2. How to define osteoarthritis
There are several "levels" of osteoarthritis:
anatomical, radiological and symptomatic
Many people have radiologically
evident but asymptomatic
osteoarthritis
Osteoarthritis is not necessarily
synonymous with "pain"
Thus, of 100 people aged over 65:
2
Société Française de rhumatologie website:
http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp
INSERM (National medical research institute) web site:
http://www.inserm.fr/thematiques/circulation-metabolisme-nutrition/dossiers-d-information/arthrose
3. Chronic degenerative joint disease
Osteoarthritis is characterised by:
gradual destruction of the cartilage (chondrolysis)
remodelling of the subchondral bone
marginal osteophytosis
and secondary synovial inflammation
3
Société Française de rhumatologie website:
http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
External facet stage 4 chondral lesion. Axial
image from a knee CT arthrography.
5. What type of osteoarthritis?
A distinction is made between:
Symptomatic osteoarthritis which causes pain and functional disability
and is visible on radiographic images
Weight-bearing joint osteoarthritis (hip and knee)
Non-weight-bearing joint osteoarthritis
(hand and shoulder)
Primary osteoarthritis
Secondary osteoarthritis arising subsequent
to other conditions (injury, malformation
or metabolic and inflammatory disorders)
5
Société Française de rhumatologie website:
http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
6. 6
Hip osteoarthritis
surrounding the hip.
Internal and external femorotibial
osteoarthritis. Knee CT-arthrography.
Rapidly destructive osteoarthritis of the shoulder, frontal
image gadolinium-enhanced T1 MRI sequence
Hand and wrist
MRI: SE T1-
weighted,
gadolinium-
enhanced coronal
image with fat
suppression.
7. Oedema and fissures
Cartilage lesions start with oedema which divides the collagen fibres
Superficial fissures appear
Chondrocytes try to compensate for the breakdown of the proteins
making up the matrix by producing growth factors
The fissures then extend down to the subchondral bone, leaving it
exposed,
The number of chondrocytes drops and their pro-destructive potential
increases
The subchondral bone becomes osteosclerotic at the pressure points
resulting in the development of cysts
Osteophytes (attempted bone repair), also known as bony spurs,
develop in marginal areas which are not under pressure
7
Société Française de rhumatologie website:
http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
8. The role of the chondrocyte
Osteoarthritis is not caused by cartilage wear and tear
only
Chondrocytes "wake-up" and start to synthesise:
pro-inflammatory cytokines (IL-1, TNF)
nitrogen monoxide (NO)
pro-inflammatory lipid mediators (PGE2)
and proteolytic enzymes (metalloproteases or MPPs and
aggrecanases) which cause cartilage matrix breakdown
8
Société Française de rhumatologie website:
http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
9. Imbalance between destruction
and synthesis
During stress, for example when subjected to
excessive mechanical load, the chondrocyte
metabolism changes
The cell becomes capable of boosting synthesis of
matrix components and proteolytic enzymes
and reduces release of anti-inflammatory mediators
or metalloprotease inhibitors produced to halt the
inflammatory process and prevent cartilage
destruction (TIMP: tissue inhibitor of
metalloproteinases, an IL-1 receptor antagonist)
This imbalance leads to digestion and destruction of
the cartilage matrix, which is then not renewed at the
same pace as new components are made
9
Société Française de rhumatologie website:
http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
11. Fine balance between formation
and degradation
Synoviocytes in the inflammatory synovial membrane
and osteoblasts in the subchondral bone are also capable
of secreting mediators, thus contributing to destruction
of the cartilage
Thus, the balance between synthesis and breakdown
of the cartilage matrix is upset in favour of cartilage
degradation
Once fragments of the matrix are released into the
synovial fluid, the inflammation continues as a result
of chronic activation of chondrocytes and the synovial
membrane
Resulting in increased synthesis of pro-inflammatory
mediators
11
Société Française de rhumatologie website:
http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
According to Piperno 2012
12. In sum,
12
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
Imbalance between synthesis and destruction of the cartilage matrix
explaining extracellular matrix loss
D’après Sellam 2011
13. Pain is a measure of increasing damage
During these flares, the
osteoarthritis is active and
inflammatory phenomena occur
This is caused by a synovial
membrane reaction: the synovial
membrane's job is to cleanse the
joint of the debris created by
cartilage breakdown
13
Knee osteoarthritis, tibial edema and synovial
inflammation. FSE T2 sagittal slices.Société Française de rhumatologie website:
http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp
14. Inflammatory flares
Recent change in pain intensity:
sudden increase in intensity over a few days
pain at night which wakes the patient up
morning stiffness lasting more than 15
minutes
+/-mechanical pain as soon as any
pressure is placed on the joint.
14
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
Onset of joint effusion
Presence of signs of local inflammation: redness
16. Does osteoarthritis always progress
in flares?
The natural history of osteoarthritis
has not yet been fully elucidated
It varies widely depending on the joint
affected and the patient
Once diagnosed, it seems to progress
in a non linear fashion
Two other patterns of progression have also
been described:
rapidly destructive osteoarthritis, which
causes complete destruction of the cartilage
within 24 months
and slowly progressing osteoarthritis,
without obvious flares
16
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
17. Evaluation tools
Different tools can be used:
Visual analogue scales for pain,
functional impairment and, in the case
of hand osteoarthritis, aesthetic impact
For leg osteoarthritis, maximum
walking distance with and without pain
and ability to complete daily tasks
Quantification of analgesic and NSAID
consumption
Several indices are used for hip or knee
osteoarthritis:
• the Lequesne index
• the WOMAC (Western Ontario and McMaster
Universities composite index)
17 Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
19. Three progressive disease profiles
Slow progress without any obvious
Progress in flares alternating with stable periods
and periods of chrondrolysis: most common
Rapid progress: rapidly destructive osteoarthritis
(total cartilage destruction in 6 to 24 months)
19
Sellam J, Berenbaum F. Arthrose. Rev Prat. 2011; 61: 675-686
In all cases, an inflammatory flare is believed to
be an indication of accelerated cartilage destruction
Which is why it is so important to treat each painful flare