From the Guidelines

A discoid meniscus is a knee cartilage abnormality that can cause chronic anterolateral knee pain.

It is one of the various etiologies of chronic anterolateral knee pain that can be diagnosed on MRI, as mentioned in the study published in the Journal of the American College of Radiology 1.
A discoid meniscus is a congenital anomaly where the meniscus is thicker and more circular than normal, which can lead to increased stress and potential tears.
MRI is a useful diagnostic tool for identifying a discoid meniscus, as well as other causes of chronic knee pain, such as patellar tendinopathy, fat pad impingement syndromes, and osteonecrosis.
The study highlights the importance of MRI in diagnosing and evaluating various knee conditions, including those that may not be visible on radiographs 1.

MRI without and with IV contrast can be used to diagnose a discoid meniscus, although contrast-enhanced images may be more accurate in diagnosing certain conditions, such as Hoffa’s disease and pigmented villonodular synovitis 1.
The diagnosis of a discoid meniscus is typically made based on the appearance of the meniscus on MRI, with a thicker and more circular shape being characteristic of this condition.

From the Research

A discoid meniscus is a rare anatomical variant with altered morphology and structure that can sometimes present symptomatically, typically in the pediatric population 2.
It is usually located in the lateral compartment of the knee and is characterized by a partial or complete filling-in of central meniscal tissue, increased meniscal thickness, disorganization of longitudinal collagen fibers, and sometimes lack of peripheral attachments 2, 3.
The discoid meniscus has deranged collagen arrangement and vascularity, which can have implications for healing after a repair 4.

Patients with a discoid meniscus may or may not be symptomatic, with mechanical complaints of locking, clicking, snapping, or pain 3, 5, 4.
Symptoms often arise due to a tear in the body of the meniscus or a peripheral detachment 4.
Magnetic resonance imaging (MRI) is essential for diagnosis and treatment planning, and a recent MRI classification provides useful information for surgical planning 5.

Asymptomatic patients usually do not require any treatment, while symptomatic patients who do not have locking are managed conservatively 4.
Surgical management of symptomatic discoid meniscus is directed toward symptom resolution while preserving sufficient functional meniscal tissue to delay or prevent the development of osteoarthritis 2.
Modern surgical techniques consist of arthroscopic saucerization of the discoid meniscus with repair of associated meniscal tears and stabilization of peripheral attachments 2, 3, 5.
Partial meniscectomy with or without meniscal repair is effective and shows superior clinical and radiological outcomes to those of total or subtotal meniscectomy during the short- to long-term follow-up 5, 4.