course of osteoarthritis

and

present

Course of osteoarthritisCourse of osteoarthritis

How to define osteoarthritis

There are several "levels" of osteoarthritis:anatomical, radiological and symptomatic

Many people have radiologicallyevident but asymptomaticosteoarthritis

Osteoarthritis is not necessarilysynonymous with "pain"

Thus, of 100 people aged over 65:

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Société Française de rhumatologie website: http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.aspINSERM (National medical research institute) web site:http://www.inserm.fr/thematiques/circulation-metabolisme-nutrition/dossiers-d-information/arthrose

http://www.rhumatologie.asso.fr/04-Rhumatismes/grandes-maladies/0B-dossier-arthrose/A0_definition.asp

http://www.inserm.fr/thematiques/circulation-metabolisme-nutrition/dossiers-d-information/arthrose

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

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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.


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External facet stage 4 chondral lesion. Axial image from a knee CT arthrography.

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 subsequentto other conditions (injury, malformationor metabolic and inflammatory disorders)

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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.

Oedema and fissuresCartilage lesions start with oedema which divides the collagen fibres

Superficial fissures appear

Chondrocytes try to compensate for the breakdown of the proteinsmaking 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

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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

8Société 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

Imbalance between destructionand 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

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According to Maheu 2012

Fine balance between formationand degradation

Synoviocytes in the inflammatory synovial membraneand osteoblasts in the subchondral bone are also capable of secreting mediators, thus contributing to destructionof the cartilage

Thus, the balance between synthesis and breakdownof 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 resultof chronic activation of chondrocytes and the synovial membrane

Resulting in increased synthesis of pro-inflammatory mediators

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According to Piperno 2012

In sum,

12Sellam 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

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

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Knee osteoarthritis, tibial edema and synovial inflammation. FSE T2 sagittal slices.Société Française de rhumatologie website:


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.


Onset of joint effusion

Presence of signs of local inflammation: redness

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According to Sellam 2011

Does osteoarthritis always progressin flares?

The natural history of osteoarthritishas not yet been fully elucidated

It varies widely depending on the joint affected and the patient

Once diagnosed, it seems to progressin 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


Evaluation toolsDifferent 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

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According to Sellam 2012

Three progressive disease profiles

Slow progress without any obvious

Progress in flares alternating with stable periodsand periods of chrondrolysis: most common

Rapid progress: rapidly destructive osteoarthritis(total cartilage destruction in 6 to 24 months)


In all cases, an inflammatory flare is believed to be an indication of accelerated cartilage destructionWhich is why it is so important to treat each painful flare

course of osteoarthritis

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