Lumbar Adjacent Segment Disease: A Modern Perspective and Review of the Literature.

Our collective understanding of the pathogenesis, risk factors, and management of adjacent segment disease (ASD) following lumbar fusion has expanded markedly in recent years, necessitating an updated and comprehensive review. ASD is now recognized as a multifactorial process in which postoperative biomechanical changes accelerate degeneration, further amplified by predisposing genetic factors. Key risk factors have been identified and linked to increased rates of ASD, including elevated body mass index, preexisting degeneration at adjacent levels, and inadequate restoration of sagittal alignment, particularly pelvic incidence-lumbar lordosis mismatch. Innovative surgical techniques, including minimally invasive approaches and robotic-assisted instrumentation, have been increasingly used and researched over the past decade with the goal of reducing the incidence and progression of ASD, although long-term evidence remains mixed. Although these advancements are promising, it is important to evaluate their efficacy, limitations, indications, and contraindications using the most current available evidence. Finally, advances in diagnostic imaging and emerging biologic therapies represent a potential paradigm shift in our understanding of the pathogenesis and preventability of ASD.