Modern Lumbar Spine Fusion Surgery

New spinal fusion surgical techniques have improved so much in the last 10+ years, patients can expect:

  • improved fusion rates
  • shorter hospital stays (in cases of outpatient or day surgeries, same day discharge)
  • plus a more active and rapid recovery period

On top of that, with better diagnostic tools and better understanding of indications for a spine fusion are improving outcomes.

Actually, before talking about new spinal fusion surgery techniques, it’s vital to note that only a very small number of people with back pain or neck pain will ever need surgery.

Data shows that 80%+ of adults will develop low back pain at some point in their lives, but the more important note is that the most painful symptoms are short seasons (days to weeks) and require little to not medical or surgical treatments. Back and neck physiotherapy will suffice.

Physiotherapy for back pain

You see, most individuals’ back and neck pains can be treated with physiotherapy management and exercise therapy, which may include

  • manual therapy
  • stretching
  • strengthening
  • heat and cold therapies
  • ultrasound therapy
  • etc

Unfortunately…for a very small percentage of people…their neck and back pains continues to persist or worse, gets more painful. It can limit their ability to move around, function and work. For these people, they may be suitable to consider spinal fusion surgery.

Another key note: in some cases, even when everyone is doing their best, be it the orthopedic or spine surgeons, the physiotherapists and the patients themselves, sometimes the lumbar spine fusion do not lead to a normal back. It’s not like other medical procedures, like say infections in the chest or urinary tract, where it can be treated with antibiotics and things go back to the way they were (most of the time).

For lumbar spinal fusion, it’s not like we can just fix the low back and its pain – the main goal of the surgery is to stop the motion at a painful motion segment in the spine. This is to minimize the pain and allowing the patient to increase his or her ability to function and enjoy everyday activities.

Spine fusion indications

The most common indicator for spinal fusion surgeries are mechanical low back pains.

Mechanical lower back pains typically happens with

  • increased activities ie activity-related
  • associated with degenerative changes in the spinal discs (such as in DDD – degenerative disc disease)
  • low-grade slippage of the spine (such as degenerative spondylolisthesis and isthmic spondylolisthesis)

The key thing is accuracy of diagnosis.

6 months of pain or longer or other

Patients who has had at least 6 months or longer of lower back pain is the most common general indication that they’re suitable for lumbar spinal fusion surgery.

Other than that, surgery is considered when there is a large deformity (such as scoliosis) or, more commonly, for back pain that does not get better with time or non-surgical treatment, such as:

  • Mechanical back pain (usually attributed to disc degeneration, called degenerative disc disease)
  • Spinal stenosis (where there is an associated deformity)
  • Isthmic spondylolisthesis
  • Fractures
  • Tumors

Then there are the differential diagnosis ie need to dive deeper to increase accuracy further. For example, spine fusion surgery is more reliable to address pain from degenerative disc disease with instability than for disc degeneration without instability.

Diagnostic studies, patient past pain and medical history as well as physical exams for spinal fusion

There are three essential aspects to understanding whether one is a good candidate for spinal fusion to treat their low back pain:

Diagnostic studies

The surgeon has a few studies that they can use to investigate the medical cause of pain.


The humble x-ray is the most commonly used imaging tool (most affordable as well). They’re to check if there’s any

  • fractures
  • bony instability
  • spinal deformities
  • tumor or cancer in spine

Mainly to check “hard” tissue ie bone….which leads to the point that often, back pain isn’t caused by bony issues. That’s why though x-rays are commonly used, they’re usually not enough to tell the medical cause of lower back pain.


Leading us to the gold standard after x-rays which is MRI scans (magnetic resonance imaging). MRI scans give very anatomically precise information on the soft tissues (and hard tissues).

What we’re looking for is the health of the discs as well as presence of any tumors or compression on the nerves.

Unfortunately sometimes, like many other imaging studies, is that some “abnormalities” that show up on MRI either

  • may not be the medical cause of the pain
  • or it’s suppose to cause symptoms but it doesn’t

Most often the disc degeneration identified on an MRI is a normal finding, secondary to aging, which occurs in more than 50% of people in their 40’s.

To add to that, a small percentage of people cannot be allowed to do MRI due to medical reasons. Such as patients having a pacemaker.

CT Scan

In cases where MRIs cant be safely done or not preferred, patient can do a CT scan with myelogram may be done.

The anatomic information from a CT scan with myelogram is very similar to that of an MRI scan. That being said, a CT myelogram is sometimes preferred or ordered as an adjunctive study to a MRI scan as it can

  • show very subtle nerve root compression and
  • also images out in the foramen better


Discograms are more controversial because it’s more invasive. It involves inserting a needle into the spinal disc and injecting dye in – if this causes patient’s normal pain to happen, then it is deduced that that specific disc is the anatomical/medical cause of the specific back pain.

From a medical standpoint, the problem with discography is two fold and both impacts on reliability:

  1. not objective – two persons can have very different viewpoints doing the same discogram
  2. skill dependent – people with different skills, experience and expertise may conclude differently

Additional problems to this is that not only is it not reliable, it’s not pleasant to patient. Discograms are more likely to confirm pain pathology rather than root cause.

Electromyography (EMG)

If there is a lot of pain in the leg, patients can go with EMG.

EMGs involve placing needles within the legs to determine whether the nerves are working properly and to help identify which nerve is compromised.

Patient history

Patient history taking is a form of fact-finding process, usually through conversation/interview to find out:

  • when the pain started
  • where to pain is located
  • if the pain travels (radiates)
  • how the pain started
  • what aggravates the pain
  • previous treatments (what works and what doesn’t)
  • patient’s preferences
  • how the pain impact and limits the patient’s activities

The doctor also needs to consider if there is other factors that contribute to the pain experienced such as in the case of depression.

Physical examination

Thorough physical examination is required to determine the evidence and extent of any nerve-involved pains and injuries – there are many different forms of tests.

As you can see, putting together all the medical information, indications, causes and history can be a complex process, especially when determining if the patient can or would benefit from a spinal fusion surgery.

Modern spine fusion techniques

The two primary types of medical devices used in a spinal fusion surgery include pedicle screws and anterior interbody cages or spacers. When it has been determined that a spine fusion is appropriate, the surgical technique utilized may vary.

Back (posterior) approach to spinal fusion

The surgical techniques that have historically been used the most comprise spine fusion surgery that is approached posteriorly, or from the back (vs. front/anteriorly, which means to go through the abdomen). There are three main posterior fusion techniques (all three are usually performed with pedicle screw fixation):

  1. Posterolateral gutter fusion surgery. Involves placing bone graft in the posterolateral portion of the spine (a region just outside the back of the spine). This type of fusion has a long history and has been the most commonly used approach.
  2. Posterior lumbar interbody fusion (PLIF) surgery. Involves placing bone graft and/or spinal implant (e.g. cage) directly into the disc space in the front of the spine.
  3. Transforaminal lumbar interbody fusion (TLIF) surgery. A TLIF is essentially like an extended PLIF, as it also involves expanding the disc space by removing one entire facet joint (whereas a PLIF usually involves gaining access to the disc space by removing a portion of the facet joints on each side of the spine)

Anterior approaches to spine fusion

A frontal approach to spine fusion allows the surgeon to place bone directly in the space between the vertebrae where the disc had been. The good thing about this approach is it can lead to a better (more solid) fusion which may translate to better pain relief if the fusion involves the disc space.

There are two main techniques for the frontal approach:

  1. Anterior/posterior lumbar fusion surgery. Incision in the abdomen, with removal of the disc and placement of bone graft where the disc material has been removed. A separate incision is made in the back to place the pedicle fixation and bone graft. Risk with this approach is that it may include a large amount of trauma to the muscles, which means longer hospital stay, and may at times be associated with a fair amount of blood loss. However, in cases where there is a lot of instability, an anterior/posterior fusion surgery can be necessary as it provides the greatest amount of stability.
  2. Anterior lumbar interbody fusion (ALIF) surgery. An anterior lumbar interbody fusion is a surgery technique that involves the placement of bone graft with a plate or secored spacer or bone graft with an anterior interbody cage within the disc space. The most efficient way to place this is through the abdomen into the disc space. Most commonly, persons who have undergone this spine fusion surgery are able to return to their activities more rapidly. This type of approach can be used in cases where there is not a lot of associated instability and the disc space is narrow. The results of stand alone anterior fusions are not as good for multilevel constructs.

Additional spinal fusion surgery factors and considerations

In addition to the spinal fusion approach used, there are a number of other factors to be considered before spine fusion surgery. The following discusses several other considerations.

PLIF and TLIF surgery

These allow for placement of bone or a cage in the disc space, increasing the fusion rate and hopefully a better clinical outcome.

There is more neurologic risk because of the need to retract the nerve roots, but that being said, there is usually no major nerve injuries. It has the advantage of placing a structural graft or device in the major weight-bearing part of the spine while avoiding a separate incision.

Bone Graft

Traditionally, bone graft is harvested from the patient’s own hip/pelvic bone to stimulate the fusion site.

In some situations, cadaver bones can be used but it doesnt work as well especially in posterior applications. Recent research advances have allowed spine surgeons to decrease the need for bone graft harvest by using substitutes such as

  • collagen sponges
  • demineralized bone matrix
  • platelet derived growth factors
  • bone morphogenic protein (BMP)*

The bone morphogenic protein seems to be the most promising so far but there is need for further research is ongoing to document the utility of these products, which allow for diminished patient trauma that can occur from harvesting bone graft from the patient’s own hip.

Minimally invasive surgery (MIS)

There is a lot of work and emphasis to take the approach of minimally invasive surgery, and the main focus on this is that if we can minimize trauma to patient’s body by using smaller incisions, that should lead to faster recovery after spinal surgery.

But, we need to tread cautiously: even if a technique is less traumatic, but if minimally invasive surgeries can lead to other issues due to lower spinal fusion, then it’s not really an advantage. The benefit needs to be significantly better consistently to take on such risks.

Spinal fusion risks and complications

So the most common risk of any spinal fusion surgery is the failure to do what it’s set out to do: failure to relieve lower back pain symptoms. In the best situations, this risk is at least 20% in single level fusions.

Where it’s two or more levels, this percentage goes up higher.

There is another risk that the vertebral bone may not fuse together after the spinal fusion surgery, and this is called pseudoarthrosis. This happens between 5-10% of the time. Some points to note:

  • research points that people who smoke has lower rate of successful spinal fusion
  • there is a risk that pedicle screws may break or become loose and may require surgery to remove or revise the screws and rods
  • front grafts and cages can move, which may require repeat spine surgery. If the anterior devices were placed anteriorly (from the front), rather than through a PLIF or TLIF (approaches through the back), it is safest to do this revision spine fusion surgery with a posterior approach (from the back).

That being said, ALL spinal fusion surgeries (all surgeries, by extension) will have potential for complications.

The good news is that most of the complications, dont happen most of the time.

More common surgery complications

The more common complications are related to normal surgeries, such as

  • infections
  • bleeding
  • aesthetic

Nerve damage risk

In some cases, nerves can be irritated and patients may experience short term numbness or weakness related to the nerve irritation. These sometimes are already experienced by the patient due to the spinal conditions in the first place.

It is very rare to lose major strength and sensation in the legs or lose control of bladder/bowel, though it may happen.

There is a very small percentage of men who after undergoing anterior spinal fusion, develop difficulties with ejaculation. There is a small plexus of nerves in front of the L5-S1 disc space that helps control ejaculation — if these nerves are affected (which can happen 1% of the time) then the valve involved with ejaculation will not close. This causes the ejaculate then follows the path of least resistance, which is to the bladder. The most significant side effect of this complication is that it is very difficult to complete conception. Potency is not affected, and the sensation of sex is still largely the same. In about half of cases this complication resolves over the course of about 6 to 12 months.

Care following spinal fusion post-surgery

Care, follow up and even physiotherapy after spinal fusion post-surgery is very, very important. I cant stress how important this is. I tell patients that there are 4 key factors as to how well we can recover post surgery:

  1. Genetics (this we cant control)
  2. Doctor skills and experience
  3. Physiotherapy and home exercise programs (the only thing we can control)

It takes approximately three months for the fusion to successfully set up and achieve its initial maturity. During these first three months, it is very, very necessary to avoid activities that may place the bone graft at risk.

Your doctor will usually restrict activities that involve

  • lifting
  • twisting or bending the lower back
  • vigorous activities such as weights, running and other sports.

Pre-operation physiotherapy helpful

Because of activity restrictions immediately following spine fusion surgery, patients always will benefit from 1-3 months of pre-surgery physiotherapy to strengthen up first.

This will help patients to recover faster (compared to a patient who has been sedentary for 12 months vs someone who has pre-surgery physiotherapy, the one with pre-surgery physiotherapy will have shorter recovery period, less pain and more confidence to return to work and life faster)

Prepare home and office

Following that, to prepare their home and work place to be more supportive such as

  • placing frequently used items within easy reach so no bending or reaching high is required
  • ordering in groceries or stocking up on groceries so you dont need to go out to buy groceries, push trolleys and carry the groceries back
  • getting extra help around house etc

Spine brace

Depending on the type of spine fusion, the patient, and the surgeon there may be a brace used after surgery.

This can be a soft corset brace or a more rigid plastic custom molded orthosis. Some spine surgeons may also augment the fusion site with bone growth stimulators.

Bones take time (and more) to fully strengthen

What you may hear is that “fractures take 6 weeks to heal” – that’s about 1.5 months. This is true on a general basis, for normal fractures.

But to add depth to that, bone strength are like the circles of a tree – it will heal in 6 weeks, but for it to become as strong as before, it needs time to fuse, evolve, layer up and thicken over the next months and years. If it’s very severe injury, it can take 2-3+ years.

No, we cannot wait till the pain go away + importance of physiotherapy

Physiotherapists are very important post-surgery pillars to give you and your body the just-right amount of resistance to

  1. improve your bone, nerve and joint healing rate
  2. recondition your weakened/deconditioned body due to sedentary and post-surgery reasons
  3. work through pain and nerve-related symptoms (if any)

These 3 points go hand in hand, and lets talk about the muscle and body deconditioning. Not enough is discussed about this. To illustrate, imagine our body’s bone structure and the muscles and tissues. The bone structure is the frame, and the muscles and tissues are the soft structures that hold our bony frame together.

  • What happens if the muscles and tissues are shortened in some areas?
  • And weak in some places
  • And when there is a recent surgery, we get fearful and do not exert properly

What happens?

What happens is that the muscles, ligaments and joints may not work as well, and can cause the joints and bones to not align well, leading to further problems like pain, increased risks of falls or reinjuries etc. Patients sometimes think that “everything will become alright once the pain goes away” but that doesnt work at all.

Pain is not linear.

We cant wait it away, or take pain meds and it’d disappear. Worse, even if we wait for the pain to go away, our body doesn’t wait – our body weakens at least 1% every day we rest and wait.

And the weaker our body gets…the WORSE the pain gets.

Every day, we lose strength if we dont train it properly, and thats why we have a number of patients who realize that the pain isnt going away 3, 6, 12 months after surgery.

Physiotherapists will help with pain management:

  • reconditioning improves the strength of the body and allows you to move safer and confidently without reinjuring
  • deal with any scarring that causes localized scar-and-operation-related pains

A frequent concern of patients is their ability to resume both recreational and occupational activities after the spine fusion. As is implied above, the more vigorous the activities, the longer it may take before the patient is able to return to them. However, even strenuous activities can be usually be resumed by six months after the spine fusion surgery.

There is a natural anxiety about resuming normal duties, although once the fusion is set, the more the back is stressed, the bigger and stronger the fusion becomes. Bone is a live tissue and responds to stress by growing stronger It generally takes about three months for the fusion to set, and once it has set up it is not fragile and is very unlikely to break. Stressing the bone involved in the fusion after three months helps the spine fusion to become stronger.

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