Update on the Split-Muscle Technique for Breast Augmentation: Prevention and Correction of Animation Distortion and Double-Bubble Deformity

Abstract

The subpectoral technique [1] and systematic analysis ofsoft tissue characteristics [2] have resulted in a more pre-dictable approach to breast implant surgery, yet certainproblems receive scant attention. Among these problemsare animation distortions and shape issues such as ‘‘double-bubble’’ deformity.In 2004, I reported the split-muscle technique as anoption that balances factors such as the need for coveragein thin or athletic women who want to avoid breast dis-tortion with physical activity [3]. Use of the split-muscletechnique in a large series also has been reported byKhan [4], with good outcomes and no significant animationproblems. Conversely, a recent survey by Spear et al. [5]found an overall incidence of 77.5% for some degree ofdistortion with subpectoral augmentation, rated as moder-ate or severe by 15% of patients. Considering that morethan 350,000 augmentation cases occur annually in theUnited States [6], most of which are subpectoral, thisbecomes a significant issue.Another problem, the ‘‘double-bubble’’ deformity, maybe related. Although this contour defect generally corre-sponds to the original inframammary fold, particularly incases with a short preoperative distance from the areolarmargin to the inframammary fold, I have routinelyobserved termination of the pectoralis muscle into theanterior capsule at the level of the external groove, whichdefines the abnormality. This may be coincidental wherethe preoperative inframammary fold is high, but the dou-ble-bubble contour occasionally develops when the areolarmargin-to-fold distance is normal. This can easily beascertained by asking the patient to flex and then observingupward pull at the level of the external groove, a phe-nomenon called ‘‘windowshading’’ (Fig. 1a, b). When thepatient is at rest, this external indentation is manifestexternally as the ‘‘double bubble’’ and corresponds to theedge of the muscle where it transitions into the capsule.The aforementioned problems occur because the portionof the muscle originating from the rib cage typically isattached at or cephalad to the inframammary fold. There-fore, it must be divided in most cases, allowing its retrac-tion superiorly (Fig. 2a, b). By definition then, the dividededge of the muscle settles somewhere between the nipple–areolar complex and the inframammary fold, where it fuseswith the anterior capsule as it develops. Contraction of themuscle unavoidably exerts pull on the capsule (Fig. 3),tethered only at its medial transition to the sternal attach-ment. For this reason, conversion to the split-muscle planecan be a useful option in cases of double-bubble deformi-ties with animation.One of the primary indications for subpectoral place-ment is upper pole coverage, afforded by the portion of thepectoralis major originating from the sternum. The costalportion provides central coverage, in which a subfascial orsubglandular plane very often is adequate because of breasttissue, even when upper pole muscle coverage is desirable.For primary augmentation using the split-muscle tech-nique, the prepectoral fascia is elevated using electrocau-tery under direct vision up to a line from the axilla to thepoint at which the pectoralis transitions from the sternum tothe rib cage. The muscle fibers then are separated along thisline to elevate the superior portion of the muscle whileleaving the inferior portion undisturbed (Fig. 4). Implantdimensions determine how far toward the insertion themuscle should be split. If an observable tendency exists forthe superior portion of the muscle to retract, a few sutures