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Patient Information Sheet : Spinal Instrumentation
: Fusion and Stabilisation Techniques
What Is it
Spinal fusion means the insertion of rods, screws and/or
ligaments into the spinal column. This can either be used to stabilise the
spine (limit movement but not abolish it completely) or fusion (attempt to
completely prevent movement between certain bones of the spine). This can
involve a single level (two adjacent vertebrae) or multiple levels. The idea
of the operation is to reduce movement between two segments of the spine when it
is thought that that particular segment is the cause of pain or dysfunction.
Fusion involves joining the vertebral bodies together (or the lowest vertebra
and the sacrum) by means of a bony bridge or bone grafting. The initial
operation often involves the use of instrumentation, using screws and rods to
help hold the vertebral bodies as still as possible whilst the bone graft takes
time to incorporate and mature.
One
form of spinal fusion involves limiting but not completely eliminating
movement between the vertebral bodies and this type of procedure is known as
spinal stabilisation. This is often done posteriorly, i.e. through the back of
the spine and involves ligaments or plastic spacers to hold the vertebral bodies
under compression (such as the GRAF ligament system) or distraction (such as the
Dynesis system) which tries to restore the normal height between the vertebral
bodies. The operation is usually undertaken for disc degeneration leading to
pain and discomfort across the lower back or following damage to the spine such
as fractures or tumours de-stabilising the spinal column. The predominant
symptom which would lead your surgeon to recommend spinal fusion procedures is
back pain rather than leg pain, particularly if the back pain is brought on by
particular movements or posture.
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Treatment Choices
Spinal fusion procedures are very much a last resort.
Before contemplating spinal fusion or stabilisation your surgeon would normally
have discussed and attempted various other less invasive treatment such as a
physiotherapy/rehabilitation programme, medication, support such as a lumbar
corset and pain management techniques including injection therapy, TENS machine,
Pilates, etc. Assuming these treatment options have not worked and have been
attempted for a period of at least six months, then spinal fusion is a
possibility. Spinal fusion can either be undertaken from the back and usually
involves use of bone graft with or without instrumentation or ligament
stabilisation such as the GRAF ligament or Dynesis ligament systems mentioned
above. Fusion can also be undertaken anteriorly using an approach through the
front. In severe or revision cases, your surgeon may even contemplate
undertaking “360º fusion” which involves approaching and stabilising the spine
through the front and then approaching and stabilising the spine through the
back. This is rarely necessary.
A relatively new procedure is total intervertebral disc
arthroplasty in which the intervertebral disc between the vertebral bodies is
removed completely and replaced with a false disc usually a combination of metal
on plastic, similar to the joint replacements used for hips and knees. These
procedures are relatively new but show encouraging early results. There are
several centres in the UK which undertake this work but it is more common on the
Continent or in America.
Most spinal fusion procedures are carried out in
association with some form of spinal decompression procedure which allows the
surgeon both to stabilise the spine by means of the spinal fusion and also
release damaged or trapped nerve roots or spinal cord. Therefore, the
majority of spinal fusion procedures are undertaken using the posterior
approach.
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The operation
I personally undertake spinal fusion with instrumentation
using pedicle screws and rods to stabilise the vertebral bodies and sacrum
whilst awaiting for the bone graft to incorporate. Normally you will be
admitted to hospital the day before operation or on the morning of the operation
if it is in the afternoon. You should ensure that any relevant xrays and MRIs
scans which you have in your possession are brought in with you, along with any
ongoing medication. The operation involves a 6-8” incision in the mid-line
of the spine posteriorly and the spine is exposed by separating the muscles and
pushing them to either side. Once the spine is exposed, any decompression of
the spine is carried out by removing bone and ligaments from around any nerves
or spinal cord as required. Then, under xray control the pedicles (bony
tunnels) of the vertebral bodies are drilled and screws are placed from the back
into the vertebral bodies at the front, through these tubes of bone. The
screws are then connected together by means of a metal rod and the whole
construct is rigidly fixed in place by means of locking nuts and then bone graft
is laid around the metalwork between the bony vertebra. The muscles are then
allowed to fall back into place and stitched together and the skin is sutured
over a wound drain. The
operation usually takes between two-four hours.
Post operatively it is important that as soon as you wake
up you begin moving as this prevents many of the common complications such as
chest infection, thrombosis and excessive scarring or adhesions on the nervous
tissue. Within 24 hours you should be able to stand out of bed and within four
or five days you should be independently mobile sufficient to go home and
continue recovery at home.
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After discharge From Hospital
Once at home you will be encouraged to mobilise little and
often. As a general rule you will be asked to stand, walk, sit or lie down for
no more than 20 minutes at any one time during the day. By changing position
frequently this helps to keep your back muscles mobile and avoids some of the
complications outlined above. Once the sutures are removed you can begin light
exercise such as an exercise bike, walking or even swimming.
At six weeks you will normally be reviewed in clinic and at
that stage you can begin to return to more normal activities including driving,
return to light work provided it is local and does not involve any manual or
strenuous work. It will be around six months before your recovery period is
complete.
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What Can Go Wrong?
Major complications thankfully are rare but can be
devastating. Along with any major operation involving the use of general
anaesthetic there are risks from the anaesthetic itself, but thankfully these
complications are now rare with modern anaesthetic techniques, certainly less
than 1 in 1000. In terms of the surgery there are significant complications
such as :
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Infection.
Around 1 in 10 surgical wounds become infected (superficial infection)
but this is often easily treated with a simple course of antibiotics.
Deep infection of the spine itself is rare (1 in 100) but much more
devastating. This is associated with formation of pus (abscess) which often
requires re-operation to drain the infectedmaterial and a prolonged
course of intravenous antibiotics and wound care. The infection can get into
the spinal covering and cause severe spinal infection (meningitis). This
complication is very rare.
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Damage to the spinal cord. Damage to the
spinal cord or nerve roots again is rare, certainly less than 1 in 500. The
lumbar spine has nerve roots rather than spinal cord tissue. These nerves
control specific muscles and loss of nerve function means that sensation and
movement of a joint is severely affected on one side or the other. Damage
to the spinal cord leading to extensive loss of function involving both limbs
is very rare and would only normally occur in episodes of spinal decompression
procedures of the neck or thoracic spine.
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CSF Leak.
CSF (cerebro-spinal fluid) is the fluid which surrounds the nerve tissue and
is enclosed by a thick membrane called the dura. As I remove bone
from around trapped nerves sometimes this membrane can be damaged leading to
leakage of fluid into the tissues. This actually happens in around 1 in 25
patients who undergo spinal surgery but is usually relatively minor and I will
either patch up or stitch up the small tear at the time of surgery.
Occasionally, however, the leak of CSF fluid can persist after operation
leading to a collection of fluid under the skin or even leakage through the
wound into the dressings. The latter situation of persisting CSF leak
through the skin is known as CSF fistula and often requires
re-operation to seal up the leak. This occurs in less than 1 in 200
cases. More usually CSF leak leads to headache or nausea which persists for
a few days following the operation due to the loss of pressure of the fluid
surrounding the spinal cord (and the adjoining brain).
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Continued back pain.
Often the condition leading to spinal surgery is associated with wear and tear
arthritis. Once the worst spinal segments have been fused this will often
improve function but the patient will be left with residual arthritic pain
from the remaining spine segments. If the amount of bone removed affects
the way the lower bones or vertebrae work together it can actually cause
deterioration in the wear and tear arthritic symptoms of the rest of the
back.
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Deep Vein Thrombosis :
Pulmonary Embolus (DVT/PE). After any major operation which involves
a period of immobility or bed rest there is a tendency for blood clots to form
in the veins of the lower limbs. These blood clots (thrombosis) cause limb
swelling and discomfort. Even more worrying is when the thrombus becomes
large enough such that pieces break off and travel in the veins to the heart
and lungs causing significant damage (pulmonary embolism). 1 in 1000
patients who have a major spinal operation die as a result of massive
pulmonary embolus. By getting mobile as soon as possible after the
operation this will reduce your risk of deep vein thrombosis and pulmonary
embolus and I will often use techniques such as TED stockings, calf
compression techniques in surgery and anti coagulation such as Heparin to
reduce the risk still further. I will discuss this with you when planning
surgery.
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Failed
Operation. Spinal fusion is a successful operation generally.
Around 7 out of 10 patients who undergo this operation have significant
improvement in their symptoms and feel that the operation was worthwhile.
One in ten however get worse due to complications as those outlined above and
another 2 in 10 patients feel that their symptoms are no better. This is
either due to the fact that the nerve damage has become permanent due to
prolonged and severe compression of the nerves or the spinal segments have not
fully stabilised. Due to persisting symptoms of back pain I may elect for
you to undergo repeat scans of your back to see whether or not further surgery
is required but this would be unusual. More likely is that the operation,
although appropriate and successfully carried out, has unfortunately not
resolved your symptoms.
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Smoking and Spinal Fusions
It is well known in the literature that people who smoke, generally heal less
well than those who do not smoke. This is because the oxygenation of the
blood is reduced in chronic smokers. This affects many healing factors such
as wound infection rates, chest infection rates, etc. In particular, with
spinal fusion the incorporation and stability of the bone graft used for
spinal fusion is known to be closely related to whether or not an individual
smokes. In individuals who are non-smokers, the fusion rate, i.e. evidence
of incorporation of the bone graft across the vertebral bodies is around
95%+. Conversely, in heavy smokers, the fusion rate falls to as low as
50%. These affects are rapidly reversible and it is in a patient’s own
interest to discontinue smoking as early as possible prior to surgery and
certainly, even in a chronic smoker but one who has given up at least six
weeks before surgery, the success rate of the operation to incorporate the
bone graft is noticeably higher.
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Post Operative Scarring.
Following operation the amount of scar tissue is variable in each
individual. Sometimes the amount of discomfort from the scarring in the
muscles and tissues of the back is painful and leads to discomfort on sitting,
standing or stretching the scar tissue which is intrusive. Even more
worrying is when excessive scarring develops around the spinal cord and the
nerves, and leads to irritation of the nerve tissue which can be as disabling
and distressing as the compression caused by the bone. Such nerve scarring
(arachnoiditis) is very difficult to treat and is often made worse by
further surgery, and can only be treated by pain management techniques
including further injections and/or medication. Severe nerve root scarring
thankfully is rare, around 1 in 100 patients.
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When Can I Return to Work?
Most patients who undergo spinal fusion are usually over 50 and many have not
been able to work because of their condition. For younger patients who are
managing to work prior to their operation, I would normally anticipate at
least up to three months before you are able to return to work and then only
if your work is sedentary, i.e. office work. Any more strenuous work,
particularly that which involves prolonged sitting or bending may take up to
six months before you are fit enough and safe enough to return to your work.
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What Happens If Things Go
Wrong? Should you be unfortunate enough to develop a complication,
either as an in patient or following discharge from hospital, this will be
dealt with by either your own GP or myself. Should you develop any problems
you can phone the hospital ward and speak to the nursing staff on duty for
advice. They would normally be able to deal with most queries or suggest
suitable alternatives such as phoning your GP, attending the accident and
emergency department locally or returning to hospital, depending on the
circumstances.
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What Happens If Things Go
Wrong? Should you be unfortunate enough to develop a complication,
either as an in patient or following discharge from hospital, this will be
dealt with by either your own GP or myself. Should you develop any problems
you can phone the hospital ward and speak to the nursing staff on duty for
advice. They would normally be able to deal with most queries or suggest
suitable alternatives such as phoning your GP, attending the accident and
emergency department locally or returning to hospital, depending on the
circumstances.
- Post operative
deaths.
Thankfully this is rare, around 1 in 1,000 but can happen as a result of one
or more of the complications above.
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