This document summarizes the structure and function of articular cartilage. It covers that articular cartilage is avascular and has a low capacity for healing after injury. It has several zones with different compositions that provide elasticity and distribute load across joints. Proteoglycans and collagen fibers give the tissue its resilience and ability to withstand pressure. Damage and degeneration of articular cartilage can occur from lack of use or overuse of joints.

2.  Type of hyaline cartilage covers the bone
ends and makes smooth movements possible.
 It distributes the load across
joints,minimizing the peak stress on
subchondral bone.

3.  Relatively acellular.
 No vascular,neural or lymphatic supply
 Has little capacity to heal after injury.
 Wear resistant
 Low frictional
 Lubricated surface
 Slightly compressible and elastic

4.  Differs from hyaline cartilage in that it is
not covered by perichondrium.
 Collagen fibres of articular cartilage matrix
are of type-II which exhibit characteristic
cross banding of collagen fibres exsist.

5.  Young cartilage – typically white,smooth,
glistening and compressible
 Aged – thinner,less cellular,firmer and more
brittle with less regular surface and
yellowish opacity.
 Thickness –
 Bony end plate

6.  ZONES OF ARTICULAR CARTILAGE
1) SUPERFICIAL ZONE
Not smooth,layer of hyaluronic acid
LAMINAR SPLENDENS –most superficial
Elongated chondrocytes,relatively inactive
2) TRANSITIONAL ZONE
Thicker ,cells rounded & larger, arranged pairs
Actively engaged in matrix component
synthesis

7. DEEP ZONE
- Largest zone
- Largest collagen fibrils,highest
proteoglycan content, lowest water
ZONE OF CALCIFIED CARTILAGE
- Irregular cells pyknotic nuclei /stability
- TIDE MARK
- Continuous with subchondral plate

8.  PERICELLULAR MATRIX
- CHONDRON
- Modulate the pressure transmission
- regulation of chondrocyte response to
pressure,prevent squashing
 TERRITORIAL MATRIX
- Fibrillar basket
- surrounds the pericellular matrix

9.  INTERTERRITORIAL MATRIX
- Largest matrix compartment
- parellel arrangement of collagen fibrils
- responsible for mechanical properties.

10.  Less than 1% of tissue volume
 Rarely divide normally / cell density
decreases with age
 Synthesize matrix components-
proteoglycans constantly renewed,collagen
slow turnover
 CILIUM – Regulation of matrix turnover

11.  COLLAGEN
- Type II ,major (90%)
- Characteristic cross banded fibrils
- Type IX,X,XI minor
 NON-COLLAGENOUS PROTEINS
- Link protein /binding GAG to hyaluronic acid
- Chondronectin and anchorinCII

12.  PROTEOGLYCANS
- Family of glycoproteins large protein core
attached to GAG side chains.
- Form of large aggregates
- Provide the resilience to A.C under load

13.  Mature A.C – diffusion from synovial fluid
 Immature A.C – vascular channels in sub
chondral bone,base of cartilage,S.F
 Energy – anerobic pathway
 Microenviroment:high CO2 & low O2
 Survive for more than 2 days after death

14.  CHONDROMALACIA:
A.C damage or degeneration
 OUTER BRIDGE Classification:
Based on arthroscopic exam

15.  GRADE O- Normal
 GRADE I- Swelling & softening of intact A.C
 GRADE II-Fissuring & fibrillation over small
area < .5 inch
 GRADE III- Same over larger area > .5 inch
 GRADE IV- Erosion of subchondral bone

16.  Mitosis induced by laceration,compression,
 Superficial lacerations – doesn’t cross tidemark donot
heal.
 Penetrates the subchondral bone- reach
S.C vessels initiate healing process
 Fibrinous arcade – scaffold that directs the
mesenchymal cells to form F.C matrix
 Repaired tissue – intermediate between H.C
& F.C / poor biomehanical properties.

17.  Biphasic material – solid & liquid phase
 Fibre reinforced gel- mutually repellant
macromolecules binds water-osmotic P.
 Water resides in microscopic pores and flow
of the water induced by pressure gradient
or matrix contraction.Flow pressure
provides load support & minimize stress
on matrix.

18.  JT loading & motion required to maintain
normal adult A.C
 Immobilisation of JT cause rapid loss of
proteoglycans so deformation in response
to load will increase.
 Excessive use or increased loading affect

19.  Debridement of chondral flaps and removal
of loose chondral fragments.
 Abrasion chondroplasty
 Microfracture

20.  Periosteal & Perichondrial grafting
 Autologous cartilage implantation
 Osteochondral autograft
 Osteochndral allograft