2. Anatomy and Functions of Meniscus
• Meniscal function is essential to the normal functioning of the
knee joint.
• Menisci act as a joint filler and shock absorber compensating
for the gross incongruity between the femoral and tibial
articulating surfaces.
• Menisci prevent capsular and synovial impingement during
flexion extension movements.
• Important rotatory stabilizers.
• Essential for a smooth transition from a pure hinge to a gliding
or rotatory motion as the knee moves from flexion to
extension.
3. • Peripheral edges of the menisci are convex, fixed and
attached to the inner surface of the knee joint capsule except
where the popliteus is interposed laterally.
Perpheral edges are also attached loosely to the borders of the
tibial plateau by coronary ligaments.
Inner edges are concave, thin and unattached.
Inferior surface of the menisci are flat and superior surface is
concave.
4.
5.
6. • Medial Meniscus :
• C shaped
• Larger in radius than lateral meniscus
• Posterior horn wider than anterior horn
• Anterior horn attached to the tibia anterior to the intercondylar
eminence and to the ACL.
• Posterior horn anchored immediately in front of the attachments of
PCL posterior to the intercondylar eminence.
• Lateral Meniscus:
• More circular in form compared to medial meniscus.
• Anterior horn attached to the tibia medially in front of the
intercondylar eminence
• Posterior horn attached to the posterior aspect of the intercondylar
eminence.
• Wider body, smaller diameter, more mobile
7.
8. • Menisci are crescents, roughly triangular in cross sections
• Cover one half of the articular surface of the corresponding
tibial plateau.
• Composed of dense tightly woven collagen fibres – majority
being type 1 collagen and a small amount of type 2 collagen.
• Orientation of collagen fibres :
• Mostly circumferential
• Radial
• Perforating
9.
10. Vascularity
• The menisci are largely avascular except for the peripheral
portion.
• Divided in 3 zones from periphery to centre.
• RED-RED zone
• RED-WHITE zone
• WHITE-WHITE zone.
• Bloody supply is mainly by the lateral and medial geniculate
vessels.
• Branches from these vessels give rise to perimeniscal capillary
plexus.
11.
12. • Biomechanical study reveals that upto 150kgs of weight , the
lateral meniscus appears to carry 70% of the load on that side
of the joint.
• Medial meniscus shares the load approximately equally with
the exposed articular cartilage.
• Medial menisectomy decreases contact area by 50%-70% and
increases contact stress by 100%
• Lateral menisectomy decreases contact area by 40% but
increases contact stress by 200% because of the relative
convex surface of the lateral tibial plateau.
13. Meniscal healing
• After injury, within the peripheral vascular zone, a fibrin clott
rich in inflammatory cells is formed.
• Vessels from the peripheral perimeniscal plexus capillary
plexus proliferate throughout this fibrin scaffold.
• Accompanied by proliferations of differentiated mesenchymal
cells.
• Lesion is eventually filled with cellular fibrovascular scar tissue
that glues the wound edges together.
14. Tears of Menisci
• Traumatic lesions of the menisci are produced more
commonly by rotation as the flexed knee moves towards an
extended position.
• The most common location for injury is the posterior horn of
the menisci and the longitudinal tears are the most common
type of injury.
• Those with inadequate musculature, especially the
quadriceps , probably are at significantly greater risk of
meniscal injury
15. Mechanism of tear.
• Meniscus is usually torn by the rotational forces when the joint
moves from flexion towards extension.
• During vigorous internal rotation of the femur on the tibia, with the
knee in flexion, the femur tends to force the medial meniscus
posteriorly and towards the centre of the joint.
• A strong peripheral attachment posteriorly may prevent the
meniscus from being injured.
• If this attachment stretches, then the meniscus is forced towards
the centre of the joint.
• Meniscus is caught between the tibia and the femur and is torn
longitudinally when the joint is suddenly extended.
16. Contd.
• If this longitudinal tear extends anteriorly beyond the medial
collateral ligament, the inner segment of the meniscus is caught in
the intercondylar notch and cannot return to its former position –
thus a BUCKET-HANDLE tear with locking of the joint is produced.
• The same mechanism can produce a posterior peripheral or a
longitudinal tear of the lateral meniscus.
• The lateral femoral condyle, forces the anterior half of the mensicus
anteriorly and towards the centre of the joint.
• This strain in turn may tear the posterior half of the meniscus from
its peripheral attachment.
• When the joint is extended, a longitudinal tear occurs.
17. Types of meniscal tears.
• Longitudinal tears
• Transverse and oblique tears
• Combination of longitudinal and transverse
tears.
• Bucket handle tears.
• Tears associated with cystic meniscus.
18.
19. Symptoms
• Pain localising to medial or lateral joint line
• Intermittent or delayed swelling.
• Pain during weight bearing
• Mechanical symptoms like locking or clicking
• Pain during squatting
• Giving way of the knee.
• Locking is more common with logitudinal tears especially
bucket handle tear.
• Locking is not a pathognomonic of bucket handle tear.
• Intra-articular osteocartilagenous lose body may cause locking as
well.
20. • FALSE LOCKING
• Occurs soon after an injury in which haemorrhage around the
posterior aspect of the capsule or a collateral ligament with
associated hamstring spasm prevents complete extension of
the knee joint.
• If the patient doesnot have locking, then the diagnosis of a
torn meniscus is very difficult.
• The patient at times gives a history of several episodes of
trouble referable to the knee , often resulting in effusion and
distability but no locking.
21. Clinical Examination.
• Medial / Lateral joint line tenderness.
• Effusion
• Muscle atrophy around the knee – especially vastus
medialis
• Special tests:
• McMurray test
• Apley’s grinding test
• Thessaly test (diagnostic accuracy of 94% for medial
meniscus tear and 96% for lateral meniscus tear)
• Squat test
22. Radiology
• X-Rays :
• Anteroposterior and lateral views.
Rule out osteochondral lose body.
Osteochondritis dissecans (mimics meniscal tear)
MRI:
Diagnostic accuracy of 98% for medial meniscus and
90% for lateral meniscus.
23.
24. Treatment options
• Non – operative :
• Incomplete meniscal tear or a small (<5mm)
stable peripheral tear with no other ligamentous
injury can be managed conservstively.
• Stable longitudinal tears occuring at peripheral
vascular zone have been reported to heal without
surgical management.
• 6 weeks of knee protection in the form of long
knee brace or long leg cast.
• Crutch walking with touch down weight bearing
25. Physiotherapy
• Progressive isometric exercise programme
• Quadriceps, hamstring, gastrocnemius and soleus
strengthening
• Hip abductors, adductors, flexors and extensor
strengthening.
• Post physiotherapy gradual weight bearing.
• If symptoms donot subside or recurr after
conservative management then surgical options
of reapir or removal needs to be considered.
26. Operative management
• Partial meisectomy
• Total menisectomy
• Meniscus repair.
• Most of the degenerative changes in the knee joint occurs after
total rather than partial menisectomy.
• After partial menisectomy, there is less articular cartilage
degeneration.
• Amount of degeneration is directly proportional to the amount of
meniscus removed.
• If the torn meniscus produces almost daily symptoms, frequent
locking, chronic effusions, then the pathologic portion of the
meniscus should be removed.
• If a significant amount of the peripheral rim of meniscus can be
preserved then the long term outcome is improved.
27. • Complete removal of the meniscus is justified only if the torn
meniscus is irrepairable.
• Total menisectomy is no longer the treatment of choice in young
athletes or other people whose daily activity requires rigorous use
of the knee.
• Partial medial menisectomy generally are favourable with 88% to
95% of the patients reporting a good to excellent results.
• Ideal indication for meniscal repair:
• Acute 1-2 cm longitudinal peripheral tear(red-red or red-white
zone) in a young individual.
• Studies have shown that clinical outcomes were slightly better
when plate rich plasma was used in open repairs of horizontal tear
extending into avascular zone.
