ANTERIOR LUMBAR INTERBODY FUSION (ALIF)

What is an anterior lumbar interbody fusion (ALIF)?
Why might I need an ALIF?
When is an ALIF not recommended?
How is the diagnosis made before deciding upon surgery?
What are the alternatives to an ALIF?
How does an ALIF compare with other types of fusion surgery?
What are the potential benefits of an ALIF?
What are the possible outcomes if treatment is not undertaken?
What are the specific risks of an ALIF?
What are the risks of anaesthesia and the general risks of surgery?
What are the implications of surgery?
How does revision lumbar spine surgery differ from ‘virgin’ surgery?
What do I need to tell the neurosurgeon before surgery?
What do I need to do before surgery?
Will I need further investigations?
Who will perform my surgery? Who else will be involved?
How is an ALIF performed?
What happens immediately after surgery?
What are my discharge instructions following ALIF?
What do I need to tell my surgeon about after the operation?
What are the results of surgery?
What are the costs of surgery?
What is the consent process?

What is an anterior lumbar interbody fusion (ALIF)?
A spinal fusion is a surgical procedure which results in two or more bones being joined together in a solid and stable fashion by bridges of bone between them. The aim is to stop movement across that particular segment of the spine.

An anterior lumbar interbody fusion (ALIF) is an operation on the lower back which is performed from the front, in other words through the abdomen. It is most commonly used to treat lower back pain resulting from a damaged or degenerate intervertebral disc, or spondylolisthesis (slippage of one bone on the other). The goal is to stabilise the spine so that pain (and sometimes deformity) is reduced.
Anterior lumbar interbody fusion (ALIF) involves the removal of one or more intervertebral discs and the joining of two or more spinal bones (vertebrae) together using screws and a cage.


Why might I need an ALIF?
An ALIF is advised for some patients who may have the following conditions:

  1. Discogenic lower back pain (pain arising from the intervertebral disc)
  2. Spondylolisthesis (slippage of one vertebra on another, with pain and instability)

Surgery is usually recommended when all reasonable conservative measures (pain medications, nerve sheath injections, physical therapies, braces etc.) have failed.

When is an ALIF not recommended?
An ALIF may not be recommended when there is:

  1. Obesity (this makes the approach difficult)
  2. A history of multiple abdominal surgeries (this may make the approach hazardous)
  3. Significant pressure on the spinal nerves (this requires a decompressive procedure, which is performed from the back)

In some cases, an ALIF may be followed by a posterior decompression and/or stabilisation procedure.

How is the diagnosis made before deciding upon surgery?
Making the diagnosis usually requires taking a history of the problem, as well as a neurological examination. The history (symptoms or complaints obtained from the patient) is the most important aspect of the assessment.

Important questions often include:

  • Has there been an injury?
  • Where is the pain?
  • Is there any numbness?
  • Is there any weakness?
  • Have you had the same or a similar problem in the past?
  • Have you had any weight loss, fevers, or illnesses recently?
  • Have you had cancer in the past?
  • Are there any problems when you urinate or open your bowels?

Investigations are extremely important, and may include the following:

  • CT scan
    • usually an early investigation
    • shows the anatomy of the bone and joints very well
    • an abdominal CT scan will show the position of the blood vessels in relation to the discs, and helps with surgical planning
  • MRI scan
    • gives more detailed information about the discs and nerves
  • CT Myelogram
    • usually performed if an MRI cannot be carried out for some reason
  • Standing X-rays and X-rays taken bending forward and backward (flexion-extension X-rays)
    • to assess for potential spondylolisthesis and instability
  • Nerve conduction studies and/or a nerve sheath injection with local anaeasthetic
    • to confirm which nerve (or nerves) is causing the symptoms
  • Facet joint blocks and/or a nuclear medicine scan (lumbar SPECT)
    • if pain arising from the facet joints is suspected
  • Provocative lumbar discogram
    • if pain arising from an intervertebral disc is suspected
  • Nuclear medicine bone scan
    • if cancer of the spine is suspected
  • Bone density scans (DEXA scan)
    • if osteoporosis is suspected

Sometimes a second opinion from another neurosurgeon or a neurologist, pain physician, orthopaedic surgeon or rheumatologist may be sought.

What are the alternatives to an ALIF?
A number of alternatives to a ALIF may exist, depending upon your individual circumstances. These include:

  1. Pain medications. A number of medications may be useful for pain. These include the standard opioid and non-opioid analgesic agents, membrane stabilising agents and anticonvulsants, as well as the most recent agent to be released- Pregabalin. Special medical treatments such as Ketamine infusions may be appropriate in some situations.
  2. Nerve sheath injections. Local anaesthetic may be injected, under CT scan guidance, around the compressed nerve. This is also known as a ‘foraminal block’. Patients frequently obtain a significant benefit from this procedure, and surgery can sometimes be delayed or even avoided. Unfortunately, the benefit obtained from this procedure is usually only temporary, and it tends to wear off after several days, weeks, or sometimes months. This procedure is also an excellent diagnostic tool, especially when the MRI scan suggests that multiple nerves are compressed and your neurosurgeon would like to know exactly which nerve is causing your symptoms.
  3. Physical therapies. These include physiotherapy, clinical pilates, osteopathy, hydrotherapy, chiropractic, acupuncture and massage.
  4. Activity modification. Sometimes simply modifying your workplace and recreational activities, to avoid heavy lifting, prolonged sitting, and repetitive bending and twisting, allows the healing process to occur more quickly.
  5. Other surgical approaches. These include:
    • lumbar microdiscectomy
    • lumbar decompression (also known as a laminectomy and rhizolysis)
    • non-instrumented fusion: where bone is laid down without using screws or cages to stabilise the spine
    • posterolateral instrumented fusion: where screws are placed but the disc space is not fused by inserting a cage
    • posterior lumbar interbody fusion (PLIF)
    • transforaminal lumbar interbody fusion (TLIF)
    • artificial disc replacement (arthroplasty)
    • disc nucleus replacement (nucleoplasty)
    • spinal cord stimulation

You should discuss these alternatives, together with their potential benefits and risks, with your neurosurgeon.

How does an ALIF compare with other types of fusion surgery?
An ALIF approach has several advantages over spinal fusions performed from the back (via a posterior approach), including PLIF, TLIF, and posterolateral fusion:

  • the muscles of the lower back remain undisturbed, with less postoperative back pain
  • the spinal nerves are not manipulated, so there is less chance of nerve damage
  • more extensive disc removal and disc space preparation is undertaken, with better fusion rates

The main disadvantage of an anterior approach is that the spinal nerves cannot be decompressed (when this is required, a posterior approach is indicated).

What are the potential benefits of an ALIF?
The goals of an ALIF may include:

  • Reduction of back pain
  • Stabilisation of an unstable spine
  • Medication reduction
  • Prevention of deterioration
  • Improved lower back and leg function
  • Improved work and recreational capacity
  • Improved quality of life

The chance of obtaining a significant benefit from surgery depends upon a wide variety of factors. Your neurosurgeon will give you an indication of the likelihood of success in your specific case.

What are the possible outcomes if treatment is not undertaken?
If your condition is not treated appropriately (and sometimes even if it is), the possible outcomes may include:

  • Ongoing pain
  • Problems with walking
  • Depression and anxiety

What are the specific risks of an ALIF?
Generally, surgery is fairly safe and major complications are uncommon. The chance of a minor complication is around 4 or 5%, and the risk of a major complication is 2 or 3%. Over 90% of patients should come through their surgery without complications.

The specific risks of an ALIF include (but are not limited to):

  • Failure to fuse (non-union)
  • Fail to benefit symptoms or to prevent deterioration
  • Worsening of pain
  • Infection
  • Blood clot in wound requiring urgent surgery to relieve pressure
  • Cerebrospinal fluid (CSF) leak: this risk is much higher in revision (re-operation) surgery
  • Surgery at incorrect level (this is rare, as X-rays are used during surgery to confirm the level)
  • Blood transfusion
    • surgery is performed very close to the large blood vessels that go to the legs
    • injury to these large blood vessels may cause substantial blood loss
  • Screw and/or cage breakage, movement, or malposition, sometimes requiring further surgery
  • Cage or graft dislodgement (expulsion)
  • Nerve damage (weakness, numbness, pain) occurs in less than 1%
  • Major neurological problems are fortunately rare, but include:
    • paraplegia (paralysed legs)
    • incontinence (loss of bowel/bladder control)
    • impotence (loss of erections)
  • Chronic pain (may require further surgery)
  • Failure to fuse (pseudoarthrosis)
  • Adjacent segment disease (deterioration of the disc above or below due to the extra stress caused by the fusion)
  • Injury to the bowel, ureter (the tube running from your kidneys to the bladder), or spermatic cord
  • Retrograde ejaculation in men
    • occurs in less than 5% of cases (the real figure is probably closer to 1%)
    • the nerves (known as the superior hypogastic plexus) that control ejaculation are draped over the front of the L5-S1 disc
    • these nerves are very sensitive, and ejaculation can be disrupted
    • ejaculation then occurs into the bladder, rather than out through the penis
    • erection and sex drive are rarely affected
    • it often resolves with time (several months to a year)
  • Incisional hernia (this may require corrective surgery)
  • Post-operative ileus (slowing of the bowels, which usually settles over a few days)
  • Injury to the diaphragm or kidney
  • Deep venous thrombosis and pulmonary embolism (formation of blood clots in the leg veins, and these may break off and travel to the lungs, which can be life-threatening)
  • Death (this is extremely rare)

What are the risks of anaesthesia and the general risks of surgery?
Having a general anesthetic is generally fairly safe, and the risk of a major catastrophe is extremely low. All types of surgery carry certain risks, many of which are included in the list below:

  • Significant scarring (‘keloid’)
  • Wound breakdown
  • Drug allergies
  • DVT (‘economy class syndrome’)
  • Pulmonary embolism (blood clot in lungs)
  • Chest and urinary tract infections
  • Pressure injuries to nerves in arms and legs
  • Eye or teeth injuries
  • Myocardial infarction (‘heart attack’)
  • Stroke
  • Loss of life
  • Other rare complications

What are the implications of surgery?
Most patients are admitted on the same day as their surgery; however some patients are admitted the day before.

Patients admitted the day before surgery include those who:

  • reside in country regions, interstate, or overseas
  • have complex medical conditions or who take warfarin
  • require further investigations before their surgery
  • are first on the operating list for the day

You will be given instructions about when to stop eating and drinking before your admission.

Several X-rays of your back will be taken during surgery to make sure that the correct spinal level is being fused, and also to optimise the positioning of the screws and cage. It is critical that you inform us if you are pregnant or think you could possibly be pregnant, as X-rays may be harmful to the unborn child.

You will wake up with a catheter (tube) in your bladder, and a drip in your arm. These will be removed around 24 hours after surgery. It is important that you get up and walk around either on the evening of your surgery or the next day. You will need to wear stockings to prevent blood clots after your surgery.

A CT scan will be performed the day after surgery to check the position of the screws and cage. You will be fitted with a custom-made lumbar brace which you will need to wear whenever you are walking or sitting for 3 months after surgery.

You will be in hospital for between 3 and 5 days after your surgery (on average). This is occasionally followed by a 5-7 day period of inpatient rehabilitation.

You will be given instructions about any physical restrictions that will apply following surgery, and these are summarised later in this section.

There is significant variability between patients in terms of the outcome from surgery, as well as the time taken to recover. You will be given instructions about physical restrictions, as well as your return to work and resumption of recreational activities. You should not drive a motor vehicle or operate heavy machinery until instructed to do so by your neurosurgeon.

You should not sign or witness legal documents until reviewed by your GP post-operatively, as the anaesthetic can sometimes temporarily muddle your thinking.

An important issue relating to spinal fusion is that by fusing level of the spine, slightly increased stress is placed upon the levels directly above and below the fusion. This increases the risk of degeneration at these levels and, therefore, the possibility that you may need further surgery in the future. You should discuss this issue further with your neurosurgeon.

Fusion of the lumbar spine results in a degree of loss of movement in the lower back, mainly in terms of bending forwards and backwards. For a one level fusion, this loss of movement is usually barely noticeable (if at all). There is usually a small but definite loss of movement following a two level fusion. Three or four level fusions are only occasionally carried out, due to less satisfactory postoperative outcomes.

It is critical that you stop smoking for at least 12 months after surgery (but preferably forever!). Smoking impairs the fusion process and leads to worse outcomes after spinal surgery.

How does revision lumbar spine surgery differ from ‘virgin’ surgery?
The risk of complications from lumbar spine revision surgery (surgery after a previous spinal surgical procedure) is significantly higher than in first-time procedures. This is due to a number of factors, particularly scar tissue formation around the nerves and the distortion of the usual anatomical structures. Spinal fluid (CSF) leakage from a hole in the lining over the nerve roots is a significant risk, but is usually managed successfully without serious long-term consequences.

It is also more difficult to relieve pain and restore function in revision surgery, as the nerves may have been damaged by longstanding compression and previous interventions.

It is important be aware that the possibility of experiencing long-term back pain is increased with revision surgery.

What do I need to tell the neurosurgeon before surgery?
It is important that you tell your surgeon if you:

  • Have blood clotting or bleeding problems
  • Have ever had blood clots in your legs (DVT or deep venous thrombosis) or lungs (pulmonary emboli)
  • Are taking aspirin, warfarin, or anything else (even some herbal supplements) that might thin your blood
  • Have high blood pressure
  • Have any allergies
  • Have any other health problems

What do I need to do before surgery?
Before your surgery it is imperative that you stop smoking, and you should not smoke for at least 12 months after. Smoking impairs the fusion process and leads to worse outcomes following spinal surgery.

If you are fairly overweight, it is advisable that you engage in a sensible weight loss program before you surgery. Please discuss this with your GP and neurosurgeon.

In order to prevent unwanted bleeding during or after surgery, it is critical that you stop taking aspirin, and any other antiplatelet (blood-thinning) medications or substances including herbal remedies at least 2 weeks before your surgery.

If you normally take warfarin, you will usually be admitted to hospital 3 or 4 days before your surgery. Your warfarin will be ceased at that time (it takes a few days to wear off) and you may be commenced on shorter-acting anti-clotting agents for a few days. These can then be stopped a day or so before surgery.

Ideally, you should take a Zinc tablet a day, commencing one month before surgery, and continuing for 3 months after. This should help wound healing.

Will I need further investigations?
Most patients will have had X-rays of their back, as well as a CT scan and MRI. Sometimes standing and ‘dynamic’ X-rays of the lumbar spine are performed, with X-rays taken leaning forwards and backwards; this is to determine the presence and site of any instability.

In some patients there is uncertainty either about the diagnosis or exactly which disc or discs in the back are responsible for their symptoms: in those patients, a provocative lumbar discogram, nerve conduction studies and/or a nerve block may shed light on the diagnostic issues.

If you have not had an MRI for over 12 months before your surgery, or if your symptoms have changed significantly since your most recent MRI, then this investigation will need to be repeated to make sure that there are no surprises at the time of surgery!

Who will perform my surgery? Who else will be involved?
Surgery will be carried out by your Precision Neurosurgery surgeon.

An experienced vascular surgeon usually performs the approach, in order to make the operation as safe as possible. You will be reviewed by the vascular surgeon before a final decision to proceed with an ALIF is made.

A surgical assistant will be present and an experienced consultant anaesthetist will be responsible for your general anaesthetic.

How is an ALIF performed?
A general anaesthetic will be administered to put you to sleep. A breathing tube (‘endotracheal tube’) will be inserted and intravenous antibiotics and steroids injected (to prevent infection and post-operative nausea). Calf compression devices will be used throughout surgery to minimise the risk of developing blood clots in your legs. A catheter will be inserted into your bladder to prevent bladder distension during surgery and to monitor urine output. You will be placed face-up on the operating table.

Your abdomen will be cleaned with antiseptic solution and some local anaesthetic will be injected.

An 8-12cm incision is made on the left side of the abdomen or in the midline, usually just below your umbilicus (belly-button). The abdominal muscles (rectus abdominus) are gently pulled to one side and the sac containing the abdominal contents (peritoneum) is similarly retracted. This is known as a retroperitoneal approach.

Sometimes, a transperitoneal approach is utilised: the peritoneum is incised and the abdominal contents retracted to approach the spine more directly.

The large blood vessels that run to the legs (the aorta and vena cava) are gently mobilised retracted off of the anterior aspect of the spine. The ureter is also identified and protected. At L5-S1, the superior hypogastric plexus is gently mobilized to expose the disc space.

A small needle is then inserted into the disc and an x-ray is performed to confirm that the surgeon is at the correct disc is being exposed.

A microdiscectomy is performed. This is done by first cutting the outer annulus fibrosis (fibrous ring around the disc) and removing the nucleus pulposus (the soft inner core of the disc). Disc removal is performed using a combination of special instruments.

The boundaries of the disc space (the vertebral end-plates) are then carefully prepared to facilitate fusion.

A special interbody cage (made of carbon fibre, PEEK, or trabecular metal) is then inserted into the disc space and secured in place with screws. This cage is typically filled with a combination of bone shavings, tricalcium phosphate, and bone morphogenetic proteins.

A final X-ray is taken and the wound is closed with dissolving sutures or with staples.

What happens immediately after surgery?
It is usual to feel some pain after surgery, especially at the incision site. Pain medications are usually given to help control the pain. While tingling sensations or numbness is common, and should lessen over time, they should be reported to your neurosurgeon.

Most patients are up and moving around within several hours of surgery. This is encouraged in order to keep circulation normal and avoid blood clot formation in the legs.
You will be able to drink after 4 hours, and should be able to eat the next day (once you have developed bowel sounds).

A CT scan will be performed the next day to check the position of the screws and cage.
You will be discharged home when you are comfortable, usually after 3-5 days.
What happens after discharge?

You will need to wear a special brace for 3 months after surgery whilst you are sitting, standing or walking. You will need to take it easy for 8 weeks, but should walk for at least an hour every day. You should avoid sitting for more than 15-20 minutes continuously during this time.

At 6-8 weeks it is likely that you will be able to return to work on “light duties” and to drive a motor vehicle on short trips. This, and the step-wise progression in your physical activities, will be determined on an individual basis.

Bear in mind that the amount of time it takes to return to normal activities is different for every patient. Discomfort should decrease a little each day. Increases in energy and activity are signs that your post-operative recovery is progressing well. Maintaining a positive attitude, a healthy and well-balanced diet, and ensuring plenty of rest are excellent ways to speed up your recovery.

Signs of infection such as swelling, redness or discharge from the incision, and fever should be brought to the surgeon’s attention immediately.

You will be reviewed after 6-8 weeks by your neurosurgeon. Until then, you should not lift objects weighing more than 2kg, and should not engage in bending or twisting movements.

The results of fusion surgery are not as good in patients who smoke or are very overweight. It is therefore important that you give up smoking permanently before your surgery and try to lose as much weight as possible.

You should continue wearing your TED stockings for a couple of weeks after surgery.

What are my discharge instructions following ALIF?

Diet: Maintain normal healthy diet, high in fibre to avoid constipation
Medications: You may be prescribed analgesia (pain medications), muscle relaxants, and stool softeners. Be aware that some pain medications can cause constipation. Please take only the analgesia that has been prescribed for you.
Activity: Allowances

-

Frequent short walks (at least 1-2 hours per day)

- Travelling by car is allowed for short distances. If you are making longer trips, break the trip up into 20 minute segments, getting out of the car for a few minutes to go for a short walk.
- Walking up and down stairs.
  Restrictions
(aimed at protecting
your back
and allowing healing to occur)

-

No sitting for longer than 20 minutes at a time or as directed by your neurosurgeon
- Do not bend from the waist (you should bend at the knees)
- No twisting
  -

No stretching or reaching for items above your head

  - Sleep with a pillow between your knees when lying on your side
  - Do not lift anything heavier than 2kg for the first 6 weeks post-operatively. Light housework only – no hanging washing out on the line, carrying baskets of clothing, no vacuuming, lawn mowing.
  - No driving for at least 6-8 weeks after surgery
  - No vigorous exercising/playing sports until you are cleared by neurosurgeon to commence these.
 

Strict bed rest IS NOT required or recommended.

Smoking: Smoking impairs wound healing and fusion. Stopping smoking will probably improve outcomes.
Wound Care:
  • You will have either dissolvable sutures or staples.
  • Have GP check your wound 4 days after discharge. A new dressing will be applied and this is to remain on for a further 4 days then is to be removed. Staples will usually be removed 7-8 days after surgery.
  • Keep wound dry for 12 days after surgery.
  • Shower if the dressing is intact. If the wound becomes moist, it will need to be dried and a new dressing applied.
  • Report any redness, discharge, persistent oozing or drainage from the wound to your GP or to the Precision Neurosurgery Registered Nurse.
  • Avoid swimming, spas or baths until your wound has completely healed, or until you are cleared by your neurosurgeon to commence these.
  • Keep taking your Zinc tablets daily for 3 months after surgery (this helps wound healing).
  • You should gently rub Vitamin E cream into your wound commencing 3 weeks after surgery and continuing for 6-12 months (this may reduce scarring).

What do I need to tell my surgeon about after the operation?
You should notify your neurosurgeon or the Precision Neurosurgery Nurse Specialist, and should also see your GP if you experience any of the following after discharge from hospital:

  • Increasing leg pain, weakness or numbness
  • Worsening back pain
  • Problems passing urine or controlling your bladder or bowels
  • Problems with your walking or balance
  • Fever
  • Swelling, redness, increased temperature or suspected infection of the wound
  • Leakage of fluid from the wound
  • Pain or swelling in your calf muscles (ie. below your knees)
  • Chest pain or shortness of breath
  • Nausea or vomiting
  • Severe constipation
  • Any other concerns

What are the results of surgery?
Overall, over 75% of patients will obtain a significant benefit from surgery, and this is usually maintained in the long term.

It is important to note that few patients become completely free of symptoms- the goals are pain and medication reduction, as well as prevention of deterioration.

Despite performing a technically satisfactory operation, a solid bony fusion does not always occur. Patients can control certain factors which may be important in determining whether or not a solid fusion occurs, including:

  • Smoking. It is advisable to quit smoking before undergoing a spinal fusion procedure, and not to resume smoking afterwards. Nicotine often prevents solid bone from bridging the disc space.
  • Motion. Bone generally forms better if motion is limited. Patients are therefore advised to wear a lumbar brace and to avoid bending, lifting, and twisting for three months after surgery.

What are the costs of surgery?
Private patients undergoing surgery will generally have some out-of-pocket expenses.
A quotation for surgery will be issued, however this is an estimate only. The final amount charged may vary with the eventual procedure undertaken, operative findings, technical issues etc. Patients are advised to consult with their Private Health Insurance provider and Medicare to determine the extent of out-of-pocket expenses.

Separate accounts will be rendered by the vascular surgeon, anaesthetist and sometimes the assistant, and hospital bed excess charges may apply. Medical expenses may be tax deductible (you should ask your accountant).

You should fully understand the costs involved with surgery before going ahead, and should discuss any queries with your surgeon.

What is the consent process?
You will be asked to sign a consent form before surgery. This form confirms that you understand all of the treatment options, as well as the risks and potential benefits of surgery. If you are unsure, you should ask for further information and only sign the form when you are completely satisfied.