Fusion For Low Back Pain (Lumbar Fusion) - Spinal Fusion Surgery

General Information

The most common cause of low back pain is degeneration ("wear and tear") associated with normal ageing and injuries to the spine.

Low back pain is common and requires surgical treatment in only a small minority of patients (see spine surgery for treatment of neck or back problems).

Surgery is recommended only for selected patients with persistent or recurrent pain causing significant interference with quality of life and after a period of non-operative (physical therapy, pain management) treatment.

Surgery for low back pain is a reasonably major undertaking. The recovery period can be prolonged - recovery is usually 90% complete at three to four months but some patients continue improving for six to twelve months.

Surgery for low back pain is generally considered to give good or excellent results in 70% to 80% of carefully selected patients.

Patient selection is all important - consistently good results are only obtained when the correct operation is performed on the correct patient for the correct reason.

For the vast majority of patients the recommended surgical procedure is a lumbar fusion (joining the lumbar vertebrae together "bone to bone").  In a very small minority of patients with disc pathology only and normal facet joints (the joints at the back of the spine) disc replacement is an option.  Disc replacement has the theoretical advantage of maintaining some motion in the disc and better protecting the adjacent discs.

Spinal fusion surgery is performed at one or two levels if the painful level can be determined with confidence and the remainder of the lumbar spine is relatively free of degenerative change and can take over the function.

Patients who undergo a one or two level fusion do not generally notice any stiffness or loss of movement and their lumbar spine may in fact feel more mobile because of a reduction in pain. 

A good or excellent result does not mean the patient will never experience some lower back pain but rather there will be very useful or marked improvement in the pain with improved quality of life and function.

A good or excellent result implies one to 2 years later the patient considers the procedure was very worthwhile and would undergo it again under similar circumstances.  This should occur in 70% to 80% of carefully selected patients.

With modern techniques fusion can be achieved reliably in 95% of patients (less in smokers) but achievement of fusion does not always translate to a good or excellent result.

There are many techniques for obtaining a lumbar fusion but broadly fusion can be achieved through a Posterior Approach (the incision is on the lower back) or an Anterior Approach (the incision is on the abdomen).  Sometimes one approach is preferable over another depending upon the MR findings and the age, sex and build of the patient.

Posterior Approach

Spinal Fusion Surgery is performed under general anaesthetic.

Optical magnification (microsurgery) is used.

The operative time varies between 2 and 4 hours.

Spinal fusion surgery always involves insertion of 2 screws into each vertebrae (pedicles screws) joined by rods and the laying of bone graft (taken from the pelvis through the same incision) up and down each side of the spine.

Spinal fusion surgery often also involves removal of the inter vertebral disc and insertion of a spacer (cage) containing bone graft into the disc space.

Sometimes additional products (eg BMP) are used to assist fusion.

Anterior Approach

Surgery is performed under general anaesthetic with an incision on the lower abdomen.

It is necessary to mobilise the large vessels (aorta, vena cava, common iliac arteries and veins) on the front of the spine to access the inter vertebral disc.  If difficulties are anticipated a Vascular Surgeon may help with the procedure.

A spacer (cage) is inserted into the disc space. 

Usually the cage is filled with a bone graft substitute to assist fusion - bone grafts are avoided if possible.

Post Operative Course

Patients usually rest in bed the day after surgery then stand to take a few assisted steps on the second day after surgery.

On day 3 patients are usually walking to the toilet and the urinary catheter is removed. 

Patients usually go home on day 4 or 5 when their pain is under control with oral tablets, when they are able to get in and out of bed and up and downstairs. 

Walking is the only exercise which is necessary in the first six weeks following lumbar fusion surgery.  Walking is increased progressively with the aim of walking 1km to 2km outside within two weeks of surgery.  Patients may swim if desired after 2 weeks.   After 6 weeks most patients will benefit from an exercise programme, often gym based, supervised by a physiotherapist.

Sitting or standing in one position can be uncomfortable for several weeks - simply move about or change position. 

Some patients improve slowly, others quickly but improvement is progressive.  Most patients have returned to sedentary work at 4 to 6 weeks, light manual work at 2 to 3 months and heavy manual work at 4 months.

It is difficult to damage the fusion but excessive activity undertaken too early can result in pain and slower progress.  The patients who make the best recovery gradually increase their level of activity as the days and weeks pass.

You will leave hospital with a waterproof dressing which should be removed one week later.  Simply peel off this dressing as if it was a big "band aid".  The stitches under the skin dissolve.  No suture removal is necessary.

Driving is normally resumed within 3 to 6 weeks when it feels safe and comfortable.

Complications

As with any spine surgery, infection, nerve injury or spinal fluid leak requiring further surgery occur in less than 1% of patients (and closer to 0% in my Practice). 

Failure of the spine to fuse occurs in up to 5% of patients and in some of these further surgery may be required. 

Incomplete pain relief is most important "complication" to be discussed prior to lumbar fusion surgery.

With further ageing or injury to the spine painful degeneration can occur at adjacent levels and sometimes further surgery is required in the future.

Complications Related to the Anterior Approach

Injury to the vessels on the front of the spine can result in significant bleeding and if difficulties are anticipated a vascular surgeon will assist with the procedure.

In males there is the theoretical risk of interference with sexual function.

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