Radial Meniscal Tear

Radial tears start from the free edge (white zone) and extend perpendicular to the long axis of the C-shaped meniscus. The tear may propagate to outer zone and become full-thickness, so-called "trizonal". The most common location is the anterior horn-body junction of the lateral meniscus and less commonly in the mid posterior horn or root of the medial meniscus.

Radial Meniscal Tear: Pearls

May be degenerative or traumatic, vertical, millimeters in size, on the inner edge of the lateral meniscus more commonly than the medial meniscus
May only be seen on one or two sections and in one plane²
Meniscus appears truncated

Radial Mensical Tear: Pathology

Radial tears can affect the hoop strength of the meniscus allowing for decreased function and possible meniscal extrusion.³

Radial Meniscal Tear: Location

Posterior horn of the medial meniscus
Junction of the anterior horn and body of the lateral meniscus³

Radial Meniscal Tear: Differential Diagnosis

Meniscal flounce can be mistaken for a radial tear in coronal MRI scans.¹

Radial Meaniscal Tear: MRI

Large radial meniscal tears may result in the ghost meniscus sign.³

Radial Meniscal Tear: Treatment

Small and asymptomatic tears are usually managed conservatively. Debridement and saucerization is preferred in symptomatic (greater than 8mm depth) and unstable gapped tears.²

Radial Meniscal Tear: References

Nguyen JC, De Smet AA, Graf BK et-al. MR imaging-based diagnosis and classification of meniscal tears. Radiographics. 2014;34 (4): 981-99.
Pomeranz SJ. Gamuts & Pearls in MRI & Orthopedics. Ohio, The Merten Company, 1997.
Weerakkody Y., et-al. Radial Meniscus Tear: Radiopaedia (sourced 10Jan2018): https://radiopaedia.org/articles/radial-meniscal-tear

Radial Meniscal Tear: Example

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GIF - 3D Axials on 1.5T High Field Oval

Image 1 - RAPID Axial PD isoFSE Fat Sat (0.8mm)

HISTORY:

Patient injured left knee while playing football in 2015. Left knee pain x2 years. The pain comes and goes depending on activity. No history of surgery or cancer.

FINDINGS:

Lateral retinaculum, MPFL, and patellar alignment are normal. Focal full-thickness fissure of the inferior trochlear groove, with no high-grade chondromalacia of the remaining trochlear or patellar cartilage.

Quadriceps tendon, patellar tendon, and flexor mechanism are unremarkable.

Chronic tear of the ACL without anterior tibial translation. No traumatic tear or injury of the PCL or lateral collateral complex. Chronic thickening of the proximal MCL suggestive of remote injury without active inflammation. 1.5cm vertical tear of the posterior horn medial meniscus contained within the red-red healing zone, with diminutive appearance of the medial meniscal body suggestive of autodigestion. Complex radial flap tear (GIF; image 1) of the lateral meniscus extending from anterior horn-to-posterior body 2.5 to 3cm in length with multiple parameniscal cyst formation projecting from the posterior body and anterior body.

No effusion or intraarticular bodies.

No high-grade chondromalacia of the medial or lateral compartment cartilage.

Musculature and marrow signal are normal. No posterior soft tissue mass or bursal cyst. The neurovascular bundle is intact.

CONCLUSION:

Chronic tear of the ACL without anterior tibial translation.
Complex radial flap tear of the lateral meniscus 2.5 to 3cm in length extending anterior horn-to-posterior body, with multiple parameniscal cyst formation projecting from the posterior body and anterior body..
Chronic vertical tear of the medial meniscus posterior horn 1.5cm in length contained within the red-red healing zone, and diminished appearance of the meniscal body suggestive of autodigestion.
Chronic thickening of the proximal MCL suggestive of remote injury.
Focal full-thickness chondral fissure of the inferior trochlear groove.