Tuesday, March 24, 2009

Osteoarthritis grading systems

So your doctor has said you have Grade III osteoarthritis.

Is this better or worse than Grades I and II?

What does it tell you?


Firstly, there is more than one classification of arthritis - so this complicates things.

Two of the more common are the Kellgren and Lawrence Grading system and the Outerbridge.


The Kellgren and Lawrence system is based on xrays and consists of Normal, Grade I, Grade II, Grade II and Grade IV.

It measures the presence of typical features of osteoarthritis:



  • Joint space narrowing - bone is visible on xray but the articular cartilage that covers it is not. A normal joint therefore appears to have a space between the bones. Any decrease in space implies a reduction in cartilage cover.

  • Osteophytes - small bony projections that form around joint margins. Thought to be a result of the body trying to increase joint surface area to decrease pressure. They are responsible for limiting range of motion and can cause pain.

  • Sclerosis - this means 'hardening' and is a sign of osteoarthritis, seen as increased white areas in the bone at the joint margins



If your knee is classified as normal it is unlikely you would be reading this. There is no evidence of any wear.

Grade I : Unlikely narrowing of the joint space, possible osteophytes


Grade II: Identified small osteophytes, possible narrowing of the joint


Grade III: Multiple, moderately sized osteophytes, definite joint space narrowing, some sclerotic areas, possible deformation of bone ends


Grade IV: Multiple large osteophytes, severe joint space narrowing, marked sclerosis and definite bony end deformity.


As you can see by the description, the higher the number the worse things get.

The Outerbridge Classification is also scored from zero to grade IV but is made from arthroscopic appearance rather than xray findings.

Grade 0 = Normal

Grade I: Softening and swelling of the articular cartilage

Grade II: Partial thickness fissures

Grade III: Full thickness fissures

Grade IV: Bone exposed

The two scales are comparable throughout with the end point, Grade IV, being what is typically described as 'bone on bone'.

The higher the grade of osteoarthritis, the higher the probability of symptoms such as pain, stiffness and swelling.
I say probability because the correlation between the extent of degenerative disease and symptoms is not as strong as most people would think. There are many people with knees far from normal walking around blissfully unaware. There are also the unfortunate few with relatively minor degenerative changes who suffer severe pain on a daily basis.

These classification systems are the tools that Orthopaedic Specialists use to monitor the progression of the disease process. They also give information about which treatment options are appropriate and which may no longer be of assistance.

Having Grade IV arthritis does not mean that you have to have a knee replacement. It may mean that from a surgical point of view it is the only operation that can be offered, but as usual the advice remains......
If you can continue on as you are, do so.
If you just can't bear it anymore, talk to a surgeon

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