Meniscal Extrusion: A Key Modifiable Driver of Meniscal and Cartilage Degeneration.

PURPOSE OF REVIEW: To critically examine the evidence addressing whether meniscal extrusion represents a distinct and clinically meaningful pathologic entity, elucidate its underlying biomechanical and anatomic causes, and review current and emerging strategies for diagnosis and management. This review synthesizes contemporary literature on imaging criteria, pathophysiology, and the evolving role of restorative interventions, particularly meniscus centralization, in mitigating extrusion-related joint degeneration. RECENT FINDINGS: Meniscus extrusion (> 3 mm radial displacement) exists as both physiologic and pathologic, associated with root tears, radial tears, and osteoarthritis. Normative values (e.g., < 2 mm in healthy knees) and cut-offs (> 2–3 mm for pathology) vary by imaging (MRI/US). Etiology involves hoop stress loss and meniscotibial ligament disruption. Treatments like root repair and centralization may reduce extrusion, improve biomechanics (e.g., contact pressure/area), and enhance outcomes (e.g., KOOS scores improved by 20–30 points post-centralization). Meniscal extrusion is a real and clinically significant consequence of meniscal biomechanical failure, most commonly related to root disruption and peripheral instability. Treatment paradigms have shifted from symptom management toward biomechanical restoration, with growing evidence that meniscus centralization can reduce extrusion and improve clinical outcomes. Nevertheless, long-term prospective data are required to establish whether these interventions can meaningfully alter the natural history of knee osteoarthritis.