This lower back fusion surgery post is essential reading for anyone contemplating surgery for back pain

Below I have recommended an article which describes the techniques of lower back fusion surgery and their success rates.  I have made a few comments along the way. I’m afraid the piece is quite technical, but essential for anybody considering spinal fusion surgery. I have copied and pasted large sections (in italics) and also added my thoughts along the way.

I regularly see patients suffering from 'Failed Back Surgery Syndrome' (FBSS) where the outcome from lower back fusion surgery is either residual pain or increased spinal pain. This being the case, I would urge all non-surgical treatment means be exhausted before contemplating spinal fusion. It is so much more difficult to have success with conservative management when a spine is still painful after back fusion surgery. 

In fact, the spectre of failed back surgery is so miserably alarming for patients, that in May of 2014 I wrote a short 42 page Kindle eBook. May I suggest this is essential for anyone at the point of a knife.

[Image]: These pedicle screws (bolted to the plate at the back) are to stop further forward slip of L5 on the sacrum 

Interesting Article About Lower Back Fusion Surgery

Comparison of low back fusion techniques: transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) approaches

Chad D. Cole, Todd D. McCall, Meic H. Schmidt, and Andrew T. Dailey
Curr Rev Musculoskelet Med. 2009 June

The authors of this lower back fusion surgery article explain the history of spinal fusion and the difference between the two major types of lumbar fusion: the (PLIF) posterior lumbar interbody fusion (with and without pedicle screws) and transforaminal lumbar interbody fusion (TLIF).

Interbody fusions involve the complete removal of the intervertebral disc from between the vertebral bodies and then packing out the evacuated disc space to allow it to grow rigid, or fused. The earliest interbody fusions involved filling the disc space by using the patient’s own (autologous) bone chips from their hip bone (iliac crest) and then encasement for several months in a plaster of Paris body suit. The bony chips acted as a sort of ‘bony scaffolding’ to which new bone could attach and grow.

Although the PLIF technique is more difficult than another ‘intertransverse fusion’ (involving bone graft spans between the bony sprigs (the transverse processes) at the sides of the vertebrae) the PLIF procedure worked better in terms of the bones fusing (in excess of 85%). It is interesting (to me) that surgeons deem this operation successful when they achieve fusion, rather than rendering the patient free of pain. 

It appears that the PLIF technique is fraught with ‘complications related to blood loss, dural/neural injury, graft extrusion, and inflammation of the lining of the delicate sac protecting the spinal cord (arachnoiditis)’.

‘Because of the technical challenges, the use of the PLIF procedure remained significantly limited until the 1990s, at which time the advent of pre-formed supplementary interbody implants (and the necessary instruments for inserting them) increased the technical ease and subsequent popularity of this technique. Structural implants, such as synthetic cages or premilled allograft (living material from the same species but not genetically identical) have now become a standard part of PLIF to support and stabilize the disc space until bone graft unites the bone of the opposing vertebral endplates’.

Slightly over-sized and highly perforated cages or baskets filled with autologous bone chips also evolved that were literally rammed into the disc space to 'seed' bony fusion. 

The article goes on to say: ‘More recently, interbody cages have become popular and are now composed of a wide range of materials, such as titanium mesh, carbon fiber, and polyether ether ketone (PEEK). Not only have fusion rates improved with this evolution, but technological advances in these implants have also improved their safety and ease of application, further adding to the popularity (with surgeons) of the PLIF procedure. Finally, augmentation of the PLIF procedure with the addition of pedicle screws increases the stability of the construct and has been reported to increase the fusion rate of this procedure compared with stand-alone grafts.’

PLIF surgery involves pulling aside the thecal sac containing the descending spinal nerves inside the spinal canal and retracting the nerve roots in their exit canals (foraminae). This is highly disruptive and can result in puncture of the thecal sac’s protective casing (dura) and extensive nerve damage. It is harder again with revision surgery (for ‘failed back surgery syndrome’ FBSS) because of extensive scar tissue invasion inside the spinal canal. 

‘At times, PLIF requires violation of the structural integrity of both facet joints to achieve adequate graft placement, which may increase the immediate postoperative instability and lead to failure, if pedicle screw instrumentation is not added.’

In Lower Back Fusion Surgery, What is a Pedicle Screw?

Pedicle screws are often used as an adjunct to PLIF fusion. They are rather long and provide firm fixation through the pedicles in the neural arch, across into the vertebral body. The screws themselves do no fixation. Screws are placed at two or three consecutive spinal segments and are connected at the back by a stout rod. Screwed rigid, they help stabilise the interbody junction at the front of the spine until the fused level has taken.