Posterior Lumbar Interbody Fusion (PLIF) Surgery in Sydney
What is a posterior lumbar interbody fusion or PLIF?
A posterior lumbar interbody infusion (PLIF) is a surgical procedure designed to stabilise the lumbar spine. As part of the procedure, the intervertebral disc is removed, the nerve roots are decompressed, and the spine is realigned (if required). The main reasons for performing this procedure are spinal stenosis, spondylolisthesis, and discogenic mechanical back pain. However, there are other circumstances such as degenerative scoliosis where the procedure may also be indicated.
What are the indications for a PLIF?
A PLIF 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 a PLIF over simple decompression are that it may restore the anatomical alignment of the lumbar spine, provide a more extensive decompression, and treats any instability of the spine that may exist as well. There are also a variety of other reasons for performing a PLIF at one or more levels in the lumbar spine.
Spondylolisthesis & Spinal Stenosis
The most common indication for PLIF surgery is spondylolisthesis which may be associated with instability of the spine and / or spinal stenosis. 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.
Discogenic / Mechanical back pain
Lumbar spinal fusion is sometimes performed for mechanical back pain. Before recommending this procedure, patients must be aware of three facts:
- 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)
- Surgery is not a stand-alone treatment and pateitns need considerable physical therapy after surgery to gain the most benefit
- 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.
How is an open PLIF performed?
The open PLIF operation is performed under a general anaesthetic the with patient lying face down on a specialised operating table. The incision is marked and the patient prepared. The incision is made in the middle of the back for a standard open PLIF, and the length will depend on the patients and the number of levels that require surgery.
The muscles are dissected from the posterior aspect of the vertebrae. The spinous process and lamina of the level in question are moved. This also normally includes part of the facet joint on each side at that level. This exposes the main dural sac containing the fluid and nerve roots. The nerve roots as they pass through their foramen and the nerve roots going down to exist at the next level are also exposed. The disc is then removed from each side, and the surface of the vertebral bodies above and below the disc, (that is the endplates), are prepared. Interbody cages, packed with the bone that has been removed from the spine at the start of the operation, are inserted into the disc space on each side. Bone graft is also packed between the cages.
Bone screws are then inserted on each side above and below the level that is to be fused. These bone screws, called pedicle screws, are inserted with the assistance of intraoperative navigation or Stealth. These screws are joined on each side by a rod and smaller set screws. The vertebrae are usually gently compressed and the set screws tightened.
In some cases, further bone graft is placed down each side of the spine. This is referred to as a posterolateral bone graft. The bone graft used in the procedure is obtained from the bone that is removed at the start of the operation that is the lamina, spinous process and facet joints. Bone is generally not taken from the patient’s pelvis unless there is a specific reason.
At the end of the operation a drain is in the wound and an epidural catheter is also 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.
What is a minimally invasive PLIF?
In some instances, a minimally invasive procedure can be performed. Minimally invasive PLIF involves making several small incisions in the skin to place the pedicle screws percutaneously. This is done with the assistance of intraoperative navigation or Stealth. The interbody cages are normally placed through one side (as a TLIF). The procedure relies on indirect decompression of the nerve roots. This may work well in some patients but in other patients an open procedure may be more appropriate for their condition. The aim of performing the surgery using this technique is to reduce the operative trauma to the spinal muscles, thereby reducing blood loss and post-operative pain and speeding recovery.
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. For the first night after surgery an epidural is used to deliver pain relief. The epidural catheter is placed at the time of the surgery and is normally removed the next day. It is not uncommon for patients to experience numbness in their legs due to the epidural which resolves shortly after it is stopped. Once the epidural is removed another form of analgesia is normally used which may be through a drip and/or tablet. 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. There is normally a drain left in the wound which is removed after 24-48 hours. 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 the SAN, Hills Private Hospital, 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 CT scan is arranged.
A second follow-up appointment is normally scheduled for 3 months. Prof Owler will review the post-op CT scan 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 PLIF 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 can be significant with PLIF surgery. In most patients, the operation is at one level only and the risk of requiring a blood transfusion is low (<5%). However, when two or more levels are involved, the risk of requiring a blood transfusion will increase.
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.
Persistent or recurrent pain in the leg can occur for several reasons. 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.
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.
During the procedure, a small tear may occur in the covering of the nerves (dura). This dural tear will result in leakage of spinal fluid. Therefore, when it occurs it is repaired with sutures. The tear happens because the spinal canal can be very tight and because adhesions may develop between the degenerative structures and the dura. If this occurs, it is repaired at the time. The patients are normally asked to stay flat in bed for 24 hours after surgery and the drain will be kept in for a longer period. In most cases, there are no other consequences and the recovery proceeds as normal. However, in some patients the leak will continue and this may necessitate a return to the operating theatre to re-suture or repair the leak.
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.
What are the expected outcomes from PLIF 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 back pain allowing them to reduce their analgesic requirements and resume their normal activities.
When a PLIF is performed for mechanical back pain, 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, 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. All patients are normally taught core-strengthening exercises. These should be continued independently by the patient at home indefinitely.