Aesth Plast Surg (2015) 39:171–172 DOI 10.1007/s00266-014-0430-3
LETTER TO THE EDITOR
BREAST
Some Comments on Soft Tissue Measurements in Breast Augmentation Tim Brown
Received: 26 May 2014 / Accepted: 15 November 2014 / Published online: 6 December 2014 Ó Springer Science+Business Media New York and International Society of Aesthetic Plastic Surgery 2014
Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. As every surgeon rapidly discovers, the appearance of a breast following augmentation is influenced as much by the surrounding soft tissue envelope as it is the shape of the implant [1, 2]. Patients who have an appropriate implant for their base width and are of a normal body mass index (20–25) usually obtain a good aesthetic appearance if the surgery is undertaken with due care and attention to detail. Patients with a BMI outside the ‘‘normal’’ range present some unique challenges that need to be addressed to produce a pleasing result. Most surgeons undertake an assessment of the patient’s soft tissue envelope, either intuitively or by a formal system such as the ‘high five’ [3]. Whilst these measurements examine the breast envelope, it is helpful to examine how these variables might relate to the whole patient’s body composition. A series of pre-operative breast augmentation patients (n = 102) had their height, weight, breast width and soft tissue thickness at the lateral sternal margin (LSM) measured using callipers (Accu-Measure Fitness 3000, Greenwood Village, CO) at the level of the 4th costo-sternal junction. Analysis indicated that soft tissue thickness at the LSM was positively correlated with weight, BMI and breast width (Pearson’s correlation, significance taken as p \ 0.01). Width was also positively correlated with T. Brown (&) Suite 2, 8-12 Gibb Street, Berwick, VIC 3806, Australia e-mail: [email protected]
height, weight and BMI. This indicated that as BMI and weight increased, so did LSM (Tables 1, 2). A Kruskal Wallis analysis of BMI grouped into three levels, \19, 20–25 and [26, and indicated that individuals of different BMI groups did not have significantly differing LSM (Table 3); however, there was a significant effect of width. Empirically, one might expect that the thickness of tissue at the LSM would be related to both weight and BMI, which is an indirect measure of body composition, and the data from this study do confirm that expectation to an extent. Whilst the thickness of soft tissue at the LSM increases with BMI, it does not reach a significant difference in the BMI range of 19–26. The 1-cm rule (2 cm pinch test) is often quoted by various authorities and manufacturers as an adjunct to breast implant sizing, with an assumption that all patients have the same thickness of soft tissue coverage at the LSM. Patently, this is not completely true, as from this study, a patient with a narrow breast will have less soft tissue than those with a broader breast. However, in patients within a normal BMI range, the rule of thumb is valid, as LSM measurement in these individuals is on average 22 mm, and does not vary greatly for BMIs of 19–25. In their discussion, the ‘‘high 5 system’’, Spear and Low make a distinction between tight/elastic skin and a tight/ loose or normal envelope for an implant [4]. Vegas and Martin del Yerro [5] expanded on this idea and proposed an interesting analogy between plastic materials and the mechanics of a breast following augmentation. They describe two different types of breast: stiff, non-flexible and compliant. Whilst at the present, we have no way of measuring mechanical compliance in a breast, intuitively a thicker layer of soft tissue over the implant seems likely to make a breast less compliant, and might therefore be a reasonable substitute measurement. The data in this study
123
172
Aesth Plast Surg (2015) 39:171–172
Table 1 Means and standard deviations of all variables Variables
M (mm)
SD
N
Height (cm)
166.48
6.74
102
Weight (kg)
60.79
9.34
102
BMI
21.91
2.30
102
Width (cm)
14.57
2.69
102
LSM (mm)
21.19
7.63
102
BMI Body mass index, soft tissue thickness measured at LSM lateral sternal margin Table 2 Correlations amongst all variables Variables
Height
Weight
BMI
Width
LSM
Height
–
.456**
-.086
.242*
.131
Weight
–
BMI
.845** –
Width
.496**
.340**
.405**
.302**
–
.204*
LSM
–
Pearson’s correlation. * p \ .05 ** p \ .01, 2-tailed BMI body mass index, soft tissue thickness at LSM lateral sternal margin
Table 3 Soft tissue measurement at LSM and BMI BMI
M (mm)
SD
N
\19
13.48
1.78
22
20–25
14.59
2.26
70
[26
16.85
5.11
10
Kruskal Wallis analysis indicated no significant difference between three groups
indicate that patients who have a narrow breast have significantly less tissue at the LSM than those with a broad base, and as such are likely to behave in mechanically different ways. Given that human tissue is plastic, thinner individuals will over time produce a more compliant breast compared with those with a thick soft tissue envelope, which may account for long-term deformities seen in these patients with large implants. Dramatic weight loss following surgery can produce a need for revisional surgery, when the implant may no longer be appropriate for that patient’s new reduced frame as both base width and soft tissue thickness have changed.
123
In treating patients who have a higher than normal BMI, it is worth making the point that the implant chosen by a surgeon is appropriate for their body habitus at that time, and if they are planning any major weight loss such that their BMI, weight and breast width will shift into a normal range, and it is possible that their implant may no longer be a good aesthetic choice. In terms of tissue mechanics, the reduced parenchymal thickness converts a stiff, non-compliant breast to a flexible, plastic one. Whilst weight also correlates well with LSM measurements, it does not reflect the patient’s height, which is a fixed variable, so discussions in terms of BMI may be of more use in discussions with individuals. The majority of these measured observations will be intuitive to surgeons who undertake breast implant surgery on a regular basis. However, it is not uncommon for a patient to be focused on implant volume, and it is worth emphasizing the importance of soft tissue envelope characteristics during a consultation, and the effect it will have the aesthetic outcome. Consequently, when showing pre- and post-operative images to patients illustrating different implant volumes, it is our practice to group photographs by patient BMI and base width. Conflict of interest interest to disclose.
The author declares that he has no conflicts of
References 1. Khan UD (2009) Selection of breast pocket using the pinch test in augmentation mammoplasty: can it be relied on in the long term? Aesthet Plast Surg 2009(33):780–781 2. Brown T (2013) Patient expectations after breast augmentation: the imperative to audit your sizing system. Aesthet Plast Surg 37(6):1134–1139 3. Tebbetts JB (2002) A system for breast implant selection based on patient tissue characteristics and implant-soft tissue dynamics. Plast Reconstr Surg 109:1396–1409 4. Spear SL, Low M (2002) A system for breast implant selection based on patient tissue characteristics and implant-soft tissue dynamics (discussion). Plast Reconstr Surg 109:1410–1412 5. Vegas MR, Martin del Yerro JL (2013) Stiffness, compliance, resilience and creep deformation: understanding implant-soft tissue dynamics in the augmented breast: fundamentals based on materials science. Aesthet Plast Surg 37:922–930
LETTER TO THE EDITOR
BREAST
Some Comments on Soft Tissue Measurements in Breast Augmentation Tim Brown
Received: 26 May 2014 / Accepted: 15 November 2014 / Published online: 6 December 2014 Ó Springer Science+Business Media New York and International Society of Aesthetic Plastic Surgery 2014
Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. As every surgeon rapidly discovers, the appearance of a breast following augmentation is influenced as much by the surrounding soft tissue envelope as it is the shape of the implant [1, 2]. Patients who have an appropriate implant for their base width and are of a normal body mass index (20–25) usually obtain a good aesthetic appearance if the surgery is undertaken with due care and attention to detail. Patients with a BMI outside the ‘‘normal’’ range present some unique challenges that need to be addressed to produce a pleasing result. Most surgeons undertake an assessment of the patient’s soft tissue envelope, either intuitively or by a formal system such as the ‘high five’ [3]. Whilst these measurements examine the breast envelope, it is helpful to examine how these variables might relate to the whole patient’s body composition. A series of pre-operative breast augmentation patients (n = 102) had their height, weight, breast width and soft tissue thickness at the lateral sternal margin (LSM) measured using callipers (Accu-Measure Fitness 3000, Greenwood Village, CO) at the level of the 4th costo-sternal junction. Analysis indicated that soft tissue thickness at the LSM was positively correlated with weight, BMI and breast width (Pearson’s correlation, significance taken as p \ 0.01). Width was also positively correlated with T. Brown (&) Suite 2, 8-12 Gibb Street, Berwick, VIC 3806, Australia e-mail: [email protected]
height, weight and BMI. This indicated that as BMI and weight increased, so did LSM (Tables 1, 2). A Kruskal Wallis analysis of BMI grouped into three levels, \19, 20–25 and [26, and indicated that individuals of different BMI groups did not have significantly differing LSM (Table 3); however, there was a significant effect of width. Empirically, one might expect that the thickness of tissue at the LSM would be related to both weight and BMI, which is an indirect measure of body composition, and the data from this study do confirm that expectation to an extent. Whilst the thickness of soft tissue at the LSM increases with BMI, it does not reach a significant difference in the BMI range of 19–26. The 1-cm rule (2 cm pinch test) is often quoted by various authorities and manufacturers as an adjunct to breast implant sizing, with an assumption that all patients have the same thickness of soft tissue coverage at the LSM. Patently, this is not completely true, as from this study, a patient with a narrow breast will have less soft tissue than those with a broader breast. However, in patients within a normal BMI range, the rule of thumb is valid, as LSM measurement in these individuals is on average 22 mm, and does not vary greatly for BMIs of 19–25. In their discussion, the ‘‘high 5 system’’, Spear and Low make a distinction between tight/elastic skin and a tight/ loose or normal envelope for an implant [4]. Vegas and Martin del Yerro [5] expanded on this idea and proposed an interesting analogy between plastic materials and the mechanics of a breast following augmentation. They describe two different types of breast: stiff, non-flexible and compliant. Whilst at the present, we have no way of measuring mechanical compliance in a breast, intuitively a thicker layer of soft tissue over the implant seems likely to make a breast less compliant, and might therefore be a reasonable substitute measurement. The data in this study
123
172
Aesth Plast Surg (2015) 39:171–172
Table 1 Means and standard deviations of all variables Variables
M (mm)
SD
N
Height (cm)
166.48
6.74
102
Weight (kg)
60.79
9.34
102
BMI
21.91
2.30
102
Width (cm)
14.57
2.69
102
LSM (mm)
21.19
7.63
102
BMI Body mass index, soft tissue thickness measured at LSM lateral sternal margin Table 2 Correlations amongst all variables Variables
Height
Weight
BMI
Width
LSM
Height
–
.456**
-.086
.242*
.131
Weight
–
BMI
.845** –
Width
.496**
.340**
.405**
.302**
–
.204*
LSM
–
Pearson’s correlation. * p \ .05 ** p \ .01, 2-tailed BMI body mass index, soft tissue thickness at LSM lateral sternal margin
Table 3 Soft tissue measurement at LSM and BMI BMI
M (mm)
SD
N
\19
13.48
1.78
22
20–25
14.59
2.26
70
[26
16.85
5.11
10
Kruskal Wallis analysis indicated no significant difference between three groups
indicate that patients who have a narrow breast have significantly less tissue at the LSM than those with a broad base, and as such are likely to behave in mechanically different ways. Given that human tissue is plastic, thinner individuals will over time produce a more compliant breast compared with those with a thick soft tissue envelope, which may account for long-term deformities seen in these patients with large implants. Dramatic weight loss following surgery can produce a need for revisional surgery, when the implant may no longer be appropriate for that patient’s new reduced frame as both base width and soft tissue thickness have changed.
123
In treating patients who have a higher than normal BMI, it is worth making the point that the implant chosen by a surgeon is appropriate for their body habitus at that time, and if they are planning any major weight loss such that their BMI, weight and breast width will shift into a normal range, and it is possible that their implant may no longer be a good aesthetic choice. In terms of tissue mechanics, the reduced parenchymal thickness converts a stiff, non-compliant breast to a flexible, plastic one. Whilst weight also correlates well with LSM measurements, it does not reflect the patient’s height, which is a fixed variable, so discussions in terms of BMI may be of more use in discussions with individuals. The majority of these measured observations will be intuitive to surgeons who undertake breast implant surgery on a regular basis. However, it is not uncommon for a patient to be focused on implant volume, and it is worth emphasizing the importance of soft tissue envelope characteristics during a consultation, and the effect it will have the aesthetic outcome. Consequently, when showing pre- and post-operative images to patients illustrating different implant volumes, it is our practice to group photographs by patient BMI and base width. Conflict of interest interest to disclose.
The author declares that he has no conflicts of
References 1. Khan UD (2009) Selection of breast pocket using the pinch test in augmentation mammoplasty: can it be relied on in the long term? Aesthet Plast Surg 2009(33):780–781 2. Brown T (2013) Patient expectations after breast augmentation: the imperative to audit your sizing system. Aesthet Plast Surg 37(6):1134–1139 3. Tebbetts JB (2002) A system for breast implant selection based on patient tissue characteristics and implant-soft tissue dynamics. Plast Reconstr Surg 109:1396–1409 4. Spear SL, Low M (2002) A system for breast implant selection based on patient tissue characteristics and implant-soft tissue dynamics (discussion). Plast Reconstr Surg 109:1410–1412 5. Vegas MR, Martin del Yerro JL (2013) Stiffness, compliance, resilience and creep deformation: understanding implant-soft tissue dynamics in the augmented breast: fundamentals based on materials science. Aesthet Plast Surg 37:922–930
