Meniscal Tissue Degradation as Meniscal Tissue Degradation as the first sign of Osteoarthritis.the first sign of Osteoarthritis.THE PROCESS OF MECHANOTRANSDUCTION IN THE MENISCAL TISSUE.

Barbara ZielinskaMichigan University of Technology

Structure of the MeniscusStructure of the Meniscus

C-shape (wedge-shape in cross-section profile) disks of fibro cartilage

Interposed between the condyles of the femur and tibia

Strong attachments to bone

Inner 2/3 poor vacularization

HUMAN KNEE – top view Pho

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HUMAN KNEE – cross-section profile

MotivationMotivation

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 definitionProject 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

Clinical Treatment of Meniscal Clinical Treatment of Meniscal TearsTears

Meniscal repair– Does not heal in avascular

zone (Arnoczky, S.P. 1992; King, D. 1936)

Allograft– Poor fixation technique– Difficulties with finding a

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– 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)

DIFFERENT TYPE OF TEARS

Horizontal

Radial

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Aims of the studyAims 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 ModelFinite Element Model

FRONT VIEW

TOP VIEW

FEMUR

FEMUR CARTILAGE

TIBIA CARTILAGE

MEDIAL MENISCUS

LATERAL MENISCUS

TIBIA

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.

Simulations of Medial Partial Simulations of Medial Partial MeniscectomiesMeniscectomies

5 %

10 %

30 %

ANT-CENT CENT POST-CENT POST

ANT-CENT POST-CENT

60 %

ANT-CENT-POST

Intact CaseIntact CaseMEDIAL MENISCUS, SUPERIOR SIDEMEDIAL MENISCUS, SUPERIOR SIDE

MAX L3= 9 %MAX CP = 4.669 [MPa]

MEAN CP = 1.570 [MPa]

CONTACT PRESSURE (CP) AXIAL STRAIN (LE3)

POSTERIOR

ANTERIOR

Measurement of GAGsMeasurement of GAGs

Release of GAGs into the media after load from tissue explants is a sign of tissue matrix destruction.

GAG's Concentratiom vs. Compression

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Load applied

Co

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.05 Mpa

.1MPa

Controls

GAG Concentration

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10

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60

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% Compression (Load)

Co

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10%

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Controls

Measurement of PGEMeasurement of PGE22

PGE2, an intracellular signaling molecule, is high in patients with OA and is necessary in the cell death process.

PGE2 TOP

-100

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200

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C

5%

10%

15%

20%

PGE2 BOTTOM

-150

-100

-50

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400

C

5%

10%

15%

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Real time RT-PCRReal 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