Symmastia (also known as synmastia) is a condition that occurs when breast implants sit too close to the middle of the patient’s chest. Extreme cases can even lead to the “uniboob” look. Fortunately, it is a rare complication of augmentation mammoplasty surgery.
Developmental symmastia can occur without prior surgery in patients who have breast hypertrophy and an aberrant soft-tissue connection across the midline.
Dr Spear (4th reference article below) noted (bold highlight is mine):
Based on our experience with postaugmentation synmastia, a number of facts have emerged. All of the implants were subpectoral. The majority of these women had undergone more than one operation. Many of them had undergone successive operations to enlarge the size of their implants and breasts. Many of them had large implants, arbitrarily defined by us as greater than 400 cc or with a diameter of 14 cm or more. Several of the patients had associated chest wall skeletal deformities, and some had undergone simultaneous mastopexy at the time of their breast enlargement.
Prevention of symmastia is much better than having to try to fix it. Care must be taken in dissection of the pocket, especially medially. It is preferable to use implants that “fit the body.” By this I mean, implants should not be wider than the available hemithorax of the individual patient. Try to get the patient to use a smaller implant or perhaps a high profile with a smaller base width. Avoid excessive detachment of the pectoralis muscle’s medial sternal attachments.
Correction of symmastia requires restoration of the presternal subcutaneous integrity and medial closure of the pocket. Techniques to achieve this include capsulorrhaphy, capsular flaps, AlloDerm or other materials, adjustable implants, explantation with delayed reimplantation, and change to a subglandular pocket. All have drawbacks in terms of reliability, technical difficulty, and convenience.
1. Symmastia: The Problem of Medial Confluence of the Breasts; Plast & Reconstr Surg 73(2):261-266, February 1984; Spence, Robert J.; Feldman, Joel J.; Ryan, James J.
2. Surgical Reconstruction of Iatrogenic Symmastia; Plas & Recontr Surg 121(3):143e-144e, March 2008; Foustanos, Andreas; Zavrides, Harris
3. The "Neosubpectoral" Pocket for the Correction of Symmastia; Plast & Reconstr Surg 124(3):695-703, September 2009; Spear, Scott L.; Dayan, Joseph H.; Bogue, David; Clemens, Mark W.; Newman, Michael; Teitelbaum, Steven; Maxwell, G Patrick
4. Synmastia after Breast Augmentation; Plas & Reconstr Surg 118(7S):168S-171S, December 2006; Spear, Scott L.; Bogue, David P.; Thomassen, John M.
5. Correcting Symmastia; Steven Teitelbaum, MD, FACS Website (nice photos)
6. Correction of Symmastia After Augmentation; Thomas M. DeWire, Sr., MD, FACS Website (nice photos)
7. YouTube Video of Symmastia Repair
8. My Breast Augmentation & Chin Revision (YouTube Video)