Minimally Invasive Spine Surgery - XLIF Procedure

XLIF stands for “eXtreme Lateral Interbody Fusion” and is a new, minimally invasive way of fusing the discs of the spine. It was developed in the mid 2000s by a Brazilian surgeon, Dr Pimenta, and has recently come into popularity in the USA and now Australia.

Why is a fusion done?
Fusion is usually indicated when a disc has worn out. Discs can wear out for a number of reasons, the most common being just ageing and degeneration, similar to the way hips and knees wear out over time. Sometimes trauma or previous surgery can accelerate the process. A degenerate disc can be seen on MRI scans. Usually the bad disc causes back pain. Sometimes the vertebra can go out of alignment as well and compress nerves in the lumbar spine causing leg pain, numbness or weakness. 

The idea of fusing the disc is first to correct the alignment of the vertebra and take pressure off the nerves, second to get rid of the painful disc itself and third to create long term stability of the spinal segment after solid bony fusion takes place. Bony fusion is similar to the healing of a fracture and takes 6 to 12 months to achieve maximum strength. Sometimes screws are placed into the vertebra from the back as well to give extra stability if needed so that fusion can take place. You may need to wear a back brace for a few weeks after the surgery as well.

How is XLIF done?
In XLIF, a small incision is made on your side, just above the hip bone. Dilators are placed down to the spine to spread the psoas muscle, which lies on the side of the lumbar spine internally. A retractor is then slid down in place so that the surgeon can see the disc. The disc is removed with curettes and various instruments and then a “fusion cage” is inserted into the disc space. Cages are made of a special hard type of plastic called PEEK (polyethylethylketone). Usually the cage is packed with a special type of artificial bone matrix that encourages the bony growth and the fusion to take place. These days, we do not tend to take bone from your hip from a separate incision.

XLIF Cage Image
An XLIF "cage" - made of hard plastic.
The internal spaces contain the bone graft material.

A 2-level XLIF on post operative Xray

What are the advantages?
There are many advantages of this new procedure over traditional ways of performing disc fusions:
  • The incision is much smaller
  • There is no muscle destruction
  • The operation is faster (about 1 hour per disc)
  • There is almost no bleeding
  • The correction of spinal alignment is much better and more reliable in the long term
  • Multiple levels can be done through the same small incision
  • There is less post operative pain
  • The infection risk is almost zero percent.
  • Patients can be up walking the next day and home after just a few days
Disadvantages and complications
There are of course some down sides to any surgical procedure. In general these are very rare.
  • The procedure is not suitable if your problem is at the lowest lumbar disc (L5/S1). You may need an anterior or posterior approach for this.
  • There are some nerves running through the psoas muscle on the side of the spine that we need to be careful of. We routinely perform nerve monitoring constantly to make sure these are not being damaged but there is still a small risk. Some patients will have some temporary numbness on the thigh that usually gets better within a few weeks. The risk of a nerve injury leading to permanent weakness or numbness in the leg however is very small, about 1%. The risks of complete paralysis are extremely unlikely.
  • There is a very small risk of major vessel injury and bleeding, sometimes requiring a blood transfusion.
  • There is a very small risk of damaging other organs, such as the bowel, kidney, spleen or lung.
  • There are the general risks of any surgical procedure and anaesthetic, including heart attack, stroke, infection, deep vein thrombosis and pulmonary embolus.
  • There is a remote chance that any of these can cause death or a major disablement.
What is the success rate?
The definition of ‘success’ depends on what we are talking about exactly but in general 
  • The chance of helping your leg pain is around 80-90% ie very good
  • The chance of helping back pain is somewhat less – around 70%
  • The chance of the fusion occurring in the long term is very high: 90%
  • The chance of needing a further operation or re-operation is very low: 2-3%
So overall, if done for the right reasons, it is a very safe and effective operation.