**Abstract**

This chapter mainly focuses on medial meniscus posterior root tear which is the point of attention nowadays because it is the common degeneration process and can lead to early-onset osteoarthritis of the knee without treatment. The biomechanics of the medial meniscus root tear is similar to total meniscectomy. Hence, early detection and diagnosis will lead to better outcome. Most cases with medial meniscus root tear also have degenerative change of the knee. Meniscal extrusion is a common finding in magnetic resonance imaging (MRI) which represent impairing of hoop stress function of the meniscus. Patient selection and understanding of the natural history of the disease is a particularly important. Options for the treatment including conservative treatment, surgical treatment such as partial meniscectomy, meniscus root repair, or reduction of meniscal extrusion. Outcome of these treatments are variable depending on the condition of the patients. Long term outcome of surgical treatment revealed lower rate of knee replacement compared with conservative treatment.

**Keywords:** Meniscus root tear, Medial meniscus root tear, Medial meniscus tear, Meniscus extrusion
