Knee: Meniscus
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Kyung Jin Suhkyungjin.suh@gmail.com
Doctor Radiology, Daegu, KOREA

MedialLateral

7.7
10.2

11.6

9.6

10.6 mm
Posterior > Anterior horn

10.6 mm

Posterior = Anterior hornMedialLateralRadial fiber
Circumferential
fiber
Perforating
fiber

Circumferential(longitudinal)
fiber

Radial (tie)fiberRed zone and White zone

Hauger O. Radiology 2000

Red zone (3 mm): repair
Medial meniscus: 10-30%
Lateral meniscus: 10-25%

White zone (5 mm): meniscectomy

Hauger O. Radiolgy 2000

Red zone vs white zone
Perimeniscal tissue: blood vessels, adipose tissue, irregular collagen fibers

Meniscal Tear
Classifications by O'Connor
1. Longitudinal tears
2. Horizontal tears
3. Oblique tears
4. Radial tears
5. Variations
Flap tears, complex
tears, degenerative tears
Surg Annu 1977;9:267

1. Longitudinal tears
2. Horizontal tears
3. Oblique tears
4. Radial tears
5. Variations
Flap, complex, degenerative
bucket-handle tearMeniscal Tear
Longitudinal

Horizontal tear
Flap tear
Flipped horn tear

Vertical tear
Bucket handle tearRamp tearOblique tear

RadialRadial tear
Root tearParrot beak tearComplex Tear

Free edge tear
Meniscocapsular separation
Meniscal contusion

Meniscal Tear Types
Describe Based on Classification
Longitudinal horizontal tearLongitudinal vertical tearLongitudinal oblique tear
Flap tear
Flipped tear
Radial tearParrot beak tear
Bucket handle tearRamp tear
Root tearComplex tearFree edge tear
Meniscal contusion
Meniscocapsular separation

Interobserver Reliability of the International Society of Arthroscopy,
Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)Classification of Meniscal Tears

Horizontal flap
Vertical flap
RadialComplex

Horizontal
Longitudinal

Am J Sports Med 2011;39:926-932

Interobserver Reliability of the International Society of Arthroscopy,
Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)Classification of Meniscal Tears

Am J Sports Med 2011;39:926-932

Meniscal Tear
Imaging Criteria
Meniscal contour
Meniscal signal intensity
Meniscal morphology alteration
Displaced meniscal fragment
Abnormal intrameniscal signal intensity
Extending to articular surface
At least 2 sections
Sensitivity/specificity= 93/88%
Medial/lateral meniscus=79/95%

Meniscal Tear
Imaging Criteria
Meniscal contour
Meniscal signal intensity
If seen on single image
50% of medial meniscal torn
30% of lateral meniscal torn
Associated with radial and parrot-beak tears

Exception
Discoid shape with intrameniscal signal
Meniscal cyst

Meniscal Tear
Imaging Criteria
Meniscal contour
Meniscal signal intensity
If seen on single image
50% of medial meniscal torn
30% of lateral meniscal torn
Associated with radial and parrot-beak tears

Exception
Discoid shape with intrameniscal signal
Meniscal cyst

Meniscal Tear
Role of Imaging
What I report should include• Location• Type• Partial vs complete• Zone• Length• Associated abnormalities• Stability vs instability

Interobserver Reliability of the International Society of Arthroscopy,
Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)Classification of Meniscal Tears

Longitudinal Tear
Horizontal flap
Vertical flap
RadialHorizontal
Longitudinal

ComplexLongitudinal vertical tear
TraumaInterobserver Reliability of the International Society of Arthroscopy,
Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)Classification of Meniscal Tears

Horizontal Tear
Longitudinal horizontal tear
Horizontal flap
Vertical flap
RadialHorizontal
Longitudinal

ComplexInterobserver Reliability of the International Society of Arthroscopy,
Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)Classification of Meniscal Tears

Radial Tear
Horizontal flapVertical flap
RadialHorizontal
Longitudinal

ComplexInterobserver Reliability of the International Society of Arthroscopy,
Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)Classification of Meniscal Tears

Vertical Flap Tear
Horizontal flap
Vertical flap
RadialHorizontal
Longitudinal

Complex

Oblique tearParrot-beak tearInterobserver Reliability of the International Society of Arthroscopy,
Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)Classification of Meniscal Tears

Horizontal Flap Tear
Horizontal flap
Vertical flap
RadialComplex

Horizontal
Longitudinal

DDx
MM: SM tendon anterior horn

Interobserver Reliability of the International Society of Arthroscopy,Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)Classification of Meniscal Tears

Complex Tear
Horizontal flap
Vertical flap
RadialHorizontal
LongitudinalComplex

Free Edge Tear

Meniscocapsular Separation

Meniscal Contusion
14/M
Football injury 5 days ago

Bucket-handle Tear

Meniscal fragment
in intercondylar notch“Double PCL sign”

Bucket-handle Tear
Broken-handle Tear

Condylar Entrapment

Jack and Jill Lesions

Leaking Bucket
Peripheral (rim) failure
Radial, horizontal
Meniscocapsular separation

Meniscal Root Tear

MMAntMedPostLatLM

30/M
“Pop"
when squatting weightsLaPrade Classification of Meniscal Root Tears
Based on Tear Morphology

LaPrade CM et al. Am J Sports Med 2015;43(2):363

Ramp TearMedial meniscus posterior horn
Resist anterior translation of tibia
Association with chronic ACL tears

Ramp lesion

Wrisberg Rip
Lateral meniscus posterior horn
Peripheral failure
Association with ACL tear

ACL tear
23/M→Anterior
Soccerinjury translation of lateral meniscus
ACLtear→ Meniscal
avulsion relate to PM fascicles and/or Wrisberg ligament→ Lateral meniscus posterior horn tearMeniscal CystMeniscus
Unstable meniscus
Definition
A tear in which the meniscus or a meniscal fragment isdisplaced or can be displaced by a probe

1.
2.
3.
4.

A tear that on inspection of probing isgreater than 9 mm in length… has multiple directions
A large radial tear of a radial tear withwide separation at the site of tear
A gap at the site of tear that may
collect fluid≈ 30 mm

12 mm

13 mm

9 mm

Meniscus
Unstable meniscus
Greater than 1 cm in length tearMore than one morphologic tear pattern
Displaced meniscal fragment
High signal on T2 within tear planeRadiology 2016;281: 23-40

Discoid MeniscusWatanabe Classification

Complete type

Incomplete
Cover <80% of plateau

Wrisberg-ligamentWrisberg-ligament Type
Lack posterior capsular attachment“Snapping knee”

MRI Criteria> 15 mm> 20%> 3 absent bow-ties

Meniscal Tear
Role of Imaging
What I report should include• Location• Type• Partial vs complete• Zone• Length• Associated abnormalities• Stability vs instability

ISAKOS Classification
1. Tear depth
2. Location
3. Radial location
4. Central to the popliteal hiatus
5. Tear pattern
6. Quality of tissue
7. Length of tear
8. Indicate the amount ofmeniscus that was excised bydrawing on the diagram andcrosshatching the part that wasremoved.
9. What percentage of themeniscus was excised?

ISKOS: Horizontal
Resnick: Longitudinal horizontal
Stoller: Horizontal cleavage
Other: Degenerative fish- mouth

RSNA 2017 DPS

ISKOS: Horizontal flap
Resnick: Displaced longitudinalhorizontal
Stoller: Radial with longitudinalvertical component flap tear ofoblique

RSNA 2017 DPS

ISKOS: Bucket-handle
Resnick: Bucket-handle
Stoller: Bucket-handle

RSNA 2017 DPS

47/M MVAMedial meniscus:
Posterior horn tear, Mixed type tearwith posterior Root extension,
LaPrade type 3. Partial depth andZone 1 to 3 location, Tear maximal
length about16 mm, Good Poor
quality of tissue. No central topopliteal hiatus. Multiseptatedmeniscal cyst in medial and posterior
extensions.
Lateral meniscus: Normal shape andsignal intensity