Cosmetic

Nonsurgical Breast Enlargement Using anExternal Soft-Tissue Expansion SystemRoger K. Khouri, M.D., Ingrid Schlenz, M.D., Brian J. Murphy, M.D., and Thomas J. Baker, M.D.Key Biscayne and Miami, Fla.

Less than 1 percent of the women interested in havinglarger breasts elect to have surgical augmentation mam-maplasty with insertion of breast implants. The purpose ofthis report is to describe and test the efficacy of a non-surgical method for breast enlargement that is based onthe ability of tissues to grow when subjected to controlleddistractive mechanical forces. Seventeen healthy women(aged 18 to 40 years) who were motivated to achieve breastenlargement were enrolled in a single-group study. Theparticipants were asked to wear a brassiere-like system thatapplies a 20-mmHg vacuum distraction force to eachbreast for 10 to 12 hours/day over a 10-week period. Breastsize was measured by three separate methods at regularintervals during and after treatment. Breast tissue waterdensity and architecture were visualized before and aftertreatment by magnetic resonance imaging scans obtainedin the same phase of the menstrual cycle. Twelve subjectscompleted the study; five withdrawals occurred due toprotocol noncompliance. Breast size increased in allwomen over the 10-week treatment course and peaked atweek 10 (final treatment); the average increase perwoman was 98 6 67 percent over starting size. Partialrecoil was seen in the first week after terminating treat-ment, with no significant further size reduction after upto 30 weeks of follow-up. The stable long-term increase inbreast size was 55 percent (range, 15 to 115 percent).Magnetic resonance images showed no edema and con-firmed the proportionate enlargement of both adiposeand fibroglandular tissue components. A statistically sig-nificant decrease in body weight occurred during thecourse of the study, and scores on the self-esteem ques-tionnaire improved significantly. All participants werevery pleased with the outcome and reported that the de-vice was comfortable to wear. No adverse events wererecorded during the use of the device or after treatment.We conclude that true breast enlargement can beachieved with the daily use of an appropriately designedexternal expansion system. This nonsurgical and nonin-vasive alternative for breast enlargement is effective andwell tolerated. (Plast. Reconstr. Surg. 105: 2500, 2000.)

Approximately 16 to 19 million women inthe United States between the ages of 18 and49 have an expressed interest in breast enlarge-ment1,2; however, despite a resurgence in pop-ularity, only about 130,000 (0.7 percent) ofthese women underwent surgical breast aug-mentation in 1998.3 Reluctance to undergosurgery for cosmetic reasons, perceived adversesequelae from the implants, and cost are themost cited deterrents to this surgical recourse.2

We developed a system and a method ofexternal soft-tissue expansion and tested its ef-ficacy as a nonsurgical alternative for breastenlargement. The principle behind this ap-proach is the capacity of tissues to grow whensubjected to sustained, low-level, mechanicaldistraction. For centuries, tribes from severalcultures have applied this principle to enlargevarious body parts.4,5 Surgically implanted tis-sue expanders are now routinely used in plasticsurgery to incrementally increase the amountof skin and soft tissue available to performmultiple staged reconstructive procedures.6–8

Orthopedic experience with the Ilizarov proce-dure has demonstrated the feasibility of length-ening extremities by a process of gradual dis-traction that grows the bones and associatedsoft tissues.9–11 New devices have extended theuse of this principle to advance facial bonesand correct retruded faces.12,13 Cell biologistshave devoted considerable research towardelucidating the mechanism of mechanotrans-duction, the process by which mechanical ten-

Received for publication December 1, 1999; revised February 7, 2000.Presented in part at the Annual Meeting of the American Society for Aesthetic Plastic Surgery, in Dallas, Texas, May 16, 1999, and at the 10th

Anniversary Meeting of the European Association of Plastic Surgeons, in Madrid, Spain, May 21, 1999.Roger K. Khouri, M.D., is a shareholder of Biomecanica, Inc. None of the other authors have any financial interest in or have received any

direct benefit from Biomecanica, Inc., except for Ingrid Schlenz, M.D., who received partial salary support from Biomecanica, Inc., during thestudy period.

2500

sion is converted into growth-promoting sig-nals.14–17

Current therapeutic applications of tension-induced tissue growth require surgical inter-vention to insert either an inflatable siliconeshell as the force-transducing device or bonepins and screws as links to the distractionframe; however, the approach presented hereis entirely nonsurgical. Sustained, low-levelnegative pressure (vacuum) provides the out-ward distractive force that stimulates breast tis-sue enlargement. The nonsurgical breast-enlargement system was designed by one of theauthors (R.K.K.); in a pilot study on two sub-jects (four breasts), he found evidence that thedevice was effective (unpublished data). Thepresent study represents an independent testof its safety and efficacy in a larger population.

MATERIALS AND METHODS

Soft-Tissue Expansion

The nonsurgical breast-enlargement systemincorporates two semirigid plastic domes, eachslightly larger in volume than the correspond-ing breast to be enlarged. A brassiere garmentsupports the two domes, and the device is wornlike a brassiere (Fig. 1). Each dome has anoutlet port for vacuum application and a gel-filled bladder at the rim that circumscribes theouter margins of the breast. An adhesive, hy-poallergenic silicone gel applied to the skin-contact surface of each bladder maintains avacuum seal with the skin. A battery-powered,microcomputer-controlled vacuum pump isconnected to outlet ports on each dome byplastic tubing. Pressure sensors and reliefvalves are used to maintain a vacuum pressure

of 15 to 25 mmHg. To document protocolcompliance, the microcomputer records tem-perature and pressure every 10 minutes andstores the data in its memory.

A number of suction-based devices havetouted the ability to induce breast enlarge-ment.18 These are considered to be mostly in-effective novelty items and are ridiculed by theestablishment in plastic surgery.19 Althoughthe basic idea behind stretching to induce en-largement is sound, these novelty devices lackthe necessary design elements to appropriatelydeliver, over a prolonged period of time, asustained, controlled mechanical distraction tocause breast growth.

We built the system by deliberately takinginto account known physiologic constraintsand bioengineering principles. Pilot testing ofa succession of prototypes led us to identifyand refine four novel critical design featuresthat ensure safe and effective function (U.S.patent #5536,233; U.S. patent #5662,583; U.S.patent #5676,634; U.S. patent #5695,445; U.S.patent #5701,917; and other patents pending).

Balancing of Forces and Optimization of Pressures

The total outward force (Fout) exerted by thevacuum on the breast is equal to the product ofthe aperture area of the dome (A) and thevacuum pressure (Pv). This force is balanced byan equal counter-force against the chest skinunder the bladder rim (Fin) that is equal to theproduct of the area of the bladder rim (R) andthe pressure transferred to the skin (Ps). Cap-illary perfusion starts to drop precipitouslywhen the pressure (whether positive or nega-tive) exerted on the skin and underlying tissuesexceeds 20 to 30 mmHg.20–23 Sustained pres-

FIG. 1. (Left) Diagram showing the translucent plastic domes and gel-filled bladder rimsplaced over the breasts. The microcomputer-controlled vacuum pump fits inside a pocket of thebrassiere garment. (Right) Photograph of the nonsurgical breast-enlargement system as worn bya participant in the study.

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sures above this limit lead to tissue damage. Tomaximize distraction without compromisingthe circulation of the distracted breast or thatof the compressed skin under the rim, theabsolute values of Ps and Pv must equal thisupper limit of tissue tolerance. This optimiza-tion of the absolute pressures requires the areaof the bladder rim (R) to be equal to theaperture area of the dome (A), as shown in thefollowing equations.

Fin 5 Fout

A 3 Pv 5 R 3 Ps

If Pv 5 Ps, then R 5 A

The skin contact area of the rim bladder istherefore designed to be approximately equalto the area of the aperture of the dome (Fig.2). This constraint can only be avoided if thepressure is allowed to alternate, decreasing thevacuum level every few minutes to allow theskin under the rim to reperfuse, and then re-establishing the vacuum for the next cycle. Weelected not to use alternating pressure becauseof the power drain it imposes on the batterypack.

Control of Shear Forces on the Skin

The inward pull of expansion stretches thebreast skin close to the limit of its elastic defor-mation.

At the periphery of the breast, if the skin isheld firmly by the inner lip of the bladder rim,this stretch imparts a strong shearing force (Fs)to the skin, which can combine locally with thecounter-force (Fin) to cause peripheral skinblistering and breakdown.24 To reduce this po-tentially damaging shear force, the peripheralbreast skin under the inner lip of the rimshould not be fixed but allowed to move in-ward. To accomplish that, the rim must deflectradially inward for the distance needed to re-cruit additional skin and reduce the shearstress to a tolerable level. In addition, this fea-ture reduces skin stretching and the resultantundesirable skin expansion, while focusing thedistraction on the deeper breast tissue.Through a succession of prototypes, we foundthat a rim bladder approximately 2.5 cm highprovides the necessary arc of inward deflection(Fig. 3).

Pressure Distribution and Avoidance ofPressure Points

To evenly distribute the pressure on the skin,the rim must be a fluid-filled bladder. A semi-fluid silicone gel, however, has mechanicalcharacteristics closer to those of live tissues andinterfaces better with the torso. We found thatthe conforming cushion effect of a gel-filledrim complies best with the motion of the torsoduring routine activities, while evenly distribut-ing the pressure and accommodating individ-ual variations in surface contour. This featureof the system allows it to prevent both thedevelopment of localized pressure points andbreaks in skin contact that can lead to loss ofvacuum.

Maintenance of Low-Level Vacuum Seal

To prevent air leaks and to maintain the lowvacuum seal with a low contact pressure, thecontact surface of the rim against the skin mustbe sticky. Loss of the stickiness led to repeatedloss of vacuum, excessive activity of the pump,and a rapid power drain of the battery pack. Alayer of tacky, hypoallergenic silicone gel wasadded to achieve the proper seal effect.

Methods

After Institutional Review Board (IRB) ap-proval for the study and after obtaining written

FIG. 2. The contact area of the rim with the skin sur-rounding each breast must be relatively large to distribute thepressure caused by the distraction counter-force. F(out) in-dicates the resultant force of distraction applied to the breastenclosed under the dome aperture area (A) by the vacuumpressure [P(v)]; F(in), the resultant counter-force inflictinga pressure [P(s)] to the chest wall under the rim area (R). Tobalance the forces and to optimize the pressure to the highestcontinuously tolerable level, the rim contact area (R) is ap-proximately equal to the dome aperture area (A).

2502 PLASTIC AND RECONSTRUCTIVE SURGERY, June 2000

consent, we enrolled 17 female volunteers atone study center. Inclusion criteria were an agebetween 18 and 40 years; general good health;high motivation for breast enlargement; cur-rent cup size of AA, A, or small B; agreement touse medically accepted birth control for theduration of the study; and willingness to com-ply with stringent protocol requirements. Vol-unteers were excluded from the study on thebasis of a positive urine pregnancy test; ongo-ing lactation; history of breast surgery, disease,cyclic engorgement, trauma, or pain; presenceof a breast mass; severe ptosis of the breast;history of chronic dermatitis; and any hor-monal therapy besides birth control pills.

Participants were required to wear thebreast-enlargement system for 10 to 12 hoursper day every day for 10 weeks. Failure to usethe system for 2 consecutive days or for morethan 3 separate days in any given 2-week periodwas compensated for by an extra 2 weeks ofapplied use. Progress was monitored by visits at1, 3, 5, 7, and 10 weeks into treatment, and at1, 4, 8, 20, and 30 weeks after the terminationof treatment. Breast dome size of the systemwas increased as needed to accommodate thegrowing breasts. Breast size was monitored dur-ing visits by standardized photographs, volumemeasurement using both a bead displacement

technique (modified from Campaigne et al.25 )and the Grossman-Roudner device,26 and thedifference in chest circumference measured atthe level of the nipple versus the level of theinframammary fold. Body weight was closelymonitored, and a larger than 5 percent varia-tion was grounds for study withdrawal. Plastermoulages of the torso were made at baseline, atthe end of the treatment period, and at the4-week follow-up visit.

Baseline magnetic resonance imaging (MRI)examinations with breast surface coils wereconducted before treatment began betweendays 6 and 14 of the menstrual cycle. Axial andcoronal views were obtained using T1 andSTIR imaging sequences.27–29 At least 1 weekafter completion of the treatment phase (andin the same phase of the menstrual cycle as thefirst MRI), a follow-up breast MRI was obtainedusing the same imaging planes and pulse se-quences. The paired scans were read andgraded by a radiologist experienced in MRIwho was blinded as to the sequence of theexaminations.

Three of the women who experienced thegreatest amount of growth were recalled 26weeks after treatment for random needle biop-sies of the breast. The tissue was processed forhistologic examination with hematoxylin and

FIG. 3. Distraction of the breast inside the dome stretches the skin. If the peripheral breastskin is held firmly at the inner edge of the rim, a strong shear force [F(s)] combines with thecounter-force [F(in)] to cause skin damage (left). A rim that can deflect inward allows peripheralchest wall skin to move inside the dome. This recruitment of skin reduces the amount of breastskin stretch and the potentially damaging shear force [F(s)] (right).

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eosin staining; the samples were read by abreast pathologist.

All participants also completed self-esteemand opinion-of-use surveys both before and af-ter treatment. To obtain direct feedback onthe change produced by the use of the system,a simple linear numeric scale was designed. Ina 10-item satisfaction questionnaire, the partic-ipants gave responses using a five-point scale,ranging from “strongly disagree” to “stronglyagree” with each statement.

Changes in breast volume, chest measure-ment, and body weight were statistically com-pared with a paired t test. Changes in responsesto the questionnaire were analyzed with a non-parametric (Wilcoxon sign rank) test.

RESULTS

Seventeen women were enrolled, and 12completed the study; the five withdrawals weredue to protocol noncompliance. All partici-pants found the breast-enlargement systemcomfortable to wear although somewhat obtru-sive under tight-fitting clothes. Most preferredto wear it at home and slept with it at night.They used the system an average of 10.4 hoursper day. It took an average of 14.7 weeks(range, 10 to 18 weeks) to complete the effec-tive 10-week treatment period because of set-backs from the occasional inability to use thedevice. At some point during the course ofexpansion, some women experienced transientand completely reversible dysesthesia of thenipple that was probably caused by stretch ofthe sensory nerves. There were no serious ad-verse events, pressure sores, or significant der-matological reactions attributable to the use ofthe device.

The average breast volume (mean 6 stan-dard error of the mean) of the participantsbefore initiating treatment was 192 6 64 ml or203 6 73 ml, as measured by bead displace-ment or the Grossman-Roudner device, respec-tively. The volume immediately after the 10-week treatment was 347 6 67 ml or 344 6 62ml (bead displacement or Grossman-Roudnerdevice methods, respectively; p , 0.0001 com-pared with baseline volumes for both mea-sures). An immediate recoil effect (loss of en-largement) occurred over the first follow-upweek; this was followed by a plateau and a netstable volume increase of 103 6 35 ml or 111 646 ml (bead displacement or Grossman-Roudner device methods, respectively; p ,0.0001 compared with baseline volumes for

both measures). This is a net increase of 55percent over the initial breast volume (Fig. 4).Every participant experienced a net volumeincrease (range, 15 to 115 percent of initialvolume). The volume changes were paralleledby a 5.3 6 0.7 cm increase in the differencebetween circumferential chest measurementsat the nipple level versus the inframammaryfold (p , 0.01 compared with the baselinedifference; Fig. 5). Volume measurement ofthe plaster moulages showed the same increasein breast size as measured by the bead displace-ment and the Grossman-Roudner device. Atlast follow-up, the participants were still wear-ing new bras at least one cup size larger thantheir pretreatment size.

The breast volume enlargement was not as-sociated with an increase in body weight dur-ing the course of study. Quite the contrary, astatistically significant trend toward bodyweight reduction occurred in the months after

FIG. 4. Breast volume increase over the course of the 10weeks of treatment and the additional 30 weeks of follow-up.(Above) Measurements obtained by the bead displacementmethod. (Below) Measurements obtained by the Grossman-Roudner device. Data are means 6 standard deviations.

2504 PLASTIC AND RECONSTRUCTIVE SURGERY, June 2000

treatment (p , 0.02; Fig. 6), possibly as a re-sponse to improved self-image.

All women expressed satisfaction with theoutcome. This was reflected by changes in thebaseline scores on the questionnaire after com-pleting the treatment (Table I). The womenfelt their breasts were lifted after treatment andthat the enlargement had a natural and aes-thetically pleasing shape (Figs. 7 through 9).

In each case, the posttreatment MRI con-firmed an overall increase in breast size. Nospace-occupying lesions, breast cysts, or othermasses were present on pretreatment or post-treatment MRI scans. The T1 images showed aproportionate amount of fat and fibroglandu-lar tissue, with preservation of the native archi-tecture of the breast. STIR images of posttreat-ment breast tissue did not demonstratesubstantial increased signal intensity, i.e., therewas no evidence of significant breast edema(Fig. 10). However, when the peak-enlarged

breasts were imaged within hours of deviceapplication, a higher water tissue content wasapparent (unpublished data).

Histologic examination of the biopsies takenfrom six of the most enlarged breasts revealedunremarkable, normal breast tissue paren-chyma and architecture.

DISCUSSION

Breast size in the healthy premenopausaladult woman is stable and varies only with preg-nancy, hormonal intake, body weight fluctua-tion and, to a smaller extent, during the men-strual cycle. Our study carefully controlled forall these factors. The participants were initiallyscreened with a pregnancy test, and they usedcontraceptive measures throughout. If thewomen were on birth control pills before en-rollment, they kept taking the pills and noadditional hormonal treatment was given.Body weight was carefully monitored duringthe study and, in fact, significantly decreasedwhile breast size increased. The most consis-tent decrease in body weight was seen after theparticipants had completed their initial wear-ing period. Except for the interim recordings,all breast volume measurements were madeduring the first phase of the menstrual cycle.Therefore, although the study could not beblinded and it included no controls, the sub-stantial breast growth measured should be at-tributed to the use of the device.

To our knowledge, this noninvasive externaldistraction device is the only documentedmethod of nonsurgical, nonpharmacologicbreast enlargement. The nonsurgical systemwas well tolerated, with no complications. Allpatients who completed the effective 10-weektreatment course achieved a significant in-crease in breast size, even after posttreatmentrecoil. This increase in breast size was still ob-served at 30 weeks posttreatment. The growthappears to be evenly distributed among all tis-sue elements of the breast, with preservation ofthe normal composite tissue architecture.

Stretch is good for a cell; it is the mechanisminvolved in normal tissue growth, regenera-tion, and homeostasis.15 The phenomenon ofstretch-induced tissue growth is widely preva-lent, and it has been studied in vitro and in vivofor many years. Cells in culture will respond tolongitudinal stretching by an increased mitoticrate and by realigning their shape and cytoskel-eton parallel to the direction of force.30–32 Ex-perimental studies of tissue expansion have

FIG. 5. Breast enlargement as determined by the increasein the difference between the chest circumference at thenipple level and that measured at the inframammary fold(mean 6 standard deviation).

FIG. 6. Relative change in body weight during the studycompared with the enrollment weight (mean 6 standarddeviation).

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shown fibroblast changes consistent with theproduction of new extracellular matrix.33,34 Alltypes of tissues studied grow and regeneratenormal tissue when subjected to mechanicalstretch, including the skin,6,35,36 bones,9–12 bow-els,37 lungs,38 urogenital viscera,39 blood ves-sels,30,40 nerves,40,41 skeletal muscle,10,42 cardiactissue,43 and smooth muscles.30 A number ofwidely used medical devices rely on this prin-ciple to generate skin for wound closure,7,44,45

to reconstruct the breast after a mastecto-my,46,47 to elongate entire extremities9 and,

more recently, to restore deficient mandibles12

and entire faces13 to normal. Ilizarov9,10 dem-onstrated in the laboratory and in the clinicthat distraction is the only known means ofinducing true tissue regeneration in the adult.

How the tissue responds to external distrac-tive forces is not fully known. Cells experiencea variety of forces throughout their lifetime.They sense the balance of mechanical forcesthat surround them and translate changes intobiochemical signals by a mechanism calledmechanotransduction.15 Cells are mechanically

FIG. 7. Representative photographs of a woman in the study. Left, frontal views; right, obliqueviews; above, views before treatment; below, views after treatment with the nonsurgical breast-enlargement system at 30 weeks of follow-up.

TABLE IChange in Response to Self-Esteem Questionnaire

Questionnaire StatementChange in

Score p

1. I like my breasts just as they are now. 1.8 ,0.012. I like the size of my breasts just as they are now. 1.9 ,0.013. I am satisfied with feedback from others concerning the change in my breasts. 0.9 NS4. I am now concerned that my body image is not attractive unless I have larger breasts. 20.7 NS5. I now have difficulty wearing light clothes or bikini beach wear due to my small breast size. 21.0 NS6. I now feel comfortable wearing beach wear. 1.4 ,0.057. I have difficulty showing my breasts during intimate interaction with my partner. 20.6 NS8. I enjoy looking at myself in the mirror in the nude. 1.1 ,0.059. I feel embarrassed when I or someone else looks at my breasts. 21.2 NS

10. I feel embarrassed when someone else touches my breasts. 21.3 ,0.05

Subject responses to the 10 questions ranged from 1 to 5: 1 indicated “least likely to be true” and 5, “most likely to be true.” The numbers in the table indicatethe difference in responses for each question (after 2 before treatment). Numbers greater than zero identify questions for which the participant response was morestrongly in agreement after treatment. Statistical comparisons for each question were made with the Wilcoxon sign rank test. p . 0.05 was considered not significant(NS).

2506 PLASTIC AND RECONSTRUCTIVE SURGERY, June 2000

linked to other cells and to the extracellularmatrix through their cytoskeleton and its sur-face receptor system.15 Integrins are thought tobe the transmembrane receptor link betweenthe mechanical deformation of the extracellu-lar matrix caused by external forces and theresultant internal cytoskeletal conformationalresponse. Mechanical stretching of the extra-cellular matrix induces integrin clustering andligand binding to form macromolecular scaf-folds called focal adhesion complexes, whichmechanically link the extracellular matrix withthe cytoskeleton and bring the tensional forcesinto balance.48 This balancing of the mechan-ical forces involves tensegrity, an architecturalsystem in which structures stabilize themselvesby counteracting the forces of compressionand tension.49 The formation of focal adhesioncomplexes also mediates the stimulus-couplingresponse with the activation of kinases, ionchannels, and growth factor receptors.48,50–53

Mechanically induced rearrangements of thecellular cytoskeleton are also directly linked tothe nucleus to initiate cell division. This pro-cess is the subject of intense research and manyauthoritative reviews.14–17,48–54 From a teleolog-ical viewpoint, whenever stretched and de-formed, cells in the tissue sense the need tospread; they then respond by proliferating un-

til the gap is filled and the normal balance isrestored again.15

In view of the substantial societal demand forbreast enlargement (16 to 19 million women inthe United States), the application of this phe-nomenon of stretch-induced tissue growth tothe breast was bound to be forthcoming. Bytaking into account biomechanical and physi-ologic constraints and after extensive prototyp-ing, we discovered four critical design featuresand determined the most effective and safedistraction pressure. The nonsurgical systemused in this study applies an external, low-level,sustained traction that is effective and well tol-erated. To stimulate tissue growth, however,the distraction must be continuous and sus-tained over a prolonged period of time. This isthe reason why failure to continuously use thedevice leads to setbacks and necessitates addi-tional compensatory wear time. Although thenumbers are too small to evaluate statistically,it seems that the greatest effect was observed inthe participants who used the system the mostintensively (hours/day) and the most continu-ously (missed no days).

The tissue growth achieved in this study isgenerated by the same basic mechanism ofphysical distraction as occurs with surgicallyimplanted bone lengthening and tissue expan-

FIG. 8. Representative photographs of a woman in the study. Left, frontal views; right, obliqueviews; above, views before treatment; below, views after treatment with the nonsurgical breast-enlargement system at 30 weeks of follow-up.

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sion devices.6–13 Subcutaneously implanted tis-sue expanders, silicone bladders that are filledwith saline, act on the overlying skin and asso-ciated tissues. There is an initial elastic(stretch) response, followed by the inductionof mitosis35 and a remodeling of the connectivetissue extracellular matrix36 in the stretchedtissue. As the tissue expands (with a resultantreduction in tension), more saline is added tothe bladder to continually exert tension andcause growth. The Ilizarov bone-lengtheningsystem and related devices work similarly: atransverse osteotomy sets up bone callus forma-tion, which is then gradually distracted, allow-ing the newly forming bone to be extracted(grown) at the callus site.9–11 Associated softtissues (muscle, nerve, vessels, etc.) are alsodistracted, with an initial stretch and deforma-tion response followed by true tissue growth,which occurs evenly along the distracted area,not just at the level of the callus.40

Under the effect of the external three-dimensional pull applied by the nonsurgicalbreast-enlargement system, the breast tissuegoes through several stages in its expansion.During the early phase, fibroelastic fibers, ini-tially loosely spaced around fat and fibroglan-dular cells, are stretched. Elastic deformations,along with some increased water edema ac-

count for some noticeable growth after a shortperiod of use. This early volume increase in-cludes no true tissue growth and is totally re-versible. It is only after continued use and sus-tained stretch that true tissue growth isstimulated. The stretched cells respond to thesustained deformation by undergoing mitosisand the deposition of additional extracellularmatrix. With sustained use over a number ofweeks, the incremental component of true tis-sue growth adds up on top of the reversibleelastic deformation and extracellular fluid ac-cumulation. This accounts for the markedpeak enlargement seen at the end of the treat-ment phase and the recoil observed 1 weeklater as both old and new tissues return to theirresting state. At the end of a 10-week cycle ofuse, breast volume is expected to approxi-mately double, with half of this gain remainingas long-term growth. The final tissue seems tobe stable over a 30-week follow-up, and it has anormal histologic appearance.

The MRI evaluation was used to gaugewhether breast augmentation changed the ra-tio and distribution of fatty and fibroglandulartissue (as depicted on T1 images) and to de-termine whether there was increased watercontent or inflammation after treatment (seenon STIR images). In all cases, the increase in

FIG. 9. Representative photographs of a woman in the study. Left, frontal views; right, obliqueviews; above, views before treatment; below, views after treatment with the nonsurgical breast-reduction system at 30 weeks of follow-up.

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the size of breasts after treatment correlatedwith nearly equal increases in fatty and fi-broglandular tissue, without discerniblechanges in the tissue architecture. Increasedsignal intensity on STIR images was not appar-ent; this suggests that increased water content(due to edema and/or inflammation) was notpresent. Although contrast-enhanced MRI ismore sensitive in the detection of breast cancerand benign processes, such as dysplasia andinflammatory breast disease,28,29 the noncon-trast images did not demonstrate any overtchanges that would suggest the development ofdisease when comparing posttreatment andpretreatment images.

Concern that stretching the breast wouldaccentuate any degree of ptosis was not borneout by the study results. The most noticeableinitial impression by all the participants wasthat of a breast fill and lift. In the ptotic breast,there is a discrepancy between the loose skinenvelope and the relatively smaller contents.The forces of distraction, therefore, are di-

rectly transmitted through the loose skin tocause an enlargement of the tighter contentsbefore skin enlargement occurs. It is expected,however, that gravity acting on the now-largerbreast will naturally tend to cause some ptosiswith time.

Another major concern about this breast-enlargement system is whether its applicationstimulates or accelerates latent breast cancer.Although the number of participants and thetime course for follow-up are too small to de-termine this, several related findings do notsupport a cancer-inducing/stimulating effectby tension-induced tissue growth. Mechanicalforces are not known to be carcinogens. Theforce used by the device is trivial comparedwith the ones that constantly act upon thebody. This vacuum pressure of 20 mmHg rep-resents a 2.5 percent drop in atmospheric pres-sure. It is equivalent to the pressure changeexperienced before a storm or when climbingto the top of a high tower, and it is 4 to 7 timesless than the pressure change experienced in-

FIG. 10. T1-weighted coronal MRIs of a participant at baseline (above) and after treatment(below) show an increase in size with a proportionate increase in fatty tissue (white) and fi-broglandular tissue (gray). Note that there is no change in the distribution or appearance of thefatty and fibroglandular components.

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side the cabin of a commercial aircraft. Thetotal mechanical pull exerted by the device onthe breast is approximately equivalent to theforce exerted by gravity on a large, 2-kg breast.This amount of force leads to downward (uni-dimensional) growth of the unsupportedlarger breast, an effect well-known to plasticsurgeons performing reduction mammaplas-ties. Numerous epidemiologic studies havefailed to reveal any increased cancer incidencein the larger, heavier breasts that are subjected,over a lifetime, to a mechanical stretch similarto that of the nonsurgical breast-enlargementsystem.55–58 This experiment of nature provesthat mechanical forces acting on the breast arenot carcinogenic.

Ilizarov devices do not have an associatedcancer induction with their use in distractionof the extremities.9 Skin is the most cancer-prone organ in the body, yet skin expandershave been used for decades without any reportof cancer arising in the expanded skin.7,8,59,60

Furthermore, these tissue expanders havebeen applied in breast reconstruction aftermastectomy, stretching the residual breast tis-sue that has a high likelihood of tumor recur-rence (it is well accepted that even the mostradical of the mastectomies leaves some breasttissue behind). Yet more than 20 years of ex-perience in thousands of women has con-firmed that breast reconstruction with tissueexpansion does not increase the incidence ofcancer recurrence.42,43,60–63 Furthermore, in anexperimental model of rat mammary carci-noma, tissue expansion induced engrafted tu-mor regression and even a reduction in thespread of visceral metastasis.64

We can only speculate as to why the breastsseem to retain their newly gained growth afterthe rapid elastic recoil and the loss of tissueedema. Aside from mechanical stretch, growthfactors and hormones can also stimulate tissuegrowth. The administration of these factorsstimulates new tissue growth; the survival ofthis growth is critically dependent on the con-tinued presence of the hormonal stimulus.65–68

The new tissues regress by apoptosis on with-drawal of the growth factor. Tissue growth in-duced by mechanical stretching, however, mayremain, even after the withdrawal of the me-chanical stimulus. Experiments of nature fa-miliar to plastic surgeons demonstrate howthese two types of induced tissue growth maydiffer. With weight gain or pregnancies, growthof the adipose tissue or of the uterus is hor-

monally mediated, whereas the growth of theoverlying skin is induced by secondary mechan-ical stretch. After weight loss or deliveries, themechanical stretch and the supporting scaffoldregress, while skin growth often remains as acosmetic problem.

Plastic surgeons are also familiar with theptosis that follows the removal of a breast im-plant. Here, sustained stretch by the implantinduces the growth of the tissue in the breastenvelope. The resultant ptosis will not recoilwith time, and the enlarged tissues will notshrink back. Similarly, when a tissue expanderis rapidly inflated and removed, no significanttissue growth occurs, only reversible stretchand recruitment. However, when an inflatedexpander is kept for a few months, its removalis followed by permanent wrinkling of the skin.That soft tissues recoil after losing their struc-tural support is not universally true. It is thepresence of inflammation that may cause un-derlying scarring and some degree of contrac-tion. The nonsurgical breast-enlargement sys-tem was designed to specifically avoid anysignificant tissue inflammation.

In summary, this system offers women ameans of enlarging their breasts without thepain and risk of surgery or the perceived long-term health risks associated with surgical im-plants. The process is slow and gradual; thearbitrarily chosen 10-week course does notmatch the immediate size gain that follows theinsertion of an average sized breast implant.Additional use beyond 10 weeks is required toachieve further growth. This gradual processgives women more control over the change intheir appearance. Because the tissue growth islocal and autogenous, the result is more natu-ral looking, as opposed to the artificial appear-ance that can often accompany breast im-plants.

Roger K. Khouri, M.D.Dermatology and Plastic Surgery328 Crandon Blvd., Suite 227Key Biscayne, Fla. 33149rkhouri@biometicsllc.com

ACKNOWLEDGMENTS

The study was supported by Biomecanica, Inc., Miami,Florida (owner of the patented Distraction AugmentationMammoplasty technology). The authors thank Marita Eisen-man-Klein, M.D., and Jurgen Holle, M.D., for assisting withthe study, Ann Pando, Ph.D., for designing the psychologicalquestionnaire, and Brian Cooley for editing the manuscript.

2510 PLASTIC AND RECONSTRUCTIVE SURGERY, June 2000

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