Superficial Abdominal Skin Laxity Versus Rectus Diastasis: Distinct Pathophysiological Entities With Different Functional and Reconstructive Implications in Modern Abdominoplasty.

Abdominal contour deformities are commonly described as "abdominal flaccidity," but they reflect distinct underlying anatomic components with different functional and surgical implications. This narrative review aimed to revisit the concept of abdominal flaccidity, propose a conceptual framework distinguishing cutaneous laxity from musculoaponeurotic weakness, clarify the anatomic and functional differences between superficial abdominal skin laxity and rectus diastasis, and discuss their implications for contemporary abdominoplasty. Indexed literature and seminal historical studies were synthesized to examine abdominal wall anatomy, imaging, post-pregnancy and post-weight loss deformities, fascial plication, mesh reinforcement, and current abdominoplasty strategies. The evidence supports that skin laxity primarily affects the cutaneous-subcutaneous envelope, whereas rectus diastasis reflects attenuation and widening of the linea alba with loss of midline tension, dynamic bulging, and, in selected patients, functional impairment. Contemporary abdominoplasty has evolved from dermolipectomy to individualized contour surgery integrating liposuction, selective undermining, vascular preservation, progressive tension concepts, and tailored management of the musculoaponeurotic layer. No single reconstructive technique is universally superior; however, phenotype-based evaluation improves indication, operative planning, perioperative safety, and outcome interpretation. Abdominal contour deformities should therefore be approached as a spectrum rather than a single entity in plastic surgery practice.