Spinal fusion surgery refers to operations that are performed on the bones, discs and soft tissues of the spine. Almost all fusion surgery is performed on the lumbar spine (lower back) and a lateral lumbar interbody fusion operation is a common and increasingly utilized method to achieve a successful lumbar fusion. A lateral lumbar interbody fusion may be performed on one or two or more levels of the lumbar spine simultaneously.
A lateral lumbar interbody fusion may be needed for several reasons. The most common reason is instability at one level of the lumbar spine caused by previous nerve root decompression surgery (which reduces the strength in the stabilising soft tissues around the joint). This is especially common in the over 60’s patient group as the joint/s have had more time to destabilise.
An anatomic defect known as a pars defect which is essentially a fracture to the stabilizing parts of the vertebrae, normally sustained as an adolescent may be another reason why a lateral lumbar interbody fusion is needed.
Thirdly, in cases of intractable spinal pain when there is evidence of pathology at one particular level a lateral lumbar interbody fusion may be considered. The fusion should stop movement at that joint, thereby, reducing pain levels. All other treatment options including analgesia, physiotherapy and injections will be considered prior to a fusion operation, however.
A lateral lumbar interbody fusion is carried out in hospital under general anaesthetic. You will be admitted the evening before the operation. This allows you time to settle in and be prepared. You will not be able to eat for eight hours prior to surgery although you will be able to drink small amounts of water up to four hours before.
A lateral lumbar interbody fusion is performed by turning the patient on their side after they are anaesthetised. This enables the surgeon to make an incision and access the relevant levels of the lumbar spine from the side.
To achieve the fusion, the surgeon will firstly use xrays to identify the disc to be removed. The skin will then be marked and two incisions made in the lower torso.
Carefully, a muscle called the psoas and the abdominal organs will be pushed aside manually by the surgeon to avoid any damage to these tissues. A tube known as a dilator will then be inserted above the disc to be removed and a retractor tool will be used to split the muscles and allow the surgeon to more easily visualise and work on the spine.
The entire disc will then be removed with specialised tools and replaced with a combination of a bone graft and a metal fusion cage. Sometimes, instrumentation known as pedicle screws will also be inserted depending on the underlying cause for the instability and pain.
This specific type of fusion cannot be considered when one of the joints requiring the fusion is the lowest joint in the spine – the L5/S1 joint. This is because the iliac bones of the pelvis inhibit the surgeon from gaining access to the joint adequately. This may also apply to patients with an anatomically low L4/5 joint for the same reasons. In these circumstances the normal fusion technique is known as trans-forminal lumbar interbody fusion referred to as a TLIF.
There are some specific risks associated with a lateral lumbar interbody fusion operation. These will be discussed in detail with you by your surgeon prior to your operation and can include:
- Failure to fuse at the operated level
- Persistent pain at the site of the bone graft (normally the iliac bone at the pelvis)
- Progression of spinal disease especially at the adjacent spinal joints which may have increased loads and movement placed on them due to the fusion
Some general complications of lumbar spine surgery which affect a very small percentage of patients can include:
- Infection can occur although our theatres have ultra-clean air operating conditions keeping infection rates to the minimum.
- Blood clots are possible after any operation and are more common in patients with some pre-existing medical conditions. However, again they affect a very small percentage of patients and have well established treatments including aspirin.
- In rare circumstances patients, may suffer a stroke as a result of a blood clot developing.
- Damage to the nerves in the lumbar spine which may result in sensory loss and weakness in the legs and in extreme circumstances loss of bladder/ bowel/ sexual function.
- The intended benefits of reduced pain and increased function may not be felt.
In general, for the first 6 to 12 weeks after a lateral lumbar interbody fusion operation you will be able to return to a sensible, independent standard of living at home ensuring that you do not push your activities too much too early. Walking around the house and up to two miles per day outside are sensible activities. You may also be instructed to ensure not to stay in one position for too long i.e. prolonged sitting or standing may increase pain levels during the initial period of time following your spinal fusion. Any weight lifted during the initial 6-12 weeks should weigh no more than a kettle.
All patients will be recalled and clinically reviewed by their spinal surgeon at 6 weeks after the operation. As well as a clinical review with your surgeon you will have a check xray which provides two important functions. Firstly, the check xray ensures that the fusion (metalwork) has remained in the right place and has not become unstable itself. Secondly, the xray provides further evidence that there is no sign of infection around the fusion.
In general, patients can expect to feel a significant reduction in their pre-operative pain levels very early on as the painful spinal segment or the spinal segment responsible for the nerve compression has now been fused. In spite of the activity restrictions noted above, most patients who have undergone a lateral lumbar interbody fusion operation at only one level are back to full activities of daily life at their 6 week review. Some patients with multi level lateral lumbar interbody fusions may notice the benefits of the operation take a little longer.
Following your operation, nurses, doctors and physiotherapists on the ward will monitor your function and help you to get back to independence as quickly as possible. Following your discharge our expert spinal physiotherapy team will continue to monitor your progress in an outpatient clinic and where necessary advise you regarding appropriate strategies to:
- Reduce pain following lumbar fusion surgery
- Reduce spinal stiffness following lumbar fusion surgery
To enable the best possible results following spinal fusion surgery your surgeon and expert spinal physiotherapist may advise you to limit higher level activities for 6 to 12 weeks after your operation. Furthermore, your activity should be very gradually increased. Once at a point where your surgeon is happy for you to increase your function to normal levels, Circle Health’s spinal physiotherapists will work closely with you to:
- Increase strength in your spine
- Increase balance and co-ordination
- Where necessary prepare you for a return to sports & other higher level activities.