Meniscal Tears

Mensical Tear Posterior Horn 1Mensical Tear Posterior Horn 2


Mechanism of Injuries


Rotational force incurred while joint partially flexed & extending

- caught between femoral & tibial condyles

- usually valgus & ER / varus & IR




MM: LM 2:1


Medial Meniscus more common

- less mobile

- usually posterior horn tear


Acute ACL

- lateral Meniscus


Chronic ACL

- medial meniscus


Tibial plateau fracture

- 50% incidence


Relatively common in asymptomatic knees

- 13% < 45 years

- 36% > 45 years


Medial meniscus anatomy


C shaped fibrocartilage

- posterior horn larger than anterior horn

- capsular attachment on the tibial side is the coronary ligament

- thickening of the capsule from tibia to femur is deep MCL


Medial Meniscus NormalPosterior Horn Medial Meniscus Normal


Lateral meniscus



- covers a larger surface of the tibia than MM

- anterior and posterior horns attach closer to each other

- anterior horn adjacent to ACL

- posterior horn behind tibial eminence

- ligaments of Humphrey and Wrisberg are attached to posterior horn

- popliteal hiatus posteriorly


Lateral Mensicus NormalKnee Arthroscopy Popliteus




Circumferential type I collagen fibres

- radial fibres to anchor them

- more random mesh structure at surface

- fibrochondrocytes


Blood Supply



- entirely vascular at birth

- inner 1/3 avascular by 1 year

- adult blood supply by 10


Outer 10 - 25% vascular

- genicular arteries

- perimeniscal capillary plexus


Inner 2/3

- nutrition via diffusion


Synovial fringe

- femoral and tibial surface

- does not contribute to the meniscal blood supply


Nerve supply


Similar distribution

- peripheral tears more painful than central tears

- proprioception




1.  Transmit and distribute forces over plateau

- load sharing flexion > extension

- shock absorbing


Total medial meniscectomy

- 100% increase in contact stresses


Total lateral meniscectomy

- 200-300% increase in contact stresses


2.  Secondary stabilisers

- posterior horn resists anterior translation in flexion

- important in ACL deficient knee




1.  Longitudinal Tears


Mensical Tear Posterior HornMeniscal Tear Posterior Horn


Most common

- vertically oriented tear parallel to edge of meniscus

- usually of posterior part of meniscus

- may occur in either meniscus

- extent varies


A.  Incomplete 

- usually inferior surface

- may have been complete then healed

- very common posterior horn lateral meniscus after ACL rupture


Knee Arthroscopy Healed Meniscal Tear Undersurface Lateral MeniscusKnee Arthroscopy Healed Meniscal Tear Lateral Meniscus Top Surface


B. Complete


Mensical tear complete longitudinal


C.  Bucket handle 

- displaces into intercondylar notch

- may be central or peripheral

- cause of locked knee

- can damage chondral surface over time


Bucket Handle Tear MM displaced anteriorly arthroscopyMeniscus Bucket Handle Flipped Anteriorly


Mensicus Locked Lateral Bucket Handle


2.  Horizontal Cleavage


More common in older patient

- horizontal cleavage plane between superior & inferior surfaces of meniscus

- posterior 1/2 of MM

- mid-segment of LM


Meniscus Horizontal Tear


3.  Oblique


Vertically oriented full-thickness tear 

- runs obliquely from inner edge of meniscus out to body of meniscus

- if base posterior, referred to as posterior oblique tear & vice versa


4.  Radial 


Vertically oriented full thickness tear 

- extends from inner edge radially to periphery


Meniscal Radial Tear



- doesn't extend to periphery



- extends to periphery


Parrot beak tear 

- incomplete radial tear with anterior or posterior extension 


5.  Complex


Elements of all above

- usually in longstanding meniscal lesions


6.  Degenerative


Complex tear of degenerative meniscus / usually OA


Degenerative Meniscal Tear


Blood Supply Classification


Red - Red Tears

- peripheral 3 mm

- capsulomeniscal junction

- good blood supply

- both sides vascularised


Red - White Tears

- only one side of tear vascularised


White - White Tears

- peripheral

- neither side vascularised




History of injury

- twist with weight bearing

- may not be a specific injury especially in middle-aged patient


Swelling usually delayed 6 hours & mild 

- can be chronic from synovial irritation

- may be rapid haemarthrosis with capsular tear



- only with longitudinal tears / bucket handle tear


Giving Way

- may occur with other knee disorders

- i.e. loose body, instability, weak quadriceps







- along periphery of meniscus

- along joint line

- pain secondary to synovitis in adjacent capsule


McMurray's Test 

- tests menisci posterior to collateral ligaments

- point heel towards meniscus testing

- positive test is palpable or audible snap or click


1. Fully flex knee

2. Place leg into full IR -> tests LM

3. Extend to 90°

4. Place leg into full ER -> tests MM

5. Extend to 90°




Standard Knee Series

Exclude SONK / loose bodies / OCD / tumour


MRI Classification


Stoller 1987 J. Radiol.


Grade 0 

- normal homogeneous low signal intensity


Grade I 

- globular increase signal in meniscus

- doesn't reach either surface


Meniscus MRI Increased Signal


Grade II 

- linear increase signal, doesn't reach surface

- myxoid intra-meniscal degeneration / partially healed tear


Mensical Tear Incomplete


Grade III

- increased signal intensity communicates with meniscal surface

- 70-90% accurate for true tear

- accuracy MM > LM


Anterior Horn Meniscal Tear Stoller Grade 3Medial Meniscus Posterior Horn TearMRI Meniscus Tear Posterior Horn


MRI Pitfalls / Normal Findings or Variants


Ligaments of Wrisberg PMFL & Humphrey AMFL


Ligament Wrisberg


Transverse Anterior Meniscal Ligament


MRI Intermeniscal Ligament


Signs of bucket handle tear meniscus


1.  Double PCL sign

- medial Meniscus


Medial Meniscus Tear Double PCL


2.  Absent bow tie sign

- should see bow tie image on 2 consecutive sagittal slices of 5 mm


3.  Fragment in notch sign


Medial Meniscus Bucket Handle Tear Fragment in Notch


4.  Anterior flipped meniscal sign

- torn fragment flips over the anterior horn of the affected meniscus


Medial Meniscus Bucket Handle Tear Anterior Flipped MeniscusAnterior Flipped Meniscus Bucket Handle


5.  Truncated meniscus


Bucket Handle Tear Truncated Meniscus




Mainstay of diagnosis and treatment


Bone Scan


Don't forget SONK in differential

- 60 yr old female with normal x-rays

- acute onset pain



Should usually show up on MRI




Surgical Indications


Painful locking / clicking with disability

Acutely locked knee

Repairable meniscus in combination with ACL injury

Repairable meniscal injury in young




1.  Leave / non operative treatment

2.  Excise

3.  Repair

4.  Meniscal transplant


Non Operative Treatment


Essentially the asymptomatic patient


A.  Stable partial thickness (< 50%)

B.  Stable longitudinal < 1 cm long

C.  Small < 3 mm radial tears


ROM exercises + quads drill