Posterior Lumbar Interbody Fusion (PLIF)

What is a PLIF?

PLIF stands for Posterior Lumbar Interbody Fusion. It is one of the most common and effective lumbar operations performed by Mr Cunningham. The specific technique used is a modern combination of a wide decompression, which allows a thorough decompression of the neurological structures, together with a 360° fusion to give the patient the best restoration of lordosis and opportunity to achieve fusion.

Why do I need a PLIF?

Conditions that are treated with a PLIF most commonly give the patient various combinations of sciatica (pain down one or both legs), pain in the buttocks that stops the patient from standing or walking, tiredness in the legs, or worsening posture with them slowly having to lean further and further forward or to the side.

When we perform a PLIF, the goals are;

  1. decompression of nerves
  2. establishment of a fusion mass, and 
  3. restoration of lordosis.

A PLIF is most typically used for degenerative spondylolisthesis but may also be used for the treatment of other forms of spondylolisthesis, foraminal stenosis, recurrent disc herniations, or as part of a treatment algorithm to treat scoliosis or sagittal imbalance when non-operative treatments have failed.

How is a PLIF performed?

A PLIF is performed with the patient lying face down on a special operating table that supports the body and yet allows free access to the spine. A midline incision is made and the muscles gently retracted to the side.

There are four main steps which need to be completed. These may be performed in any sequence or may be performed concurrently. 

  1. Decompression
  2. Interbody fusion
  3. Stabilising instrumentation
  4. Posterolateral grafting

Decompression: When a nerve is squashed or compressed, it needs to be released. This is called a decompression. The decompression is performed by removing any bone, ligament and/or disc material that is pressing on the nerves and causing symptoms. Although a decompression can sometimes be performed indirectly by distracting the two vertebrae apart, a PLIF allows for a meticulous direct decompression.

Decompression of lumbar spine demonstrating the rear of the disc space
Decompression demonstrating the disc space

Interbody fusion: The disc space becomes what surgeons refer to as the “interbody” space once disc material is removed. Any disc material left behind can interfere with the fusion. A patient and careful surgeon can clear almost the entire disc space using a PLIF technqiue.

Following disc clearance, one or more titanium cages are inserted to hold the interbody space apart. This marks the beginning of the reconstruction phase of the procedure. The cages are chosen to take into account each patient’s size, bone quality, shape and lordosis requirements. The cages are an “open” design that encourages bone to grow around and through them. A large amount of bone graft is then packed into the interbody space to fill the void and encourage fusion.

Stabilising instrumentation: Titanium screws are inserted into the pedicles of the vertebrae and connected to each other with rods. The rods are often reinforced again by a connection between them called a cross-link. These screws are the strongest method we have of holding the vertebrae and should normally hold the bone still while the interbody space bone graft solidifies. This is the step when lordosis is finally set.

Posterolateral grafting: Any remaining bone graft is placed within a space that runs between the two transverse processes.

Following this, the wound is irrigated and meticulously closed, usually with a dissolving suture.

Postoperative CT scan of PLIF demonstrating screws, cages, decompression, bone graft
Postoperative CT scan demonstrating PLIF cages and bone graft in interbody space, pedicle screws and substantial decompression

How long will I stay in the hospital?

Most people stay in the Epworth for about 5 days, but this can be quite variable. Most patients go straight home. However if you need some more time to get back “on your feet”, rehabilitation as an inpatient or outpatient can be organised.

What happens after I go home?

The most important thing to remember to do when you get home is to walk. It’s that simple. Every day set yourself a goal and walk a little further. Afterwards, reward yourself with a lie-down. Refrain from any activities that involve bending, lifting and twisting. Keep within the boundaries of what feels comfortable. There’s nothing to be gained from “breaking through pain barriers”. 

Touch base with your GP. See them at the two-week mark to remove the dressing and check your pain relief. 

Most people can return to driving 4-6 weeks later when you feel that you have really good control of your legs again.

What are the risks?

All operations have risks.  Every time you drive a car there is a risk of a crash, but we still drive (or ride or walk or take public transport) because the outcome is worth it – you get to your destination the vast majority of the time. We drive safely, and in a similar manner, operations performed safely by an experienced team are usually worth the risks.

Any major operation has risks of infection, bleeding, and those associated with a general anaesthetic such as cardiac and pulmonary complications.

Infection is fortunately very rare but if it does occur, may involve multiple “washouts” and a prolonged wound healing time. Diabetic patients are at a higher risk of infection.

Bleeding is usually not a big risk with a PLIF but a “cell saver” is used to recycle your blood and return it. Transfusions are uncommon for single-level fusions but this rate increases with multiple levels.

Cardiac and pulmonary complications from the anaesthetic are minimised by making sure you are as healthy as you can be. Many patients are assessed preoperatively by a physician to make sure they are “medically optimised”. Obviously smokers are at a higher risk of these sorts of complications, as well as those patients with chronic cardiac or pulmonary conditions.

Many people are concerned about paraplegia or losing the ability to walk with spinal surgery. Fortunately, in the lumbar spine, the spinal cord has finished its journey from the brain and what is left are individual nerves. There are safe to gently manipulate and the risk of injuring a single nerve is less than 1%.

In the long term, we need to ensure that the interbody space becomes fused, or in other words, that bone joins the two vertebrae together. This is usually assessed with a CT scan. If this doesn’t occur it is known as a pseudarthrosis or non-union. This can be a cause for persistent back pain. Smokers and people with chronic medical conditions have a higher rate of this complication, and the L5/S1 level is the most commonly affected.

Persistent leg pain needs to be investigated to ensure there is no ongoing compression of the nerves. In some patients, and in particular, where the nerve compression and pain have been present for a very long time, pain can persist despite a complete decompression.

A hole in a strong membrane called the dura can occur, most commonly when an operation is being performed in an area that has previously been operated on. The dural tear is repaired at the time of the operation and rarely causes long term problems, but may cause headaches and wound healing problems.

This list is not exhaustive and extremely rare complications can and do occur in any type of operation. Examples of these would include visual loss, wrong level surgery, anaphylaxis, and death.

Anyone contemplating elective surgery should be happy that they have considered sensible non-operative treatments and that their condition is significantly impacting on their quality of life. Mr Cunningham is happy to discuss any concerns you or your family have at length.