Discussion: Is Rotation a Concern with Anatomical Breast Implants? A Statistical Analysis of Factors Predisposing to Rotation
In this clinical series, 531 patients underwent primary bilateral breast augmentation with Natrelle Style 410 (Allergan PLC, Dublin, Ireland) breast implants. The implants were placed through an inframammary incision using a dual-plane pocket dissection. No drains were used and the patients had a postoperative protocol that included wearing a nonwired sports bra for 3 weeks continuously followed by another 3 weeks during the daytime only. Activity was increased after 3 weeks and sports and vigorous exercise were allowed after 3 months following surgery. The authors reported a 1.88 percent implant rotation rate affecting 3.58 percent of patients. They found no significant correlation between risk of rotation and factors such as body mass index and parity. However, they reported a statistically significant trend with increased risk of rotation with increasing bra cup size.
Before any discussion about breast implant rotation, we need to clarify what is meant by rotation/malrotation, as these terms have been used ambiguously in the literature. In some cases, during surgery, anatomical implants are intentionally oriented off the vertical axis, and this should not be considered rotation/malrotation. Once healed, an anatomical implant can rotate several ways. The implant may rotate clockwise or counterclockwise from the position that was established during surgery. However, in our experience,2 clinically apparent rotation more commonly occurs when an implant flips back to front—the back surface of the implant becomes anterior. Patients with this problem usually report suddenly noticing a difference in the appearance of their breast(s). When discussing rotation, another important consideration is the difference between clinically apparent and clinically undetectable rotation. Sieber et al.3 recently used high-resolution ultrasound to demonstrate a 29 percent anatomical implant rotation rate (42 percent of patients) that was clinically undetectable in most cases.
There are several significant issues with the methodology of this study. First, the authors included patients with at least 6 months’ follow-up, and the mean follow-up time was 11.95 months; however, in our experience,2 rotation can occur at any point in time and typically occurs later than 6 months postoperatively. The authors observed in this study that the average time after surgery at which rotation occurred was 9.8 months (range, 3 to 35 months). It is likely that this article underreports the clinically apparent rotation rate and a certainty that it underreports clinically undetectable rotation. Also, if rotation is clinically undetectable in most instances, we need to ask the question, “Why do we use anatomical implants if we and our patients cannot detect the difference in many of these cases?”
Of several factors that were examined, the only statistically significant trend was between increasing bra cup size and increased risk of rotation. There are several fundamental flaws with this. First and foremost, there is no standard in bra cup sizing that translates into any objective measurement—a cup size does not equal an exact volume. Many clothing manufacturers use “vanity sizing,” making the labeled size even less reflective of the true size.4 Furthermore, bra cup size was patient reported, adding even more variability.
The authors make several statements in this article that have been asserted as matter of fact but are really speculation.