Millesi's Classification of Nerve Fibrosis Remains Underutilized in Modern Peripheral Nerve Research

Peripheral nerve fibrosis is a major determinant of surgical outcome and functional recovery after nerve injury, yet standardized approaches to assess its extent remain scarce. Decades ago, Hanno Millesi introduced a comprehensive classification system that grades the degree of fibrosis according to the anatomical layers affected, ranging from paraneurial to endoneurial involvement. Despite its conceptual clarity and clinical relevance, this system remains largely underutilized in contemporary peripheral nerve research. Recent experimental models addressing perineural scarring and anti-fibrotic strategies rarely apply Millesi's classification, thereby limiting comparability and translation of findings. Here, we argue that greater integration of Millesi's classification could enhance experimental design, improve standardization, and guide the interpretation of preclinical and clinical studies on peripheral nerve regeneration. Renewed attention to this underutilized framework may bridge the gap between histological observations, experimental interventions, and the surgical decision-making process in peripheral nerve surgery.