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Body of medial meniscus

The medial meniscus is a C-shaped fibrocartilaginous structure within the knee joint, functioning as a load distributor, shock absorber, and stabilizer. The body of the medial meniscus represents the central portion, interposed between the anterior and posterior horns. It is thicker peripherally where it attaches to the joint capsule and thinner centrally where it faces the tibial plateau. Compared to the lateral meniscus, the medial meniscus is broader, less mobile, and more frequently injured.

The meniscus is composed of fibrocartilage with predominantly circumferentially arranged collagen fibers, allowing it to resist hoop stresses. Its structure permits even distribution of weight-bearing forces across the tibiofemoral joint and protects articular cartilage from degeneration.

Synonyms

  • Middle segment of medial meniscus

  • Central body of medial meniscus

  • Medial meniscal body

Relations

  • Superiorly: Contacts the femoral condyle articular cartilage

  • Inferiorly: Rests on the tibial plateau cartilage

  • Medially (peripherally): Fused with the joint capsule and connected to the deep fibers of the medial collateral ligament (MCL)

  • Laterally (centrally): Faces the joint space, thinner free edge exposed to synovial fluid

  • Anteriorly: Continuous with the anterior horn of the medial meniscus

  • Posteriorly: Continuous with the posterior horn of the medial meniscus

Function

  • Shock absorption during weight bearing

  • Load transmission and distribution across medial compartment of the knee

  • Joint stability, particularly in limiting anterior translation of the femur on tibia

  • Lubrication and nutrition of articular cartilage

  • Proprioception via mechanoreceptors in its capsular attachments

Clinical Significance

  • Meniscal tears: The body of the medial meniscus is a common site of horizontal, vertical, or complex tears due to its limited mobility and strong capsular attachments

  • Degenerative changes: Frequent in osteoarthritis with extrusion or thinning

  • Association with MCL injuries: Because of its attachment to the deep fibers of the MCL

  • Meniscal extrusion: Seen in chronic degeneration, correlates with progression of osteoarthritis

  • Arthroscopy and repair: Important site for suture or meniscectomy procedures

MRI Appearance

T1-weighted images:

  • Meniscal body shows low signal intensity relative to surrounding fat

  • Tears may appear as linear or irregular hyperintense signal extending to articular surfaces

T2-weighted images:

  • Normal meniscus appears as low signal intensity triangular structure

  • Tears or degeneration appear as bright intrameniscal signal reaching the articular surface

STIR (Short Tau Inversion Recovery):

  • Meniscus normally remains dark

  • Edema, tear, or degeneration shows bright signal within or adjacent to meniscus

Proton Density Fat-Saturated (PD FS):

  • Meniscus appears dark low signal

  • Pathology (tear, degeneration, contusion) shows bright hyperintense signal against fat-suppressed background

T1 Fat-Sat Post-Contrast:

  • Normal meniscus shows minimal or no enhancement

  • Post-surgical or inflamed meniscus may show focal enhancement

  • Abscess or synovial pathology nearby can cause adjacent enhancement

MRI Arthrogram Appearance

  • Normal meniscus: uniform low signal triangular structure with no contrast penetration

  • Meniscal tear: contrast fills the tear line, delineating extent and configuration

  • Useful for detection of subtle or recurrent tears, especially post-surgery

CT Appearance

Non-Contrast CT:

  • Meniscus not well visualized, seen as soft tissue density structure

  • Degeneration or calcification may be seen in chronic cases

Post-Contrast CT (routine):

  • Limited utility for direct meniscal evaluation

  • Surrounding joint capsule or synovium may enhance in pathology

CT Arthrogram Appearance

  • Normal meniscus: appears as a solid triangular soft tissue density, surrounded by injected contrast in joint space

  • Meniscal tear: contrast tracks into the tear, sharply outlining margins

  • Allows high-resolution delineation of tear pattern, extrusion, and associated chondral lesions

MRI image

Body of medial meniscus sagittal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Body of medial meniscus axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Body of medial meniscus coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000