Transcript 3D Finite Element Model of Medial Meniscus Meniscectomy

Meniscal Tissue Degradation as
the first sign of Osteoarthritis.
THE PROCESS OF MECHANOTRANSDUCTION IN
THE MENISCAL TISSUE.
Barbara Zielinska
Michigan University of Technology

C-shape (wedge-shape
in cross-section profile)
disks of fibro cartilage
 Interposed between the
condyles of the femur
and tibia
HUMAN KNEE – top view

Strong attachments to
bone
 Inner 2/3 poor
vacularization
HUMAN KNEE – cross-section profile
Photos from: Knee Meniscus- Basic and Clinical Foundations, 1992, Raven Press NY
Structure of the Meniscus
Motivation

Studies show that the meniscus is involved
in the early stages of OA development.

A better understanding of the loading
environment and biochemical response of
meniscal tissue may help us understand the
etiology of OA.
Project definition

FE model of medial partial meniscectomy
MEASUREMENT OF THE CHANGES IN THE CONTACT PARAMETERS ON
THE MENISCUS AFTER DIFFERENT PARTIAL MENISCECTOMIES

Biochemical tests on the post incubated media
MEASURMENTS OF THE AMOUNT OF VARIOUS MOLECULES RELEASED
INTO THE MEDIA AFTER DIFFERENT LOAD CONDITIONS

Real time RT-PCR
MEASURMENT OF THE GENE EXPRESSION IN THE MENISCAL TISSUE
AFTER DIFFERENT LOAD CONDITIONS

Meniscal repair
– Does not heal in avascular
zone (Arnoczky, S.P. 1992; King, D. 1936)

DIFFERENT TYPE OF TEARS
Allograft
– Poor fixation technique
– Difficulties with finding a
Horizontal
donor of correct size
(Paletta, G.A.,et al., 1997; Peters, G.A. et al.,2003; Felixs,
N.A. & Paulos, L.E., 2003)

Partial meniscectomy
Radial
– Changes in contact area and
stress distribution contribute
to osteoarthritis (OA)
(Baratz, M.E. et. al., 1986; Fukubayashi, T. & Kurosawa, H.,
1980; Cole, B.J., 2004; Rangger, C., et al., 1995; Cox,
J.S., et a;., 1975; Wyland, D.J., et a;., 2002; Fahmy, N.R.J
et al., 1983)
Bucket-handle
Photos from: Knee Meniscus- Basic and Clinical Foundations, 1992, Raven Press NY
Clinical Treatment of Meniscal
Tears
Aims of the study

Examine changes in contact parameters on
superior surface of meniscus after medial
meniscectomy.

Examine changes on lateral meniscus after
medial meniscectomy.
Finite Element Model
FEMUR CARTILAGE
FEMUR
MEDIAL MENISCUS
TIBIA CARTILAGE
FRONT VIEW
TIBIA
LATERAL MENISCUS
Donahue, T.L., et al., A finite element model of the human knee joint
for the study of tibio-femoral contact. J Biomech Eng, 2002. 124(3):
p. 273-80.
TOP VIEW
Simulations of Medial Partial
Meniscectomies
ANT-CENT
CENT
POST-CENT
POST
5%
10 %
ANT-CENT
POST-CENT
ANT-CENT-POST
30 %
60 %
Intact Case
MEDIAL MENISCUS, SUPERIOR SIDE
POSTERIOR
ANTERIOR
CONTACT PRESSURE (CP)
MAX CP
= 4.669 [MPa]
MEAN CP = 1.570 [MPa]
AXIAL STRAIN (LE3)
MAX L3= 9 %
Measurement of GAGs
GAG Concentration
GAG's Concentratiom vs. Compression
80
80
70
Concentration
5%
50
10%
40
15%
30
20%
Controls
20
Concentration
70
60
60
.1MPa
30
Controls
20
10
0
0

.05 Mpa
40
10
% Com pression (Load)
20% Load
50
Load applied
Release of GAGs into the media after load from
tissue explants is a sign of tissue matrix destruction.
Measurement of PGE2
PGE2 TOP
PGE2 BOTTOM
600
400
350
500
300
250
400
C
5%
300
10%
200
15%
20%
100
200
150
100
50
0
-50
0
-100
-100
-150

PGE2, an intracellular signaling molecule, is high in
patients with OA and is necessary in the cell death
process.
C
5%
10%
15%
20%
Real time RT-PCR

Measurement of Collagen, COX-2 and
MMPs gene expression.
– COX-2 is responsible for elevation of the PGE2
level
– MMPs- enzymes which are capable of
collectively degrading all kinds of extracellular
matrix proteins