knee arthritis - perth ortho

Keith Holt - Perth Orthopaedic and Sports Medicine Centre © - 2017

Dr Keith Holt

Osteo-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 condition.

What 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).

Wear or damage to this is generally known as 'osteo-arthritis'

and may be primary (where the surface just wears out

prematurely - i.e. degenerative), or secondary (where the

damage is caused by direct injury, inflammatory conditions

such as rheumatoid arthritis, infections and so on).

Arthritis secondary to injury

A 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. 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 arthritis

Degenerative 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. Indeed, there is no evidence that marathon runners'

knees wear out any quicker than couch potatoes'. In fact,

Knee Arthritis

A normal right knee Arthritis following knee injury

The 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-ray

This knee shows normal gaps

No gap at all indicates bone on bone arthritis. That is, there is no remaining lining (bearing surface)

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the 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 wear.

Diagnosing arthritis?

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 obtained.

Plain 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 20º bent (20º of flexion), the most sensitive x-ray

is one taken from behind the knee when weight bearing in

that position. This view is very important, not only for primary

diagnosis, but also when trying to assess severity.

Another 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 worthwhile.

Eventually, 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. Indeed, such treatment often aggravates the situation

and can make the symptoms worse.

MRI 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 arthritis

MRI - arthritis with stress fracture

X-ray - very advanced arthritis

Bone on bone wear (no

remaining lining)Normal gap

(lining thickness)

End stage wear

Right Knee

Bone translocation

Cysts

Spurs

Thin 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)


Arthroscopy, where the joint surfaces can be inspected,

can be normal early on. 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. 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.

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 role.

The 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. It is a shearing compression injury, which is not all that

uncommon in twisting turning sports, but particularly rugby.

A near normal knee

More advanced osteo-arthritis

Mild wear

Moderately advanced wear

Mild wear

Some meniscal

loss

Mild osteo-arthritis

Right medial femoral condyle

Right medial tibial plateau

Right medial meniscus


and they do cause increased pressure to be applied to part

of the joint, leading to premature wear. A straight legged

person places 60% of their weight on the inside (medial

compartment) of their leg, and 40% on the lateral. That is

what the joint is designed to take. A bow legged (varus) person

places more than 60% of his weight on the inside half of the

joint, whereas a knock kneed (valgus) person places more

on the outside half of the joint. In each instance, one side of

the joint becomes overloaded and the other side becomes

unloaded or even unused. This means that the stresses on

the overloaded side of the joint are higher than normal, and

hence, premature wear may occur in that half of the joint.

This, in association with loss of meniscal function, can be

devastating for the joint in the longer term.

A common scenario is that there is degenerative breakdown

of the meniscal cartilage, presenting as a painful knee, often

of sudden onset. Degenerative tears of the menisci can be

very painful, they do not heal by themselves and, for the

most part, cannot be successfully repaired. Treatment, by

removal of the torn parts of that cartilage (partial or total

menisectomy), usually relieves the pain but, it also leads to

increased pressure on the articular or lining cartilage because

the stress is now focused on a smaller area, hence, wear of

the lining surface or osteo-arthritis may occur.

Without any deformity this increased pressure on the ends

of the bone may not be all that significant but, if there is also

Other causes of wear stem from overload of the hyaline

cartilage lining, rather than from direct injury. Such abnormal

forces are commonly seen after menisectomy, where a

meniscal cartilage is removed for a tear. Particularly important

with this, is the effect of any mal-alignment of the leg, which

can also change the forces within the joint.

Meniscal cartilage loss

The menisci (meniscal cartilages - sometimes known as 'the cartilages') function as fillers to spread the load between the surfaces of the femur and tibia. The ends of these bones are not the same shape, and thus, the menisci are needed to make up for that incongruity. They primarily function somewhat like shock absorbers but they also have a secondary role to enhance lubrication and nutrition of the articular or lining cartilage.

Loss of a meniscus (particularly the lateral one) leads to a poor spread of weight across the joint surface. This means that loads are taken over smaller areas of the joint, and hence, pressures are higher, causing increased rates of wear of the lining surface (the hyaline cartilage). It also follows, that the more meniscus that is lost, the faster that wear occurs.

Mal-alignment of the leg

Another cause of increased wear is a mal-aligned (crooked)

leg, such as a knock knee deformity (valgus) or a bow leg

(varus) deformity. These are not uncommon in the community

After loss of a meniscus, it can be seen that the lateral (outside) part of the knee has higher contact pressures because of the convex on convex structure of that part of the joint. Hence, wear in the lateral (outside) compartment of the knee develops more rapidly than it does in the medial (inside) compartment of the knee, where the joint is convex on concave. This wear (osteo-arthrits) ultimately leads to the end of impact loading type sports, including all running. Ultimately, it may also lead to knee replacement.

In the normal knee, the meniscus is a mobile structure that makes the joint spaces congruous and spreads the load over a wide area of the joint lining (articular surface). By increasing the area of distribution of the contact force, the local pressures are reduced and wear is prevented.

Loss of meniscus causes high pressures to be experienced at the point of contact of the femur and tibia. This pressure, especially at the time when impact loading is occurring, can exceed the breakdown strength of the lining of the joint (hyaline cartilage). This causes breakdown (wear) of that lining which, in essence, is osteo-arthritis, and which, once begun, will become progressive with time.

Meniscus filling in the gaps between the bone ends

Meniscus removed leading to point loading within the joint


Valgus (knock kneed) knees, which have gone on to lateral compartment osteo-arthritis. As the lateral side wears out, the bones on that side get closer togerther and hence the valgus deformity gets worse. This increases the load on that side of the knee even further and increases the rate of wear.

The 2 lines crossing the centre of the knee are the line from the centre of the hip and the line to the centre of the ankle. These should be in line. The angle between them is the angle of deformity.

an underlying deformity, then this extra increase in pressure

may become very significant. The combination of a varus leg

(bowed) and a resected or non-functioning (torn) medial

meniscus will always lead to arthritis on the inside part of the

knee (medial compartment arthritis). The time scale for this

depends on the amount of remaining meniscal function, the

degree of bowing of the leg, and the activity of the person.

Loss of the outside meniscus, associated with a valgus (knock

kneed) leg, leads to progressive osteo-arthritis of the outside

of the knee (lateral compartment arthritis) and, in general, this

progresses more rapidly than its medial counterpart because

of the relatively more important role of the lateral meniscus

compared to the medial. It is to be noted in passing that,

the commonest cause of retirement from elite sport in the

world today, is a lateral meniscal tear that requires resection,

leading to premature osteo-arthritis.

In the above cases, the arthritis that develops in a mal-

aligned leg following meniscectomy (or meniscal failure), is

likely to progress to the extent that, it will be visible on plain

X-rays within 10 years from the time of the original surgery.

Depending on the above factors however, this can be as

quick as a few months.

Progression of disease occurs as the wear increases, because

the deformity increases. As the wear causes the lining on the

ends of the bone to become thinner, so the bones on that

side of the knee become closer together. This then causes an

increase in the deformity which, in turn, causes increased

force to be exerted on that side of the knee, and hence, an

increased rate of wear. Essentially therefore, the problem

spirals. The worse it gets, the more rapid the progression.

When this progression becomes apparent, if the other side of

the knee is normal, and the patient is young, the treatment of

choice may be to re-align the leg: to put the weight through

the other side of the knee, thus sparing the worn side (rotating

tyres if you will). This is called osteotomy (cutting the bone).

What are the symptoms of arthritis?

Initially there may be no symptoms at all. Eventually however,

pain and swelling do become a feature. Sometimes this just

occurs gradually with no particular starting event. Other

times however, an injury may activate the arthritis, such

that a damaged or worn out joint which previously gave

little or no trouble, may suddenly start to be painful and

give considerable trouble. Frequently, the accident or injury

that initiates this is relatively minor and causes very little

new damage to the joint itself. For some reason however,

an arthritic joint becomes intolerant of injury and can be

rendered symptomatic through even a small event.

As the arthritis becomes more and more progressive, the

joint tightens up and the range of motion frequently starts

to become restricted. Initially there may be just a slight

inability to straighten the knee. With time however motion

is lost at both ends of the range, with both an inability to

fully straighten (extend) the knee, and an inability to fully

bend (flex) the knee, becoming apparent. In addition to

this, uneven wear may occur as described above, causing

the knee to become progressively valgus (knock kneed) or

progressively varus (bow legged).

Frequent symptoms of arthritis, are pain and stiffness after rest.

First thing in the morning therefore, the knee may not want to

work too well, but it warms up with use. It is also helped by

local heat, such as when in the shower. In contradistinction,

it is worse in cold wet weather. As the arthritis progresses,

the periods of flare up get worse, and closer together, until

it starts to hurt all the time, frequently disrupting sleep. In

addition, function starts to deteriorate such that walking

distance gradually reduces, ultimately to 100m or less.

Why does arthritis hurt?

Nobody really understands exactly why arthritis hurts. There

are some nerves in the ends of the bone and, potentially, these

may hurt. If this is the main cause of the pain however, then

Centre of knee

To centre of hip

To centre of ankle

This line from the centre of the hip

to the centre of the ankle should pass through the centre of the knee. This is the centre of weight

bearing


of reactive swelling in the joint and, if taken with breakfast,

they may give more mileage on the joint during the day.

They decrease stiffness both after sitting, and first thing in

the morning. By the time of replacement therefore, the joint

may be a bit more worn out compared to someone not taking

medication, but the time to replacement is usually longer. The

fact that the joint may be a bit more worn out at the time of

replacement, is usually of little consequence in terms of the

eventual success of that procedure.

Standard anti-inflammatory agents seem to work best for most

people. These do have some potential for causing ulcers or

erosions in the stomach if used for extended periods, however,

if taken with food, and in soluble form (spreading the area

of absorption), this risk can be greatly reduced. Similarly

suppositories can be used at night when not eating and these

are very helpful in decreasing morning stiffness. Drugs such

as ibuprofen and diclofenac, which are freely available over

the counter, are just half strength anti-inflammatory tablets.

These drugs work well, particularly noting that diclofenac

will last twice as long as ibuprofen.

If necessary, a drug that reduces acid production in the

stomach, will also decrease the risk of ulcer formation. Some

of the older style ones such as ranitidine, are available over the

counter. More modern ones like nexium require a script. On

balance however, the newer ones are not much better than

the old ones, and they may actually have fewer side effects.

Cox-2 inhibitors are newer anti-inflammatory drugs which

were introduced with the hope that they would have less of

the gastric side effects than the conventional ones (NSAIDs

- Non-Steroidal Anti-Inflammatory Drugs). These do work

but they are not as reliably effective as the older style anti-

inflammatories mentioned above. In addition, they are not as

free from gastric side effects as was initially thought. In this

group are Celebrex (which contains a sulphur moiety and to

which some people will therefore react), and Mobic. Some

others in this group (e.g. Vioxx) have been withdrawn from

the market because of an increased risk of cardiac events.

It now turns out that this group all interfere with a cardiac

protective enzyme, and hence, are probably not suitable

for long term use.

Cortisone injection is a mainstay of treatment. Cortisone is

a strong anti-inflammatory agent and, by injection, it can be

delivered directly into the site of the problem. Although the

actual drug may only last 6 or 7 days, the anti-inflammatory

effect may be such that prolonged relief is provided for

months. Side effects are uncommon and generally transient.

Long term reviews also suggest that detrimental effects to

the joint are minimal, albeit that some types of cortisone are

perhaps better for the joint than others.

When an arthritic joint has been stirred up or aggravated,

it does not explain why so many arthritic joints do not hurt.

Another theory says that it is the lining of the joint, the capsule

(the synovium) that hurts. Every joint has a capsule, which is

a glad bag type of wrapping around it, and which keeps in

the joint fluid. This capsule is lined by a special layer called

the synovium which is very sensitive. In the normal joint this

layer is not irritated. If the articular lining cartilage starts to

fragment however, some of those fragments can float free in

the joint, and these can become extremely irritating to the

synovium. This irritation then causes pain and it also causes

those synovial cells to increase their fluid production and

hence to make the joint swell. Unfortunately however, simple

lavage of those particles does not often help the pain or the

swelling. Hence, this is not the sole explanation for the cause

of pain in these joints.

What is the treatment?

A good reference for this, is a summary of the world literature

that was made for the American Academy of Orthopaedic

Surgeons. It is listed below. Within this, there is also a further

link to more detailed information, if required.

http://www.drrmarx.com/pdf/JBJS-AAOS-clinical%20

Practice.pdf

Initially the treatment may be very simple and may include,

modification of activities to avoid impact loading type sports,

anti-inflammatory tablets or regular paracetamol, and weight

loss. In addition, physiotherapy and guided exercise regimes

may help. Being fitter makes the arthritis hurt less, so an

appropriate exercise regime, avoiding aggravating activities,

will help. The object of conservative care is to decrease the

rate of wear and to make the arthritic joint hurt less, covering

it up with medication if needs be. Nothing known can stop or

reverse the progression of the wear. Along those lines, there

is no evidence for glucosamine, chondroitin, fish oil, Krill oil,

etc., although some people claim some pain relief with these.

Weight loss is paramount among the treatments that are

available. Premature arthritis has been strongly associated

with obesity, and reduction to more normal weight (BMI)

is associated with a decrease in the rate of wear, a slowing

down of the wear process and a reduction in symptoms. It

should be strongly considered if BMI is high and, if unable

to be controlled by correction of diet and introduction of

exercise, then consideration of bariatric surgery should be

contemplated.

Anti-inflammatory agents are very useful. They are designed to

cover up the problem somewhat but, given that the problem

is in effect incurable, this may effectively delay definitive

treatment (such as replacement surgery) and considerably

improve lifestyle for some years. They decrease the amount


is more likely to aggravate than to help.

Although the results are not always as good as one would hope

for, the fact that the procedure is relatively minor makes it

attractive. Despite being minor to undergo however, recovery

can be prolonged, and it has to be remembered that a good

number of these joints will ultimately require replacement

to get the best long term result.

One last reason to consider arthroscopy is that it is a useful

procedure for determining what the rest of the joint is like. As

such, it may help when trying to determine if a re-alignment

procedure (osteotomy) would be worthwhile considering.

Not only can the good side of the joint be inspected, but

the patella and its tracking can also be visualised. This then

helps determine how the patella might be treated at the

time of osteotomy.

Chondroplasty is essentially an arthroscopic clean up of the

damaged areas, smoothing them out and removing loose

pieces of articular lining. In an acute injury, this can induce

a healing response but, this is limited and the joint does

not produce hyaline cartilage again. What is produced is

fibro-cartilage or scar tissue, the same as would be seen if

a piece of skin were to be lost or irreparably damaged (e.g.

burned). The resulting fibro-cartilage is not a low friction

bearing surface, and hence, does not tolerate motion over

a long period of time. Nevertheless, it is better than having a

pot hole or defect in the lining on the end of the bone, and

it may seal up the edges of the pot hole so as to decrease

the rate of expansion of that hole. In addition, if reasonable

filling of the pot hole can be achieved, then reasonable pain

relief may be obtained.

Micro fracture and burring are essentially techniques which

cause increased bleeding from a defect that is down to

bone. They are designed to encourage scar formation and,

by exposing the marrow of the bone itself, the theory is that

bone marrow cells (which are stem cells), will exude into

the defect and help in the healing process. Unfortunately,

whilst the theory is good, the reality is that you still just get

scar tissue in the defect and it does not heal. Micro fracture,

where a small spike is pushed across the end plate of the

bone repeatedly therefore, has turned out to be no better

than burring or roughening the end of the bone.

If a defect is large, recent in origin, and on just one surface,

the option of choice initially, is to make the bony base of the

defect bleed by one of the above techniques - to encourage

this scar formation. To maximise scar fill of the defect, it

is then best to have 6 - 8 weeks, non-weight bearing, on

crutches. The scar which forms, hopefully, will be thicker,

and will fill the defect better, thereby improving the overall

result, leading to prolonged improvement in joint function.

an injection may return it to its previous quiescent state. If it

does not, then other treatments may be indicated but, all of

these other treatments may have consequences greater than

any perceived problems caused by cortisone.

Synvisc and related products were introduced in Canada

more than a decade ago. This group of compounds contain

normal joint fluids with their proteoglycan molecules. The

idea is to replace the damaged proteoglycans in an arthritic

joint with more normal ones. These substances only lasts a

few weeks before being fully degraded, but long term relief is

occasionally noted. The problems with this range of products

are many. They are very expensive ($500 per injection per

joint, for which there is no rebate available), they are animal

products and hence, very occasionally, the joint may react

to them, and they do not actually change the amount of

wear in the joint. On the plus side however, they do not

burn any bridges and, if they fail, the joint can still be treated

successfully. In addition, if they help, they can be repeated.

Therapy etc. There is no doubt that exercise and being

generally fit makes the arthritis feel better. Note however

that it does not make the actual arthritis (wear) better, and

indeed, using the joint a lot will actually increase the wear

rate, particularly if the exercise is impact loading (such as

jogging). The rate of wear depends on use, and can best be

slowed down by modifying that use.

Often people describe building the muscles up around the

joint as a treatment. Unfortunately, whilst it sounds good,

it is myth. It helps to be fit, but it does not have to be the

knee that does all the exercise. Think of it as putting a bigger

engine into a car with worn out tyres. It sounds better, it may

even go better, but the tyres are still worn: and, if you drive

the car harder, the tyres will wear quicker.

Arthroscopy may be considered if there are mechanical

problems or if there are symptomatic meniscal tears present.

Simply cleaning up an arthritic joint, like cleaning up a pot

hole on the road, does not fix the problem. There is now quite

good literature evidence to suggest this, and therefore, unless

there is something in the joint that can be fixed, arthroscopy

is not recommended.

Where there is a meniscal tear, the chance of improvement

by arthroscopy is better but, of course, it is not a cure for

the arthritis. For most people however, when the joint first

gets bad, it is usually the degenerating meniscus that hurts

rather than the arthritis. Unfortunately, the only way to

find this out, is to deal with the meniscal tear and see if it

helps. If this is done, figures would suggest that about 70%

will show some improvement, 20% will be unchanged or

minimally improved, and 10% somewhat worse. As the

arthritis becomes more advanced of course, these figures will

deteriorate, ultimately reaching the stage where arthroscopy


Lower Femoral Osteotomy

For lateral

compartment osteo-arthritis in a valgus left

knee

High Tibial Osteotomy

For medial compartment osteo-arthritis in a varus left

knee.

These techniques work best when used in acute injuries to

the articular surface, and in the young. They do not work

well for established arthritis, where the area of wear is large,

or where both sides of the joint are involved. They also do

not work well where there is a significant mal-alignment. In

these settings, other treatments are better.

Osteotomy is a time honoured, well proven, procedure, in

which the limb alignment is changed to unload the bad side

of the joint, and to load up the good side. In order for it to

work, the good side has to be fairly much normal. If it is not,

then transferring weight to that side will merely transfer the

problem to that side.

In the young, where replacement is not a viable option, and

where there is an alignment problem, osteotomy remains

the procedure of choice. A varus (bow legged) knee with

arthritis on the medial side (inside) is made valgus (knock

kneed), and vice versa. In order to do this, one of the leg

bones will need to be cut and the angle changed. It turns

out that, in varus knees, the deformity is usually in the tibia,

so this is the bone in which the correction will take place. In

a valgus knee, the deformity is usually in the femur and not

the tibia. The usual reason given for this, is that, in a valgus

knee, the lateral femoral condyle is small (underdeveloped -

hypoplastic). In this deformity therefore, the correction must

be in the femur. In either instance, it is important to correct

the deformity in the appropriate bone, so that the joint line

stays horizontal. If the joint becomes sloped, then it can be

subject to shearing forces, which may, in turn, contribute

to further wear.

It is to be noted that, in order to change the forces at the

joint level, the correction has to be in the bone. It cannot

be achieved by the use of orthotics or similar devices: these

merely rotate the bone and do not actually adjust the varus/

valgus angle. Unloading braces do similar, but these are bulky,

uncomfortable and not suitable for long term use. Hence,

these are regarded as devices designed to test, whether or

not, an unloading procedure will help. They are not a therapy

in their own right.

Osteotomy is not a last resort procedure, even though it

is a moderate sized procedure to do. Essentially, if there is

wear and an associated deformity, it should be done sooner

rather than later. For most people this means within the next

6 - 12 months, but it does depend on the extend of the wear,

the symptoms and so on. It also depends on age. If you are

approaching 60 and the knee is not too symptomatic, the

best option may be to do nothing and wait until the pain is

bad enough to go straight to knee replacement. If you are

in your twenties, then this maybe the only way of delaying

replacement for a significant length of time.

The results of osteotomy are good. Indeed, the likelihood of

delaying replacement 5 years is 85%, and the likelihood of

delaying replacement 10 years is 75% (though even better

in some series). Having got to 10 years, many will indeed get

15 - 20 years out of this procedure. The reason this happens

is that, by unloading the bad side of the knee, the pain either

completely, or mostly, disappears. For those in whom this

does not happen, early replacement remains an option but,

as judged by the above figures, this is a small number overall.

In order to achieve this level of result, the leg needs to be

some 3 - 5 degrees over corrected, placing the majority of

the weight on the good side of the joint, and significantly

unloading the worn side. Nowadays, this correction can be

done with the aid of 'in theatre' computer navigation, which

helps get the alignment corrected more accurately than was

previously possible.

The advantage of an osteotomy is that it remains your knee.

This means that, it still bends as far as it used to, and it does

not have the restrictions of a replaced knee. In addition,

whilst running is not advocated (even if there is no residual

pain), activity can certainly be moderately vigorous. Again

therefore, this is the procedure of choice in the younger

patient; always remembering that a good osteotomy is like

Arrows indicate the size of the inserted

wedge.

Arthritic side

Arthritic side


having a normal knee, whereas a good knee replacement

never is. It is always to be remembered therefore, that, a

poor result from an osteotomy can be dealt with by knee

replacement but, a poor result from a replacement, may be

un-fixable.

The concept of osteotomy is reasonably simple in that, the

bone in question, has to be cut across, then opened as a

wedge until the desired correction is achieved. The bone

is then fixed with a strong plate, and the wedge shaped

defect, thus created, is filled to encourage healing. Various

fillings are possible, including bone graft from one's own hip.

Whilst the latter encourages more rapid healing, and is the

graft of choice in those over 55, where union may be slow,

there are now many bone substitutes, some of which have

growth factors in them to help healing. Accordingly, because

of the problems associated with bone harvest from the hip,

this method is only used when clearly indicated. For the

majority, the newer bone substitutes, with growth factors in

them, seem to work very well: hence, these are considered

the standard for this procedure at present.

Recovery from osteotomy is similar to recovery from a

broken leg (which is essentially the same thing). The bone

will take about 6 weeks to begin healing, and it will hopefully

go on to full union over the next several months. As the plate

is strong however, immediate weight bearing is possible.

This does not mean that one should walk directly on this,

but standing is certainly possible. Mostly, crutches are used

for a few weeks so as not to overload the leg. By about six

weeks however, they can generally be totally discarded. As

the bone becomes better united, it will feel better, and more

normal activity will be possible. Most people know when it

definitively joins.

Overall, it may take 9 - 12 months to gain maximum benefit

from this procedure, bearing in mind that the worn area of

the knee remains worn. This part however is unloaded so,

given time, it gradually loses pain and feels more normal. If

the recovery of the joint is thought to be slower than expected

however, and particularly if it is still swollen, it can be injected

with cortisone. This can be done at any time in the recovery

period because the cortisone goes into the joint and not into

the bone: hence it does not interfere with healing.

In the first 3 months, anti-inflammatories (including nurofen

etc.) should not to be taken. This is because they slow down

or prevent bone healing, which subsequently may be difficult

to treat. Similarly, smoking should be ceased, as this is a major

cause of bone non-union.

Knee replacement is the treatment of choice if the arthritis

is advanced, if it involves all of the knee (so that there are

no good bits left to transfer the load to), if there is a marked

tightening of the joint with loss of full extension, or if the

patient is over 60 years of age, where union of the bone

can be an issue. Similarly, when osteotomy eventually fails,

or if it does not give the desired pain relief early on, knee

replacement can be performed.

Stem Cell therapy

The hope of the modern world is that we will be able to

reverse and cure osteo-arthritis by using either stem cell

therapy or genetic engineering. If we could just re-grow a

knee like the lizard re-grows it's tail, we would not have to

do replacement surgery any more.

This is certainly the dream but, as yet, that is still what it is.

Whilst an enormous amount of research is being done in this

area, to date, there has been little, if any, documented long

term success for these therapies. This may be because, just

being able to grow these cells, is not enough. Targeting them

to the right areas and getting them to form normal looking

hyaline cartilage (with its very special matrix of collagen

arcades), still eludes us: and, after all, it is the extracellular

matrix that is the mainstay of this tissue. The cells are few

in number, deep in the tissue, and non-structural. They are

merely the maintainers of that matrix.

Knee Replacementfor end stage osteo-arthritis


Chondral grafting has been our biggest foray into stem cell

type therapies. It involved sending some normal articular

(hyaline) cartilage to the laboratory, growing this by forcing

the cells to divide, and then re-implanting those cells some

5 - 6 weeks later. The cells are taken from normal parts of

the joint that are not used too much (so that minimal harm

is done). The harvest is done via the arthroscope as a day

case procedure, and the cells are sent away to the laboratory

for culture.

The cells are grown with the aid of tissue growth factors and

other advanced tissue engineering techniques. When ready,

they are placed onto a membrane and implanted directly

into the defect. The membrane is glued in with an absorbable

glue, and the cells transfer across from the membrane to

the bone end, where they grow. The joint then needs to be

protected for some weeks until the area is stable enough to

allow weight bearing. The cells continue to grow over 1 - 2

years, usually filling, or partly filling, the defect.

For some years we did this procedure and, in the short term,

some people did seem to do well. Unfortunately, over 5 years,

the results were less good, and many of these cases ended

up coming to knee replacement. Given the time it took to

go through this and to fully recover, these results did not

really justify continuing use of this technology. Similarly, the

figures were such that ,the government has now withdrawn

all medicare rebates for such procedures.

Whilst there may still be a place for this type of procedure

therefore, it is likely that it will need better technology.

Unfortunately, with current technology, the cells often

degenerate to fibro-cartilage (scar) rather than staying as

hyaline cartilage, a result that could have been obtained by

making the bony defect bleed and then not weight bearing

on it for 6 - 8 weeks. Also, these cells do not form the normal

matrix which constitutes the majority of the lining tissue,

and hence, the new tissue does not survive the stresses of

everyday use. To achieve the latter will need better tissue

engineering techniques or better technologies altogether.

Injectable stem cells are the big thing on the internet at the

moment. They come with hope and hype, and some miracles

are touted. Unfortunately, there is no evidence for any of this

at the present time. Because it is simple to do, comes without

major surgery, and the procedure contains the buzz words

'stem cell', it seems very enticing. It would be fabulous if it

worked but, currently, it is looking like 21st century snake oil.

Because of all of the above factors however, it has enormous

placebo effect, so sorting out the real results from placebo

ones will take time.

The evidence so far is that, for a stem cell to work, it has

to be an appropriate cell: and we know for instance, that

bone marrow is a better source than fat or muscle tissue. We

also know that the cells have to be targeted. They cannot

just be injected into a joint, be expected to find the defect

and then start to fill it. Similarly, they cannot be expected

to convert damaged hyaline cartilage cells into cells which

will then start dividing, make new matrix and heal a defect.

All this needs to happen in a controlled fashion and, even if

that is occurring, we may still have to deal with alignment

issues, meniscal deficiency and so forth. It is very complex

and we are not there yet. The next coupe of decades could

be interesting however.

Questions and concernsPlease contact Dr Holt’s office

Phone: +61 8 92124200Fax: +61 8 94815724Email: [email protected]

Further information can also be obtained on this and other related topics, such as:OsteotomyKnee replacementRehab after knee replacement

at: www.keithholt.com.au

Links of Interest:to the AAOS (American Academy of Orthopaedic Surgeons) guidelines on arthritis treatment

http://www.drrmarx.com/pdf/JBJS-AAOS-clinical%20Practice.pdf

http://www.aaos.org/research/guidelines/OAKSummaryofRecommendations.pdf

knee arthritis - perth ortho

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