patient was aware of that. The improvement in the group of patients with tuberous breasts is more dependent on the technique for managing breast tissue than on the type of implant used – anatomical or round – and this case supported that because in other cases where appropriate tissue rearrangement had been done, excellent results were registered (Fig. 6). Several studies, including Kolker and Colins, support this conclusion [30, 39, 40]. The patient with the double-bubble deformity scored her level of satisfaction as “very satisfied” at 12 months, which exemplifies that the well-informed patient preoperatively is the satisfied patient postoperatively.

Limitations

Firstly, to date it is still not possible to verify the exact mechanism of implant deformation in vivo. Diagnostic imaging by MRI is the most powerful tool for evaluation of the interaction between the device and the soft tissue [18, 19]. However, to fully imitate the natural situation, augmented patients should be imaged in the upright position. Unfortunately, MRI scans to fit vertically positioned patients are not yet available [19]. That was the reason why MRI was not used as a clinical assessment method of the study itself. However, it is a standard recommendation to every single augmented patient in author’s practice to undergo MRI screening for silent implant ruptures at 2 or 3 years post-implantation, and every 2 years thereafter in accordance to the guidelines of all the renowned plastic surgery societies worldwide.

Only SRSG implants filled with low cohesive gel were studied. In smooth round devices, plastic surgeons can choose among the full range of gel cohesiveness, unlike anatomical implants where, in addition to surface texturization that is inevitable, the surgeon normally receives a firmer gel. Future studies should compare results of patients augmented with SRSG implants of different cohesiveness since that could impact the final breast shape. Another future study could compare clinical outcomes of the same profile implants with smooth and texture surfaces. Thus, one would be able to appreciate more accurately the degree to which the texturization itself could affect the final aesthetic outcome when round implants are applied.

The clinical part of the present study is a retrospective descriptive review based on a single author's experience and perceptions. Ideally, a multicenter, prospective study with a longer follow-up could better evaluate the long-term results of low cohesive SRSG breast implants.

Conclusions

By properly selected SRSG implant and good surgical technique, any aesthetic outcome of a retropectoral breast augmentation could be obtained. The full range of breast shapes and contours, from well-contoured breasts with aesthetically appealing linear upper poles and tight, convex lower ones to breasts with excessive fullness and an augmented look, are fully achievable with no concerns regarding the potential risk of BIA-ALCL and other issues of texturization. Considering the crisis with textured devices, plastic surgeons must pay more attention to smooth implants to be able to meet patient wishes and expectations while keeping also prioritizing patient safety. After having been in use for about 60 years, it is imperative for a prospective study with a longer follow-up focused exclusively on SRSG devices to be conducted.