Reconstruction of the Lumbar Spine

If you are reading this page as a patient it is imperative that you have first read the page on spine anatomy and mechanics AND the page on the causes of back pain and that on radiculopathy, and the page on minimally invasive spine surgery. If you haven't then a lot of what follows will not make sense.

The goal of spine surgery is to alleviate the symptoms of back and leg pain. Remembering of course that leg pain can have both radicular components and motion segment components. Spine surgery can get rid of severe, disabling, pathological pain both in the back and legs. It rarely, if ever, gets rid of simple aches and pains that would be considered normal for the average age and sex matched individual. No spine surgeon on the planet can turn back the clock and give you the spine of a 21 year-old gymnast and so realistic expectations on behalf of the patient are required. If you are a patient reading this page you must acknowledge that you have symptoms for a reason - something has gone drastically wrong in your spine for all the reasons mentioned in the 'back pain' page and the 'radiculopathy' page. The end result of successful spine surgery needs to be protected as much as your native spine needs to be. Nature cannot be cheated to the extent that you can expect to have surgery on your spine and then get back to doing whatever was responsible for your demise in the first place. Add to that the genetic predisposition to early degeneration in your discs, if you have this, and you will start to realise that spine surgery aims to get people out of trouble or prevent impending disaster so that you can get on with your life cognizant of the need to take measures to stay out of trouble and prevent further possible disasters. Because of this, spine surgery, no matter how successful, often takes someone to either the next stage of their life, or at least sideways down a different lifestyle.

Modern spine surgery focuses on reconstructing the spine. In other words restoring the anatomy, as close as possible, to the non-degenerate state. This means replacing the lordosis, especially at L4/5 and L5/S1, and restoring disc height (and therefore stability) to each motion segment responsible for your symptoms without causing too much in the way of collateral damage in the process.

3 level reconstruction

Reconstructive spine surgery is different from decompressive spine surgery (where the roof is removed from the back of the spine to free up nerves and the spinal cord) and different from "fusion in situ" surgery where, following a decompression, the spine is fused in whatever deformed position it was in prior to surgery. There are circumstances were purely decompressive spine surgery is indicated but in my practice I perform this very rarely. The philosophy behind fusion in situ surgery really stems from the days when the instruments and technology to reconstruct the spine were not available. In some instances fusion in situ works by providing stability to a deformed segment of the spine but often leads to further surgery being required at a later date because of the consequences of being fused in an unbalanced position.

Reconstruction, as mentioned previous, aims to restore height and lordosis to each degenerate segment. The old adage about skinning cats in many ways applies to spine surgery and every spine surgeon you see will tell you his / her way is the best way. The truth is that provided you are in the hands of someone that understands the importance of restoring anatomy, has a good track record, can openly talk to you about his / her failures with as much honesty as their successes, and appears to be omni-competant - in other words have the ability to decide on the method of reconstructing your spine depending on what's most appropriate for your pathology as apposed to what they can / can't do - you are likely in good hands.

For example the patiet whose x-ray is on the right had 3 level degenerative disc disease at L3/4, L4/5 and L5/S1. The lower two levels have had height and lordosis restored and stabilised with a cage/plate construct packed with bone substitute, the L3/4 level has been reconstructed with a moving disc replacement which is a prosthesis that moves physiologically with the remaining spine. In this case 12 degrees of flexion / extension was produced at L3/4. You can see that the neuroforamen at each operated level has been opened up (and now looks equal in size to the unoperated levels above) by expanding the disc space which is why this patient's leg pain disappeared. The back pain decreased by about 80% as a result of the pain generator (the degenerate disc) being removed, and the facet joints located in their normal position. The base of the neck was repositioned over the sacrum restoring overall spinal balance. This operation usually takes about 2-3 hours to do and requires 5-6 days in hospital. Return to work is possible on light duties about 4-5 weeks later and about 6 months of physiotherapy to get the full benefit.

 

 

RESULTS OF RECONSTRUCTIVE SPINE SURGERY

It is impossible to predict exactly what result in terms of symptom reduction will be achieved by reconstructing someone's lumbar spine. The main reason for this is that in subtle ways every single person's spine, and their degenerative pattern, is different. The results depend on how many levels need to be reconstructed, how badly degenerate they are, whether or not the nerves are radiculopathic (as opposed to radiculitic), the presence of any medical / psychiatric problems, the patient's general physiology, the patient's expectations and personality, and lastly but almost universally confounding, the involvement of legal proceedings and workcover (or any third-party insurer) claims. Many patients come to our clinic now having already had some form of non-reconstructive spine surgery in the past which can make results unpredictable as a result of scarring and adhesions. As a general rule patients who have had reconstructive surgery fall into one of three groups post-operatively.

1 - EXTREMELY SATISFIED - About 75%-80%% of patients report at the 6 month follow-up that they are extremely satisfied with their symptom reduction. Usuaully this means they have experienced between 70% - 80% relief of their pain and a similar improvement in function. Some of these patients report this degree of pain relief quite quickly, some take the full 6 months to get there. It is not unusual for a younger patient with single or two level disc disease, with the appropriate level of motivation and rehabilitation to experience 100% relief of their symptoms. In a paradoxical way these are the patients who worry us in terms of their ability to wind up in trouble later on because of a tendency to return to the same level of activity which led to their demise.

2. SATISFIED - About 15%-20% of patients report at the 6 month follow-up that they still have some back and leg pain but it is considerably better than before surgery. Usually they rate their symptom reduction around the 60-65% mark. Usually these are patients who have had prior spine surgery, usually of a purely decompressive (as opposed to reconstructive) nature, or patients who have severe nerve damage (radiculopathy) and whose nerves are still regenerating / recovering. Some patients who have been treated with high doses of narcotics for decades because of severe pain become narcotic dependent and even successful surgery cannot get them free of the dependency, and so the perception is that they still have pain. Patients under the jurisdiction of workcover and who are involved in legal proceedings have a higher chance of ending up in this group and we have no intelligent ideas as to why.

3. NO BETTER - Overall about 5% of patients will say that reconstructive surgery has not changed their symptoms one bit. The reasons for this can sometimes be worked out as other things come to light in the months following surgery, but not always. Patients who have significant osteoporosis (soft bone), medical complications, abnormal psychometric personalities, legal issues and a poor motivation to improve, or complications from surgery fall into this group. It is actually very rare to find a patient in this group because of something going wrong during surgery. If anything is not quite right during surgery it is usually picked up right away and corrected. Sometimes, however, a patient can be completely normal, have a perfect diagnosis, cross all the boxes to make a good candidate for surgery, have technically exellent surgery performed and still not get a reduction in their symptoms. This is extremely rare and usually no explanation is available. At the end of the day our decisions to operate are based on subjective tests, experience, a clinical history and examination and a patient's personal decision that the risks are worth undertaking based on the severity of their symptoms. We use evidence based medicine to guide this process and all the data from this evidence clearly talks about failure rates.

 

RISKS OF RECONSTRUCTIVE SPINE SURGERY

All surgery, from having complex brain surgery for example to banding of haemorrhoids, has it's risk profile. The risks of reconstructive spine surgery can be divided into 2 categories.

1. Major risks - these are complications which if they occur mean that the surgery has essentially failed and you may even be worse off than before surgery. These complications are extremely rare and include things like deep infections around the spine, nerve damage, damage to any of the structures that need to be moved out of the way to get access to the spine like the bowel, ureters and major blood vessels, aspirating food contents into the lungs during anaesthesia, formation of blood clots in the weeks following surgery (DVT) or their lethal counterpart - pulmonay embolism and significant medical complications as a result of unstable co-existing pathologies which may or may not be evident at the time of booking surgery. These complications are devastating if they happen but fortunately, extremely rare. In this day and age the biggest factor leading to failure of spine surgery is osteoporosis - soft bone. We have found through bitter experience that pre-operatively testing for soft bone is unreliable. If encountered and recognised during surgery some measures can be taken to mitigate against the reconstruction collapsing.

2. Minor risks include things like superficial wound issues, temporary urinary or chest infections, ileus (which is where the bowel goes to sleep for a few days as a result of the anaesthetic and being manipulated during surgery), 'odd sensations' form nerves waking up and regenerating, allergic-type reactions to bone graft substitutes, some increased pain for a while as your spine gets used to it's new position and alignment etc. etc. These complications may linger around for a few weeks or even months but usually have no long-term adverse affect on the outcome provided advice and treatment is followed.

Prior to any surgery you will be provided with a comprehensive leaflet which details all the risks relevant to your operation, and any specific risks relevant to you and be given plenty of time to understand it fully.

HOW IT IS PERFORMED.....

This is not going to be a lession on how to operate, but rather an introduction to how a modern spine surgeon plans reconstructive surgery.

approaches

 

Tests such as discography, nerve conduction studies, MRI, dynamic x-rays etc etc indicate what levels need to be reconstructed. It is then decided how each level is to be approached. Different levels are best approached using different methods. Different types of degeneration are reconstructed with different types of technology. Sometimes the approach taken to a level in the spine depends on what technology is to be deployed there. Sometimes a patient's anatomy dictates what approach is best used. Sometimes it is simply what approach I feel most comfortable using, on the basis that the easiest, and least stressful operation usually has the best outcome. Whether PLIF (posterior), ALIF (anterior), XLIF (extreme lateral) or AXIALIF (trans-sacral ) approaches are used, if you have multiple motion segments involved it is likely you will have a combination of approaches. Often these will be performed in one operation but many times it is better, and safer to perform the operation in two stages spaced a few days apart. Another reason for performing the operation in two stages is to assess the clinical efficacy of stage 1 prior to making clinical decisions about other parts of the spine, requiring an opportunity to talk to or stand / walk the patient in between stages.

Every patient more-or-less gets an individualised reconstruction. Just because there is degeneration in a motion segment doesn't mean that it has to be operated on or reconstructed. The goal in every patient is to perform enough surgery to get someone out of trouble without exposing them to unnecessary surgery and therefore unneccessary risks. Everyone over the age of 60 will have degeneration to some degree in all their discs but usually only 2 or 3 need reconstructing. I try very hard to place some motion preservation (ie disc arthroplasty) in my reconstructions. There is good evidence in the literature from a well respected spine surgeon called Huang that a disc arthroplasty, if it performs and moves physiologically (over 5 degrees of flexion but not over 15 degrees), prevents adjacent segments in the spine form becoming symptomatic. There is an old adage that there is little value in having your spine operated on as it hastens the demise of discs higher up in the spine. This is a direct result of old-fashioned operations that expose the motion segments higher up with large, tissue destroying approaches to the spine and by operations that fail to restore height and lordosis. No-one really knows if peforming minimally invasive fusions increases the risk of degeneration spreading to adjacent segments. Depending on what you read in the literature the rate of adjacent segment degeneration with anterior fusions varies from 8% to 40% between 5 and 15 years following surgery. That literature however is not clear on what diagnostic tests like discography, if any were performed to assess the other discs prior to surgery and many of those anterior procedures were coupled with traditional, open, posterior procedures which we know damage the motion segments above! The bottom line is that the evidence in the literature pertaining to adjacent segment degeneration is clouded with so many variables that do not apply to the modern spinal practice that it is chaotic to read. Many spine surgeons, including myself, believe that the risk profile of other discs in the spine is not changed by operating on the very degenerate segments when minimally invasive techniques are used. Those discs are aready over-worked considerably by the spinal imbalance and instability caused by the degenerate segments, and their fate was probably sealed long before surgery.