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Gert Kristensen, M.D.
Aalborg, Denmark
Norway 2007
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????? Treatment ????????
How do we treat
meniscus lesions
in
year 2007 ?
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Role of the menisci?
! Load distribution
! Shock-absorbtion
! Mechanic stabilization
! Lubrication
! Proprioception
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Role of menisci in load distribution on
the cartilage
40
35
30
25
20
15
10
5
0
Contact area
0
1
2
Intact knee
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3
4
Load
meniscectomy
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5
Menisci fills the empty space between
the femoral and tibial condyle in the
knee
Medial
condyle
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Lateral
condyle
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Menisci fills the empty space between
the femoral and tibial condyle in the
knee
Medial
condyle
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Lateral
condyle
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3D-reconstruction from MR-microscopy
!
Lat. Fem.
!
Meniscus
!
Lat. tibia
Setton et al. 1999
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Tibio-femoral contact pressure maps in vitro
A AMIS ET AL
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Consequence of meniscectomy:
8Grade of cartilage lesion
dependent on size of meniscal
resection
8Meniscus healing dependent on
communication with vascular
area
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Consequence of meniscectomy:
Radiological changes
after meniscectomy (107
knees, 5 mth - 14 years)
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Consequence of meniscectomy:
Newer literature confirms a higher incidence of Fairbanks
changes even after arthroscopic resection, latest F.
Chatain with 22.3% increase in joint space narrowing
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Meniscus anatomy
Ultrastructure of the
meniscus
Semi-circular fibres are
basis for the hoop-forces
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Menisci transforms axial load to tensile
load, the so called ”hoop-forces”
+ load
- load
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Meniscus load transmission
! 50% in straight knee
! 85% in 900 flexed knee
! This is due to a decrease in
condyle radius during flexion
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Consequence of meniscectomy:
If normal load is
concentrated on a
smaller area the load
in this area
becomes abnormal
Leads to osteoarthritis
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The role of the meniscus as stabilizor
20
Anterior displacement in mm:
15
10
5
0
30
60
90
120
Normal knee
ACL cut
Med. Meniscus cut
ACL AND Meniscus cut
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Flexion (degree)
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That’s why the anterior
drawer test doesn’t function if
medial meniscus is intact
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Thus an intact
meniscus is of great
importance for the
normal function of
the knee
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Menisci are mobile structures!
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Menisci are mobile structures!
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Posterior excursion of menisci
during flexion:
Medial meniscus:
5.1 mm
Lateral meniscus:
11.2 mm
(Thompson, Fu 1991)
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Lubrication
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!
74% weight is water
!
Compression
squeezes out water
into joint space
!
Allow smoother
gliding of surfaces
!
Also increases
contact area
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Blood supply to the medial
meniscus
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Blood supply to the lateral
meniscus
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RED/
RED
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RED/
WHITE
©
WHITE/WHITE
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!
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Vascular supply to
the menisci
originates from
medial and lateral
genicular arteries
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Vertical
Sutures?
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Vascular supply to the meniscus is affected
by vertical sutures (Albrecht-Olsen – a
study in pigs – personal communication)
Suture
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Meniscus structure
Central 2/3 radial and circumferential
Peripheral 1/3 circumferential fibers
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Meniscus structure
!Femoral lamina
!Tibial lamina
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NERVE INNERVATION
Nociceptors
! Mechanoreceptors
! The menisci are a source of
proprioceptive information regarding
position, direction, velocity, acceleration
and deceleration of the knee
!
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Meniscus nerve supply
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Meniscus nerve supply
Free nerve endings have been localized in
the meniscus
! At least 3 different mechanoreceptors
have been identified so far
! The anterior and posterior horns have
the richest nerve supply
! Menisci no doubt play a role in
proprioception
!
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Meniscus nerve supply
Free nerve endings have been localized in
the meniscus
! At least 3 different mechanoreceptors
have been identified so far
! The anterior and posterior horns have
the richest nerve supply
! Menisci no doubt play a role in
proprioception
!
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Norway 2007
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