spinal fusion

Risks with posterior lumbar spinal fusion

Spinal Fusion in the lumbar spine will involve all the risks related to decompression but also include the risks related to implant insertion like pedicle screws or disc spacers used to promote fusion. There are several techniques that will fall within the category of spinal fusion so don’t let the terms plif,tlif,MIDLF(R) confuse you.

at the same time every approach / technique has different advantages and different risk to benefit profile so please try to understand why your surgeon has chosen one technique over the other

With the operation the aim is to decompress some nerves,  give them a chance to recover and also to fuse the spine. Fusion is referred as the bony union of 2 vertebrae in this case, and it forms a paradox to the normal moving segment between 2 vertebrae that an intervertebral disc provides you with. The success of the operation and the rate of neurological improvement of your symptoms will depend on the ability that your nerves have to recover, the quality of the bone and the ability to fuse but also to your overall health.  As a result of chronic compression of the nerves sometimes the outcome is not as good as the patient would expect, even after a satisfactory decompression and fusion.

 Potential risks with surgery

Infection. Following surgery you may suffer from infection which could be superficial and treated with a short course of antibiotics, or it could be deep seated which may require several weeks or even months of intravenous antibiotics (if that’s the case you may need a large calibre central intravenous line inserted). The infection could further affect other parts of your body, including the lumbar disc space (diskitis), the spine (osteomyelitis), the nervous system itself (meningitis-encephalitis), or even cause a generalised spread of the bug in your blood stream (septicaemia). You may also need to have your wound re-explored for a wash-out and there is also a possibility that the metalwork inserted may have to be removed. 

Haemorrhage, Major Vascular Injury, Haematoma. Throughout the operation you may bleed which I will try to control with various techniques. If you happen to bleed from one of your major vessels (usually by perforation by one of the surgical instruments) this can become life-threatening. Last but not least following an operation you may develop a blood clot (haematoma) that may need to be evacuated-drained surgically. 

Deep venous thrombosis, pulmonary embolism. While having an operation or in your post-operative course your blood circulation may slow down and you may develop blood clots that can block part of your circulation. This can happen in your legs or it may even affect your lungs in which case it may become life-threatening. 

Life at risk. As already mentioned there is a very small chance of your life being at risk mainly due to a catastrophic haemorrhage from one of your major vessels or as a result of pulmonary embolism. 

Nerve damage (paralysis of legs, bowel, bladder – sexual dysfunction). During the operation there is a risk of your nerves being injured leading to weakness or even paralysis of one or more muscles of your legs and feet. Such weakness and paralysis can also affect your bowel-bladder and sexual function. As a worst case scenario you may end up with complete paralysis from your waist down, with double incontinence (bowel & bladder) and sexually impotent. 

Durotomy (that may require another operation up to an insertion of a permanent Lumpo-peritoneal shunt). During the operation the outer 2 layers of the sac that protects the nerves can be torn and the cerebro-spinal fluid (CSF) within this sac will start leaking. Most of the time this can be controlled on site with various techniques and quite often you may not even realise that you suffered such a complication. There are a very small percentage of patients where we may have to consider a wound exploration, a temporary external drain or even a permanent drain to divert the CSF from your spine to your abdomen. 

Perineural fibrosis. During the healing process of your wound your organism may develop more scar tissue than normally expected.  If that’s the case you can end up with worsening symptoms as a result of direct compression of the nerves from the scar tissue or as a result of tethering of your nerve roots limiting their range of movement inside the spine. 

Positional complications or neuropathy. While I perform the operation you will be placed prone on an operating table and certain parts of your body may be irritated or injured (eyeballs, peripheral nerves, lips, breasts, groin skin, genitalia). For such complications regardless of  all the measures I take, it is directly related to your body weight and shape. There is also a small possibility that one of your peripheral nerves (not the ones that I’m going to decompress) may get indirectly injured as a result of prolonged pressure while in theatres. This can cause numbness and weakness in various parts of your body. 

No improvement or worsening of symptoms. Regardless of the success or not of the operation you may not improve or you may even end up worse. Please refer to the “Aim of the operation” section. 

Disc reoccurrence or incomplete disc removal (Applicable only if disc removal is performed). The lumbar disc that I will try to remove during my operation may not be a complete one and therefore there is a possibility of suffering a disc prolapse reoccurrence. 

Implant failure or migration, Construct failure. During the operation I’m going to insert several pieces of metalwork to stabilize your spine and probably a cage at the front of your spine. Any of these can either break or migrate, causing neurological compromise and also raising the chances of needing a repeat surgery. 

Pseudoarthrosis. The operation that I’m going to perform is considered a temporary measure until your spine fuses. There is a possibility of not achieving a solid bony fusion in which case your spinal stability relies on the metalwork and therefore you are at risk of an implant fracture as a result of biomechanical fatigue. 

Adjacent level disease. Following my operation there is a possibility of developing further degeneration at the adjacent segments of the level where I operated. This is the result of the adjacent segments having to support and compensate for any degree of movement you have lost at the fused segment of your spine. Such deterioration may require further surgical fixation and fusion. 

Anaesthetic risks. There are risks with general anaesthesia like anaphylaxis, teeth injury-fracture, bruising of lips-tongue-eyes, which the anaesthetist will discuss with you on the morning of the operation. 

COVID-19 related risks (24% mortality rate). Covid-19 infection is a condition that we continuously learn from. There are several anecdotal cases or reports about the effects of it. One of the biggest studies involving 1128 patients from 235 hospitals in 24 countries reports a 23.8% 30-day mortality (death) and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. 

Unexpected risks. Regardless of my thorough description, please keep in mind that there are always unexpected risks that can happen with such a major operation. 

Factors which may affect spinal fusion and your recovery

There are a number of factors that can negatively impact on a solid fusion following surgery, including:

• smoking; • diabetes or chronic illnesses;
• obesity; • malnutrition;
• osteoporosis; • post-surgery activities (see note)
• long-term (chronic) steroid use. (or recreational activities);

Of all these factors, the one that can compromise the fusion rate the most is smoking. Nicotine has been shown to be a bone toxin and inhibit the ability of the bone-growing cells in the body (osteoblasts) to grow bone. Patients should make a concerted effort to allow their bones the best chance to heal by not smoking.