Dynamic Contour Irregularities in Implant-Based Breast Reconstruction: Long-Term Aesthetic Outcomes After Direct-to-Implant Versus Tissue Expander Techniques

<b>Background</b>: Animation deformity (AD) is a well-known complication of submuscular implant placement. However, dynamic contour irregularities have also been reported in prepectoral reconstructions, but their mechanisms and classification remain unclear. <b>Methods</b>: In this prospective, single-center study, 67 patients underwent either direct-to-implant (DTI, n = 33) or tissue expander (TE, n = 34) reconstruction. Among these, 56 patients had subpectoral and 11 patients had prepectoral implant placement. Patient-reported outcome measures (PROMs) were assessed using the BREAST-Q. Aesthetic outcomes were rated by four plastic surgeons using the Breast Aesthetic Scale. Breast animation deformity was evaluated clinically and photographically by an expert panel using two distinct classification systems. <b>Results</b>: The mean follow-up period was 78 (±45) months. No significant differences were found between DTI and TE groups in BREAST-Q scores or overall aesthetic outcomes. Bilateral reconstructions showed significantly higher aesthetic ratings (<i>p</i> = 0.001). AD was observed in 61.2% of patients, with significantly higher prevalence in the DTI group (<i>p</i> = 0.02). Six patients with prepectoral reconstruction demonstrated dynamic contour irregularities distinct from classical AD. A new definition for this phenomenon is proposed. <b>Conclusions</b>: DTI and TE reconstructions achieve comparable long-term patient satisfaction and aesthetic outcomes. The observed cases of dynamic implant contour irregularities (DICI) in prepectoral implant placement underscore the need for a more nuanced classification of contour irregularities in implant-based breast reconstruction beyond the established concept of AD.