Extreme Lateral Lumbar Interbody Fusion (XLIF)
What is an extreme lateral lumbar interbody fusion or XLIF?
An extreme lateral lumbar interbody infusion (XLIF) is a surgical procedure designed to stabilise the lumbar spine. It is a minimally invasive procedure that is performed from the lateral aspect of the body. The spine is approached by a path behind the abdominal contents (retroperitoneal) and through a muscle called the psoas muscle.
As part of the procedure, the intervertebral disc is removed and a large cage inserted between the vertebrae. A plate may then be placed across the vertebrae to provide further stabilisation. Alternatively, posterior percutaneous pedicle screws may be placed to provide additional stability.
Decompression of the nerve roots relies on indirect decompression. It is very useful in restoring disc height and in realigning the spine; both coronally and sagittally. The procedure cannot be used at the L5/S1 level but can be used at higher levels in the spine. The main reasons for performing this procedure are like those for PLIF: spinal stenosis, spondylolisthesis and discogenic mechanical back pain. However, there are other circumstances such as degenerative scoliosis where the procedure may also be very useful.
What are the indications for a XLIF?
An XLIF may be performed for a variety of reasons. The most common indications are those of Spondylolisthesis, spinal stenosis and mechanical back pain. The advantages of an XLIF is that is minimally invasive and as the interbody cage is large, it can be used to restore disc height and realign the spine. It can also be performed at multiple levels in the spine.
Related conditions to XLIF
What is a spondylolisthesis?
Spondylolisthesis is a condition where one vertebral body moves forward in relation to the next. This forward ‘slip’ can occur for a variety of reasons. These most common varieties of spondylolisthesis are:
Discogenic / Mechanical back pain
Lumbar spinal fusion is commonly performed for mechanical back pain. Before recommending this procedure, patients must be aware of three facts:
1. Surgery for back pain (as opposed to leg pain) in the absence of pathology such as spondylolisthesis is not as successful as other surgeries (see below).
2. Surgery is not a stand-alone treatment and the patient needs considerable physical therapy after surgery to gain the most benefit.
3. Surgery is not designed to necessarily cure back pain, but to reduce the pain to a level that will allow them to function more normally.
To be a suitable candidate for surgery for mechanical back pain, patients need to have been through other conservative treatments and have failed these treatments. In most instances, they will also be referred to a pain management specialist to ensure that all other reasonable alternative strategies have been exhausted.
Spinal stenosis with deformity
Spinal canal stenosis is a condition where the diameter of the spinal canal becomes too small. The nerves passing through this region become compressed. This normally causes symptoms of neurogenic claudication. Neurogenic claudication is simply leg pain associated with walking which is relieved by rest. It is often accompanied by back pain. In many cases this can be treated by a simple laminectomy to create more room for the nerves. However, where there is pre-existing spinal deformity such as a curve (scoliosis) or slip (spondylolisthesis), there is a risk of further spinal deformity after laminectomy and therefore this may be supplemented by a fusion procedure.
More recently there has been a greater understanding of the importance of the overall alignment of the spine. When there is a loss of alignment, compensatory mechanisms are needed to prevent the patient from falling forward. These mechanisms include tilting of the pelvis and extension of the spine. This can cause pain and deformity. Correction of sagittal balance may relieve these symptoms.
How is an XLIF performed?
The XLIF operation is performed under a general anaesthetic with the patient laying in the lateral position on a specialised operating table. The incision is marked on the side of the patient and the patient is then prepared.
The muscles of the side of the abdomen are then split to enter the retroperitoneal space. The psoas muscle which is located on the side of the lumbar spine is then entered using a dilator. The position of the dilator is checked by intraoperative x-rays. The passage of the dilator is guided using neuro-monitoring. There are important nerves that located within the psoas muscle and it is important to know the location of these nerves to avoid injury to them.
The disc is exposed using a special retractor. The disc is incised and the disc space cleared. The end plates of the vertebrae are prepared and a cage, which is packed with synthetic bone material, is then implanted. The position is checked with an X-ray.
Depending on the number of levels being fused a lateral plate with several bolts may be placed. Alternatively, posterior percutaneous pedicle screws may be inserted.
Depending on the number of levels being fused, a lateral plate with several bolts may be placed. Alternatively, posterior percutaneous pedicle screws may be inserted.
An O-arm intra-operative CT scan is performed to check the final position of the instrumentation. The wound is then closed using dissolving sutures. A dressing is applied and the patient is returned to the supine position before they are awoken from the anaesthetic. Once awake the patient goes either to the recovery room or straight to the HDU/ICU.
The following is a useful link: www.nuvasive.com
How long is the hospital stay?
The hospital stay is normally around 4-7 days in total but varies depending on the patient and their underlying condition.
What happens during the hospital stay?
During the hospital stay the patient receives daily physiotherapy. Patients will receive prophylactic subcutaneous heparin injections and are required to wear stockings to prevent DVTs.
After surgery, there is normally some discomfort and analgesia is provided. Due to the approach through the psoas muscle, there is commonly some groin and thigh discomfort on the side of the approach. This usually settles over a few days. Constipation is a common complaint after surgery and is usually due to analgesics. You should inform staff if this becomes an issue.
The wound is normally cleaned and the dressing changed each day. After discharge no dressing is required. You may shower and then pat the wound dry with a clean towel afterwards. While the wound may get wet, do not soak it in the bath or in a pool for at least 2 weeks after the surgery. Do not rub the wound. If there are any concerns such as excessive redness, pain or ooze then you should have your GP review the wound as the first step.
Will I require inpatient rehabilitation?
Most patients can be discharged directly home as they are independently mobile and self-caring. However, some patients, particularly those who are older or who live alone may benefit from a short stay in a rehabilitation facility such as SAN Rehab, Hills Private Rehab, Mt Wilga or Lady Davidson Hospitals. Another more local facility may also be used for patients that who are not from the local region.
If there is any doubt, we can assess your progress a few days after the surgery to see what may work best for your circumstances and recovery.
What can I do when I go home?
After discharge, it is advisable to rest for 2 weeks which should consist of normal daily activities. One should maintain a good posture as advised by the physiotherapists, for example, you should not slouch in a chair. You should not spend too long in any one position.
When can I drive?
Once you feel more confident then activities such as driving can resume. Normally one can drive after 2 weeks from the date of surgery. But most of all you need to feel confident.
When can I return to work?
A return to work depends on the work environment. Those with sedentary jobs can usually begin to go back to work after 4-6 weeks. Those with more manual jobs should wait at least 6-8 weeks but it should be discussed with Prof Owler prior to surgery and again at the follow-up appointment.
When do I follow-up with Prof Owler after surgery?
We will make an appointment to see Prof Owler 6 weeks from the date of surgery or thereabouts. At that visit any concerns can be discussed and the wound will be checked. If there are any significant problems, then you should contact his office earlier. At that time a follow-up x-ray is arranged.
A second follow-up appointment is normally scheduled for 3 months. Prof Owler will review the post-op x-rays and inform the patient of the result.
Further follow-up may be arranged to ensure that you are progressing well and answer any questions.
What are the risks associated with the surgery?
All surgical procedures have risk. There are risks common to all surgeries such as infection, bleeding, deep vein thrombosis (DVT), pulmonary embolism and those associated with a general anaesthetic.
In relation to XLIF surgery, most infections that occur are superficial and easily treated with antibiotics. However, very occasionally, a deep-seated infection can occur and this may require removal of the pedicle screws and may result in further surgery and chronic pain. Pre-existing diabetes increases the risk of this complication.
Bleeding is usually minimal with XLIF surgery and is one of the advantages. However due to the proximity to significant blood vessels there is a small risk of significant bleeding.
The spinal cord is normally well clear of the site of the surgery. In the lower lumbar spine, the spinal cord has changed into a group of nerve roots called the cauda equina. While patients commonly worry about complications such as paraplegia and incontinence, such problems are very rare. More common is the chance of injuring one nerve root at the site of the surgery and the risk of this is approximately 1% and may result in numbness or weakness of the leg which may be permanent.
The lumbar plexus is a group of nerves that travel through and upon the psoas muscle after they leave the spine. The use of neuro-monitoring aims to avoid injury to these nerves. However, there is a small risk of lumbar plexopathy which can result in weakness of the quadriceps muscle. This normally recovers.
As mentioned previously, it is not uncommon to experience thigh or groin discomfort in the post-operative period which is related to psoas muscle.
Persistent or recurrent pain in the leg can occur for several reasons. It may be that there is a disc recurrence as mentioned above. However, some patients will experience leg pain because of changes that occur in the nerve itself after it has been compressed severely or for an extended period, i.e., neuropathic pain. Some patients will develop scar tissue around the nerve. Some scarring is normal as it is the body’s natural response to healing. However excessive scar tissue is thought to be a reason for recurrence of pain as well.
In relation to the fusion itself, there is a risk of the bones not healing together as one, i.e., non-union / failure of fusion. The risk of this is small and most patients will not have symptoms but it may result in back pain and revision surgery. There is a risk of adjacent segment disease. As the spine is fused at the level(s) of the pathology, more stress is placed across the levels above and below the level of the fusion. This may accelerate changes at those levels and cause similar problems, sometimes requiring surgery.
This is not an exhaustive list of potential complications but this information provides an overview of the more common complications that patients may be exposed to.
There are numerous other very rare complications that may also occur including those associated with a general anaesthetic such as reactions to medication, visual loss, and operation at the incorrect level despite the use of x-rays.
What are the expected outcomes from XLIF surgery?
The outcome of surgery is dependent on the indication for surgery and often the severity and duration of symptoms prior to surgery. No guarantees can be given in relation to the surgery.
Pain is the most common symptom of radiculopathy and, in most cases, is the first symptom to improve; often immediately after the surgery. Pins and needles may take longer but tend to improve quickly. Numbness takes the longest period to recover, perhaps even over 12 months and some patients may not experience full recovery of numbness. Weakness has variable recovery depending on severity and duration before surgery. Some patients will experience recovery immediately while others may have persistent weakness despite the surgery. Normally physiotherapy is required to treat weakness.
Overall, about 90% of patients will experience significant improvement in pre-operative symptoms while a further 10% will not improve as much as is hoped and 1-2% percentage will be worse off in relation pain or some other problem. Neurogenic claudication normally responds well to surgery. Over 90% of patients are expected to improve significantly with surgery. With successful surgery, they can normally begin to increase their fitness and increase the distances that they can walk and the time that they can stand for. Back pain associated with spondylolisthesis normally also improves. About 80% of patients will experience significant improvement in their pain allowing them to reduce their analgesic requirements and resume their normal activities.
When an XLIF is performed for mechanical back pain alone the expectations are different. We would expect that 70% of patients will experience a significant improvement in their pain such that they can reduce their analgesics and begin to return to their previous activities. However, this will vary depending on the nature of the underlying problem as well as the duration of symptoms prior to surgery.
As mentioned earlier, there are several points that are emphasised to patients undergoing spinal fusion surgery for back pain. These are that the aim of surgery is to reduce the pain to a level where the patient can function more effectively but that the surgery will not cure their pain; that the surgery is not a stand-alone treatment and that it is expected that the patient will need extensive spinal physiotherapy and treatment to recondition the muscles and other regions of the spine, and that as previously mentioned, the rate of success is significantly lower with surgery for this indication than for others.
What ongoing care is needed for the spine?
The main reason for on-going care of the spine after fusion surgery is to avoid injuring the levels adjacent to the site of a fusion. However, it also helps reduce the chance of long term lumbar spinal pain. Prof Owler’s philosophy is to attempt to return the patient to a normal active life rather than place onerous restrictions on the patient.
However, there are two aspects of spinal care that are important to patient’s that have undergone surgery.
The first, and somewhat obvious, advice is to avoid activities that may reinjure the spine. In the simplest form this includes not lifting heavy or awkward objects. As a general rule, no-one should generally be lifting weights above 20Kg. In the short term the lifting restrictions are much less (see above). When lifting, good technique should be used such as keeping the knees bent and back straight while keeping the object being lifted close to the body. People should avoid simultaneous lifting and twisting. Those who are golf enthusiasts should wait 3 months after surgery before resuming golf.
The second aspect to long term care is maintaining spinal fitness. This includes weight loss, core strengthening and on-going exercise. The best exercises are those which are non-impact such as swimming and cycling.