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Knee Arthritis - Perth Ortho

Keith Holt - Perth Orthopaedic and Sports Medicine Centre - 2017Dr Keith HoltOsteo- Arthritis is a condition in which there is wear and tear of the smooth bearing surfaces of a joint. Initially this wear may not give rise to symptoms. Ultimately however, pain, stiffness, and even deformity may result. A range of treatments, from anti-inflammatory tablets through to replacement, are available to help in the various stages of this is Arthritis ?The term ' Arthritis ' literally means 'inflammation of a joint'. There are many causes of this but, the end result of all of these processes, is a joint where the smooth, low friction bearing surfaces on the ends of the bone become worn out. This special surface (made of hyaline cartilage) is the same shiny white surface that can be seen on the end of a lamb (or other animal) bone, and is responsible for the extremely low friction bearing surfaces of our major joints (about ten times less friction than the best man made bearing surface).

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Transcription of Knee Arthritis - Perth Ortho

1 Keith Holt - Perth Orthopaedic and Sports Medicine Centre - 2017Dr Keith HoltOsteo- Arthritis is a condition in which there is wear and tear of the smooth bearing surfaces of a joint. Initially this wear may not give rise to symptoms. Ultimately however, pain, stiffness, and even deformity may result. A range of treatments, from anti-inflammatory tablets through to replacement, are available to help in the various stages of this is Arthritis ?The term ' Arthritis ' literally means 'inflammation of a joint'. There are many causes of this but, the end result of all of these processes, is a joint where the smooth, low friction bearing surfaces on the ends of the bone become worn out. This special surface (made of hyaline cartilage) is the same shiny white surface that can be seen on the end of a lamb (or other animal) bone, and is responsible for the extremely low friction bearing surfaces of our major joints (about ten times less friction than the best man made bearing surface).

2 Wear or damage to this is generally known as 'osteo- Arthritis ' and may be primary (where the surface just wears out prematurely - degenerative), or secondary (where the damage is caused by direct injury, inflammatory conditions such as rheumatoid Arthritis , infections and so on). Arthritis secondary to injuryA major joint injury, where the surface is directly damaged (as happens in at least 10% of anterior cruciate ligament injuries), is essentially a seed for the onset of osteo- Arthritis proper. The damaged hyaline cartilage not only doesn't make any attempt to heal itself, but rather, the area of damage slowly deteriorates with time, gradually enlarging. In that initial injury, a piece of the lining tissue (hyaline cartilage) may be exploded out of the weight bearing surface creating a pot hole.

3 That pot hole then, like all pot holes, gets gradually bigger because of the inevitable breakdown of the edges. Eventually, the weight bearing part of the joint becomes a large area of bare bone with no bearing surface at all and, this in turn, wears out its counterpart, the surface which it articulates with on the other side of the joint. This goes on to become advanced osteo- Arthritis and, as might be expected, it is hastened by impact loading type activities such as running and jumping. Primary or Degenerative arthritisDegenerative osteo- Arthritis , rather than anything else, has to do with inheriting a joint with a short 'use by' date. No one knows why some people's joints wear out early and why some do not, albeit that the pathologic changes that occur are somewhat understood. The thing about degenerative Arthritis is that it is not caused by sport, exercise or physical jobs.

4 Indeed, there is no evidence that marathon runners' knees wear out any quicker than couch potatoes'. In fact, knee ArthritisA normal right kneeArthritis following knee injuryThe gap between the bone ends is not a gap, but rather, it is the thickness of the articular surface (hyaline cartilage) which cannot be seen on an x-rayThis knee shows normal gapsNo gap at all indicates bone on bone Arthritis . That is, there is no remaining lining (bearing surface)Same PatientKeith Holt - Perth Orthopaedic and Sports Medicine Centre - 2017the only evidence for these factors is just the opposite, with obesity being a proven cause of premature Arthritis of the weight bearing joints. Having said the above however, it is clear that once a joint is damaged, or is starting to wear, then the more it is used, the more rapidly it will Arthritis ?

5 Despite all the available tests, the diagnosis of osteoarthritis can be difficult to make in its early phases, and it can be missed. Plain x-ray, despite its simplicity, is still one of the best methods of diagnosing this: especially when special views are x-ray imaging remains the mainstay of initial diagnosis. It is the cheapest of the investigations and, once the wear starts to progress, it is the easiest to assess. It is not because the lining tissue becomes visible on X-rays, but rather, as the lining tissues start to wear, the gap between the bones becomes visibly narrower. As the area of most wear usually involves those areas which are in contact whilst weight bearing with the knee 20 bent (20 of flexion), the most sensitive x-ray is one taken from behind the knee when weight bearing in that position.

6 This view is very important, not only for primary diagnosis, but also when trying to assess feature which may be seen is small bone spurs (osteophytes) which protrude from the side of the joint. It is thought that these develop as a consequence of increased stresses on the underlying bone, and they do get bigger as the osteo- Arthritis progresses. Whilst easily visible on an x-ray however, they do not in themselves cause too many problems, and removing them is rarely , other changes also start to appear: such as cysts in the bone and bone build up (sclerosis), all of which indicate progressive osteo- Arthritis . Cysts are particularly characteristic of advanced wear, representing joint fluid that is being pushed into the unprotected underlying bone. They represent a failure of that underlying bone to cope with the increased stresses being imposed upon it and, usually, imply that treatments such as an arthroscopic clean up (chondroplasty) will probably not help.

7 Indeed, such treatment often aggravates the situation and can make the symptoms is good in that it can not only see the joint lining, it can also see if there is swelling in the underlying bone. Thus, it can detect stress reactions and stress fractures, additional problems that sometimes occur under an area of wear. CT arthrogram, where a radio-opaque dye is put into the knee and the area is CT scanned, is perhaps the best method of determining the thickness of the articular surface, and it is very sensitive to defects in that lining. Unfortunately however, it does not see the underling bone and cannot detect swelling or stress injury to the bone; factors that maybe very important in trying to determine the best treatment option. X-ray - moderate arthritisMRI - Arthritis with stress fractureX-ray - very advanced arthritisBone on bone wear (no remaining lining)Normal gap (lining thickness)End stage wearRight KneeBone translocationCystsSpursThin lining (light grey on bone end)Stress fracture (dark area)Stress fracture (dark area)Underlying swelling in the bone (white area)Normal lining(light grey)Keith Holt - Perth Orthopaedic and Sports Medicine Centre - 2017 Arthroscopy, where the joint surfaces can be inspected, can be normal early on.

8 When the Arthritis presents as pot holes in the joint surface, arthroscopy provides a very good assessment. Sometimes however, the lining can by intact and look smooth, but it is actually thin. In this instance, arthroscopy is not so helpful. Clearly, no one test is optimal and sometimes more than one test is necessary to work out the exact pathology. What is the cause?The cause in the degenerative joint remains unknown. We know that the chondrocytes, the hyaline cartilage cells which lie on the deep surface of the cartilage layer, start to produce less of the osmotic molecules (proteoglycans) which hold fluid in the lining layer. It is this fluid that is responsible for the sponginess of the lining, and therefore, is responsible for the forgiving nature of that layer during impact loading. In addition to this however, the majority of this layer is made up of collagen arcades which look like arches under a microscope.

9 These are responsible for the strength that the hyaline lining has, hence, when the chondrocytes fail to maintain this structure (the extra-cellular matrix - the tissue outside the cell), the surface is susceptible to wear and degradation. That is - osteo- Arthritis . When looking at the microscopic structure of the hyaline cartilage, it is important to note that the cartilage cells (chondrocytes) are few and far between, and they are deep in the tissue, near the bone. These cells, in themselves, are not the structural element of the lining tissue but rather, they manufacture and maintain the matrix of that tissue (the collagen arcades, proteoglycans etc.), which is the structural element. They only divide, at most, once in a persons' lifetime, and hence, they have little or no capacity to heal any damage.

10 Once they start to fail or die, they are not replaced: the matrix fails and osteo- Arthritis (wear) ensues. The evidence would suggest that, with age, the chondrocytes become less able to maintain the extra-cellular matrix. Hence, the hyaline cartilage layer becomes more brittle and becomes more susceptible to stress related injury and wear as one gets older. In some however, that wear develops prematurely and, whilst the cause of that is unknown, genetic factors are known to play a cause in the injured joint is clearer. When a traumatic injury to the joint has caused significant injury to the articular layer, it will not recover. If this injury involves a defect, where a piece of lining tissue has been exploded out of the joint surface, then this is a permanent injury. This sort of injury usually occurs with a twisting injury when the joint under load.